Dual 6 Volt vs Dual 12 volt battery FWC option

[Vic Harder]

IMO, Vic is our resident, non-EE, all thing electrical/solar guru. Sorry to put that label on you Vic, but, you've earned it through research and hard work.

Bill

Yikes. I admit I have an opinion, based on research and now experience. Others here also have those things, often WITH experience and and education. I'm only an electronic tech, and that was a long time ago.

Thanks for the kudos. I only hope I am helping people, not confusing them more.

 

[JaSAn]

. . . IMHO, FLA batteries are a non-starter, and off-topic, battery for a slide-in, bolt-on pop-up campers. When batteries are stowed inside these campers, off-gasing can be a very life-threatening health issue. Seriously, you do not want to down this path for your health. FLA batteries MUST be stowed in a well ventilated area where gases are not going to be inhaled; not your typical pop-up camper setup . . .

If you have health problems related to outgassing of lead-acid batteries, you should not have any LA battery inside your camper. AGM batteries will vent the same vapors as FLA, just not as quickly (they need to build up a little bit of pressure before venting). And they vent for the same reasons, usually overcharging.

My FLA batteries lose ~ 200 micro-liters of water per day, not enough to measure. They are in the front right corner of the camper, under my bed. They are vented but I wouldn't need to; I bought into the 'must vent FLA batteries' mantra when I was building out the Grandby. Since then I have learned more about the care and feeding my batteries.

 

[Wallowa]

Well this topic has been beaten to death...

Question though...if FLA and AGM batteries both vent vapors [aqueous] then when do I need to re-fill my AGM?

Hey, everyone take a deep breath, clean air of course, and do whatever gets you through the night...to each their own....

Phil

 

[klahanie]

^ yeah, for sure, good call.

now about that forklift story ...

... on second thought, never mind.

I'm putting the whole battery thing on my DND list, no worries

 

[radarcontact]

I like this topic, and I've had 12V AGMs and now 6V FLAs. So far I like the 6V performance much better. Yes, the watering and care is more with flooded batteries, but not so much that, for me, it's a deal-breaker. Haven't had any issues with venting/gassing. I had a VW van years ago, and I sat right on top of the FLA battery for years without blowing up, so I'm going on experience LOL. Golf cart batteries are combat tested, and they do a good job deep cycling.

IMO, it's just a personal preference whether you go AGM or FLA. FLA are cheaper, but I wouldn't be opposed to AGMs again when the time comes, just bec. I can forget about watering. But, I'm fairly sure I'd go with 6V again in series over two 12V parallel. Less weight, more Ah for your money.

 

[abqbw]

Does anyone have any experience with the Centennial brand 6v batteries? Specifically the CB6-224. It looks like it should be comparable to the US AGM 2000 6v battery that FWC installs as an option? Vic-perhaps you could look at the specs and give an opinion?

The reason I am interested in this battery is because they are in stock at my local Battery Systems and I would like to get some 6v batteries this week ahead of a 3 week boon docking trip to the borderlands of New Mexico.

 

[Wallowa]

Fact or fiction...

Will two 6 volt batteries in series fail to function in our campers if one cell in either battery dies?

Then of course, has anyone ever had one cell or more cells fail?

Thanks...trying to grind all this information down to the most reliable system.

Phil

 

[Ace!]

I abused two 6v batteries and hardly maintained them, shook the shiite out of them offroad too and never had a failure. It probably happens, but I don't think it would be the norm. Just like anything else that fails, you get back home or to the battery store and you get it fixed. Shouldn't lead to sudden death or anything. My thought is two 6v batteries is a fine way to go, if you're so inclined, I just think 12v is easier.

 

[Wallowa]

I abused two 6v batteries and hardly maintained them, shook the shiite out of them offroad too and never had a failure. It probably happens, but I don't think it would be the norm. Just like anything else that fails, you get back home or to the battery store and you get it fixed. Shouldn't lead to sudden death or anything. My thought is two 6v batteries is a fine way to go, if you're so inclined, I just think 12v is easier.

Thanks Ace...I understand that battery cell failure is not the norm in 6 or 12v...

Just unsure if one cell of a 6v system in series fails does the whole system go down? The parallel vs series question.

Phil

 

[JaSAn]

Will two 6 volt batteries in series fail to function in our campers if one cell in either battery dies?

The short answer is = Yes, you will no longer have a 12V battery bank.
But, things will not be much better with a parallel 12V system. The battery with a bad cell will draw down the good battery unless it is identified and separated out of the bank quickly.

I have had cells quickly go bad in 12V starter batteries in off-road vehicles, probably from something falling off a plate and shorting the cell out. But usually it is a slow voltage loss in one cell. One reason I like FLA is I can check individual cells for specific gravity if I suspect one cell is weak.

The only reason to be cautious of 6 volt batteries is if you have critical medical equipment that needs to be powered. But even there you need to build redundancy into your system so if one battery goes dead (6V or 12V) you have enough power until you can replace it.

