Bafang HD cuts power and turns off

[Drum]

One problem I struck that sounds similar: Bad contact between the battery and its mounting base.

The battery had contacts at the bottom, with matching contacts on the base that mounts to the frame and carries the batteries.
The contacts on the batteries were fairly solid "blades", and the contacts on the mount were slightly flexible strips that were bent to "pinch" or press on both sides of the battery contacts.

The flexible contacts on the base were not "pinching" tight enough, just touching the battery contacts lightly. The bike would sometimes cut out after hitting a pothole in the road, or when the motor was asked to work hard.
Re-bending the base contacts so they pressed harder on the battery contacts solved both problems.
Worth checking this area if you have a removable battery.

 

[Adri]

Great Thanks Drum! Will check it out

 

[santhoshs]

Hi

I have the same issue. The display would on for a second and then completely blank. Similar to this - https://www.youtube.com/watch?v=ucHvGcHRQoQ

My set-up is BBS02, battery 48V. I have a video of my circus - https://youtu.be/3iqs2WkcalU. It may be observed

1. the voltage of the wire coming from battery is about 53V.
2. if i connect one of the battery wire (either the positive or negative) to the wire from BBS02 the voltage remains same.
3. if i connect both wires of the battery (positive and negative) to the wires from BBS02 the voltage drops.

Before doing test (the video) i have changed the BMS (suspecting this as culprit) but the problem still continues. Any guidance would be very helpful.

 

[Adri]

Hi there
I have had exactly the same issues and struggled to find the cause. Batteries tested like you have done. Similar results. Supplier suggested the following routes and after re-checking all i found the problem.
Try to do a stress test on the battey. Meaning, connect a voltage meter which can monitor what the battery does once the motor needs to work. If voltage drops.. and returns to normal when you stop it may be a cell or two which is defected and causes the drop. Have all cells in the battery case tested.
Ensure the magnet on the wheel is in exact alignment.
Use an alternative monitor to ensure it is not your monitor (screen).
Then check and check again all connections and loose wiring or burnt areas (if slight currents will still pass, with breaks)
My problem in the end was one connector port on the battery mount was very slightly burnt (i did not pick it up at first neither did 2other guys you really need to do a very close inspection. This caused the voltage drops, the cut-outs, all the symptoms. Once that connector was replaced (i replaced the whole mount)
All returned to normal again.
Good luck. It is bloody frustrating. I know so well
Hope you find the problem very soon

 

[Djoze]

Hi everybody,

Problems appeared yesterday, two days after the installation of a BBSHD and a 13S4P 48V 14.5Ah shark battery equipped with Sanyo cells, all from AliExpress.
The battery was purchased a year ago and worked perfectly on a TSDZ2 48V 18A.

With my new BBSHD, I cycled 100km (60 miles) the first day, with joy and good mood. But yesterday, after 15km, while I was pedaling with a battery almost full and a 500W assistance, the engine suddenly stopped assisting me. The assistance came back after a few seconds before shutting down again, then the problem became more and more frequent until the screen started to turn off completely a few seconds after indicating a battery voltage drop.

I found the problem this morning: it was a short circuit between the battery and the cable connecting the BBSHD. At this point, the aluminum part of the battery is very close to the cables, but it is insulated with adhesive. This was never a problem with the TSZD2's 18A max, but the 30A I inflicted at times generated an electric arc that melted the aluminum. If there was not this hole in the aluminum, a little molten plastic and a blackened area, I probably would never have found the fault because the wires were wrapped in electrical tape and they did not touch aluminum. But 48V / 30A requires more precautions!

View attachment 3

So I ground a part of the aluminum to create a bigger space between the connectors and the aluminum support and I seriously sheathed the connectors, in particular the areas of welding.
Since then, joy and good mood are back, everything works perfectly!





For those who have similar problems (voltage drop, sudden power off, display off), it may be worth trying to isolate this junction battery / cable. This may be a recurring problem on shark batteries similar to mine.

 

[fechter]

Nice work.

In the picture, it looks like the connection between the pins and the short wire going to the Anderson connectors got hot enough to melt. This is typically caused by a bad connection there which heats up. At some point something shorted there too. I'd guess it got hot first, then melted the insulation allowing a short. Making sure those connections are really solid will prevent problems in the future.

 

[endrew]

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

off topic:
The bike looks great! what model is it?

 

[Alextk]

I had simmilar issues where it would run for a little bit and then shut off. After reading true the comments here, where someone found the reason for it was a bad connection between the battery and the battery mounting. I checked the battery mounting on the bike but it was all good, no melted cables or any sign of short. But when i inspected the battery connection ( the one on the battery that slides onto the mount ) I noticed that both of the + connections had melted broken off on one side, leading to bad connection and most likley cousing shorts whenever there are slight vibrations. For now i bent the copper plates slighly more togheter, makeing a more tight fit until i can replace the whole connector. If u have simmilar shut downs its worth looking more closely at the battery / battery mounting connection.

 

[tomjasz]

There are kits to change out the connections. But not for all models of Shark cases.
I've found that some left on bike and seldom if ever removed tend to corrode in wet environments.
A good spot for Boeshield or ACF50. The packs that are taken off often tend to wear out where the pack meets the base.

https://electricbike.com/forum/forum/knowledge-base/batteries-aa/12542-luna-hardcase-battery-documentation

https://youtu.be/JAEU_ImFaGA