Misc. battery hookup?

[1stmate]

Hi all-

Quick question about battery mixing- can I do it?

I have a small solar set up, primarily for emergency/power outage usage (worked great for 11 days in Dec). I have a mix of batteries, including trolling, auto, & even a garden tractor battery! They are all 12v of course, but can they be ganged together (w/out damage) in parallel with all the various a/h capacities?

Thanks in advance,
Jack in NH

[flatwater]

I'm not that good at solar but from what I have read the batteries should be of equal size. But with that said , you may get by with it for a while

[PaulNKS]

Jack,
I think you are asking for trouble. The weakest battery will pull the rest down... Your battery bank will only be as good as the weakest one. Not only that, but the shallow "auto" and "lawn" type batteries will not last long. They are not designed for heavy duty or deep cycles like the proper batteries.

If you don't buy batteries designed for solar, you need to go with deep cycle 6 volt batteries. They are the only ones that are heavy duty enough for solar. RV and marine batteries claim to be deep cycle but aren't. They are a "hybrid" between a deep cycle and the shallow cycle auto battery. They aren't heavy duty enough either.

My first set of 6v batteries lasted 6 1/2 years. I bought the first ones for $57 each. I replaced them just a few weeks ago and they were up to $94, I think. Since I live on a farm and claimed they were for my tractors, I didn't have to pay all the sales taxes on them either. Actually, he told me if they are for my farm office I wouldn't have to pay tax.... lol

I hope that helped... I wouldn't use any of the ones you have.

Good Luck,
Paul

[kmccune]

Man ain't that the truth,old batteries will kill good batteries real quick.The people I used to work for would try that on Mack trucks-they would start when it was warm-first cold morning,break out the jumper cables.Always replace in sets and the easier you are on the batteries the longer they will last.
Paul have you heard in the grapevine anything about any improved types of storage batteries?At any cost?It would be so nice if we could capture more solar&leave the Dino in the ground.I do know that some of the utilities have some huge (Megawatt or more) chemical storage units for peak demand-Kevin

[PaulNKS]

Paul have you heard in the grapevine anything about any improved types of storage batteries?At any cost?It would be so nice if we could capture more solar&leave the Dino in the ground.I do know that some of the utilities have some huge (Megawatt or more) chemical storage units for peak demand-Kevin

Kevin,
I haven't heard much... I know there are a lot of things being worked on, but I haven't heard anything about new storage. Maybe 12vman knows.....?

[kmccune]

How about it 12Vman,any new storage on the horizon?Kevin

[12vman]

Within the price range of most common folks, lead-acid batteries still rule. Some of those can be pricey but you get what you pay for. In most cases, the 6 volt golf cart battery is the best for smaller set ups, IMO..

Mixing different capacity (aHr.) batteries with the same voltage and charging them together isn't good. The charger or in the case of using a charge controller, the battery with the largest capacity will be seen over the rest and over charge the lower capacity batteries. The controller will sense resistance (or, load) from the larger battery(s) and hold the voltage up during the bulk charge period and boil the smaller ones to death.

[kmccune]

Thanks.12vman,good explaination-Kevin

[1stmate]

As usual, thanks to all for their generous input.

I’ve been using the batteries individually, as the load presented to them is very small & the panel input is often greater than the load. So, I guess I’ll stay that way until I procure a few “good” batteries.

BTW Don, I took your advice from back in 12-’07 on the HF battery charger (for small batteries from 12v) & it works great! Thanks again…

Jack in NH

[12vman]

No problem, guys. That's what this place is all about.

Thank you.. ;)