<html><head></head><body>Oh a picture of the tractor with yard is at <a href="https://imgur.com/a/nd2CSyZ">https://imgur.com/a/nd2CSyZ</a> <div class="gmail_quote">On November 9, 2019 3:48:47 PM EST, David Tiefenbrunn <davidtief@comcast.net> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> <pre class="k9mail">Hi Chris, Since you are running these batteries, I am curious - how often do you have to add water to them? How do they do as far as sitting - loose charge / self discharge? Dave On 11/9/2019 1:47 PM, Chris Zach wrote: <blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #729fcf; padding-left: 1ex;"> Been doing leaves all day. When the tractor really slows down I noticed that turning off the deck and blower got me some more power to the main motor. So something is wrong with the battery pack. Drove it till it was pretty much dead, then parked, put the blower and the deck on and started checking voltages on the BB600 cells. Most were at 1.0v (pretty low) however one cell in pack 1 was down to .4 volts under load, 2 in pack 2 were down to .4 and .6 volts, and one in the third pack was reading a solid 0.0v. Not good. So I turned off the blower+deck and checked voltages again. Aside from the dead cell in pack 3, rest of cells came up to 1.1 or so volts. Time to pull the bad cell. Put the rest of the pack on charge, checked the cell and it was at 2.00 volts to 3 volts. Bad. Pulled it out, took it to the shed, and on a lark hooked it up to a 1.5 volts power supply. Sure enough it was pulling 2a no problem. Interesting. I then remembered one of the bolts was a bit loose, and the interconnects were pretty filthy. So I cleaned it up, cleaned up the bolt threads on the wire wheel, sprayed electronics cleaner into the bolt holes on the battery with a straw, cleaned up the nickel plated interconnects, and put it back in the battery. Now it reads a happy 1.4v under charge and after a drive was reading 1.0 under load at the end with the rest of them. You can't kill these damn batteries. Well unless you overcharge them terribly with a bad E15 charger and a cap that takes the pack voltage to 45v. I then checked the other cells that were low: Pulled two of them, cleaned them up, cleaned the contacts, put them back in. Now they are reading better. I think I'll pull the last one that's reading low and clean it up as well. So BB600's are nice, and do live for awhile, but the interconnects are a true pain: Tighten the stainless steel bolts too tight and they will break off. Not tight enough and the interconnects lose contact. But they do seem to last.... C<hr> Elec-trak mailing list Elec-trak@cosmos.phy.tufts.edu <a href="https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak">https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak</a> </blockquote><hr>Elec-trak mailing list Elec-trak@cosmos.phy.tufts.edu <a href="https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak">https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak</a> </pre></blockquote></div> -- Sent from my Android device with K-9 Mail. Please excuse my brevity.</body></html>