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Discussion Starter #1
Hi all -

Thanks to the generosity of a fellow EV driver, Project ForkenSwift is
no longer driving on worn out, grossly mismatched, bulging, leaking, 6v
floor sweeper floodies (!) that the local forklift company was supplying
us for free to get the car running.

Instead, this summer we received a collection of used 3 & 4 year old
Exide floodies out of a Ford Ranger EV (
http://www.austinev.org/evalbum/600 ) and a VW Jetta EV.

My question revolves around the fact that we were given *twenty*
batteries. (And he wouldn't even let us pay for them - not even the
equivalent refund he would have gotten from the recycler! Nice guy!)

Considering the "beer budget-ness" of the 48v ForkenSwift, 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.

thanks-
Darin

Project ForkenSwift
http://www.evalbum.com/1146
http://forkenswift.com

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Discussion Starter #2
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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Discussion Starter #3
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
--
View this message in context: http://www.nabble.com/best-approach-for-using-2-battery-packs--tf4604890s25542.html#a13264545
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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