Battery cut off

lolo234

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Feb 24, 2024
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Geneva
Hi everybody,

A problem arose on both my etrike and my ebike (homemade, alibiba sourced parts, throttle accelerator). When I accelerate more than a flick of the throttle, it cuts out and only restarts when the contact between the battery and the controller is disconnected and reconnected, and if I apply too much throttle it cuts out again. At first it happened sporadically (and only when aaplying full throttle for several seconds), then more and more frequently, until it became systematic with every acceleration and as soon as I put on more than a fillet of throttle. I have 3 different batteries and 3 different controllers, and whatever the combination, the problem is always there... At first, I thought it was an impalanced cell that was forcing the bms to take safety measures (because, not reaching a sufficient voltage, it falls below the safety threshold in the blink of an eye)) but I sacrificed one battery and check every cells that was in very nice shape (4,1 to 4,16v)...

So I decided to plug in the voltmeter while the trike was in operation (with a 48v battery)... When you accelerate, the voltage drops very sharply: a flick of the throttle brings the voltage down from 53v to 43v, but as soon as I apply too much throttle, the voltage drops below 38v and the trike shuts down. The trike can't restart and the voltage drops to 6-9v. Even if I wait a while, the voltage stays at this level and nothing starts up again, and if I try to switch on the control screen, the voltage drops to 1v. On the contrary, if I push the trike, the voltage rises again, but it's residual (even if I raise the voltage to 40v by pushing it, when I switch the screen back on, it drops to 6-9v and nothing moves). If I disconnect the battery from the controller, the voltage will instantly rise to 53v and if I reconnect everything will work again until I put too much throttle again and it falls back to 6-9v and so on

Ps: I'm using 3p batteries with 1000 and 2000w controllers and a 750w geared motor and a 2000w direct drive... could 3p be too sparse and cause these voltage drops?

Thx a lot for your help, my son and I would be so happy !!!
 
power connect can wear & stretch a bit over time. I don't know how much use you've had on those connections
a bit of dielectric grease in connector might help, but if worn you may be able to purchase a replacement
connection as I have for my NCM. Actually they gave me one free when I bought a new battery.
 
power connect can wear & stretch a bit over time. I don't know how much use you've had on those connections
a bit of dielectric grease in connector might help, but if worn you may be able to purchase a replacement
connection as I have for my NCM. Actually they gave me one free when I bought a new battery.
Thanks for the answer... Unfortunately I even suppressed the connectors to be sure it wasn't the problem and it is not...
 
If anyone interested I bought a high amp bms I'll first fit it on one of my 14s3p and if not enough, I'm going to add some parallel raw to the battery by adding some of my other 14s3p battery cells.

Will post the results in a few weeks
 
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