(ET) Connecting a 36v (soneil) charger to E-15

[john rieffel <rieffelj union edu>]

I'd like to supplement (i.e. replace, but not remove) my stock E-15
charger with a soneil I bought about a year ago.

Working from the E-15 service manual, can anyone suggest the best
place to wire in the charger?  This is my first wiring job on my
otherwise fully functioning E-15, so I need to build up a bit of
courage to start poking around.   Despite what is ostensibly a
bachelor's degree in engineering, and a Ph.D. on top of that, I'm
still struggling to map the diagrams of the service manual to the
physical view of the device itself.

I imagine it's as simple as splicing the V+ and V- of the new charger
to their corresponding wirings coming out of the old charger, but I
have no idea where those are.

Thanks for your guidance!
jr