12v system battery

Hey guys I need to buy a battery for my 12v system I know a deep cycle Marine battery is the standard. I was just wondering if there’s a certain brand or amp that is the Preferred.


A group 27 from WalMart seems to be the standard, works for me. Mine was about $100.

I’ve said it before and I stand by it. If you plan on being in business for years, just go lithium iron phosphate. Yes they are 3-4x the cost, but you most likely won’t need to buy another one ever. 6000+ cycles. You get full power for 95% of its capacity too, so no 10-11v when you run it a long time, they stay 13-14v the whole time.

Buy one, cry once, right?


I agree with you that lithium is currently the way to go for long term use, but there is quite a bit to understand before you go down that road because they operate differently and have some special considerations to think about when you are designing the whole system. They are NOT a drop in replacement for deep cycle, lead acid, AGM batteries. Most people are not going to want to pony up the $750-1000 for a quality lithium battery that MIGHT last 10 years versus spending $100-150 for a run of the mill deep cycle RV/marine battery, even if they had to replace it every year. Picking one up from your local auto parts or discount store versus having to order one online, pay shipping, and wait for it to arrive is also a hurdle for many. They have their place, but in the back of a truck or trailer for our use case is probably not it.

  • Brand is not too important, but if all you see is foreign writing on the label, stay away from that one.
  • You’re using a battery box of some kind, right? If you’re not, you definitely should be. It will help you secure the battery in place, protect it from things that it won’t agree with like bleach, and protect everything else from it too.
  • That box is designed to hold a certain sized battery; get that size (commonly a group 27-31)
  • Something around 100 Ah is both reasonably priced and should have enough energy to power your typical things. Now if you have a lot of stuff, unusually high draw stuff, or will be running stuff all day long, you should definitely put some more thought into your overall system design… or at least buy 2.

Go pick up a autolite gold at Wal-mart depending on what group you need. Like $100, lasts around 12 hours. Your not going to beat the return on investment with that battery.

Anyone have objections to the following battery? I came across a “like new” one for $50 and am thinking of pulling the trigger on it. It would just be to run my 12v pump, one strobe light, and occasionally 2 pod lights.


Looks like a good deal to me….

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$50 is a heckuva deal. I personally am not a huge fan of AGM batteries due to them losing their capacity over time and being sensitive to overcharging but for $50 I’d probably run it into the ground as many times as I could.

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What @DisplacedTexan said. I tried a few of them over the years, wasn’t real happy with them, but for $50, what the heck

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I can tell you that the Schertz Box absolutely nuked two AGM lawn mower batteries in less than two hours of run time. Brand new and theoretically not undersized but they just could not handle it. I now run the box off of the parallel 12v batteries for my soft wash system. I don’t think they even know that box is there.

Thank you all. The cheapo $33 lawn tractor battery I picked up at Lowes two years ago decided it wasn’t going to do it for me anymore. It still worked fine to run my little LED strobe light all day this past Monday while washing, but the 12v pump runs about 45 seconds before you can hear it start to slow down due to the battery voltage dropping rapidly.

Have you tried reconditioning it? I’ve had pretty good luck with that on my little batteries in the past. Just not the AGM ones lol

I’ll have to look up whatever reconditioning a battery is.



Hell, I don’t get that involved. Just slap it on the charger and jam the “Recondition” button and voilá

Something about charging it at a higher voltage initially then dropping down to a lower voltage for an extended period. I don’t know. It works though!

You’re trying to drop the sulfation from the cells with the heavy current

That’s probably right but I just prefer to assume it’s



Perfect… you can’t be that sick. You’re at the top of your game lol