wesleyb82
10 mW
I collected a bunch of old 5AH Lipo packs that had bad cells, dissemble them and made a 14S2P 10AH pack. All the cells had at least 4AH capacity when discharging at 1C to 3.0v. I charged them all, joined the parallel wires then after 12 hours I connected a 14s BMS (https://www.ebay.com/itm/232964067324). This is the charger I am using: https://www.ebay.com/itm/163251540511. Finally I am using this wattmeter: https://www.ebay.com/itm/223191693943
The pack discharge wires connect through the wattmeter shunt to the controller and the wattmeter is setup with a 43v LVC that activates a buzzer to alert of LV condition. The wattmeter is power from ground + #4 (~15v). The charge port connects through the BMS so that the BMS can control the HVC.
After 5-10 uses @ ~4AH per use, all of a sudden after 4AH of usage the wattmeter LVC alarm is going off and is reporting <43v! I took apart the pack and cells 1-4 are reading [3.45,1.15,3.57,3.20] all other cells are 3.95v. My first guess was that there was a bad or weak cell in the #2 position which dragged down the surrounding cells. I replaced the cells with less than 4AH of capacity but after one more use the symptoms have returned, this time the readings are 1-3 [2.59,1.70,0.12] and the rest are 3.88v.
Anyone have any ideas what is going on here? My first thought was the 1-4 cells are powering the wattmeter but the power consumption is obviously extremely low. I usually just stack 6s lipos and use a balance charger and this is the first time using a BMS of this type and hope someone has some suggestions, thank you
By the way this is for a modded MX650, 1800w BLDC, 65A controller, 11t/80t. Taller spring and spacers in the front forks. It hauls. The controller is a neck snapper which makes it a handful. It is wild.
The pack discharge wires connect through the wattmeter shunt to the controller and the wattmeter is setup with a 43v LVC that activates a buzzer to alert of LV condition. The wattmeter is power from ground + #4 (~15v). The charge port connects through the BMS so that the BMS can control the HVC.
After 5-10 uses @ ~4AH per use, all of a sudden after 4AH of usage the wattmeter LVC alarm is going off and is reporting <43v! I took apart the pack and cells 1-4 are reading [3.45,1.15,3.57,3.20] all other cells are 3.95v. My first guess was that there was a bad or weak cell in the #2 position which dragged down the surrounding cells. I replaced the cells with less than 4AH of capacity but after one more use the symptoms have returned, this time the readings are 1-3 [2.59,1.70,0.12] and the rest are 3.88v.
Anyone have any ideas what is going on here? My first thought was the 1-4 cells are powering the wattmeter but the power consumption is obviously extremely low. I usually just stack 6s lipos and use a balance charger and this is the first time using a BMS of this type and hope someone has some suggestions, thank you
By the way this is for a modded MX650, 1800w BLDC, 65A controller, 11t/80t. Taller spring and spacers in the front forks. It hauls. The controller is a neck snapper which makes it a handful. It is wild.