On Jan 27, 2011, Chris Zach <cz alembic crystel com> wrote:
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
_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo.cgi/elec-trak