Re: (ET) Trouble with battreis, speed control, and mower???

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

Is your charger working right?  Do the batteries gas (bubble) freely at 
the end of the charge?  If you're not sure, try charging the batteries in 
12 volt series pairs with a known-good auto battery charger.  That may 
also solve the imbalance.  They should come up to 12.50 - 12.85 specific 
gravity.  If they won't charge beyond 12.25 or so, they should be 
considered near or at the end of their useful lives.

The low SG, low open circuit voltage (on the "fuel" gauge), and high 
voltage drop in operation all indicate either that the pack is well below 
full charge, or has a bad cell.  

I hope you have a multimeter.  If not, go to Radio Shack and spend at 
least $30 for a modest DMM.  Measure the voltage of each battery in the 
pack and look for one that's about 2 volts lower than the others -- that 
would indicate a bum cell.  If the voltages are within a half-volt or so, 
the batteries are either not properly charged or are sulfated.

Were they fully charged when you stored the tractor?  A battery stored 
for weeks or months when fully or even partially discharged will become 
sulfated.  This is a permanent loss of capacity.  In spite of what the 
snake oil makers tell you, sulfation should be considered irreversible.

Some people claim that "pulse desulfators" help.  I haven't tried them; I 
think they're overpriced for what they are.  If you want to play with 
them, there's a do it yourself circuit in Home Power magazine this month.

However, I suspect that you'll get the same effect (if there really is 
any) with a long (days or weeks), slow (1-2 amp) equalization charge.  
The ET charger may be a bit crude for this, but if your batteries are 
sulfated anyway, overcharging is the least of their worries.

I don't consider the cost of 6 golf car batteries to be very high.  First 
try charging with the auto battery charger as described in the first 
paragraph above.  If they don't improve, replace them.

The speed control problem is probably unrelated to the battery problem.  
The switches are sealed, so you can't really clean the contacts. This 
shouldn't be too tough to solve, though.  The "homeowner's manual" has an 
excellent flowchart style troubleshooting section.  If you don't have a 
copy, get one from Technical Services.

The mower motor's lower bearing should be replaced.  Check the upper one 
too.  The lower bearings always go first, in part because people clean 
their mower decks with running water, which washes grease out and dirt 
in.  If they're not replaced as they wear, the armature can strike and 
break a field magnet.  Rough bearings are cheap and easy to fix; magnets 
are expensive and usually require motor replacement.  So you might as 
well do all the bearings in the deck motors at the same time, at least 
the lower ones, as "magnet insurance."

Let us know how you make out.


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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