Bafang HD cuts power and turns off

Joined
Dec 1, 2015
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302
Location
Me Tarzan, Eugene
I got a new HD unit for my lady, and everything mounted up great.

The wiring is all functional...rode smooth and powerful for a mile...made her smile so big!
...but after the first mile it started turning itself off....over and over.

When the bike is in the repair stand it runs fine...seems to be able to hold high speed for long periods without any issue when in the stand....seems perfect and normal...tried two different batteries with identical function.
...but when the bike is riden it turns itself of after about a minute or any load...in both PAS or Throttle modes.
...I tried shaking the bike to see if it was shorting while bouncing around...but it was fine.

The display turns off in less than a minute every time it is riden...then wont turn back on till the battery has been unplugged and replugged. (like a modem)

so in my best guess...it seems that when it is in the air on the stand, it uses very few watts/volts to push the wheel....but when it is under load and riden, the watts/volts peak much higher...which causes it to overload and turn off.

The batteries are 52v20a from Luna, and both work dandy on other bikes too.

I do not have the included E-brakes mounted because I read they were optional...and I prefer hydraulic nice brakes....is this part of the problem?
I will try the other display I bought...and other throttle I bought....don't know what else to try.

So...is there a voltage cutoff function that is activating to easily? or a setting that can be changed?
or...is the display/controller/something malfunctioning or defective?
or...am I a newb missing an obvious easier answer?

I hope this is enough info to get some help...not sure what to do here...thanks y'all.
DSC_0001.jpg
 
Do you have a cable so you can check the controller settings? Sounds like the low voltage cut out is set wrong. That's what mine does when it hits the LVC.
 
It could be that the BMS (battery management system) in the batteries is too sensitive. The BMS thinks there is a short and shuts down to protect the battery.
 
I don't have the programing cable...or a PC....I'm on a Mac.
What would I do about a sensitive BMS?
The battery charged fully was at 55v, rode less than a mile...should be plenty of voltage, shouldn't register low.
 
I don't think it's to do with the battery since it works on another bike , right? A programing cable is cheap if you can barrow a laptop. If not maybe contact seller and send it back for them to diagnose. What does the battery level on the display show? When it gets near LVC it will only be one bar and then the last bar will start flashing and then it will go blank and off.
 
Leebolectric said:
I don't have the programing cable...or a PC....I'm on a Mac.
What would I do about a sensitive BMS?
The battery charged fully was at 55v, rode less than a mile...should be plenty of voltage, shouldn't register low.
55V is really low for a fully charged 14S battery @ 4.2vpc. Might be something to check out?
 
I have two chargers, and two batteries...all identical.
They are both 52v Samsung 29e 18650 20.3ah batteries from Luna and work nice
They both charge identically to 55.1v-55.5v or so.
The Luna site listed the batteries as high power and good for the Bafang.
Both batteries work PERFECT with my Tangent kit....but I don't know batteries well enough to compare types.
I don't know electricity well enough to know why, I just know it makes me go fast and smile.

This Bafang puts out a steady 25-30mph when the bike is in repair stand and full thumb throttle.
It can hold this speed for a good while...no shut down issue when run without friction or load.
The display reads 100% full battery...no low battery warning.

I have a message in to LUNA about the Bafang, and they are quick with responses...but the holiday may effect that.
I will see if I can borrow a PC and get that cable...I'll try anything to see her smile like that again :D
 
Okay, the batteries are may not be the problem, because they have such a large capacity. But you should address the charging issue with Luna at some time, because they are not charging properly to full 58.8V, indicating a problem with chargers or battery BMS.
 
Get a volt meter and measure the output of your charger. This should tell you whether the problem is the charger or battery BMS.
My EM3ev charger puts out 58.8volts and my $30 Luna charger puts out 59.4volts.
 
Ok...I'm a bonehead admiting fault here....I don't know if this is the overall issue...but I noticed something.

I had the charger set to 80% charge...not 100%...so the low voltage is my fault.
I will see what happens when I charge it fully...will report back later.

doh! :p
 
The motor should still run on 80% charge. I charge all my batts to 80% most of the time.
 
New development!

I tried my other display, a 963...originally operated with a 965 display. I bought a spare based on advice here.
The 963 works PERFECT, did a dozen laps around my backyard till I ate a tree...seems proper.
Will report back on longevity after a long ride or two.

