Re: (ET) Charger Problems?

["David Roden (Akron OH USA)" <roden ald net>]

On 15 Jun 2001, at 7:51, marty canada wrote:

> During the charging process I did some volt meter checks. Each battery
> read 6.22 v or higher up to 6.30 which seems pretty well balanced to me. 

If those are the voltage measurements with the charger connected, they 
are very low.  A 6v golf car battery should reach about 7.5 volts (some 
say 7.75 volts) at end of charge while still connected to the charger.

It may be that your charger's output is too low.  Are your batteries 
gassing freely (bubbling) at the end of charge?  If not, they are not 
fully charged.

Try charging the batteries in pairs using a known-good ordinary 12v 
automotive charger.  It may take as much as 24 hours per pair, depending 
on how discharged they are and how much output your auto-battery charger 
can attain.  

When the charge is complete, check the batteries' specific gravity using 
a good quality hydrometer (available from battery specialists).  They 
should read 1.250 (old batteries) to 1.280 (new batteries) when fully 
charged.  Individual cells should be within about .010 of one another.
        
If the batteries were gassing freely for several hours but specific 
gravity is still below 1.250, your "new" batteries may have been damaged 
by long-term undercharging, which causes sulfation.  The snake-oil 
salesmen have various "cures" for sulfation.  Some people think they 
work, but I think that you can usually accomplish about as much as their 
expensive gadgets do with a good equalization charge.  

Ideally this would be done with a constant current charger.  First give 
the batteries a normal charge, then give a 12-amp charge for 4 hours with 
no voltage limit.  Or, try a 4 or 5-amp charge for 12 to 36 hours.  You 
may be able to do the latter with the ET charger, possibly adding a 
series resistance to limit the current.

If this doesn't bring the SG up, replace the batteries.


David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1979 General Engines ElectroPed 24vdc
1974 Honda Civic EV 96vdc
1970 GE Elec-trak E15 36vdc
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