(ET) Snow at last (blower data)

[Christopher Zach <czach computer org>]

Well, we finally got some snow here in MD. About a foot and a bit of the 
wettest, heaviest, thickest stuff you can imagine. It's been in the 
30-40's so the ground was warm but it still blanketed everything.

So I fired up the E20 with the two strings of BB600 NiCDs (36v, 30ah 
rated each, more like 35ah) and started blowing. Got about 2 feet before 
I realized you *always* need chains. Put chains on. Rubber straps are 
nice for chains. Put the third battery pack on (third string of BB600's) 
and went to town.

Using the E-meters I noticed that I was pulling way over 240amps when 
driving uphill in LL and blowing this snow. Very thick and heavy stuff. 
The blower motor was struggling at times (and that's a big motor) so I 
backed off a bit speed-wise. Reading the power meter is a bit pointless 
since it is buried in the red. So my goal was to keep the auger spinning 
at a reasonable speed.

The blower never clogged. I'm sure now the POR15 paint is exactly what 
you need. Slick as glass, much better than crisco or anything. And after 
two winters, not a scratch on it.

Snow comes out like thick soup. But it does work.

On one of the downward runs the blower cut out. Great. So I pulled over 
and checked the breaker. It looked to be not set, but according to my 
ohmmeter it had failed open. So I bypassed it temporarily; and continued 
to blow.

After finishing everything, I checked the E-meters. I had pulled well 
over 75ah from the pack, and it wasn't sagging below 35 volts. Well over 
an hour of blowing snow. One of the stings was about 5ah lower than the 
other two, so they are discharging slightly out of sync at high current 
draws. But without a doubt the BB600's can handle the load.

In fact I think they are a little "too" good. Their voltage doesn't sag 
when you have 400 amp spikes, so although they really *do* kick butt 
with the blower auger, they do heat up the pack wires. In addition they 
will not "sag out" and drop the relays on a serious overload.

Another issue is duty cycle. I could probably blow another hour at full 
blast, and at some point I'm going to exceed the 1 hour rating on these 
motors. Especially the blower motor; it's a sealed model and is rather 
warm right now. Also I think unless I upgrade the main wiring to the 
contactor and the accessory plug I will overheat the main power wires. 
Might upgrade those lines to 6 gauge in the spring or better.

So overall the batteries and the blower seem to work well, given the low 
temps and the high current draws.

Chris