Charging two 6 volt batteries question

[David_L6]

If I were to use two 6 volt batteries rather than one or two 12 volt batteries would I still use the Progressive Dynamics PD4045 or would I have to buy something different?

[Dale M.]

For the most part, the charger does not *see* two 6volt batteries wired in series or two 12 volt batteries wired in parallel (physically what you see/have)... It *sees* a 12 volt battery... Because two 6 volts batteries in series, electrical equals a single 12 volt battery or two 12volt batteries wired in parallel equals a 12 volt battery and charger does not know the physical difference in what you decide to use... All charger knows is there is a 12volt *battery* connected to it...

Not sure why you are considering 2 6volt batteries as they are becoming harder to find, unless its a weight/capacity (amp hour) issue...

Dale

[David_L6]

OK. That makes sense. Thanks for the explanation. I thought that's how it worked but I wasn't sure.

To answer your question... From what I've been able to find on the RV and marine forums I can get more amp hours from two 6 volt batteries than from two 12 volt deep cycle batteries and I'll also get longer life out of the batteries.

[Shadow Catcher]

It is all pretty much same same. I have a single 150 AH Lifeline AGM that is 100# I do not have to be concerned about self discharge or watering and it will take a charge faster than a wet cell.

[Dale M.]

OK. That makes sense. Thanks for the explanation. I thought that's how it worked but I wasn't sure.

To answer your question... From what I've been able to find on the RV and marine forums I can get more amp hours from two 6 volt batteries than from two 12 volt deep cycle batteries and I'll also get longer life out of the batteries.

NO matter what people tell you, size matters..... Personally I would not want to mess with multiple batteries.... One huge 12 volt should do it....

Dale

[eamarquardt]

At the two ends of the spectrum there are starting batteries and really deep discharge batteries. Starting batteries are designed to provide short burst of high amperage current to start vehicles. They are not meant to be discharged very deeply w/o damage. Deep cycle batteries won't deliver as high a current in a short burst but are meant to supply a lower current for longer period of time and are built to withstand deeper discharges before recharging w/o damage. "Marine" batteries are a compromise and somewhere in in middle in terms of service and discharge.

Again, there is no difference between two 6 volt batteries or a single 12 volt battery IF the two six volt batteries are the same brand and the same age. You should not mix different types of 6 volt batteries together to get 12 volts. Just like all the 6 cells in a single battery are "matched" the cells in two 6 volt batteries should be "matched" for optimum performance and life.

If you are going to go below 40-50% of your battery's capacity between recharging it you will obtain better performance and life from true deep cycle (6 volt golf cart batteries are the most common) rather than "marine batteries". If you're going to keep em pretty much topped off then "marine" batteries will be fine.

The only added complexity of two six volt batteries is you'll have to mount two batteries instead of just one and you'll have one extra wire to connect the two together. Aside from that there is really no difference.

Here are some references.

http://www.ehow.com/about_6537345_can-m ... cart_.html

http://forums.woodalls.com/index.cfm/fu ... t/true.cfm

http://www.justanswer.com/car/62phd-xx- ... ttery.html

[bdosborn]

I use two 6V golf cart batteries and will replace them with the same when they finally give out. I've used them for 3 seasons now and they don't show any signs of reduced capacity. I use a lot of juice too with the DVD player and the 12V refrigerator (around 40 amp-hrs a night). It might be over kill for the average user however, you should add up your nightly amp-hr usage and use that as a guide to picking a battery. The teardrop had a single 12V deep cycle battery that worked fine but we used less juice in it than our current camper.



I use a PD9140 to charge them.

Bruce

[bdosborn]

It is all pretty much same same. I have a single 150 AH Lifeline AGM that is 100# I do not have to be concerned about self discharge or watering and it will take a charge faster than a wet cell.

I'm gonna be looking long and hard at AGM when my batteries need replacement.

Bruce

[bdosborn]

Not sure why you are considering 2 6volt batteries as they are becoming harder to find, unless its a weight/capacity (amp hour) issue...

6V golf cart batteries are true deep cycle type, with big, beefy plates to better withstand the abuse of deep discharges. You can find them at Sam's Club, Walmart and Costco fairly cheaply compared to *true* 12V deep cycle batteries, which are getting very expensive. As Gus explained, marine deep cycle batteries are an unhappy marriage between a deep cycle and start battery, doing neither chore especially well. Golf cart batteries are typically the cheapest $ per amp-hr.

More Battery info

Bruce

[David_L6]

Two 6 volt AGM batteries is what I have in mind.

Thanks to everyone for the information and opinions.

