undercharged relocated battery w/alternator

[RSB]

yes, the combiner override times out, so I'd need to directly wire them together. But what's the point of testing further to see if the batt would recharge in a timely manner (5 hrs vs. 14 or something) if we already know the combiner wouldn't work (when the batt is discharged to this capacity)? Perhaps I just realized the weakness to this type of battery management system. The low voltage disconnect can be useful but not when trying to recharge a deeply discharged battery with a lower output alternator!

That poor alternator, thought he’d dodged a bullet… eepwall:

Ryan, can you use the battery combiners’ “manual combine” feature in continuous mode or does it time out? Or can you just directly wire the two batteries together for charge testing?
Point is; the Odyssey is 68AH battery. Discharged 50% it only needs 34 amps to fully charge – (that is if you have the voltage, and time, to fully charge).

You’ve come this far, I’d now take the combiner out of the equation - like so (not to patronize):

couldn't I figure this out in the first few minutes? For example, the aux battery reads 11.10 volts after sitting overnight. After directly wiring the batts together, I start the truck and drive around and the aux batt shows a fairly constant charge of 30 amps. Isn't this all I need to determine how long it would take to charge the battery back to 100% capacity (12.8 volts)?

Discharge the house battery
Start the truck
Combine the batteries
Drive for a couple hours (or more?)
Stop and shut off engine
Disconnect the batteries
Wait minimum 5 hours
Measure each battery voltage

interesting! and I didn't think about using a charger to top-off the battery. Now that I think about it, this is very common! Fire departments do the same thing. They plug-in their rigs every time they're back in station. Clearly, I'm oblivious.

thanks David for your help!

As an alternative to a HO alt I’d also consider a 2nd house battery. As in two 80% charged house batteries, topped up at home with a smart 3 stage charger.

 

[RSB]

wow, thank-you for the well thought-out response!

yes, 0/1 gauge wire was used throughout. Agreed, my battery monitor was what prompted this whole thing! I have a Xantrex LinkPRO w/programable algorithms built-in that can even tell me the time remaining until the batt is fully discharged. It's awesome.

I didn't realize how much heat had an impact! after starting the truck this morning, the solenoid stayed connected and supplied just over 13 volts! :Wow1: I was very surprised. Thank-you for the information.

The alternator in a vehicle is not designed to fully charge a battery, compared to the charging system in a blue water sail boat, which might have 3 stage charging with battery and alternator temperature sensors and compensation algorithms. You can do what you can to help it out, with thicker, shorter charge wire but if the thicker wire is only between the isolator solenoid and second battery, and you are relying on the OEM wiring between alternator and engine battery, then 4/0 gauge will do nothing extra when wired between the isolator and second battery.

If you do not add thicker ground wires as well, then you will not increase the amps or current. Put a thick ground wire from alternator to the engine/ frame. Between battery and engine and frame, frame and engine. Give it multiple paths.

My Dodge Van has a 130 amp externally regulated alternator. I have seriously upgraded the charging circuit. I have 1 engine battery and 2 flooded true deep cycle house batteries 115 a/h each. I also have solar and a battery monitor which reads alternator amperage, and this tool has been a big eye opener.

My Voltage regulator is internal to the engine computer, but luckily it only throttles back the output after the batteries reach full charge, or once ~14.5 volts is met. The only other times the voltage is lower than 14.5, is at low rpm, with depleted batteries. Once it reaches 14.5 volts, the alternator only puts out enough amperage to hold that 14.5 volts. Unfortunately that amp number can be 15 amps despite my batteries being over 70 amps from full. So If I were to rely on the alternator to fully charge the batteries, I'm looking at close to 5 hours.

Even though my batteries could easily accept 40 amps, the alternator only needs to produce 15 to 20 amps, if that, to hold the 14.5 volts, so that is all it does. So my 130 amp alterantor is gonna need 5 hours of engine speeds above 1800 rpm to replace 70 amp hours into my batteries. It sucks, but that's the way it is, on my vehicle, on yours, and nearly every one out there.

I also suffer from despicable amperage at idle speeds when the alternator is hot. It simply cannot make more than 32 amps at idle speed when hot. If I have my high beams on, and blower motor on high, 10 amps are flowing from my batteries. The alternator simply cannot make the amperage at low rpm to make enough current to keep the batteries up in the 14's. You cannot add more load to the alternator and expect it to charge your batteries any faster.

Since your Toyota's voltage regulator was designed to never go above 14, as soon as it sees 14 volts, it only allows the alternator to make enough current to keep this voltage, this your battery is never gonna fully charge via the alternator in any hour long drive. Not gonna happen.

Even if You got an alternator that is designed to make big amps at low rpm's, the limiting factor is the voltage regulator. Once that voltage setpoint is reached, it cuts the alternator down.