It looks like the 965 display had a defect, causing it to shut off....or so I'm guessing.

WooHoo! ...other than this rain :roll:
 
Yes the batteries are best charged at only 80% in order to get the most cycles out of your pack is what I have been reading. 3amp slow charge is also better for the longevity of the pack rather than the 5amp charge if you are not in a hurry I have read.

One bonus for having that program cable is you can at least see what the controller settings are set at. You then can decide if you want to change those settings, and then if you do want to change them, you can. Who knows something weird may have been entered into the LVC settings but I doubt that but at least with the program cable you can see what parameters have been programmed into the controller from the factory to help you trouble shoot this problem. I also got from Eric at Luna the little watt meter that Luna sells, its awesome! Its a nice little unit to have paired with the Bafang kit to give some feed back for trouble shooting things or to confirm your max current settings are actually working.
 
Just a thought. I helped install a BBS-HD a few days ago and it also seemed to turn off after a few minutes. However, I recall the owner reading off some settings and one of them was the auto off after XXX. I remember him saying it was set to 3 minutes. It did seem like it was turning off after about that time. We had not installed the spoke magnet so I thought the problem may have been connected. We also have an er30 that may have always been there but it was raining the day we got it running and did not look at that time. When we had a problem we noticed the error 30...

He has been riding and it may be resolved. I will be hearing from him soon I'm sure.
 
Auto off is the display lighting. Er30 is a communication problem. Bad connection. Damaged harness or similar. Can be the speedo connection. I like to hook everything up on the bench first. But all accessories need to hooked up to get the full picture. Easier to trouble shoot before it's installed. My way after the first install problem.
 
Update...all running great, display was only issue.
So stoked I took the tips posted in this forum to buy spares of the parts for easy troubleshooting.
Thanks for all the help....wheeeeeeee!
 
I'm having this exact same issue, but trying a new display didn't solve it for me. Seems to occur especially at higher assist levels. Screen flickers then shuts off. Right before shut off, battery incorrectly shows super low voltage. I can turn it back on immediately, battery shows 41.8 volts (36 volt downtube battery). And it will run fine in the bike stand.
 
Folks like empowered have troble shooting kits with all the electronic parts likely to go bad. That said, i’d never own another BBSxx anything without a spare display, controller, harness and throttle. That way there will be the shortest delay to get running again. Unless its machanical. But when I sold my last BBSHD, i had all the likely mechanical replacements as well. I hate hunting and waiting for parts, especially when out of stock. If you don’t need them you can always sell and recover most of the investment. My new mac motors have all their spare too.
 
Same as Dalysea.
The monitor seems not to be the problem.
Any other suggestions?
I am in the process of importing a new controller (next step?) since my batteries seem to be fine. Monitor seems to be fine... still having same issues of power cut offs.. going on again.. and yes, battery flickers when it cuts out but voltage metre shows battery is still full.
Frustrating being in Africa and hoping the next trial will work but huge delays since i have to import every part
(First I bought new batteries. Then a new monitor.. 🙄😥)
 
Sounds almost like a bad connection between the battery and controller. If the voltage on the display drops right before it cuts off, it seems like it's doing what it's supposed to do when the battery gets low.

Another possibility is the BMS in the battery is cutting off. This could be from one cell getting too low or if the current draw from the controller was too high. If the BMS cuts off, there would be no power to the display, so it would go dark and stay off.

The best thing is to have some kind of monitor on the battery voltage when riding (other than the factory display). Then you could tell if the battery voltage is dropping when it cuts off.
 
Thanks fechter
Do you know what kind of monitor would be able to test voltage - while riding?
 
BMS reset
I all else fails and I consider a BMS reset/ jumpstart, is this procedure safe? I do not want to damage batteries.
 
Adri said:
Thanks fechter
Do you know what kind of monitor would be able to test voltage - while riding?
Something like a CycleAnalyst is the standard approach, but they are a bit expensive. Just a regular digital voltmeter will work if you can devise a way to attach the wires. Sometimes you can unplug the main battery connector, then jam some skinny wires into the socket and plug it in again. Use tape to hold the skinny wires in place.

With Anderson connectors, you can often jam a skinny wire into the back to make contact.

Like the picture below, only using wire instead of the probes. Use tape to keep the wire in place and run it to the probe tips with more tape. You need it to say working while riding.

Anderson_Probing_c.jpg
 
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