used batteries... are they worth it?

[jackluminous]

Hi all,

Somebody has offered me a sizable battery bank (for free) and I am wondering if it's worth the trouble. My setup is really small at present (a single 54-watt solar panel) and I haven't obtained any batteries for it... I am looking at purchasing about 220Ah capacity at 12 volts for about $100. That should suit my needs for quite a while.

The battery bank offered to me has 11 2-volt AGM batteries (apparently there were 12 wired in series parallel and used in a 12-volt system, but one of the cases cracked). The individual offering these batteries tells me that when the bank was hooked up and working it stored 1500Ah. They have not been hooked up for about a year. He disconnected them because he had them hooked up with another bank of wet cell batteries; the AGM bank was preventing his wet-cell bank from getting fully charged.

It seems to me I could use 6 of the batteries wired to produce 750Ah at 12 volts and keep the remaining 5 as backup.

Of course this used bank is free so there is a sense of "what do I have to lose". Only I would have to build a storage space for them (currently I don't have room to store that much weight in an enclosure without building something) and I have no immediate plans to implement much more charging capacity than my single 54-watt panel. It will also cost me some money for the wiring to interconnect that many batteries.

So basically I am asking for an idiot check... am I an idiot to pass this up?

[Tritium]

You can get 2 Flooded Lead Acid of that capacity at Sam's Club for a little more than that new (golf cart batteries, 6V at 220aH).

Thurmond

[jackluminous]

Sorry if I wasn't clear in my post. The AGM battery bank is being offered for free and would theoretically provide 750Ah capacity.

The alternative is buying flooded golf-cart batteries, 220Ah, for about $100.

I can put the 2 golf-cart batteries in a simple battery box I already have. I would have to build something new for the 6 AGMs. Just wondering if all that effort makes sense with a single 54-watt solar panel to charge the AGM bank.

[Tritium]

I am a pack rat so I would go for it. I currently have about 4000 lbs (24) of 2V wet cells I got from the telephone company I work for waiting for a place to be built so I can use them. Even if I don't get them in service they have a scrap value of about $1000.

Thurmond

[halfcrazy]

hey if there free i would try them what have you got to lose besides a little time

[TheCasualTraveler]

    I'm a firm believer in novices using used batteries to learn battery basics on. Use these to learn how to pick 6 that are fairly equal, learn how to test them, keep the water level up, do load tests etc. then you'll be ready to give new ones the care they need.

[scottsAI]

Jackluminous,

Hard to turn down free batteries.

I use 8 golf cart batteries as a backup home power system and 100w solar (not connected)

Important to keep batteries charged up or they go bad... The 5 spares must be charged if expect to use in the future. Lead value as most metals dropped through the floor. Cant get anything for iron any more.

The over sized batteries will take up all your solar power just keeping them topped off. (maybe not enough). Will need another charger to replace anything you use.

Inexpensive cables can be made with a bit of work.

Question is what do you need the batteries for?

Learning... then get them.

Power backup? Yep go get.

What other reason?

The price is divine, what is your time worth? What is learning worth?

Have fun,

Scott.

[SparWeb]

...am I an idiot to pass this up?

Yes.  Go for it!

I scored a free stack of AGM batteries and they're still pumping juice 18 months later.

If the batteries you get are only 50% good, then you still have 700 Ah of storage to play with.

[jackluminous]

Thanks everybody for the sage advice!

I've decided to buy the golf-cart batteries for $100 AND take the free AGMs. I figure it would be good to have an appropriately-sized bank for the system I intend to rely on, and then pick up the AGMs for learning and experimentation. I will need more solar panels and another charge controller to take advantage of the AGMs but I figure I can try to scrounge up some working used/damaged panels for cheap or free.

Since the AGMs have been sitting unused for a year I expect them to have little or no charge. All I have to charge them is my 54-watt panel and a 500-watt generator, so I am wondering if it's best to take the AGM bank to a battery specialist in town to have them charge it up for me. What do y'all think?

Once I identify the 6 keepers out of the 11, any ideas on what to do with the 5 oddballs?

[ruddycrazy]

I might be a bit late on this thread but about free or cheap secondhand batteries.

4 years ago I scored 30 6 volt 105AH agm's for $240 and they are still going strong as my main shed bank. 3 years ago I scored 24 2 volt 275 AH agms for $400  3 years old and never off float, that is my shed backup bank. I have used the main bank for a 6 hour major machining job in my RE machineshop and they only dropped 2 volts. That backup bank ran my bridgeport mill for a 6 hour job and only dropped a volt.

So yes cheap or free batteries if you can get them GO FOR IT and if any are faulty eh just use em for a dumpload on your next wind turbine project.

Cheers Bryan