Basically you have few options Your 13.8 volts is the limiting factor.

You can add a voltage dropping Diode in the alternator sense wire, so the voltage regulator sees a lower voltage and allows the alternator to put out more amps at higher volts, but this only works with externally regulated alternators.

You can try adding a separately regulated alternator, but with a shared ground, things can get a little complicated.

You can try keeping the battery and alternator cooler. Most all computerized vehicles try to regulate battery charging voltages by temperature. The higher the temperature,the lower the charging voltage. It might have a battery temp sensor, or it might just guess using the coolant temp sensor or an ambient air temp sensor and a programmed algorithm.

this is what I didn't realize I need to do. I haven't heard any discussion about this being the norm w/dual battery systems but it makes sense!

Basically, whenever you deplete your batteries, when you get home, you need to top them off by plugging a charger into the grid. That helps keeps the batteries healthy, and reduced stress on your charging system.

one of those bad boys would be nice!

Here is a link to a chart showing how much better a 120 degree alternator performs than a 190 degree alternator.

http://www.betamarinewest.com/balmar/6-series-sheet-web.pdf
You can also see how some of the lower amp alternators produce more amps at lower rpms than the higher amp alternators. Keep in mind, these are the Balmar alternators, pretty much the top dog in the blue water sailboat world, where they need to reliably recharge a large bank of batteries as quickly as possible at lower rpms. They perform way better than a vehicle alternator/ charging system that was designed to top off a small, single, slightly depleted starting battery.

thank-you again for your input. I think a new plug-in charger is in order. :ylsmoke:

 

[jdholder]

RSB -

Sent you an e-mail.

I have an extra Guest Charger for sale.

 

[wrcsixeight]

Some claim that unless a battery can reach and hold acceptance voltages (14.2 + volts) for a few hours, that it will never be truly fully charged. One guy on RV net found that they could not get the specific gravity of flooded batteries to read fully charged unless they got the batteries up into the mid 15's for a few hours.

Obviously you cannot check the electrolyte on an AGM, and you do not want voltages that high.

In your one post you state that when your solenoid isolator senses 13.2 volts on the engine battery, it combined the batteries(11.5 volt house batt), which dropped the voltage to 12.2 and then the isolator disconnected the batteries. That is a lot of voltage drop. Leads me to thing the engine battery is pretty weak. What did revving the engine to in this instance? Your alternator obviously cannot keep up at idle speed, few could, but what about at higher rpms?

When my house batteries are low, and I start the engine on the engine battery, then turn my manual switch to both, then engine note changes as the charging amps go from 8 to 60 amps. The house battery voltage at start up was down around 12.1 volts, and after switching to both, at cold Idle speed, despite 60 amps, the voltage only slowly climbs from 12.8. When I rev the engine the amps go up to the high 70's but the voltage goes up to 14+ quickly, and then drops back to the low 13's back at idle. The hotter my engine gets, the lower the idle speed. The hotter my alternator gets, the more pathetic it's output becomes. Much much worse than the Balmar graphs in my previous post's link. I have also reduced my alternator pulley size from 74 to 67mm. This did not make much of an amperage difference, but it does raise the voltage higher faster when the house batteries are low.

While we can rule out your 1 and 0 gauge cabling itself as the cause for voltage drop, we cannot rule out the connectors on those cables.

Next time you have the batteries lower, test the voltage at the alternator terminals. Then test the voltage putting the negative probe on the house battery negative and the positive on the alternator. Even with a depleted house battery this should be within .5 volts of the first reading.

Also, despite the quality of Odyssey batteries, taking them down into the 11 volt range is no good for them. Leaving them down there is no good either. If you use that many Amp hours overnight, you need more battery so as not to deplete the battery so much.

When you get a grid powered wall charger, get one that can meet the charging specs listed by Odyssey. My Crown batteries say to charge at 20 amps at 14.5 volts. My 25 amp charger cannot do 2 of these batteries at that rate, but when I combine 2 or more charging sources and come close to meeting this rate, the batteries later hold a higher voltage with the same amount of usage.

When you do get a good grid charger, let it fully charge them at it's highest setting, then put a big short lived load on them to drop the voltage( remove the surface charge) to the 12.8 range again, then put the charger back on them at the next highest setting. You might need to do some "Smart charger" fooling so it does not instantly go into float mode. Like letting the loads drop the battery voltage to 12.4 and turn on the charger before the voltage bounces back up.

Some people have reported success with "desulphating" chargers, like the vector/ black and decker 1093, in bringing back sulphated batteries. I have noticed small improvements on my old batteries when using a friend's batteryminder 2/4/8 amp desulphating charger.

