Dual Battery Shore Power Charging Question

[AndrewP]

I still don't like the National Luna controller bouncing back and forth between the two batteries and think it makes more sense to charge them individually once a month as has been suggested.
- Chris

Chris, you are worried about a non-problem. Your National Luna system can't tell the difference between shore power and alternator power even though it is "smart". Just let it combine, do it's job, and thus charge BOTH batteries and everyone will be happy. Let it sit on the float charger with both batteries at say 13.5 and you have prevented premature sulfation and all the batteries will be good.

As long as your charging voltage is above resting voltage, it is all good, assuming it is not overcharging.

Just my opinion, but people worry way too much about lead-acid chemistry. It's been doing it's thing for 100 years, and hasn't changed much. It has changed a little with calcium and antimony alloyed into the lead plates, but that doesn't change the fundamental chemistry.

Most modern Toyotas (post 1980) charge at 14.0 volts. This is good for every kind of battery that uses lead and sulfuric acid. Most smart chargers and solar chargers charge in the same neighborhood, maybe 14.5 during the absorb phase and 13.5 during the float. The problem is, most batteries want to see that voltage for 12-24 hours, and most people drive 0.5 hour, and that's why the charging is not sufficient.

Do not sweat the fact that you have paid way too much for a fancy Odyssey or clone at sears. it's still lead, and sulfuric acid. Let your charger do it's job, assuming you have chosen it with reasonable care.

For me, I have not found that hyper-expensive AGM batteries are any better than normal flooded lead acid batteries, and so I gave up on the Odyssey and Optima Batteries a long time ago and went back to Marine batteries from Costco. But your mileage may vary.

 

[Ducky's Dad]

Most modern Toyotas (post 1980) charge at 14.0 volts. This is good for every kind of battery that uses lead and sulfuric acid.

Odyssey says that is simply not true for their 2150 Extreme. I argued from your point of view, through three of those batteries, and finally gave up and bought the Odyssey charger to get a 14.7+V charge into my new 2150. We'll see if that solves the problem. Optimate in Canada told me in a phone call that their chargers at 14.6V worked sometimes on the 2150, but not consistently, so they were bringing out a new charger to support the Odyssey at 14.7+V. This is not my opinion, but it's what Odyssey and Optimate state to be the case for their products.

 

[AndrewP]

Odyssey says that is simply not true for their 2150 Extreme. I argued from your point of view, through three of those batteries, and finally gave up and bought the Odyssey charger to get a 14.7+V charge into my new 2150. We'll see if that solves the problem. Optimate in Canada told me in a phone call that their chargers at 14.6V worked sometimes on the 2150, but not consistently, so they were bringing out a new charger to support the Odyssey at 14.7+V. This is not my opinion, but it's what Odyssey and Optimate state to be the case for their products.

Why would they build/sell a battery designed to go into automotive systems that could not be charged by a standard automotive system? That would be foolish and tie you to plugging in your car every night. Who wants to do that? And if it is true, it would pretty much rule out using 2150s or the equivalent Sears clone in our systems.

I could see where 14.7 might be the optimum voltage for charging as fast as possible, but it's still going to charge if it's above it's resting voltage, just not as fast. I'd be more interested in what they feel is a good float voltage, because many recreational trucks sit on a float charge for months at a time, and you want that to not damage your batteries.

I feel with flooded lead acid batteries, you can open them up every 3 months and add water if needed and so the voltage they happen to be floating at is less critical.

Anyway, is it better to replace an $80 battery every 4 years or a $300 battery every 6? Just something to consider.

 

[1Louder]

Both of my batteries are AGM which I am sure the group is aware of. Great conversation. I always try to search for current threads on various topics and didn't see one for this other than the one I linked to from 2012. Always great to learn from others. Every once and a while I am able to contribute and not just ask questions. I am looking forward to writing a report on my PowerFilm 60 Watt Solar panel when it gets used this upcoming Labor Day weekend. I will be testing it on both my 2nd battery and my trailer battery.

This thread was pointed towards general maintenance and dual battery setups but they all go hand and hand. I do know quite a few people who are permanently mounting a panel on the roof of their vehicle. Granted it can never be the most efficient in a fixed position but with it being on there all the time it can certainly help keep things topped off. I may do this if I decide to permanently mount my fridge in my FJ.

Again thanks for all of the replies.... I did find some of the PDF documentation from Odyssey and have given it a read. I will also see what Optima has to say.

- Chris

 

[Ducky's Dad]

I will also see what Optima has to say.

Optima told me to never use my Odyssey Ultimizer 40amp charger on an Optima battery because it would damage the battery. I think Optima specifies shore charging input amps no greater than 20 amps (need to confirm), and Odyssey told me that the 2150 requires a minimum of 25 amps, but 40 amps is better and 50 amps is ideal (according to multiple contacts at Odyssey). So there is a big disconnect between Optima and Odyssey re chargers. My Dodge has an Odyssey 2150 starting battery and Optima Blue house batteries. My old truck has dual Optima Yellows. My wife's has an Odyssey 1500 and my soon-to-be daily driver will have a Northstar AGM. Having multiple charger/conditioners is a real pain in the ***.

