Recommended 12V Battery Brands

[chriscowles]

Is there such a thing as a 12V pure deep-cycle battery? If so, I need two to serve as backup power for my CPAP at home. My wife and I both use it. 2 x 6v is not practical for that purpose. I'd like to use the same batteries for occasional dry camping. As I usually have shore power I don't want to lug the extra weight of 2 batteries unless I expect to use them. For those reasons I hope to use 2 x 12v in parallel for dry camping, rather than 2 x 6v in series.

[f5moab]

Deka makes true deep cycle batteries, just make sure it is a DC battery (e.g., DC24) and i believe Trojan makes true deep cycle batteries too.

[DKRITTER]

Recently went to dual batteries on my Lacrosse 327 and just matched what had come on the trailer when we bought it late last year. It happened to be a 27 series NAPA so I took a picture of the top of it and walked in to the store and said do you have one of these?

Had to build a bracket to run the 2 n/s because Lacrosse put the bracket to far forward to run 2 e/w.

[chriscowles]

If I can reliably get a day's use out of 2 group 24s without risk of during in the middle of the night, that (and a small generator) may be my first step. I'll accumulate what I need to charge/maintain a pair of 12v DC batteries and but those when my pair of 24s no longer serves the purpose.

As I need 12v for emergency brakes but don't want to schlep the bigger batteries back and forth to the storage site when retrieving the trailer, I'm thinking of a much smaller 12v to keep on the trailer for brakes. What size do I need for that? Is that a good/bad idea?

[Dave Lyon]

Originally Posted by f5moab

Deka makes true deep cycle batteries, just make sure it is a DC battery (e.g., DC24) and i believe Trojan makes true deep cycle batteries too.

I use Deka as well (DC 31) and have had good luck. As others have mentioned, it should be a true deep cycle and not dual purpose.

[camaraderie]

The NAPA deep cycles are also Deka/EastPenns and will have a DC in their model number if they are true deep cycle.

[ependydad]

My local battery wholesaler (The Best Battery Company, Inc. | Baltimore, MD) had a Trojan 27TMH for something like $80-100 cheaper than anywhere I could find. I asked them easily 3 times if they were sure of the price and still feel like I won something over on them.

[twiggw]

I swear by Interstate. Got in a jam and had to buy a NAPA battery once. Won't make that mistake again. Interstate all the way.

[chriscowles]

I just looked at the battery supplied with the trailer. It's a Deka DP24. So, while it's undersized and not the ideal type, at least it's decent quality.

Considering that I rarely dry camp, that I need to assure that the batteries won't die overnight when using 2 CPAPs without humidifiers, and that I'm willing to recharge daily, is it reasonable to buy a single DP24 so I have a matched pair? My CPAP draws 3.0A max without humidifier, according to the user manual; my wife's draws 5.0A. We use low pressures so they probably draw less than that.

In addition to LED lights we may have a fantastic fan running, if warm. Also, the usual parasitic loads like gas monitors and the 12v controller for the refrigerator when operating on propane. Considering that, am I correct in believing a pair of DP24s would suffice until I choose to replace them with a pair of true deep cycle batteries?

Is it important that the batteries match? If I found a DC27 or DC31 at a price I was willing to pay, is it bad news to combine it in parallel with a DP24?

Thanks

[chriscowles]

I found some specs for the DP24 which suggests that a pair is not sufficient for my needs. If I'm reading correctly, one DP24 has a 65 AH capacity. A pair gives me 65 AH available, since I shouldn't discharge more than 50%. The CPAPs draw 8.0A max, total. That gives me 8 hrs for the CPAPs, alone, not counting any power consumption between charging and bedtime.

[mcnabbwr]

I have dual Interstate SRM-27's and they perform well, however they are only a year old. Time will tell but I'm very optimistic they will provide years of service.

[itat]

Originally Posted by chriscowles

I found some specs for the DP24 which suggests that a pair is not sufficient for my needs. If I'm reading correctly, one DP24 has a 65 AH capacity. A pair gives me 65 AH available, since I shouldn't discharge more than 50%. The CPAPs draw 8.0A max, total. That gives me 8 hrs for the CPAPs, alone, not counting any power consumption between charging and bedtime.

When you wire them in parallel you add the Ah, so if they are both 65 Ah wiring them in parallel will give you 130 Ah. You'd be a lot better off with 2 true deep cycle batteries that will be in the 100 Ah range each for a total of around 200 Ah.

[chriscowles]

Originally Posted by itat

When you wire them in parallel you add the Ah, so if they are both 65 Ah wiring them in parallel will give you 130 Ah.

I understand to add the capacity but don't I then divide by 2 to determine the usable capacity? I've read they should never be discharged more than 50%?

[GreenImp]

Originally Posted by chriscowles

I understand to add the capacity but don't I then divide by 2 to determine the usable capacity? I've read they should never be discharged more than 50%?

It is considered a "best practice" to not deplete below 50% for longevity purposes, but it's not the end of the world if you go a little below occasionally. When discussing battery bank capacity though, you normally talk total Ah capacity (because it's there if you NEED it).

[itat]

Stopped at Costco in Oshawa today. They have Kirkland brand deep cycle batteries which are supposed to be made by Johnson Controls.

Group 24 has a 95 Ah rating @ $95
Group 27 has a 115 Ah rating @ $105
Plus $10 core charge without an old battery trade-in

[camaraderie]

Originally Posted by itat

Stopped at Costco in Oshawa today. They have Kirkland brand deep cycle batteries which are supposed to be made by Johnson Controls.

Group 24 has a 95 Ah rating @ $95
Group 27 has a 115 Ah rating @ $105
Plus $10 core charge without an old battery trade-in

The specs are exaggerated. NO Group 24 or 27 has amp hours that high.
Figure 10-15 amp hours less than that in actual use situations.
That is not a slam...just advice. Make sure there is NO mention of starting or cranking amps on the label or you are probably looking at DP batts...but nothing wrong with JControl batts in general....but never have seen a true deep cycle from them other than in 6V

EDIT: Looking at some JC group 24 batteries on their web site...I see a RESERVE CAPACITY spec of 95 amp hours...Could you be confusing this with 20 hour ratings which are different and typically in the 75 amp hour range for this size battery?

[itat]

They likely are optimistic. I know they aren't pure deep cycles because they state cold cranking amps. The labels say Amp-Hours.
http://www.costco.ca/kirkland-signature-batteries.html

[itat]

BTW, Trojan claims 115 Ah for their 27TMH battery and 105 Ah for their 27TMX model.

[Cornelius]

Before I turned to the Dark Side and purchased an 8 MPG motorhome, I had an electric Chevy S-10 pick-up truck. It was powered by 24 East Penn Deka 6 volt golf car batteries (144 volts total). The Deka batteries worked great and never had a single failure during 4 years of daily driving. Sam's Club sells the Deka golf car batteries under the Duracell brand in some locations. Other Sam's Clubs sell an Energizer branded battery which I think is made by Johnson Controls. It depends on what part of the country you are located in.

[bjlyons]

I find it strange no one mentioned six volt batteries. Two six volt deep cycle batteries are much better than one 12v and will last for years.