The voltage regulators in vehicles are designed to never overcharge a single starting battery. Since starting an engine really only takes 1 to 2 percent of the batteries capacity, they size the alternator just big enough to power all the engine's loads, like the lights and blower motors.

The make the voltage regulator err on the side of safety. They do not care about the batteries longevity, they care about not overcharging the battery to the point that is boils off so much water that it exposes the plates, produces hydrogen gas, and a possible spark makes it go boom.

This is the nemesis of any additional batteries placed in a vehicle, and the only real solution is to think of the alternator as being able to supplement battery charging, and then hooking a grid powered charger into it after depleting the batteries to the 50% mark or lower or having enough solar.

How many times have you seen someone leave their lights on once, need a jump start, then 2 weeks later they are buying a new battery? It is because the alternator never has a chance to fully charge the battery. It might have enough juice to keep starting the vehicle, but all it takes is a cell phone charger to cross that threshhold.

Far too many people ( I am not saying you) think their 140 amp alternator will recharge a battery in less than an hour, which is simply impossible. Even if the alternator could produce that for any length of time(which it cannot), the battery could never accept it, nor could the stock wiring transmit it.

Alternators can only meet their ratings in Lab conditions, when cold, at high rpm, and with devices that can actually use that much power asking for it through adequate cabling.

Roasting in a hot engine compartment, at low rpm they will be lucky to make half their rating with adequate cabling. Most are probable about 1/4 their rating

 

[RSB]

thanks Jon, I didn't get the email though. I actually already ordered Odyssey's charger but I appreciate the offer!

RSB -

Sent you an e-mail.

I have an extra Guest Charger for sale.

 

[RSB]

I read 12.6 volts, so it isn't fully charged but close (12.8 volts).

In your one post you state that when your solenoid isolator senses 13.2 volts on the engine battery, it combined the batteries(11.5 volt house batt), which dropped the voltage to 12.2 and then the isolator disconnected the batteries. That is a lot of voltage drop. Leads me to thing the engine battery is pretty weak.

at higher RPMs it stays above the disconnect threshold around 13 volts after a cold start. Once it heats up though, it drops to 12.6-12.7. So, it still isn't keeping up.

What did revving the engine to in this instance? Your alternator obviously cannot keep up at idle speed, few could, but what about at higher rpms?

the ups & downs you experience sound consistent w/mine, however, at lower voltages. I suspect this is because I have an 80 amp alternator and yours is 115?

When my house batteries are low, and I start the engine on the engine battery, then turn my manual switch to both, then engine note changes as the charging amps go from 8 to 60 amps. The house battery voltage at start up was down around 12.1 volts, and after switching to both, at cold Idle speed, despite 60 amps, the voltage only slowly climbs from 12.8. When I rev the engine the amps go up to the high 70's but the voltage goes up to 14+ quickly, and then drops back to the low 13's back at idle.

I had difficulty trying to find the negative directly on the alternator, but I already know the voltage w/the neg probe on the house batt is 13.91 volts. I'll figure this out today and see if the reading is within the 0.5. The battery hasn't been recovered yet so I can still do this test.

While we can rule out your 1 and 0 gauge cabling itself as the cause for voltage drop, we cannot rule out the connectors on those cables.

Next time you have the batteries lower, test the voltage at the alternator terminals. Then test the voltage putting the negative probe on the house battery negative and the positive on the alternator. Even with a depleted house battery this should be within .5 volts of the first reading.

agreed. And this time was just so I could perform some good load tests. But I took it down a little too much...

Also, despite the quality of Odyssey batteries, taking them down into the 11 volt range is no good for them.

exactly why I need to get my hands on a charger right away! I figure the cost for fuel to get it recharged w/the alternator would be a good portion of the cost of a new charger anyway.

Leaving them down there is no good either. If you use that many Amp hours overnight, you need more battery so as not to deplete the battery so much.

I ordered one of Odyssey's 12amp chargers. I figured that'd be good enough since I don't anticipate the need for quick recoveries nor would the battery be discharged to this capacity very often. It appears to be all automatic. Here's their spec sheet:

what do you think?

When you get a grid powered wall charger, get one that can meet the charging specs listed by Odyssey. My Crown batteries say to charge at 20 amps at 14.5 volts. My 25 amp charger cannot do 2 of these batteries at that rate, but when I combine 2 or more charging sources and come close to meeting this rate, the batteries later hold a higher voltage with the same amount of usage.

When you do get a good grid charger, let it fully charge them at it's highest setting, then put a big short lived load on them to drop the voltage( remove the surface charge) to the 12.8 range again, then put the charger back on them at the next highest setting. You might need to do some "Smart charger" fooling so it does not instantly go into float mode. Like letting the loads drop the battery voltage to 12.4 and turn on the charger before the voltage bounces back up.