IMO the two big reasons for going with 6V golf cart batteries is:

1. They are the cheapest true deep cycle battery you can buy. I have $184 in 208AH of battery bank.
2. They are much easier to source than 12V deep cycle batteries. Most Sam's Club and Batteries Plus carry them, you can order and have them shipped to any Walmart. You might even be able to buy a pair from a golf course if you ask the maintenance guys nice.

jim

 

[Wallowa]

Jim,

Thanks all that makes sense...follow up question...on my motorcycles [off-road] and I assume in my other vehicles that AGM batteries were more resistant to vibration/physical impact damage than FLA lead/acid batteries....impregnated glass mats as opposed to lead plates..

Am I also correct that 6 volt batteries can have the same case size of 12 volt batteries and the big difference is the thickness of the plates in the 6v is greater than the 12v?

Not quantifiable, but I assume if a cell craps out in one of two batteries in parallel it will take some time [days, weeks, hours] before the system can't deliver 12v.

Thanks...may indeed go for deep cycle and perhaps 6v in the future when my current Exide 12v AGMs [FWC] croak..

Appreciate all the input from this thread...

Phil

 

[rando]

Just to clear up a couple of misconceptions between AGM and FLA batteries (not 6V vs 12V) - the difference between these two type of batteries is more than just that one vents and needs to have water added and the other doesn't. AGM has several other advantages over FLA:

- AGM can accept charge more quickly than FLA, which can be a significant issue if you rely on shorter periods of high current charging from you alternator to keep the camper battery charged. This is likely not an issue with a primarily solar charged system as the rate of charge is usually limited by the amount of solar power available.
- AGM has a much lower self discharge rate and is less susceptible to sulfonation than FLA, which is important if you store your camper without solar or a maintenance charger. An AGM battery will likely go twice as long as an FLA before it needs to be topped back up.
- AGM batteries are often rated to 80% depth-of-discharge (DOD) at the same number of cycles as FLA will achieve at 50% DOD - meaning that you can get 60% more power out of an AGM battery than FLA battery and still have it last the same time. Or conversely you can use a smaller, lighter AGM battery to get the same usable capacity.

Of course FLA is significantly cheaper and more widely available than AGM, and FLA works for many folks so there is no clear answer, just a bunch of factors to consider for your particular application.

 

[JaSAn]

Just to clear up a couple of misconceptions between AGM and FLA batteries (not 6V vs 12V) - the difference between these two type of batteries is more than just that one vents and needs to have water added and the other doesn't. AGM has several other advantages over FLA:

- AGM can accept charge more quickly than FLA, which can be a significant issue if you rely on shorter periods of high current charging from you alternator to keep the camper battery charged. This is likely not an issue with a primarily solar charged system as the rate of charge is usually limited by the amount of solar power available.

Yes this is true - IF you can take advantage of it. My 200W of solar can't generate enough, my FLA batteries will take all the 110V 35A charger
will deliver, and unless you have big wires from alternator to battery you can't get a big charge from you alternator.

- AGM has a much lower self discharge rate and is less susceptible to sulfonation than FLA, which is important if you store your camper without solar or a maintenance charger. An AGM battery will likely go twice as long as an FLA before it needs to be topped back up.

It is true that AGM has a lower self discharge and will be an advantage if you store your batteries untended for long periods. Mine are stored on solar or a tender when not in use.

As to sulfating, I don't see how this could be true. The chemistry is the same:

Pb(s) + PbO[SIZE=11.199999809265137px]2[/SIZE](s) + 2H[SIZE=11.199999809265137px]2[/SIZE]SO[SIZE=11.199999809265137px]4[/SIZE](aq) → 2PbSO[SIZE=11.199999809265137px]4[/SIZE](s) + 2H[SIZE=11.199999809265137px]2[/SIZE]O(l)+ 2 electrons

the S2PbSO[SIZE=11.199999809265137px]4 [/SIZE]collects on both positive and negative plates and the sulfur is returned to solution when charged (if you wait too long the lead sulfate hardens and is difficult to separate, which is one of the things equalizing does, which you can't do with most AGM batteries) .

- AGM batteries are often rated to 80% depth-of-discharge (DOD) at the same number of cycles as FLA will achieve at 50% DOD - meaning that you can get 60% more power out of an AGM battery than FLA battery and still have it last the same time. Or conversely you can use a smaller, lighter AGM battery to get the same usable capacity.

See graph from Trojan below: https://www.trojanbattery.com/pdf/AGM_Trojan_ProductLineSheet.pdf

Of course FLA is significantly cheaper and more widely available than AGM, and FLA works for many folks so there is no clear answer, just a bunch of factors to consider for your particular application.

jim

 

[Wallowa]

Seriously folks...there has been a ton of "input" on AGM vs FLA vs LiPo4 etc etc etc....

Some of the information dazzling, some of it repetitions, some of meant to impress...but in the end given the deluge of discussion on this topic we each have more than enough data to make an informed opinion and decision...

This is damn near a "what is your favorite oil' thread...My original question in starting this thread has been adequately answered..thank you.

Just my take and I could be wrong...

Phil

 

[ronaldos]

6Volt batteries have bigger plates, you can discharge and charge them more regularly than with 12V batteries. Because of this, a 6 Volt battery normally has a longer life, and a 6V battery is better used in series circuits, it is easier to add a few more volts.