Tube frame Ebike build

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Tony01

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Nov 28, 2012
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Yeah the forks on this bike are way too weak. 10mm axle stock went to 12, handlebar clamp 6 to 8ish, springs 150%. blown fork seals, leg twist at top crown… cause it’s just bolted in, not a clamp. Gonna try cutting up a spare lower triple to clamp the top as well. Probably not enough steerer to make it a real triple.
 
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Tony01

Well-Known Member
Nov 28, 2012
1,840
1,947
113
sf bay area
It’s been 4 months on this setup so far.

Monday night I tore the battery apart and balanced it. The cells were out only .03v total. My tools only go down to .01v, so I can see .005v by measuring two cells ie 3.54+3.54=7.09 which means both those cells are actually 3.545v. Got it down to where all the cells showed the same so probably .01v total with errors. Using a little RC charger plugged into the battery’s balance plugs.

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The “up” button on my primary high power charger broke; I can still adjust a setting up by sticking a piece of metal where the button used to be. To charge 110v it turns the amps down to 35a but that’s too much for a 110v plug anyway, so if I turn it down more I risk not being able to turn it back up for 50 amp level 2 charging. So I had to come up with a 110v home charging setup.

Enter boost charging. The controller has a special feature that allows me to boost voltage from any PSU by using the motor coils as a DC-DC step-up converter. Any power supply from 24v up to the minimum batt voltage will work.

So I built this 60v 20a 2s charger to boost charge, using 2x 24v 20a 500w power supplies. I’ve seen them do 700w in the past. Currently only doing 15a but I need to fix one of the PSUs to allow current up to 30 amps. In this case the PSU is giving 60v 16a which is stepped up to 77-90v 10 amps automatically by the controller.

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The boost charger power supply negative connects to controller/battery ground, and the positive connects to one of the motor phase wires. The controller auto-detects the PSU and begins the charge.