Some people have reported success with "desulphating" chargers, like the vector/ black and decker 1093, in bringing back sulphated batteries. I have noticed small improvements on my old batteries when using a friend's batteryminder 2/4/8 amp desulphating charger.

this is what I learned by this experience. And it makes sense!

This is the nemesis of any additional batteries placed in a vehicle, and the only real solution is to think of the alternator as being able to supplement battery charging, and then hooking a grid powered charger into it after depleting the batteries to the 50% mark or lower or having enough solar.

right. And this is what I was fearing after relocating the battery to the rear of the truck and why I wanted to look more into this. Odyssey told me undercharged batteries is the leading cause of premature failure and not covered under warranty. Therefore, finding a solution to this problem became my #1 priority.

How many times have you seen someone leave their lights on once, need a jump start, then 2 weeks later they are buying a new battery? It is because the alternator never has a chance to fully charge the battery. It might have enough juice to keep starting the vehicle, but all it takes is a cell phone charger to cross that threshhold.

Far too many people ( I am not saying you) think their 140 amp alternator will recharge a battery in less than an hour, which is simply impossible. Even if the alternator could produce that for any length of time(which it cannot), the battery could never accept it, nor could the stock wiring transmit it.

Alternators can only meet their ratings in Lab conditions, when cold, at high rpm, and with devices that can actually use that much power asking for it through adequate cabling.

Roasting in a hot engine compartment, at low rpm they will be lucky to make half their rating with adequate cabling. Most are probable about 1/4 their rating

thank-you again so much for your input! you're really helping me understand how this all works.

 

[RSB]

understand. And that certainly was the point of doing the test to begin with. Once I get the battery recharged enough to keep the solenoid from disconnecting, I'll be able to resume testing. No problem.

The point was simply to see if the stock alt is adequate. If your requirement is that the combiner also must work as designed and unaltered, then that is my mistake.

ahhhh, I didn't realize this. I thought it only fluctuated w/load. I think I'll go ahead and do this then. Thanks! Will post my results. I'm still thinking I might need a higher output alternator.

I don't believe the alt will maintain a constant charge until the battery is full. Rather the current (amps) and voltage output will decrease as the battery "fills".

good to know. I was hoping to hear some feedback from others who've had similar experience. Thanks for sharing this!

Unfortunatly, as you know, agm batteries typicall need higher voltages to fully charge (say the final 15%) than a typical oem flooded lead-acid battery. This is where the "you'll never fully charge an agm with an alternator" school of thought comes from. However, I have not had a problem charging my Lifeline house batteries (in a different vehicle) despite my own research induced worries.

 

[wrcsixeight]

As to 12.6 volts or 12.8 volts being fully charged, it depends on the battery. My old Dual purpose Everstarts were 12.8 volts, my new Crown Deep cycles are 12.6. The Crowns perform so much better it is almost ridiculous.

I've read how the alternator testers in AP stores are nearly worthless because they do not put any significant load on the alternator. If One of the Diodes fails it's maximum current drops by 1/3, but it still charges and will read fine on their testers. Put your voltmeter on the battery and check for AC voltage. I don't really know what AC numbers you can expect if one Diode has failed. I will ask somebody with more knowledge than myself.

Your 80 amp alternator should be able to make at least 70 amps when cold at higher rpms with depleted batteries, and the Odyssey battery should be able to accept that much for a short while if it is depleted. If the highest amp number you see during such conditions is only 2/3 of the alternator's rated amperage, then it is likely one diode in the rectifier has failed, and that can easily explain your poor numbers.

I can't say whether your 80 amp versus my "130 amp" is the cause for your lower idle speed voltages. Too many variables. Have you ever checked your trimetric or Linklite battery monitor against another voltmeter? Are you sure the only cables leading to the negative on the batteries go through the shunt? Any load/ charging source not going through the shunt will not be measured by the monitor.

If you do not need faster recharges, then the Odyssey charger should be perfectly adequate. You just can't argue with a battery charger designed by the battery maker. I would prefer higher amps, but basically per amp hour you will be charging at a higher rate than me. I've got a 25 amp charger for 230 amp hours of battery. You've got 12 amps for 64 amp hours.

The voltages and duration of the voltages listed on your chart are about the same as mine. After the charger falls into float mode, do put a heavy load on it to reduce the voltage and restart the charger. You might want to design an easy way to plug it in rather than hook up alligator clips each time.

You alternator might be grounded through it's case, in which case I'd just beef up the engine grounds from the battery, perhaps move the ground cable to the alternator mounting bolts.