[bdosborn]

Two 6 volt AGM batteries is what I have in mind.

Hold on to your hat when you see the price....


Bruce

[Bogo]

OK. That makes sense. Thanks for the explanation. I thought that's how it worked but I wasn't sure.

To answer your question... From what I've been able to find on the RV and marine forums I can get more amp hours from two 6 volt batteries than from two 12 volt deep cycle batteries and I'll also get longer life out of the batteries.

NO matter what people tell you, size matters..... Personally I would not want to mess with multiple batteries.... One huge 12 volt should do it....

Dale

Yep, one Rolls Surrette 12 CS 11P should do it. It only weighs 272lbs.

BTW, the largest commonly available battery is the 8D size. 230 to 270 Amp hours, and 160lbs each. Most marinas that handle older large pleasure craft will have them. I know in the past they were also used for starting trucks and tractors with large engines so you may find them at truck stops. A pair of Group 31 batteries has now replaced them due to being able to be lifted individually. Each Group 31 battery is only 75lbs, and a pair of them in parallel should provide 210 to 240 Amp hours at 12VDC. Modern batteries are much better at handling being paralleled, but still get a pair or set from the same production run. Don't parallel lead-acid batteries of different capacities, ages, chemistries, or general styles. If you do, then you will likely kill them, unless they are of the same chemistry and always being charged or discharged. No resting between charging and use allowed.

[David_L6]

Two 6 volt AGM batteries is what I have in mind.

Hold on to your hat when you see the price....


Bruce

I've already priced batteries. I know they aren't cheap.

[David_L6]

OK. That makes sense. Thanks for the explanation. I thought that's how it worked but I wasn't sure.

To answer your question... From what I've been able to find on the RV and marine forums I can get more amp hours from two 6 volt batteries than from two 12 volt deep cycle batteries and I'll also get longer life out of the batteries.

NO matter what people tell you, size matters..... Personally I would not want to mess with multiple batteries.... One huge 12 volt should do it....

Dale

Yep, one Rolls Surrette 12 CS 11P should do it. It only weighs 272lbs.

BTW, the largest commonly available battery is the 8D size. 230 to 270 Amp hours, and 160lbs each. Most marinas that handle older large pleasure craft will have them. I know in the past they were also used for starting trucks and tractors with large engines so you may find them at truck stops. A pair of Group 31 batteries has now replaced them due to being able to be lifted individually. Each Group 31 battery is only 75lbs, and a pair of them in parallel should provide 210 to 240 Amp hours at 12VDC. Modern batteries are much better at handling being paralleled, but still get a pair or set from the same production run. Don't parallel lead-acid batteries of different capacities, ages, chemistries, or general styles. If you do, then you will likely kill them, unless they are of the same chemistry and always being charged or discharged. No resting between charging and use allowed.

Two group 31 batteries? You mean a pair of these: http://www.newegg.com/Product/Product.a ... 08705Y6689

[Dale M.]

OK. That makes sense. Thanks for the explanation. I thought that's how it worked but I wasn't sure.

To answer your question... From what I've been able to find on the RV and marine forums I can get more amp hours from two 6 volt batteries than from two 12 volt deep cycle batteries and I'll also get longer life out of the batteries.

NO matter what people tell you, size matters..... Personally I would not want to mess with multiple batteries.... One huge 12 volt should do it....

Dale

Yep, one Rolls Surrette 12 CS 11P should do it. It only weighs 272lbs.

BTW, the largest commonly available battery is the 8D size. 230 to 270 Amp hours, and 160lbs each. Most marinas that handle older large pleasure craft will have them. I know in the past they were also used for starting trucks and tractors with large engines so you may find them at truck stops. A pair of Group 31 batteries has now replaced them due to being able to be lifted individually. Each Group 31 battery is only 75lbs, and a pair of them in parallel should provide 210 to 240 Amp hours at 12VDC. Modern batteries are much better at handling being paralleled, but still get a pair or set from the same production run. Don't parallel lead-acid batteries of different capacities, ages, chemistries, or general styles. If you do, then you will likely kill them, unless they are of the same chemistry and always being charged or discharged. No resting between charging and use allowed.

Two group 31 batteries? You mean a pair of these: http://www.newegg.com/Product/Product.a ... 08705Y6689

Not at that price... Group Number usually is physical design specification (height - width - depth - terminal type) not necessarily what chemical composition of battery...

http://www.batteryfaq.org/

If I were going Group 31 and AGM....

http://www.amazon.com/dp/B005ZJWLBM/ref ... nkCode=asn

http://www.batteriesinaflash.com/sealed ... ry-1150cca

Dale