[EVDL List]

Darin @ forkenswift dot com wrote:
> we received a collection of used 3 & 4 year old Exide floodies...
> we'd like to stretch the usefulness of these batts to the maximum.
> But until now, we've just been running what we were told were the
> "best" 8 batts in the (48v) car, and the rest have been sitting
> in a shed (charged once in July, but not maintained since that
> last charge).
>
> Should we be rotating all the batteries through the pack? One at a
> time? Should we assign batts to 2 packs and swap packs all at once?
> How often? What would you do? Any advice is welcome.

They'll self-discharge and go bad if left sitting unused for months.
From July to October is already a long time for old batteries. Check
their voltages; if any are below 6v, you've probably already lost them. :-(

The right way to store them is to put them on some kind of "float"
charger, or to charge them every month or two.

A float charger is one that holds them continuously at about 2.25 volts
per cell (6.75v for a 6v battery). It can be small, because it needs to
supply less than 1 amp per battery. It's probably easiest to find a 12v
float charger (often called a battery maintainer). In this case, connect
your 6v batteries in series pairs, and then the pairs all in parallel so
a single 12v float charger can maintain all of them at once.

The other approach is to use a 12v charger (or your regular 48v charger)
to charge up groups of batteries every 1-2 months.

It might also be a good time to get an inverter/charger, and use these
extra batteries to set up an emergency power system for your home. The
better inverters include a reasonable charger. You can use it to
maintain your batteries, and test them as well (by measuring how long
they can run a 120vac load) before the inverter shuts off).

--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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[EVDL List]

Lee Hart wrote:
> They'll self-discharge and go bad if left sitting unused for months.
> From July to October is already a long time for old batteries. Check
> their voltages; if any are below 6v, you've probably already lost them.
> :-(

I will sheepishly admit that I *knew* better to leave them sitting. And to
have left them discharged&discharging particularly through the hottest part
of the year makes it even worse.

Since starting this thread, I got all 14 batteries on the charger, and
fortunately it appears just one of them is terminal (pardon the pun).

I swapped the eight with the highest SOC (per the voltmeter) into the car -
and fully recharged the "good" pack after I removed it. And after lots of
DMM monitoring over short trips, none of the swapped-in ones appear to be
duds, (though the pack is pretty out of balance).

So I guess I'm lucky!

Thanks for the other suggestions, e.g.: using them for home back-up power.
I actually have an old UPS that I could use for just that purpose. And a
buddy got a surplus 24v UPS from work that is just sitting in his garage.
These batteries won't go to waste.

Darin
--
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