(ET) Max power consumption on snowblowing....

[Chris Zach <cz alembic crystel com>]

Ok, I have a few interesting numbers from blowing snow at the max levels.

Starting off with a mostly full pack, I ran straight into the heavy wet 
soup. Current draws were about 150a from pack 1, 145 from pack 2. This 
was on level ground, L, auger starting to slow down a tiny bit. Pack 
voltage at 34 volts. This is about the limit one should go when blowing 
snow, fast auger, just starting to bog down a bit.

At the top of the hill I went into the 2 foot packed drifts. Current 
jumped to about 200a per string, with auger running slower, voltage down 
to 32 or so.

I kept pushing and the auger slowed to the point where the snow was 
barely coming out. Current on the E-meter was 275 on string 1, 280 on 
string 2. Backed *off*.

Back to blowing. Took the pack down 18ah per side before it was running 
too slow to blow level. Given that the pack was not fully charged I 
probably had the batteries down to about 24ah per side.

Moral: It's possible to pull 500a while blowing snow. New record.

After parking I checked the interconnects on all cells. One interconnect 
was very warm, rest were cool. I'll pull that and fix it. One of the 
wires to the front accessory plug showed signs of excessive heat, I'll 
re-torque that and clean the connection.

The main power wire from the battery compartment was somewhat warm, 
might think about upgrading those wires. The other option to be honest 
would be to hook the 30 batteries in the front (currently not connected) 
straight to the tractor power buss close to the accessory relay to share 
the load between the wires in the tractor.

Charging:

Put the tractor on charge, currents to the batteries were 18a to pack 1, 
11a to pack 2. Input charge parameters as measured by the Watts up meter 
are 12.89a@120v, PF .8. Voltage at the batteries at that moment was 34v. 
So 986 watts going to batteries, 1546 watts going in, efficiency only 
63%. Blah.

So there we go. I'm glad I cleaned up all the connections over the 
summer, but this seems to be about the limits. I'm guessing I was 
putting out 17,000 watts to the motors, divide by 746 watts per HP comes 
out to around 23hp. At stall.

Explains why the Elec-trak is called an "E20" :-)

Anyway, more snow later once the batteries recharge. But I will keep the 
power levels lower.

Chris