Alternator charging can be frustrating. Having a battery monitor makes it more so because one can see how poor alternator recharging can be. I was happier when I was ignorant of it, and just replaced my batteries every 8 months, under warranty. Most places do not warranty their dual purpose"deep cycle" batteries anymore, or significantly reduced the time they will prorate it for.

The monitor has made me take the steps required to maximize charging, like adding/ upgrading lots of charging cable and grounds, minimizing/ replacing connections, and a smaller pulley. The thicker wiring made the biggest difference, but only at higher rpms. My alternator has a lifetime warranty, and I have used that warranty 5 times, otherwise I would have tried another one wound for higher low rpm amperage.

I realized the alternator pulls in air from the back for cooling. The back of my alternator is 3/4 of an inch from my exhaust manifold. What genius designed that? I made a heat shield, and that improved performance. I plan on making a better heat shield and perhaps feeding cold air to the back of the alternator, perhaps forcing cold air at the back of it with a fan.

Glad to be of assistance. It is an interesting topic in which I am still trying to obtain more knowledge.

 

[RSB]

ok.

As to 12.6 volts or 12.8 volts being fully charged, it depends on the battery. My old Dual purpose Everstarts were 12.8 volts, my new Crown Deep cycles are 12.6. The Crowns perform so much better it is almost ridiculous.

ok, I will do this too.

I've read how the alternator testers in AP stores are nearly worthless because they do not put any significant load on the alternator. If One of the Diodes fails it's maximum current drops by 1/3, but it still charges and will read fine on their testers. Put your voltmeter on the battery and check for AC voltage. I don't really know what AC numbers you can expect if one Diode has failed. I will ask somebody with more knowledge than myself.

really??! :Wow1: wow. Yes, and 30 amps is only 38% of the 80 amps or 43% of the 70. It's not even close to 2/3! However, it should be noted that this reading was taken at the aux battery, not the alternator directly. I will take another reading to see what the difference is.

Your 80 amp alternator should be able to make at least 70 amps when cold at higher rpms with depleted batteries, and the Odyssey battery should be able to accept that much for a short while if it is depleted. If the highest amp number you see during such conditions is only 2/3 of the alternator's rated amperage, then it is likely one diode in the rectifier has failed, and that can easily explain your poor numbers.

yes I have. I had suspected this but the LinkPRO does seem to be giving accurate readings. It's also not connected directly to the batteries. The positive sensing wires are connected to each side of the solenoid. I didn't see a difference more than 0.01 volts comparing the voltage directly on the batteries, so I didn't see this being a problem.

I can't say whether your 80 amp versus my "130 amp" is the cause for your lower idle speed voltages. Too many variables. Have you ever checked your trimetric or Linklite battery monitor against another voltmeter?

dang!! All along I've been thinking I had it correct but looking again, now I think I've been wrong the whole time! And this can affect readings even when charging? Looks like my winch negative and aux fuse box haven't been going through the shunt this whole time. Here's a drawing of all my negatives in my system:

Are you sure the only cables leading to the negative on the batteries go through the shunt? Any load/ charging source not going through the shunt will not be measured by the monitor.

perfect!

If you do not need faster recharges, then the Odyssey charger should be perfectly adequate. You just can't argue with a battery charger designed by the battery maker. I would prefer higher amps, but basically per amp hour you will be charging at a higher rate than me. I've got a 25 amp charger for 230 amp hours of battery. You've got 12 amps for 64 amp hours.

sounds good. I'll do that. And I was thinking the same thing about the alligator clips. I'll need a better alternative to using those every time for sure.

The voltages and duration of the voltages listed on your chart are about the same as mine. After the charger falls into float mode, do put a heavy load on it to reduce the voltage and restart the charger. You might want to design an easy way to plug it in rather than hook up alligator clips each time.

ok, I'll check that out.

You alternator might be grounded through it's case, in which case I'd just beef up the engine grounds from the battery, perhaps move the ground cable to the alternator mounting bolts.

indeed. With this system being such as investment, I'd really like it to work right! And I don't want to have it all replaced within a year either, due to my negligence.

Alternator charging can be frustrating. Having a battery monitor makes it more so because one can see how poor alternator recharging can be. I was happier when I was ignorant of it, and just replaced my batteries every 8 months, under warranty. Most places do not warranty their dual purpose"deep cycle" batteries anymore, or significantly reduced the time they will prorate it for.

The monitor has made me take the steps required to maximize charging, like adding/ upgrading lots of charging cable and grounds, minimizing/ replacing connections, and a smaller pulley. The thicker wiring made the biggest difference, but only at higher rpms. My alternator has a lifetime warranty, and I have used that warranty 5 times, otherwise I would have tried another one wound for higher low rpm amperage.

ya, that is genius. Good idea on fixing that problem. Now I'm wondering what mine looks like back there.

