Dual alternators/inverter wiring

[hangdog]

Hey Portal members,

I'm finally coming out of the closet and posting. I've just spent the last few days going over all the threads in this section that have to do with dual batteries, inverters, solar and alternators. Lots of great information which is how I came up with a wiring diagram for installing an inverter in my truck and solar on my truck camper. I have a month and a half to get this installed. I hope some of you can look it over to see if anything is going to cause a fire or if I need to add or delete anything.

The truck, a 2002 F350 powerstroke 7.3L with dual alternators, is mainly used for work, so that's the reason for adding an inverter. I separated the two alternators so they're able to charge different battery banks independently. I made the lower alternator the primary alt. to charge the start batts. I did this because I couldn't find a HO alt for that location and I figure the stock 110 amp alt should be able to keep the start batts topped off if all the truck's electronics are routed to the house batts. I have a DC Power 270ampXP alternator that will be used as the upper alt.

A few questions:

I would like to combine the batteries in case I need a jump or if one of the alternators goes bad. Is the Blue Sea ACR a good choice for this?

Do I need a fuse from the 110amp alternator to the powerpost or can I tie into the fuse that's coming off the 270 amp alt?

If the house batts get drained to 50% and I go to start the truck and the batt banks combine, will they equalize and start charging equally or will the start batts get overcharged? If the ACR is switched to off, is this even an issue?

Is some kind of regulator/A2B charger needed to charge the house batteries with the alt?

I read that it's a good idea to run a neg wire from the house batt to the alt mounting bolt. Does this need to be wired into the shunt? If so, what side?

I plan on using Anderson connectors for the solar connection between the truck and camper. Are there any special crimpers that I should be using on 10ga and bigger connectors?

Thanks for looking.

 

[DiploStrat]

Some Quick Comments

Since no one has stepped up, let me try. Gotta be quick as I am down in Louisiana, running my A/C on batteries and using cellular data.

I would like to combine the batteries in case I need a jump or if one of the alternators goes bad. Is the Blue Sea ACR a good choice for this?

-- While I love the Blue Sea ACR and an ACR can be useful in a battery combining set up, you are designing a completely isolated/parallel system. For emergency starting support, the cheapest option is a simple heavy duty switch or a solenoid with a simple switch to force a closure when needed. In normal operation you do not/not ever want to combine your two battery systems.

Do I need a fuse from the 110amp alternator to the powerpost or can I tie into the fuse that's coming off the 270 amp alt?

-- As a general rule, if the wire is more than 18 - 30 inches long, you want a fuse.

If the house batts get drained to 50% and I go to start the truck and the batt banks combine, will they equalize and start charging equally or will the start batts get overcharged? If the ACR is switched to off, is this even an issue?

-- Again, you have to decide, do you want a parallel system or a combining system? Your wiring diagram has elements of both - probably a bad idea.

Is some kind of regulator/A2B charger needed to charge the house batteries with the alt?

-- Yes, you need some form of regulator to control your second alternator. An A2B like the Sterling unit would not be a good choice. Sterling, and others do sell regulators that you could use.

I read that it's a good idea to run a neg wire from the house batt to the alt mounting bolt. Does this need to be wired into the shunt? If so, what side?

-- All of your loads must run to the high side of the shunt and the low side must be your best possible earth or ground.

Basically:

-- If your Ford runs at over 14v, I would recommend that you NOT separate the two alternators. Simply use a battery combining relay, like the Blue Sea ACR you mentioned, and take advantage of the regulation built into you Ford.

-- If your For runs at 13v, then use one alternator to charge the starter battery and build a separate alternator>regulator>battery chain from your second alternator.

N.B. Based on my experience to date with a 2013 Chevrolet, I much prefer a smart relay to combine the batteries along with a solar kit (which includes a charger/regulator) to complete the charge of your camper batteries.

I hope this is clear and helpful.

 

[hangdog]

Thanks DiploStrat for chiming in. I was afraid that I would have to figure this out on my own.

In your thread "Dissimilar Batteries", you mentioned that you'd want an isolated/parallel system. That's what got me thinking that I should do the same. Another reason for me wanting to separate the alts is the way the PCM controls them. The PCM will take the lower alt offline at startup until the glow plugs stop cycling then it will bring the alt back online. If there's not enough load to use both alts then it will cycle between the two. The problem is that the PCM isn't smart enough to know if an alt has failed. So, if it calls for the failed alt to be online then the batteries start to discharge. When the good alt is called for, it now has to work overtime to charge the batts and might not get them fully charged before it's offline again. It's a vicious cycle and probably the reason why I've gone through 3 alternators and 3 sets of batteries in the last 5 years.

The reason for tying both banks together with an ACR is for jumpstarting and being able to charge the start batts with solar/magnum inverter. Do you think this is a good idea or should I keep it simple and make it an isolated/parallel system?

-- As a general rule, if the wire is more than 18 - 30 inches long, you want a fuse.

