(ET) vacuum running on 2 battery packs

[Chris Zach <cz alembic crystel com>]

Well, I got the leaf vacuum running properly at last. Instead of having 
to plug it into the rear AMP disconnect on the tractor every time I want 
to run it (and causing massive arcs on the AMP contacts) I put in a nice 
36 volt contactor, and wired it so that a single wire coming from the 
front contactor signal source (wire 34 off 1RTN) will send a signal to 
the rear contactor to close.

In other words I turn on the mower and the blower comes on. Mower off, 
blower off.

This is good because the tractor, 3 deck motors and the very hungry 
blower motor pull a LOT of current. And since I can't use my rear 
battery box with the blower (it hangs on the back) the NiCD pack is 
really taking a strain with only 2 strings operational.

I took a look at the cells when the tractor was "discharged" and while 
most were 1.1 to 1.0 volts under load (blower plus deck) at least one 
cell was at a solid zero, and two others were slightly under 1 volt.

Pulled the zero cell and now have it on a short discharge with 10 gauge 
wire. The wire is a bit warm, so it is discharging, but the water level 
on it is *very* high, I might have over-watered it.

I might need to buy some 30% KOH electrolyte and flush it out, my guess 
is it needs new electrolyte. In fact it might not be a bad idea to do 
this to all the cells, but where can I buy a couple of gallons of 30% 
USP KaOH?

I can probably use the electrolyte from cells that I have which have 
broken bolts in them (major mess, still not sure what to do there) to 
test this cell (discharge all the way, then dump the electrolyte/water 
and replace it with just enough KOH to cover the plates then charge).

Another thought: Is there a battery voltage indicator that can handle 
displaying 30 cells? I'd love to know when one is going to zero.