Why would they build/sell a battery designed to go into automotive systems that could not be charged by a standard automotive system? That would be foolish and tie you to plugging in your car every night. Who wants to do that? And if it is true, it would pretty much rule out using 2150s or the equivalent Sears clone in our systems.

Odyssey doesn't say you have to plug it in every night, just every couple of months (but I think more frequently is better). If you have zero sulfation and never get any sulfation and can charge off your alternator at 14.7V and high amperage and drive the vehicle regularly, you can probably get by without a dedicated charger/conditioner. But I don't know anybody who can meet those conditions. Why does the Odyssey require 14.7V? I don't really know, but Odyssey says that's what their battery needs and I have been going through batteries like sweat socks, so I'm going to try listening to them. The 14.7V requirement was confirmed by Optimate (not the same as Optima), so a battery manufacturer and an unrelated charger manufacturer are telling me the same thing.

 

[228B]

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Ducky's Dad
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Why does the Odyssey require 14.7V? I don't really know, but Odyssey says that's what their battery needs and I have been going through batteries like sweat socks, so I'm going to try listening to them.

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This was my approach as well. I killed my first Odyssey AGM by not only undercharging it but also by inadvertently "dumping" it to lower than 7 volts! on more than one occasion. That was an expensive lesson. Lesson learned, glad to report. I too began listening to how the manufacturer recommended I treat my battery. The EnerSys Odyssey Ultimizer OMAX 50 1B charge profile is indeed, as Ducky's Dad noted, intended only for Odyssey-made AGM batteries that fall within a specified capacity range.
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When not using my solar setup, I use this charger on an Odyssey Group 31 AGM battery to top it off then continually float it when connected to shore 120V power. I've reprogrammed my solar charge controller (with Morningstar's help) to match the voltage setpoints that EnerSys/Odyssey recommends: an amperage-dominant bulk phase in which voltage will rise and fall according to microprocessor algorithms in each charge unit; up to 50 amps from the OMAX [or however many amps as can be delivered by solar; in my case up to 12.5 amp from two 100W panels connected in series], an absorption period of four hours at 14.7 (by this time amperage has been considerably reduced) followed with a float of 13.6 volts.
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Odyssey charge specs found here on Pages 12, 13 and 14 in this EnerSys PDF
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What is most important according to Odyssey is the absorption phase; this is where the higher 14.7 is necessary, not a lot of amperage but for an extended time period of four to six hours, ending with their recommended float voltage (between 13.5 and 13.8!) of 13.6. I have permanently installed the OMAX charger in the trailer next to the battery for convenience when and where shore power is available and use it for floating the battery (as I mentioned earlier and when my trailer is parked) -because- I could find no other "float"/ battery maintainer with output better than 13.4 volts.

 

[DiploStrat]

There isn't much new under the sun. This is a good read. http://www.autoshop101.com/forms/hweb3.pdf

If you read the Odyssey manual you will note that the only difference in charging at 14.7v and 14.2v is the length of time it will take. (N.B. these are voltages at 20C; at freezing the voltages will be much higher.) The charging voltage is the maximum voltage that the battery will accept, at a temperature, without gassing or overheating. They would not sell many of these beasts if they will not work in normal vehicles. I suspect that the Odyssey batteries in question have a fair amount of calcium in the plates, like the Delco starter batteries on my truck.

Odyssey does recommend a constant current charger, during the bulk stage only. This is a bit unusual as many chargers are constant voltage only. But again, this is for a rapid charge on shore power and oddly, they then call for an extremely long absorb charge. Most constant voltage chargers will display a declining amp rate over the same period with the same net result. The key thing to understand here, as found in the Odyssey manual and the Lifeline manual, most batteries die not because the voltage is too low (or even too high), but because they are not charged LONG enough. For a typical automotive battery, used for starting a vehicle, this is not often a problem. For a battery trying to carry a refrigerator, fans, computers, microwaves, and an air conditioner, this is a big issue. Your vehicle's alternator can produce the hundreds of amps needed for the bulk stage, but rarely will you drive long enough to accomplish the absorb stage. But, to the original poster's question, this has nothing to do with whether you use a starter or a deep cycle battery as your starter battery.

