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Re: (ET) charger problem
Wow - so many possibilities... two more things that have come to mind
are if the replacement contactors are the correct voltage and if your
field winding is getting power. But one item at a time:
Hot contactors & meter always in the red: I should have thought of this
before... if the field winding is not getting power, the armature &
compound windings will draw huge currents to move the tractor (which may
seem underpowered/slow). I generally diagnose this just "by feel"
(having experienced it before). To check with a meter, you need to
measure the voltage from the diode/varistor card to the "-" on B5. The
card is hard to get at, but look for the end of wire 6A (? what the
drawing says) where it is soldered to the board or the lead of the
varistor (black disk) may be the easiest thing to clip onto. At rest
should see 0 volts; when in either forward or reverse should see ~36
volts (put the tranny in neutral while testing). Others may know easier
ways to test this?
Batteries: Seeing ~38 volts across the pack means you are in the right
ballpark and the batteries are now connected correctly. However... the
one that was backwards for a while may have hidden damage. A load test
would be good as already mentioned. If you don't have a load tester,
then can figure a way to rig up your meter so you can watch the voltage
of that battery while using the tractor. Actaully two tests, once for
full pack voltage (should be 34-36 volts when in use, or maybe 32-33
volts if under a heavy load) and then again for the suspect battery
(each battery should stay above 5.5 volts, even when in use).
Charger: If you measure the total pack voltage, it will start around 38
volts and as soon as you turn the charger on jump up a bit and continue
to rise slowly over time. Near the end of the charge cycle (with the
charger still *on*), should be up to 42-43 volts. If the charger shuts
off before you come back to measure the final voltage, turn in back on
and let it run for ~30 minutes to stabilize at the final voltage again.
Main disconnect: if this is failing, it may be hard to get it to turn on
sometimes and/or it may generate a lot of waste heat. If get it out to
where you can look at it, it has open sides so can visually inspect it.
There is a big copper disc that gets pressed against copper studs. When
on, they should be pressed tightly together, and should appear smooth
without any pitting or pot marks. Without removing, rig up your meter to
measure the voltage drop across the disconnect switch, from say the + of
B2 to wire 2-02 on SO-2. Keep an eye on this while using the tractor -
it should be in the millivolts even when under full load. If it is above
say 0.5 volts that is definitely bad.
Contactors: As others have noted, not having the original style with the
link pin is an accident waiting to happen. However, I don't think it
would cause any of the problems you are seeing. Without the pn there is
the potential for both contactors to close at the same time and make
some nasty fireworks. Used ones could save you a little money versus the
new-old-stock. I'm also wondering if the replacements you have might
have 24 volt coils in the them. If so, they would run hot and eventually
burn out in the 36 volt system.
This got long... good luck!
paul mitchell2007 comcast net wrote:
> If I had a bad main disconnect, would the tractor sometimes run and
> sometimes not? How can I check if it's faulty?
> ...
I measured the voltage at SO-2 and got 38 volts. That's
after having mowed for about a half hour. I'll charge it today while at
work and measure it again at full charge.
--
Jim Coate
*The Electric Tractor Store*
http://www.ElectricTractorStore.com
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