(ET) Junker E15 sort of back in service

[Chris Zach <cz beaker crystel com>]

Well, after a fair amount of work, removing the clunker contactor (which 
would not close), bypassing 2A to 1a to get me into speed3, and a final 
push to fix the junk charger the E15 is operational-ish again.

Biggest challenge is the charger: It's just too much of a pain to try 
and charge the 36 volt pack with a 12 volt smart charger (30a). It takes 
all day, and is a real pain to hook up. So I needed a 36 volt charger. 
Which really doesn't exist in the 30a range that the Elec-trak's charger 
runs. Guess it's the way the world works, but even the Lester chargers 
are only 20a. To be honest I need 100a or so to properly charge the E20, 
might just have to build my own charger for this.

But in the meantime I still had that wrecked one I pulled out of the 
E20: One of the diodes was bad and the whole thing is just an ugly mess. 
So it sat by the woodpile all summer, I dragged it out of the weeds, 
cleaned it up, and installed a really nice 4 diode plate from a 12 volt 
150 amp manual Sears charger that died. They had wired 4 diodes into the 
transformer, I'm guessing they were doing a parallel pair of 12 volt 
center tapped windings to save wire or something. Regardless I put them 
in parallel pairs of two and hooked them up to the charger core. The 
center tap is negative, the lug on the diode heat sink is positive.

Wired it into the timer circuit, plugged it in (from a distance) and got 
the 42 volt DC open circuit voltage. Put it in the E15, and now I have a 
nice solid little charger. Will check the timer in an hour to make sure 
it's moving/turns off the charge.

So. The E15 runs. Not well but it does run. Speaking of which if your 
tractor is ever stuck you *can* make it go by jumpering the left side 
control lug of the top left contactor (L) to +36 volts. Note that's the 
little bolts on the front, not the big one on the side. That should get 
the tractor moving, put it in speed 1 so you have field current, jumper  
and drive it back to your work shed.

C