N.B. To the original poster, who has probably fled screaming from the room: The performance of the battery in your trailer is quite understandable. If your alternator is running at barely 14v, and assuming that your trailer is some 20 feet from the engine, and guessing that the cabling to the trailer is barely 6 AWG and has connectors, then you are probably only delivering about 12.4v to the trailer battery. Run the numbers yourself: http://www.calculator.net/voltage-d...ce=20&distanceunit=feet&amperes=100&x=20&y=15

 

[AndrewP]

N.B. To the original poster, who has probably fled screaming from the room: The performance of the battery in your trailer is quite understandable. If your alternator is running at barely 14v, and assuming that your trailer is some 20 feet from the engine, and guessing that the cabling to the trailer is barely 6 AWG and has connectors, then you are probably only delivering about 12.4v to the trailer battery. Run the numbers yourself: http://www.calculator.net/voltage-d...tance=20&distanceunit=feet&eres=100&x=20&y=15

I totally agree, except this last bit. Voltage drop is dependent on current flow and resistance. So if no current is flowing, the voltage drop is zero. So in the instance of a long run of too small wire, what you get is slow charging, because as the current increases, the voltage drops until the current flow drops to very low levels, thus supporting the voltage at a point where some current will flow. Just not as much as you would like. In reality, it self regulates and the current just flows slowly into the battery. It will eventually come up to charge but it will take a long time.

 

[Ducky's Dad]

My old alternator at nominal 160 amps on 1/0 welding cable could not adequately charge my Odyssey 2150, even with about 1300 miles of mostly highway driving in a 72-hour period, no refrigerator, no winching, no camp setup, just a lot of driving. That 2150 failed, even with multiple treatments on an Optimate 6 charger/conditioner/maintainer. Per Odyssey, my alternator voltage at 14.2-14.3V was too low for that battery without a proper conditioning charger, and the Optimate 6 at 14.6V and 6 amps was not an adequate charger/conditioner for that particular battery. My new 2150 is being charged by a nominal 270 amp alternator feeding current through 3/0 welding cable, but still at 14.2-14.3V as determined by the ECM. This alternator bench tested at 285 amps max and delivers 116 amps at idle, installed in the truck as tested last week. I'm still going to use my Odyssey 40 amp Ultimizer because I'm tired of replacing batteries. We'll see how it goes.

 

[DiploStrat]

Play with the calculator changing the target amps at will. As the amp flow drops the voltage drop decreases. Of course, so does your charge rate.

 

[4x4junkie]

I totally agree, except this last bit. Voltage drop is dependent on current flow and resistance. So if no current is flowing, the voltage drop is zero. So in the instance of a long run of too small wire, what you get is slow charging, because as the current increases, the voltage drops until the current flow drops to very low levels, thus supporting the voltage at a point where some current will flow. Just not as much as you would like. In reality, it self regulates and the current just flows slowly into the battery. It will eventually come up to charge but it will take a long time.

That may be so... However it's also the absolute last thing you want when the amount of charge your batteries typically get before you park the vehicle and shut the engine off is already far too limited... Why not force as much charge into them as you possibly can (up to your alternator's and/or battery's capability) while the opportunity is available?

 

[cactusjk]

Dirty Parts makes an upgraded alternator fuse for FJs and Tacomas to increase the charge rate with dual battery setups.

 

[DiploStrat]

To flog a dead horse, a reasonable source tells me that the FJ uses the charging system from a late '90's Hilux and it is indeed limited to 13.9v. If that is indeed true, then:

-- One would be well advised to use a Toyota style battery for starting (unless you want to rework your alternator to run at 14v+), and

-- Assuming that you do NOT want to raise your charging voltage, and you do want to run a modern deep cycle battery as your camper battery, then you should look carefully at the CETEK D250S/SmartPass or one of the larger Sterling B2B units. (I kind of like the CETEK SmartPass as it gets you more amps than a B2B on its own. especially at the start of the charging cycle when you need it most. Then, when your charge rate drops to 20A or less, it can deliver the higher voltage that is required to complete the absorb/charge cycle.)

 

[1Louder]

To flog a dead horse, a reasonable source tells me that the FJ uses the charging system from a late '90's Hilux and it is indeed limited to 13.9v. If that is indeed true, then:

-- One would be well advised to use a Toyota style battery for starting (unless you want to rework your alternator to run at 14v+), and

-- Assuming that you do NOT want to raise your charging voltage, and you do want to run a modern deep cycle battery as your camper battery, then you should look carefully at the CETEK D250S/SmartPass or one of the larger Sterling B2B units. (I kind of like the CETEK SmartPass as it gets you more amps than a B2B on its own. especially at the start of the charging cycle when you need it most. Then, when your charge rate drops to 20A or less, it can deliver the higher voltage that is required to complete the absorb/charge cycle.)

Appreciate the research. I am leaning towards that when the battery eventually dies. I will probably try the $50 mod on eBay to bring the voltage up. What I really should have done is moved the Sears/Odyssey to my trailer and put a starting battery back in the FJ. Oh well.....

 

[DiploStrat]

Bring your system up to 14v+ and you will be golden with any modern battery. If you are the least bit worried, get a shore charger that can run up the the 14.7v that Odyssey calls for and use it once a month. Just connect it to any battery and your automatic charge relay will close and share.

As noted, trailers are another issue, typically because the wiring is way too small. A trailer battery may well require a dedicated charge before every trip. I have a ton of info on these subjects on my website.