Re: (ET) Heat Generation from charging

[David C Robie <mycroftxx1 juno com>]

Yrs ago, made up a set of long test leads with clips on em.  Have velcro
on the back of one of my many cheap Asian VOM's. Also, velcro on the dash
of both tractors.  Hooking up the meter to one batt at a time,  drive up
a hill to give her a much  better load than even a load type batt tester
does.  The Edrop shows an awful lot better than just in neutral, which I
tried first.  Have a 100A load tester and a batt that  badly affects
performance and range don't move the pointer more than 1/8" in comparison
to others.
   Have a similar rig on my 20 batt Ford pickup, meter velcroed to dash.
A DPDT switch goes to a pair to each batt compartment and I have 1K 1/2W
isolating resistors on all 4 of the clips. This, then, is a 'manual
battery scanner' for a motor that pulls 400A getting away from a traffic
light.  (I note the drop, write it down, then pull over and change the
clip to the next battery in the chain).  Pulling out at full bore, I note
that reading of the different batt and write it down.
Having one batt connected in each compartment, one side of the switch is
the 'standard for comparison'  the other is the 'batt being tested' which
only that lead moves to each batt in turn.  Then the operation reverses
to do the other compartment. 
     Big Edrop is normal in a fullsize EV the question was 'how much
beyond normal' and this rig answered it fine.  Some day will write it up
for CE.   As I was, at the time, using all recycled (junkpile) batteries,
this enabled the stinkers to be weeded out among 20 of em without
spending more than ten bucks on the whole test apparatus.  Needless to
say, before doing this test, batteries must be 'equalize charged' first.
    I started doing this type test when I only had a GE 8 with series
parallel 12V car batts from the trash in her. No switch or comparison
standard needed on the tractors, just a pencil and paper and numbered
batteries so this grey haired guy would remember the readings.  Of course
removed the parallel connection and did em one compartment at a time with
the 12's (the 8 holds 3 in each compartment, be they 6 or 12.
     The world is full of fairly decent used 12V batteries at the town
recycling pits.  Some people just change em cause winter's coming on.
Been messing with PV solar and homemade windpower and EV's for quite a
number of years and only once did I have to buy a new battery.  At that
point, bought 20 of em (145's) (for the big EV)  The old ones, although
decreased to half range for the fullsize EV worked great in the tractors
and also made me a real decent 12V PV battery bank.  So most of the 12's
went away. Keep a couple around for experiments etc and for 120V inverter
when I go camping etc.  Cycle em once in a while so they won't sulfate.
If they do, who cares, decent ones are always free down at our town
recycle pit.

Dave
Weymouth MA




On Wed, 30 Aug 2006 11:05:46 -0400 "David Roden" <etpost drmm net>
writes:
> On 29 Aug 2006 at 19:01, David C Robie wrote:
> 
> > Often, the problem of 'low range, Edrop on the voltmeter'  is 
> caused by a
> > single battery being no good in comparison to the rest of the 
> pack.  The way to
> > find this easily is to measure every battery and you will find one 
> that is much
> > lower than the rest of em.
> 
> Best done with the pack under load.  A "dummy load" is darned useful 
> for 
> this, but if you don't have one, at least run the motor in neutral, 
> or jack 
> up the wheels.  The one with the lowest voltage is the problem 
> child.
> 
> You can also measure voltage of each battery shortly after starting 
> the 
> charger (measure with the charger running).  The one with the 
> >highest< 
> voltage is apt to be the stinker.
> 
> 
> David Roden - Akron, Ohio, USA
> 
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