I realized the alternator pulls in air from the back for cooling. The back of my alternator is 3/4 of an inch from my exhaust manifold. What genius designed that? I made a heat shield, and that improved performance. I plan on making a better heat shield and perhaps feeding cold air to the back of the alternator, perhaps forcing cold air at the back of it with a fan.

agreed. I've learned so much about all this and I still haven't really even put my batteries to good use yet. But that's ok, the same goes for my winch and understanding proper recovery techniques. My goal is to feel as confident using my equipment properly on the trail at all times.

Glad to be of assistance. It is an interesting topic in which I am still trying to obtain more knowledge.

 

[wrcsixeight]

I briefly tried deciphering your drawing and got a little cross eyed.

Assuming your linklite is supposed to be wired like my IPN pro remote, everything, every negative must be routed through the shunt. This is where a large negative bussbar or buss stud comes in handy. You wire the stud/ buss bar to the shunt, and all the other add on accessories(-) to the buss bar. Everything stock on the engine is grounded through the main cable to the battery, you just wire the OEM negative cable directly to the load side of the shunt. But the shunt must be rated to handle all the amp flow.

If the shunt cannot handle the amp flow from the starter or the winch, then you must not wire it to include those systems. If you cannot wire it to include the starter, then the alternator is out too, because the ground is common to both. Then your battery monitor will not see alternator amperage, and not keep an accurate reading of battery state of charge. There are was to fudge this but accuracy goes out the window and you are back at reading battery voltage and guestimation as to state of charge then what point is there in having a monitor.

You must be aware of the capability, the maximum current rating of the shunt. Mine is listed for 500 amps, and probably can handle significantly more than that for short periods( engine starting). My shunt was the only one listed as compatible with my monitor. I know Trimetric battery monitors give you the option of a 100 amp shunt or a 500 amp shunt. I do not know about Xantrex.

The only other battery monitoring systems that have not been designed to be wired this way do not use a shunt, but a hall effect sensor which clamps over the wires and detects current flowing through the existing wires. This usually requires 2 clamps, one for each direction of amp flow.
If you've got a shunt, I'm 99.6% sure everything must be routed through it for an accurate amp hour battery capacity / amp flow reading.

I have 2 wires leading from the battery side of the shunt. 1 wire goes to my house bank, 1 wire goes to my engine battery, and these are the only 2 wires which goto the negative terminals on the batteries.

Whatever you have that is wired directly to the negative terminal of the battery will not be read by the shunt/ monitor. This will not effect the voltage reading(of the house battery), but it will effect the amps listed as flowing into or out of your batteries. Your battery voltage readings must be taken at both batteries, because when that 'smart' solenoids cuts off, the monitor is only reading the house batteries.

If you only have the winch wired directly to the batteries, it is not a big deal, but the monitor will not read the winches full power draw, and your monitor might still indicate battery charging going on despite a heavy discharge going on. This will throw off the battery remaining/ amp hour from full percentages/ readings greatly.



My alternator's negative runs directly from the alternator to the shunt. My engine ground runs directly from the engine to the shunt. My frame ground runs directly to the alternator, and another wire runs directly to the engine ground from the frame ground. Other OEM devices are grounded to the firewall, or engine itself, like it came from the factory.

I've personally had no issues with ground loops. My biggest electrical noise maker is my solar charge controller, and it only seems to affect am radio and analog channel six on my TV.

Now with your "smart" solenoid, when it cuts out and separates the batteries, no amperage is making it to the house/ auxiliary battery from the alternator, but the monitor thinks it is. Since one battery cannot accept as much amperage as 2 batteries, the amp number will go down, and you will think the alternator is not producing anything close to what it should be, by looking at the monitor. The monitor will still be reading these amps and counting them off, but your house battery will not be seeing them. Preferably, with a dual battery system, you want the monitor to read only the house battery. In a perfect world the engine battery will always be at 100 percent except for the 5 minutes after starting the engine.

I wired in my manual switch (1/2/both/off)well before I got solar or a battery monitor, and the manual switch is obviously not perfect or automatic, but I know where the starter's amps are coming from, and I know where the alternators amps are going to. If I were to deplete my engine battery below 95%, I would be much less sure how much was going to my house batteries and how much to the engine battery. My system is not perfect, but I've wired it so the engine battery does not see the stereo, or any load while I am parked and ignition off, and If I have my switched turned to 2( house batteries), nothing what so ever will take anything from the engine battery but it's own ~12% monthly self discharge.

