Power supply AGM's

1556 Views 4 Replies 4 Participants Last post by Sunking, Dec 22, 2010

spdas

Discussion Starter · Dec 17, 2010

Aloha this is not a discussion to promote agms vs lithium, but I have noticed that small AGM's (such as 9hr ones) that you would find in UPS's have about 40-50% more ah versus weight compared to an Optima for instance.
Optima=520 cubic size 41 # and 50AH
UPS Bat=60 cubic 5# and 9 ah

So you can put 8.2 of these UPS batteries @ 41# in the optima space and get 74ah and even have a smaller footprint.

I recently got 100 of the UPS batteries for free from company that changes them out every 18 months, so wondering if it is worth a try to say parallel 10 and series 16 to make (total 160) 192V @90ah.

Other than "Forget it and buy Lithium" does this seem workable?

Francis

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major

· #2 · Dec 17, 2010

spdas said:
Aloha this is not a discussion to promote agms vs lithium, but I have noticed that small AGM's (such as 9hr ones) that you would find in UPS's have about 40-50% more ah versus weight compared to an Optima for instance.
Optima=520 cubic size 41 # and 50AH
UPS Bat=60 cubic 5# and 9 ah

So you can put 8.2 of these UPS batteries @ 41# in the optima space and get 74ah and even have a smaller footprint.

I recently got 100 of the UPS batteries for free from company that changes them out every 18 months, so wondering if it is worth a try to say parallel 10 and series 16 to make (total 160) 192V @90ah.

Other than "Forget it and buy Lithium" does this seem workable?

Francis

Hi Francis,

Those will not be deep cycle batteries meaning a cycle life in the dozens instead of 100s. And they likely will not have the power capability of the larger Optima, even when paralleled.

And why do you think your source is changing them out and giving them away? UPSs typically have a crappy float charger which cooks the electrolyte out of AGMs in a couple of years. Even if they are still functional when you get them, chances are they won't be for long

If they're free and you got the time to play with them, why not? But don't get your hopes up.

major

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spdas

Discussion Starter · #3 · Dec 17, 2010

Rats!! I guess there is no such thing as a free lunch! Thanks for the tip.

Francis

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DCBATTERY

· #4 · Dec 22, 2010

spdas said:
Rats!! I guess there is no such thing as a free lunch! Thanks for the tip.

Francis

Trust me I would not consider there is no such thing as free lunch. Those 12v 9ah batteries weigh roughly 7 pounds each. Depending on how much a local recycler will give you (down here in Miami the average is .20 cents per pound) you have around $140.00 worth of lead sitting in your hands.

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Sunking

· #5 · Dec 22, 2010

major said:
And why do you think your source is changing them out and giving them away? UPSs typically have a crappy float charger which cooks the electrolyte out of AGMs in a couple of years.

Well the cheap standby home units that is true, but for the commercial and industrial dual conversion and line interactive types have very high quality rectifiers built into them..

But your point is valid batteries used in Telecom are designed for emergency standby use and make for poor cycle service. I know a lot of folks who have learned this the hard way getting free batteries from telephone companies to use on solar off-grid systems. The Telcos save a ton of money giving batteries away to suckers leaving them with the disposal cost and headaches.

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