E-max 110 scooter lithium conversion

[jonescg]

Hi all,

Just a little update of another E-max 110 scooter which has been upgraded to lithium cells.

About 3 kWh (16s GBS LiFePO4 cells) is able to fit inside the scooter's belly. There's more room at the back which might be a useful place for a fan-forced charger, but for now it's just as convenient to charge off-board.



The BMS comes from EV-Power - two of the 12 cell monitors which use an NC loop to indicate continuity. If a cell goes low, the loop stops conducting and the tiny relay drops out, allowing a super bright red LED to shine in your face, and sound an awful buzzer.

View attachment 1

HVC is managed by these little balance boards. Each one begins bleeding the cell down if it exceeds 3.55 volts. At 3.56 V, the current is minuscule, but at 3.65 V there is about 400 mA of bleed current. http://ev-power.com.au/webstore/index.php/ev-power-bms/bms-cell-modules-1/lfp-voltage-balance-board.html



There are many ways you can do it, but I think an active LVC warning like the LED/buzzer, and a passive HVC by means of a balance board is a pretty easy way to go.

Hope to have the lot installed on Thursday and take it for a range test.

 

[jonescg]

Finished the conversion today. It was actually quite difficult to find a switched 12 V supply on this bike, let alone a ground.

Still, managed to get the BMS working nicely for LVC (laser bright red LED). HVC does the same thing, but only when you turn the key on. Not to worry, the balance bleeders take care of HVC

Pretty pleased with how it turned out.







I'll be doing a sort of a range test tomorrow. Only 34 km, but should get some useful data from the recharge time.