I think it will be very difficult to get the linklite to read accurately with the "smart solenoid" If you can completely isolate the engine battery from any loads while you are camped, and use a dumb solenoid, the accuracy will go way up. The problem with a dumb solenoid is it must be switched. If this switch is the ignition, then all 3 batteries are starting the vehicle. If your compressor on your fridge is running, there is a possibility the circuitry can be damaged by the low voltage which occurs when the starter is sucking 400 to 700 amps. You can manually switch the dumb solenoid, but there goes the automatic feature, and you might as well just get a big manual switch with bigger contacts and less voltage drop, but who wants a big ugly manual switch on their dashboard. I keep mine in a cabinet behind the drivers seat, but I have a van.
Everything is a compromise. You got to figure out what will work best for your needs, and what margin of error you are willing to accept.

I'm guessing my monitor itself is only 90% accurate, and my manual switching takes another 2-3% at most from that, because when I have the house batteries removed from the starter/ alternator, it still sees the amperage going to and from the engine battery and counts that as going to the house batteries, and when I switch to both, it does not know the percentage of amps going to the engine battery, it sees the amps flowing to all 3 batteries. That is why I just keep my engine battery as nearly fully charged as possible.

While your alternator could certainly be weak, and it is likely it cannot keep up when the batteries and engine rpm are low, I think a lot of confusion is being caused by how the shunt is wired and the operation of the 'smart' solenoid. For the purposes of testing the alternator amperage, I would bypass the "smart" solenoid by hooking the house wire to the engine battery post. I know National Luna states it must be hooked up in a certain fashion or it blows an internal fuse. Be careful if you do this.

 

[wrcsixeight]

Another thing is a battery can still read 12.6 or 12.8 volts, and only have 5 % of it's capacity. Put any load on it, and the voltage drops significantly, and it also reaches it's full charge very quickly. Where it once held a gallon, it now holds a pint.

One of my everstarts failed like this. It read 12.8 volts. Put a 2.7 amp load on it and it dropped quickly to 11.2 volts. Remove the load and it climbs back up to 12.6 volts pretty quickly.


The alternator amperage is measure by the shunt, where the shunt is, not at the battery or the engine battery or the house battery but in between the terminals of the shunt.

Did you get my PM about checking for AC voltage from the alt?

 

[RSB]

Bad idea if electronics are on the vehicle. Ground loops make for odd problems and can give electronics fits. Use one ground path (branched if necessary) and maintain it. A series ground path was a cause for short battery life on one of my previous vehicles due the iron engine block acting as a resistor. Now I ground multiple batteries to the same bolt.

I see a lot of mention of the charge cable size, but nothing about the ground cable size or how many junctions the ground path has. This is just as important as the charge cable.

Most Delco alternators have a boss on them for a ground cable. No idea what other alternators might also have this feature. Use a mounting bolt if necessary.

My alternator's negative runs directly from the alternator to the shunt. My engine ground runs directly from the engine to the shunt. My frame ground runs directly to the alternator, and another wire runs directly to the engine ground from the frame ground.

I re-sketched my negatives and came up w/this...

would it hurt to use distribution blocks like in this sketch? All wiring is 0/1 gauge.

thank-you for your input.

 

[RSB]

*** CORRECTION ***

the wires circled are supposed to connect to the SYSTEM side of the shunt, not the BATTERY side. The battery side only contains the single wire going to the aux batt terminal. This applies to both diagrams.

 

[wrcsixeight]

Both batteries must be on just one side of the shunt. The same side. Only the leads to both batteries should be on one side of the shunt. In your diagram, you have a battery on each side. No good. The monitor would be inaccurate in the extreme.
All charging sources, all loads must be on the other side of the shunt. Xantrex's directions must say the same thing. Are they written in chinglish?

Use of a distribution block, or buss bar, or buss stud is recommended. It is to be wired on the load/ charging source side of the shunt.

The shunt must be rated for 500 amps because the starter's amps will run through the shunt. If the starter has is's own ground wire, then that wire alone can goto a negative battery terminal, bypassing the shunt. I've never seen a starter with a separate ground wire. Doesn't mean they do not exist, just that I've never seen one.

 

[RSB]

yes, my apologies it is kinda complex.

completely understand. Yes, my shunt is rated for 500 amps too so it should sustain all my loads. It was included w/the monitor.

I briefly tried deciphering your drawing and got a little cross eyed.

Assuming your linklite is supposed to be wired like my IPN pro remote, everything, every negative must be routed through the shunt. This is where a large negative bussbar or buss stud comes in handy. You wire the stud/ buss bar to the shunt, and all the other add on accessories(-) to the buss bar. Everything stock on the engine is grounded through the main cable to the battery, you just wire the OEM negative cable directly to the load side of the shunt. But the shunt must be rated to handle all the amp flow.

