(ET) Batteries, speed control, mower motor, brakes

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

On 2 Aug 2000, at 12:53, G McPherson wrote:


> 1. The power pack I charged for three days and it brought the voltage up
> to <36 volts.

As others have written, first check the charger before assuming the pack 
is toast.  If you're not sure about the ET charber, use a known-good auto 
battery charger to charge each 12v pair, and see if they'll come up to at 
least 1.240 on the hydrometer.

If the batteries are sulfated, don't put too much into trying to salvage 
them.  Personally, I think people waste too much time trying to keep 
crispy old batteries (barely) alive.  

Buy new ones.  I like US Battery (Interstate Workaholic) and Trojan 
brands, but there are others that some people swear by.  It's not that 
horribly much (about $360), and with care they'll last 7-8 years.  

If you can't afford or don't want to spend that much, go to a golf course 
or golf car dealer and buy some used, tested batteries - maybe $60 to 
$120 for a set.  You'll get at least a few years out of them.  

Take your sulfated old batteries to the recycling center.

 
> 2. The Speed Control lever unfortunetely did no better at the full
> voltage. 

The problem could be in the switches on the speed control, or in the 
contactors.  Most likely it is on one or more of the control cards.

The control cards have a time constant to prevent abrupt acceleration.  
The problem could be an open diode, leaky capacitor, or other small 
component failure on the card.  I have found a diode literally burnt in 
two on mine.  If you're not handy with a soldering iron, you may have to 
replace the card with one  from Bill Gunn.

It could also be something as simple as dirty connections to the cards.  
Carefully remove each connection and clean the clip and PC board lands 
with a pencil eraser or fine steel wool (be sure to blow out the steel 
wool's metal dust with compressed air).  Apply a touch of Cramolin 
(available at good electronics jobbers) to the pc board lands and the 
clips and reassemble.  See if that helps.


> 
> 3. When I worked on the mover the one blade was a little stiff so I
> inverted the mover and dropped oil into what appeared to be the lower
> bearing. 

You have not fixed the problem.  You have demonstrated that the problem 
is the bearing.  

Now, CHANGE THE BEARING.   If you don't, you'll regret it.  A worn 
bearing can cause the armature to strike the field magnets and break one 
or all of them.  This is ~extremely expensive~ to repair, and not a do it 
yourself job.

OTOH, bearings are maybe $10-15.  The lower one, which is the one most 
commonly defective, is easy to change yourself in an afternoon.  All you 
need is a 2-jaw puller.

Of course if you have a storehouse of extra tractors for spare parts, 
maybe you can afford to break a few motors.


> 
> 4. I found the brakes pretty weak.

Buy Bill Gunn's brake upgrade.  It makes them work better than new.

Bill Gunn, Technical Service:  608 868-6220


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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