3000w 72v kit

[Joely]

Hi all,
I have a 3000w greenpedel hub motor, 72v 20ah battery and 72v kt-lcd3 with 35a controller.
When fully charged the battery shows 84v and the bike runs great.
After 3-4miles only using level 1,which is fine, the battery is getting to 78v and the kit turns off.
Can anyone help explain this as it's a 72v kit and I thought it'd get nearer 70v?
Thanks in advance.

 

[eee291]

Actually a 20S battery is completely empty at 60V.

You need to check weather the BMS or the Controller is cutting out.

It could be a cell in your pack that is discharging faster than the rest, which is causing your BMS to cut power to the controller.

But if the Battery is new then I guess you should look at the Kt-lcd manual and change the low Voltage cut-off.

I think I linked you this video before :lol:

https://www.youtube.com/watch?v=nh-_hqhHLNY

 

[Joely]

Thanks, yes you did send a link but the controller I was using packed up and since then I have tried one that can take more amps.
The performance is fantastic though this problem has occurred now and the supplier of the controller reckons it's the battery and the battery supplier thinks it's the controller of course!
The manual only shows set up for 48v systems but I'm told it's the same for 72v batteries but then trying to input minimum voltage is tricky.
Cheers for your help there's an awful lot to learn!

 

[eee291]

It's not hard to figure this one out.

Question is what happens when the motor shuts off? Is the Controller giving you an error code? Or showing you that the battery is empty?

If the controller display completely shuts off then that means the BMS on the Battery cut power. In which case you need to talk to the supplier, since the BMS should cut out at around 60V+.

 

[Joely]

Nice one, I get no errors at all just shuts down. I've got in touch with the supplier so will see where it goes.
Cheers