Battery Question

[jim solo]

I have been looking at batteries to use in a solar power set up in my RV. Pictured (2) below is a battery I was looking at, would two of these work with a solar power set up ? What would the opinion of the experts on this forum think about the type of, and the usability of this battery in a set up. I have no idea, and don't want to waste money.

 

[Trebor English]

First you have to figure out how much your budget will support. A $1000 battery or a $100 total is an important distinction. Figure out how much electricity you expect to use. Make a list of the devices you want to use including an estimate of how much use each day. Then figure out how you will charge the battery. Then you figure out how big a battery you want.

Then consider the battery type. AGM cost 1.5 to 2 times as much as flooded batteries in the US. Maintenance free starter batteries don't last long regularly discharging more than 5% to 10% of their capacity while golf cart batteries can go 50%.

The battery in the picture doesn't have an amp hour rating. The cell caps look like the kind that are hard to get off. That probably means the plates are a lead / calcium alloy for low water consumption.

The last time I bought a battery I searched for the one with the necessary size, group size 24 in my case. Then I looked for the highest 20 hour rate amp hour capacity, then the highest reserve capacity minutes. That's how many minutes it can put out 23 amps before it is dead. Then I looked for the one with the lowest CCA, cold cranking amps. What they have to do to make more cold cranking amps is bad for deep cycling. Finally I compared prices. I did not consider any AGM batteries due to the significant price difference.

Looking at that one battery, Rural King DC27HDT, there is nothing to compare it with. It is probably adequate and would work just fine at some level of use. That level of use isn't obvious from what information is given. That may or may not be the way you want to use it.

A completely different approach: What do you have now? Was it good enough? Did it last long enough? If you liked the old battery, get another just like it.

 

[bass_sears]

Lot of factors here, but first the basics. For deep cycle all you care about is 20 hour rate amp hour capacity, that's how many amp hours the battery can provide in a 20 hour period.

Almost any time you see cold cranking amps anywhere on a battery, or see a battery labeled as "dual starting / deep cycle" there are better options out there for pure deep cycle use.

According to this page's comments (so not the actual specs, which don't show the 20 hour amp hour capacity) this battery can provide 105 amp hours over a 20 hour period... that is quite a good rating, especially if this battery is really only $75, but it's such a good deal for that capacity that I highly doubt that's a legit spec. For example I have (legacy, would never but them myself) some Interstate dual start/deep cycle batteries that claim to have ~65ah capacity but don't deliver anywhere near as much).

Compare the battery you have to the Trojan 27MTX (a 12v, group 27 battery from a very reputable vendor), it also has a 105ah rating, which has been tried and believed in the general community... they go for about $180.

So in theory, if we were to believe the specs on this one, this is the same capacity as a Trojan for half the cost, and therefore a steal. I can't say for sure but my first thought is that's too good to be true and the claimed 105ah in the Q&A section is not accurate.

You say you're looking for two batteries, and the battery you were looking at is a group 27... do you have space for anything a little larger? If so you could go with two golf cart batteries in series, making one 12v battery, and the 6v are deeper cycle so you get more power from them. Two Deka GC15's from Lowes would run $288 total, you'd get 448ah @ 12v from that setup, vastly superior to two 12v 105ah batteries in parallel.

Also, of course, batteries are heavy and difficult to ship, so you'll have to factor in what you can get locally.

-- Bass

 

[DLTooley]

The Walmart deep cycle is a good choice for a single battery set up if your needs only require that. For a two battery setup you are better going with golf cart batteries.

Batteries Plus and Sam’s Club used to be two good sources for batteries. I haven’t looked in awhile, I’m waiting for the price of LiFePo4 to come down a little bit more.

 

[bass_sears]

Batteries Plus and Sam’s Club used to be two good sources for batteries. I haven’t looked in awhile, I’m waiting for the price of LiFePo4 to come down a little bit more.

For golf cart batteries, Deka GC15 at $144 apiece from Lowe's:
https://www.lowes.com/pd/Deka-6-Volt-448-Amp-Golf-Cart-Battery/50183775
... get a Lowe's card and you get 5% off everything at Lowes.

-- Bass

 

[B and C]

If you're new to using 12v stuff, the "marine" battery shown will work. Most people's first set of batteries are the learner set that get beaten to death from chronic under charging and chronic over discharging. A cheap set to learn from is a good way to start.

 

[tx2sturgis]

Short answer:

Yes, they will work.

 

[jim solo]

Thank you all for your input. The batteries pictured are just $75.oo each. I thought I might be able to use them as a learning experience. I do remember seeing a Deep Cycle battery at our Advanced Auto store for around the same price a year ago. I'll have to look at them again. I'll get some spec's on those next time I get to town. I'm thinking they might have been around $68.oo each.
Memory is getting slow. I need to make more notes and don't loose them.
2 or 4 is what I was thinking to get, as a Back up power source. LED lights, charging phone and laptop. I can make two pots of coffee on a fire I guess. Thanks again, this winter season has been Hell for me getting anything done. Spring and summer are coming, hope it is dryer that the past two years.

 

[billybob200138]

10% off at Lowe's if you're a Vet. HJ