If I put a switch into the system to combine both battery banks, I will definitely be using a fuse. I was wondering if it needs a separate fuse or can I tie into the one coming off the 2nd alt?

The stock alt is putting out 14.4v at idle and the specs on the HO alt is 14.8v/180amps at idle. I'm planning on using 6v FLA batts for the house bank. Do I still need a regulator between the alt and batts?

 

[pugslyyy]

My house and truck batteries are independent. The only place that they come together is a big Blue Sea 1, 2, 1+2 switch. It controls power to the house 1 = starter battery, 2 = house bank, 1+2 = both.

I really only use it for completely disconnecting the positive side of the batteries (like for welding), for emergency starting (had to do this a few times this winter before I replaced the truck batteries), or to kick-start charging the house in case of complete discharge (had to do this when I bought the truck).

It also would provide some redundancy - if one alternator failed I could bridge everything and let the remaining one charge both banks. This wouldn't be ideal because of the different battery types - but sometimes ya gotta do what ya gotta do. (I've had to do this once when the house alternator failed.)

In the normal position, the truck battery can only be charged by the alternator. The house bank can be charged by the second alternator, solar, and inverter charger (in turn powered by genset or shore power).

The only thing that I don't like about the completely independent setup is that the solar doesn't keep the start batteries topped off. In a perfect world it would maintain both banks, but I haven't come upon an elegant / minimalist way to do this. If I boondock someplace long term I could always bridge the banks when there is no load and the sun is shining.

 

[DiploStrat]

hdog,

I jumped through a lot of hoops because when I first started driving my truck, in the dead of winter, after sitting for months, the alternators were cranking out 15.5v. The Sterling Alternator to Battery Charger alarmed and had to be removed and I was convinced that I had a major problem.

Turns out:

-- The Chevrolet only jumps the voltage like that when the batteries are very low - my truck had been sitting for months while the camper was built, and when it is very cold. Other than that, the voltages track almost exactly those that Lifeline recommends.

-- So I am running a Magnum Smart Battery Combiner driving a Blue Sea solenoid, because the Magnum allowed me to set a high voltage cut out, but, in the end, I did not need it and could have saved a little bit of money by simply using a Blue Sea ACR.

After a one week trip in the winter and now into the summer in in Texas, I am prepared to say that the system works as planned.

-- Typical overnight power usage is 100 - 200 Ah.

-- Typical recovery for this is about three hours of driving during which the solenoid is closed.

-- Beyond that, the 500w of solar bring the batteries to 100% charge every night. The highest charge I have seen on a sunny day was 30A.

The system is close to idiot proof, indeed, the truck has not been connected to shore power since December.

I have not really tested the limits of running the air conditioner on batteries, but have learned the following trick, which worked well on a humid east Texas night.

-- Start engine - batteries combine.

-- Start A/C - the A/C takes on the hardest part of the cool down cycle. The batteries do NOT discharge at all at this point, as the alternators are able to supply well over 150A.

-- After about an hour, call it 0.5 USG of diesel, shut off the engine. The A/C continues to run on batteries for several hours until the temperature is low enough to allow you to open windows.

Bottom line, if your Ford has a reasonably well regulated output voltage of between 14 and 14.5v @ 70F, all you need is:

-- BIG wires - I use a pair of 1/0 cables.
-- A smart relay
-- A decent solar kit (mine is a Blue Sky from AM Solar) to complete the acceptance and float charge.

Hope this helps.

 

[hangdog]

Pugslyyy,

I remember reading a thread where you mentioned that you have separate systems but didn't go into too much detail about it.

Do you normally have the switch in the off position?

Do you prefer them to be separate or combined?

Does the starter battery + go to position 1 stud and house battery + go to position 2 stud?

What's attached to the 3rd stud of the switch?

I, too, would like the starter batteries charged via solar/shore power. That's why I'm hoping the Blue Sea ACR will work.


DiploStrat,

Great beta on the A/C cool down trick. What brand/model do you have?

Do you think you could get away with less solar and still use the same amount of AH at night?

Are the pair of 1/0 wires coming off of one alt or does each alt have 1/0 coming off them?

Are the truck batts getting topped off by the solar too?

Is your 500w inverter hardwired in?

 

[pugslyyy]

I understand, it's a little confusing - here's a better description of how it is set up.

Input 1 = Truck Batttery + Truck Charging System (First Alternator) + Truck Loads

Input 2 = House Battery + House Charging System (Xantrex, Second Alternator, Solar)

Output = House Loads

So switching to 1+2 bridges everything together. Both unmatched alternators, both unmatched battery banks, solar, xantrex. It's not really set up to run bridged - only an emergency condition. That's why in a perfect world I would have it so that solar could gently charge both systems while they still stay separate.

Until I figure out a cheap/simple/elegant way to do it, this is the way it is going to stay!

