Fully charged Battery dies with load: Why?

Stu Summer

100 W
Joined
Apr 27, 2016
Messages
147
Location
Hillsdale, NY
I have a 36V battery, 10 or 14ah, form factor like standard delivery bikes, a Hebb. Paired with a Ezee geared hub motor 350w. Satiator says it is charged, in fact, said that it was over charged to 49v. I don't know why. But more importantly, the battery is fine under no load. I taped the throttle open and the motor ran for 3 hours with the bike hanging from the rafters. But as soon as I tried to ride it, it kicked off after 1 or 2 seconds. This has now happened twice.

Why is this?

I got the bike off craigslist. When I picked it up it would run, I was able to ride it up and down the street, but it only had an extremely low power. I would guess about 30 watts. When I got home with it and hung it up, I found that one wire, the yellow one, had come loose from the JST connector below the controller. When I moved the wiring around, the motor would surge to full power. After stripping away the shrink wrap and some caulk, with the bike hanging (no load), when I reinserted the yellow wire, the bike's power leapt to the full power. Again, at the low power, with the yellow wire disconnected, the system would run. But with the additional power of the yellow wire connected, the battery dies.

Any help on figuring out what's wrong with the battery and how I might fix it would be much appreciated!
 
Sounds like you may have more then one problem. When you say the yellow wire do you mean the yellow phase wire?

As for the battery cutting out, I am thinking that you have one or more weak cells in your battery that when put under load sags so low the bms cuts off power to the bike.
 
e-beach said:
Sounds like you may have more then one problem. When you say the yellow wire do you mean the yellow phase wire?

As for the battery cutting out, I am thinking that you have one or more weak cells in your battery that when put under load sags so low the bms cuts off power to the bike.

Sounds right about the battery. I have been so putting off getting into the internals of batteries! Here I go, I guess.

The yellow wire was not a phase wire. I'm not sure what it controls. Without it connected the motor ran smoothly but at one low power. With it connected the motor responds smoothly to the throttle's whole range.
 
Your battery dies because its dead. Old lithium can often still charge to full, but its capacity to handle a load is long gone.

You might learn a lot trying to fix it, but if you want to ride, you need to shop for a new battery for this bike.
 
dogman dan said:
Your battery dies because its dead. Old lithium can often still charge to full, but its capacity to handle a load is long gone.

You might learn a lot trying to fix it, but if you want to ride, you need to shop for a new battery for this bike.
Dogman, thanks so much for the unequivocal reply. I'm wondering if anyone has used this company: https://ebikemarketplace.com/products/ezee-li-ion-electric-bike-batteries. It seems expensive. Any ideas of a cource for a new one of these batteries?

Stu
 
Look into:

ebikes.ca
em3ev
PingBattery
LunaCycle

There may be more good vendors out there, but these are the bigger names used around here.

:D :bolt:
 
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