Well, keep in mind that the lift motor does not have permanent magnets. It’s actually a series wound motor with two field windings. The power path goes from the battery, to the switch, to one or the other field, to the armature, and then back to the battery. The result is the motor *is* a series motor, so as the load increases the draw on the field and armature increases as well. Likewise if you double the voltage you double the field strength and the armature strength so power output doubles. I think the key danger is heat; more power means more heat in the motor and too much heat will short out the windings as the insulation melts. However if it can get the blower lifted in 3 seconds instead of 10-15 (what it takes when it’s struggling at 18 volts) then that could mean the motor suffers *less* damage at 30 volts than 18. Maybe. Chris From: Rob Brockway [mailto:getractor yahoo com] I don't know how accurate this is, but I have heard that a lot of DC motors are designed so they have a 50% voltage safety factor so you don't demagnetize the permanent magnets. So a 12 volt motor design will likely demag at 18 volts or higher (at locked armature amps). Interestingly if you demagnetize the motor speed will tend to increase under light load. Rob From: Christopher Zach <cz alembic crystel com> So this afternoon I had to switch the E20 over from mowing to snowblower. Note that it is *much* easier to do when you put the snowblower on two moving dollies. They’re a good height, and it’s a snap to roll the thing around the shed. At the same time I figured I would try to boost the voltage draw for my lift motor. Normally it’s tapped to 18 or so volts on the BB600 pack, right about the middle. The next closest battery terminal would be 30 volts, so I gave that a shot. *wow*. Motor zips up and down fast, lifts deck as if it was not there. So I removed the deck and put on the snowblower. Greased the lift pulley and gave it a shot. *wow*. Motor zips up and down fast, lifts snowblower as if it was not there. This is good, as normally the motor struggles to lift the blower and sometimes stalls. Now it runs it right up in a few seconds. In fact I worry that I will rip something out if it hits the highest lift point. So I reduced the lift fuse from 30a to 20a. Now, this is a “new” lift motor from Bill Gunn, top of the line. Not sure how long it’s going to last with this, but I did note that it’s duty cycle is now a lot less since it’s not farting around struggling to lift. Zip it’s up in 3-4 seconds. Then off. So now I am thinking: One of the big problems with the lift is that the motor will stall out sometimes and then trip it’s breaker. Stalling a DC motor puts a lot of strain on the commutator bars and the brushes. Is it better to have the motor still spinning (and pretty quickly I might add) at 2.5 times it’s rating? Seems like it would be drawing less current, which is good. So what’s the downside? I wonder what the switch in the lift is rated at. If I’m opening and closing way above its rating, that might blow up. Chris
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