 

[wrcsixeight]

About the manual 1/2/both/off switches, I use three of them Blue seas Mini 6007 series.
One for the ignition, one for house the loads, one for the Solar.

There are 3 main studs on the switches.

For my ignition switch,
One Stud goes directly to engine battery which I have as battery 1.
One stud is for the house battery which I have as battery 2.

The third stud is the common stud. From here I have a thick cable going to the original cable which hooked onto the (+) of the engine battery.

On the loads switch, the common stud goes to my Aux/ fuse block
On the Solar switch the common stud goes to the charge controller.

My system allows me to use either battery as house or starting, and I can divert solar to either battery independent of load.

I have one AGM battery, and one flooded battery. My observations indicate no issues with overcharging one or the other battery. When one battery is full and the other is depleted, 99%+ of the juice goes into the depleted battery, the other requiring just ~0.4 amps or less to hold 14.x volts. Clamp on Ammeters are wonderful tools.

The flooded battery wants a 15.3v finishing charge but I have the Solar set for less than this in deference to the AGM battery.

While my flooded battery is rated at 40 more amp hours than the AGM, the AGM holds higher voltages for the same amount of amp hours removed from it, at least until the 70 amp hour mark which is the most I have removed from the 90 a/h agm. Even this depleted, the AGM will crank the engine faster than the Flooded.

So While I can use either battery for house or engine starting duties, I mostly wind up using the AGM for the engine for its ability to start the engine so quickly and the flooded for the house loads. I wish I just got 2 of the AGM's, not because of the traditional battery mismatch worries, but solely for the performance aspect.

I do Not discharge the batteries in parallel, nor leave them in parallel without a charging source, as the AGM has a fully charged resting voltage of nearly 13.1v and the Flooded is ~12.65v, so the flooded will always be trying to pull current from the AGM if left in parallel.

I do not always remember to separate the batteries come sundown. The AGM has not protested, yet, at the parasitic drain of the Flooded battery.

I am not familiar with dual alternator systems.

 

[DiploStrat]

Great beta on the A/C cool down trick. What brand/model do you have? - The air conditioner is a little 6k BTU Sharp.

Do you think you could get away with less solar and still use the same amount of AH at night? - Who knows? 500w of solar gets me over 30A in bright sun. The real advantage of lots of solar comes, a bit counterintuitively, when you have less sun, as in the morning, evening, and on cloudy days. Bottom line, go with as much as you can get.

Are the pair of 1/0 wires coming off of one alt or does each alt have 1/0 coming off them? - One 1/0 cable runs (fused) from the positive terminal of each starter battery and they combine at the relay. From the relay, two 1/0 cables run to the positive terminal of the camper battery bank, again fused. After months of testing, the final set up is dead easy:

Alternator(s)>Starter Battery(s)>1/0 cable(s)>relay< 1/0 cables<Camper Batteries<Solar Controller & Shore Power Inverter/Charger

Are the truck batts getting topped off by the solar too? - Yes, indeed that is the beauty of the system; whenever there is a sustained voltage of over 13v on either side of the relay, the relay closes and the batteries are combined. (This causes them to seek the same level and causes whichever charge source is connected to begin charging.) Assuming any reasonable amount of sun, this also obviates the need for any form of maintenance charger for your starter batteries; a huge benefit for folks who don't use their truck as much in cold weather.

Is your 500w inverter hardwired in? - Yes, it is such a trivial draw that it is simply hard wired to the camper batteries with an on/off switch.

Again, the "magic" isn't very magic.

-- Modern alternators produce the 14+v needed to charge AGM batteries with little need for special regulators, etc. As you are only going to drive but so many hours a day, you are really only asking the vehicle alternator to provide the boost/bulk stage of charging. Typically, I see the amp rate really drop off after about three hours.

-- Combining battery to battery protects your vehicle warranty and assures that each charger or alternator is buffered from the other. As noted, this makes it much easier to mix and match dissimilar batteries. N.B. One assumes that the vehicle alternator is correct for the starter battery and you should set your solar/shore charger to meet the needs of your camper batteries.

-- Use of a solar kit, even if not as large as you want, assures that you have the long acceptance/absorbance charge after you shut off the engine.

-- Use of large cables lowers the resistance enough that either charger will "see" and respond to the needs of the distant battery.

Cost me a fair amount of time and money to reach this point, but so far, all works exactly as expected. Check back in a few years!

 

[unseenone]

Cool setup for the A/C. Have you considered a DC air conditioner, they are much more efficient?

 

[DiploStrat]

Don't know if DC air conditioners are any more efficient. By definition there will be a gain in efficiency if you don't need an inverter. But a Sharpe A/C is under $500 and DC units are over $2000.

 

[unseenone]

Some DC units are more than 50% more efficient, over an Inverted system. Don't know what you're going for. Nice web site by the way..

 

[DiploStrat]

Thank you. New site under construction, here: www.diplostrat.org.

(Greetin's from San Antone.)