Re: parallel packs?

[Al Godfrey <agodfrey direct ca>]

Greetings Trakees,
 What a lot of great and sudden activity here on the Elec-trak discussion 
list,
a welcome relief to the  rather over loaded EV Discussion list from which I
recently 
reluctantly un subscribed.
However, after 3 years there I learned a great deal and  there have been 
many
discourses 
held on the subject of parallel battery packs.  There are several basics to
keep in mind.

Don't even think of paralleling batteries un less they are identical. That
means the same make, 
the same model, the same size, the same age  or mfr batch.

Once you have two or more identical batteries in parallel you can treat 
them as
one big battery 
as far as charging and discharging .  The charging current will be evenly
divided so
a larger charger would be an asset to reduce the charging time. It is best 
to
let them live together 
as buddies and they will remain self equalized.

I have been watching the 24 Optima Yellow Tops in my EV carefully for 2 
years,
waiting for some sign 
that I could use as an excuse  to remove 6 of them  to put into my E-12, 
but so
far they are 
staying perfectly balanced and equalized.( The 144v pack consists of a 
series
string of 12 
parallel pairs)

Best wishes to all for 1999

Al Godfrey



At 07:59 AM 1/5/99 -0500, you wrote:
>Good answers all the way 'round. Great discussion!
>
>I'll tell you how the parallel packs goes, because I'm going to go ahead.
>Here's a few notes:
>
>- The second pack will be charged separately from the main pack (this is
>purley practical: the load charging two packs at once is, I 'm sure, too
>much. 20+ Amps for just one, after all..)
>- I'll be trying to characterize the battery packs a little: measuring
>voltage across individual batteries and across packs before, during and
>after charging, and before and after use.
>- The second pack will be disconnected when not in use.
>
>I have to get a specific gravity meausing device, too, surely.
>
>More later, thou bravest tractorists!
>
>Max
>