If the shunt cannot handle the amp flow from the starter or the winch, then you must not wire it to include those systems. If you cannot wire it to include the starter, then the alternator is out too, because the ground is common to both. Then your battery monitor will not see alternator amperage, and not keep an accurate reading of battery state of charge. There are was to fudge this but accuracy goes out the window and you are back at reading battery voltage and guestimation as to state of charge then what point is there in having a monitor.

You must be aware of the capability, the maximum current rating of the shunt. Mine is listed for 500 amps, and probably can handle significantly more than that for short periods( engine starting). My shunt was the only one listed as compatible with my monitor. I know Trimetric battery monitors give you the option of a 100 amp shunt or a 500 amp shunt. I do not know about Xantrex.

lol, correct. That looks to be the case according to the wiring diagram:

If you've got a shunt, I'm 99.6% sure everything must be routed through it for an accurate amp hour battery capacity / amp flow reading.

according to the install instruction for my monitor, it calls for only 1 wire going from the BATTERY side to the house batt. All loads and the wire going to the starter batt connect to the SYSTEM side.

I have 2 wires leading from the battery side of the shunt. 1 wire goes to my house bank, 1 wire goes to my engine battery, and these are the only 2 wires which goto the negative terminals on the batteries.

yes. And this is definitely a problem. I need to get this resolved before I can proceed further.

Whatever you have that is wired directly to the negative terminal of the battery will not be read by the shunt/ monitor. This will not effect the voltage reading(of the house battery), but it will effect the amps listed as flowing into or out of your batteries.

right. However, how so? Even w/the solenoid disconnected, the positive sensing wires are connected to each side of the solenoid. Therefore, each sensing wire can still take readings off each battery. Right? The following diagram comes to my mind:

Your battery voltage readings must be taken at both batteries, because when that 'smart' solenoids cuts off, the monitor is only reading the house batteries.

ya, and that's definitely a problem. No wonder why it was only showing a 40 amp draw under load!!

If you only have the winch wired directly to the batteries, it is not a big deal, but the monitor will not read the winches full power draw, and your monitor might still indicate battery charging going on despite a heavy discharge going on. This will throw off the battery remaining/ amp hour from full percentages/ readings greatly.

I should have mentioned it earlier, but my monitor is designed to only monitor one battery and just the voltage off the other. Perhaps this is why your monitor wiring is a bit different from mine?

Now with your "smart" solenoid, when it cuts out and separates the batteries, no amperage is making it to the house/ auxiliary battery from the alternator, but the monitor thinks it is. Since one battery cannot accept as much amperage as 2 batteries, the amp number will go down, and you will think the alternator is not producing anything close to what it should be, by looking at the monitor. The monitor will still be reading these amps and counting them off, but your house battery will not be seeing them. Preferably, with a dual battery system, you want the monitor to read only the house battery. In a perfect world the engine battery will always be at 100 percent except for the 5 minutes after starting the engine.

do you still agree w/this after taking a look at Xantrex's installation diagram above?

I think it will be very difficult to get the linklite to read accurately with the "smart solenoid" If you can completely isolate the engine battery from any loads while you are camped, and use a dumb solenoid, the accuracy will go way up. The problem with a dumb solenoid is it must be switched. If this switch is the ignition, then all 3 batteries are starting the vehicle. If your compressor on your fridge is running, there is a possibility the circuitry can be damaged by the low voltage which occurs when the starter is sucking 400 to 700 amps. You can manually switch the dumb solenoid, but there goes the automatic feature, and you might as well just get a big manual switch with bigger contacts and less voltage drop, but who wants a big ugly manual switch on their dashboard. I keep mine in a cabinet behind the drivers seat, but I have a van.

agreed.

Everything is a compromise. You got to figure out what will work best for your needs, and what margin of error you are willing to accept.

I'll comment on this one later.

I'm guessing my monitor itself is only 90% accurate, and my manual switching takes another 2-3% at most from that, because when I have the house batteries removed from the starter/ alternator, it still sees the amperage going to and from the engine battery and counts that as going to the house batteries, and when I switch to both, it does not know the percentage of amps going to the engine battery, it sees the amps flowing to all 3 batteries. That is why I just keep my engine battery as nearly fully charged as possible.

agreed. And that can be the problem entirely, since it obviously is giving inaccurate readings with it not being wired properly. After I get this fixed we'll see how things look again.

While your alternator could certainly be weak, and it is likely it cannot keep up when the batteries and engine rpm are low, I think a lot of confusion is being caused by how the shunt is wired and the operation of the 'smart' solenoid. For the purposes of testing the alternator amperage, I would bypass the "smart" solenoid by hooking the house wire to the engine battery post. I know National Luna states it must be hooked up in a certain fashion or it blows an internal fuse. Be careful if you do this.