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Re: (ET) Max power consumption on snowblowing....
Jim,
what's your data xmitter/receiver? I have been messing with some spiffy 802.15.4 stuff from Omega... is it that, by any chance?
I would collect more data if it were a little cheaper to do so... I'd love to hear what you have.
General,
Amen to minding the tire pressure.
So true about resetting the breaker! I used the butt end of handle of my chute-clog-clearing trowel as if it were a giant thumb on the rare occasions when the breaker tripped.
And I, too, am a big fan of jacking up the tractor (or any vehicle) to put chains on. Way easier than driving on to them, etc. And bungees are excellent for reliable tension with, say, tires that have air leaks. It is misery to have to get chains reseated in the middle of a storm clean-up, let alone the storm itself!
Happy deep snow to all,
-Max
On Sun, Jan 30, 2011 at 5:43 PM, Jim Coate
<jbc_lists_NO_REPLY coate org> wrote:
Ah yes, the joys of snow country. When living in Hudson Valley, NY I too took some readings with an e-meter while using the snow thrower, powered by regular lead-acid batteries. The e-meter had a wireless link to my computer inside the house so somewhere I have the second-by-second data saved.
I do remember seeing brief peaks at 500 amps (ie the e-meters limit) when digging into packed snow banks. As the e-meter was measuring the _total_ current draw from the pack, that means the 500+ amps was split between the snow thrower motor and the drive motor. In order to force the snow thrower into the snow bank that hard, figure the drive motor was pulling at least 150 amps, so that leaves 350 for the snow thrower motor. [Chris: what exactly were your meters recording?]
As detailed in the link that RJ provided, when a breaker will trip all depends on time and temperature. ie the 105 amp breaker will happily carry 200 amps for a number of seconds in freezing cold weather, whereas the (estimated) 350 amp peaks I recorded never lasted more than 1 or 2 seconds. On the other hand the breaker will open darn fast if you try and pull say 2000 amps through it at any temperature.
Yes, these are true DC rated breakers. And yes, I have replacements available for both sizes
(http://electrictractorstore.com/index.php?main_page=contact_us).
I did manage to trip the breaker a couple of times and note that it takes a really hard push to reset it. Especially with gloved and/or numb hands.
Oh, and make sure your tires are properly inflated when using chains, otherwise they will unseat themselves very quickly. And more fun with cold/numb hands will follow. So yes, I'm happy to be setting up the new home in warmer Virginia :-)
Chris Zach 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
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Jim Coate
*The Electric Tractor Store*
http://www.ElectricTractorStore.com
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