Optima batteries better? 12V? 6V?

[Frank B]

We just bought a 'new' 5th which we plan on using like our previous one, for Winter camping as well as Summer.  In the old one, I had two deep cycle batteries of the 'standard' RV/Marine variety that did us for 4 days in winter.  This new unit, however, has forced air ducted heating, and the motor on the furnace takes 6.5 amps compared to 2.7 amps in the old unit.  I'm happy to install several batteries until I get the capacity I need (probably four of them).  I have a couple of options:

Optima gel-cell batteries:  They claim better performance, with less liklihood of freezing when discharged.  However, for a battery of similar rating, the price is about double that of a 'standard' deep-cycle battery.  Warranty is 36 months on the Optima vs. 30 months for a standard battery, so no big advantage there.  Are these batteries worth their steep price during their only slightly longer lifetime?  Up here, four of them are going to set me back about $800!

Use 6 volt deep cycle batteries:  Someone has told me that four 6V deep cycle batteries (two in series paralleled with two more in series) will give better performance than four 12V batteries, all of which would be in parallel.  Any truth to this?  Also, our local Wal-Mart does not carry 6v batteries, so I'd have to buy them somewhere else.

Use four 12V batteries all in parallel.  This is the cheapest and most readily available solution.  I just wonder if is the 'best' from a performance or a cost standpoint.  30-month batteries give up remarkably close to their rated lifetime.

Finally: What is the best option for long-lasting deep-cycle cold-weather operation (can get to about -15C when we go out in the Winter).  I can insulate and rearrange one of the ducts to heat the battery compartment in winter to prevent even discharged batteries from freezing.

Any suggestions or comments appreciated.

Frank.

 

[Tom]

Frank

For clarification, Optima batteries are not gel cell; They're spirally-wound lead acid batteries.

Using 4 - 12V group 27 batteries will give you approx 420 amp hours of capacity. 4 golf cart 6V batteries will give you 440 amp hours, although this might vary slightly by brand.

I assume that fan does not run constantly (?) so I'll conservatively assume it takes an average of 5 amps instead of 6.5. Also assuming you don't discharge the batteries below 50%, so you use 220 amp hours in the calculation. This will give you 220/5 = 44 hours of using your heating with the 4 golf cart batteries. This would be reduced to 42 hours with 4 - 12V batteries.

The real advatage of the golf cart batteries is that they're made to handle repeated heavy discharging and recharging.

 

[Frank B]

Tom:

>For clarification, Optima batteries are not gel cell; They're spirally-wound lead acid batteries.<

Noted.  Thanks.

>I assume that fan does not run constantly<

Sure hope not!    Haven't run this one in the Winter yet, but the old one did less than 50%, in fact, probably more like 25%

>The real advatage of the golf cart batteries is that they're made to handle repeated heavy discharging and recharging.<

So, is there much advantage in the 4 x 6V arrangement in your opinion?  I'm guessing that golf cart batteries are going to be harder to come by, and likely more expensive.

Do you have any experience with the Optima batteries?  Are they worth the higher cost?

Thanks.

Frank.

 

[Ned]

Rather than the Optimas, I would recommend AGM batteries.  They are readily available in various sizes and although they cost about twice as much as a flooded cell battery, they will give you about twice as many discharge/charge cycles and charge up faster.  I have 4 Lifeline AGM batteries with a capacity of 440AH that replaced the original Trojan T-105 (a common size) flooded cell batteries.  Another advantage of AGM batteries is that they are zero maintenance.  They are sealed so you never have to add water.  As with any battery, you don't want to overcharge them but a good 3 stage charger will charge them properly.

 

[Ron]

Personally I have never used an Optima battery but I gained from others experience with them in that I don't intend to be getting them. ?If you are going to improve on the normal flooded cell battery then the AGM battery will provide better service but at more cost. ?When it comes time to replace the coach batteries I will be getting Lifeline or Deka AGM batteries.

 

[Frank B]

Ron and Ned:

>Personally I have never used an Optima battery but I gained from others experience with them in that I don't intend to be getting them.<

Thanks to both of you with regard to the various battery types.  While AGM has real advantages, doesn't look like they are going to be as economical in my application.  I'll probably just go with the standard RV/Marine deep discharge units I've been using.  As noted earlier, I can insulate and heat the battery area a bit to keep a discharged battery from freezing.

Thanks everyone.

Frank.

 

[Tom]

So, is there much advantage in the 4 x 6V arrangement in your opinion?

Probably not in your application.

I'm guessing that golf cart batteries are going to be harder to come by, and likely more expensive.

There's a battery distributor within 30 minutes of our place who supplies all the golf courses in the area, so for me it's easy to get hold of them. You might want to call your nearest golf course and ask where they get their batteries.

Do you have any experience with the Optima batteries?

No, which is why I didn't comment on them.

Are they worth the higher cost?

I wouldn't buy them for your application.

FWIW my coach and my bass boat both have regular wet cell deep cycle batteries. My use of golf carts is in a bank of 10 (5 pairs) running an inverter, but not on my coach.

If you go the regular deep cycle route, make sure they're not the typical "marine deep cycle" batteries which perform double duty as a starting battery and a deep cycle battery. They look the same, but have different plates and a different capacity from true deep cycle batteries.

 

[Frank B]

Tom:

>They look the same, but have different plates and a different capacity from true deep cycle batteries.<

Yes.  In looking up info on the web it appears that a TRUE deep cycle battery has much thicker plates.  I'll watch for that.

Thanks again for your help.

Frank.

 

[Tom]

You're welcome Frank. Glad to help.