Controller Trips under load

Get all your technical information about electric bikes here.
User avatar
e-beach   1 GW

1 GW
Posts: 3281
Joined: Jan 10 2012 9:48pm
Location: Any Los Angeles area beach I am at. Or Santa Monica or possibly the south bay beaches.

Re: Controller Trips under load

Post by e-beach » Mar 25 2020 7:17pm

amberwolf wrote:
Mar 25 2020 6:41pm
......and refers to the time in seconds (s) that much current is allowed. ;)
:oops: :lol:
Favorite Quotes:
"This is L.A., sugar. There is no 'over the top." Chris Erskine
"At a certain point the entropy wins." Maria Helena Braga

Current Build: ProFlex 757 Expert full suspension. Yescomusa 36v 800w Rear DD, upgraded 10AWG solid core through axle phase wires. 15ah Headway, 1000+ cycles, 80% DOD 30A Tronsung controller.

Past: Trek 4500 Yescomusa 36v 800w front DD.
Liahona, Yescomusa 36v 800w generic front DD.
1992 Trek 800, Yescomusa 800w 36v front DD.

User avatar
amberwolf   100 GW

100 GW
Posts: 29009
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group

Re: Controller Trips under load

Post by amberwolf » Mar 25 2020 7:50pm

e-beach wrote:
Mar 25 2020 7:05pm
As for a "bench test" of your system you would probably need a dynamometer for that.
to find out where the problem is, nothing so complex is needed.

just access to the mechanical brake lever for that wheel (with any ebrake wire the lever has disconnected from everything), with the bike upside down or wheel otherwise offground, and the throttle (or pas) to engage the motor, and a view of a voltmeter that is connected to one cell of the pack.

start with the first cell. engage throttle a bit to get the wheel turning, then engage the mechanical brake on the motor wheel (while still holding throttle engaged). watch the voltmeter as you squeeze the brake harder, and note the lowest voltage you get before the system shuts down. write the voltage down.

repeat this test for each cell in the pack.

if possible, measure the peak current at that same moment, but you'll need two meters for that, one for volts and one for amps. if your cycle analyst is working, then it will be the amps meter, and you can get hte amps info after the system is reset. just use the left or right buttons to scroll thru the screens until you get to the one with "amax" on it. that's the peak current. write it down, then hold the rigth button to reset it before the next cell test.

this test is a little hard on your brake pads, but it will work, unless your brakes are shot. ;)

john61ct   1.21 GW

1.21 GW
Posts: 3637
Joined: Dec 18 2018 2:06pm

Re: Controller Trips under load

Post by john61ct » Mar 25 2020 7:55pm

steverichab wrote:I found the 10Ah Prismatic LiFePo4 that I have now for $5.80 each on Alibaba
That is suspiciously cheap.

To accurately test the cells, you need to fully* charge them all in parallel at 1S

or get them fully* charged otherwise as close to the same point as possible

then put them to rest in parallel for 24+ hours

then isolate and discharge capacity test each one with a CC load, at say 0.2C, timed from full, down to 2.99Vpc

*fully for precise testing purposes (not normal cycling) could mean to 3.6Vpc the hold until amps taper down to 0.05C

steverichab   10 mW

10 mW
Posts: 21
Joined: Oct 02 2011 8:15am

Re: Controller Trips under load

Post by steverichab » Mar 26 2020 9:00am

Many Thanks to all,
First of all, I took AW's advice and left one of the packs on to charge for 20+hours and this morning it reads 58.5 V!!!!!!!!!!!!!!!!!!!!!!
I have to reassemble the other battery pack and do the same today. I will load test the first battery latter today.
What I was doing is taking the battery off the charger when the green light on the charger came on and "assuming" that the correct voltage for these packs was the 52.7V I was seeing.
No victory dance yet but I will know as soon as I can do the load test later today.
Wish me luck, Steve

john61ct   1.21 GW

1.21 GW
Posts: 3637
Joined: Dec 18 2018 2:06pm

Re: Controller Trips under load

Post by john61ct » Mar 26 2020 9:14am

That light might be the arrival of "Absorb stage" CV being held.

Many BMS only **start** their balancing around then.

If the cells are "balanced enough", stopping charging at that point is more conducive to longevity than holding CV.

User avatar
fechter   100 GW

100 GW
Posts: 14641
Joined: Dec 31 2006 3:23pm
Location: California Bay Area, USA

Re: Controller Trips under load

Post by fechter » Mar 26 2020 9:15am

One test would be to get it running with the wheel up and slowly apply load while watching the voltage and current. See at what point does it trip. You can apply load with the brake if you disconnect the brake switch.
"One test is worth a thousand opinions"

Post Reply