BBS02 just died, any pointers?

Can you give me some pointers with my Bafang BBS02 750w, it has been working fine until a couple of days back. The battery was about 3/4 charged and I rode about 1/2 mile on the flat so the motor was fairly cool. I stopped for a couple of minutes, when I got back on to the bike I noticed that the screen had shut down (quicker than was usual). So I pressed the centre button to start it back up, but it was totally dead.
I have charged the battery to full and it seems to be fine with 53v when checked with the test meter, the voltage doesn’t drop when trying to boot it back up so I assume it’s not a lack of capacity.
I have looked over all the wiring and can’t see a loose/ damaged connector or wire.
I had a good close look at the display and couldn't see anything obviously wrong, I also took out the controller, again no strange smells or anything strange.

What should be the next logical step to check, rather than just buying new parts and guessing?

Were you pushing the motor a lot before it gave up, like wide open throttle in a hard gear? I had a bbs02 controller give up in the same manor after a short sharp hill climb and it didn't feel particularly hot on the outside. It just shut off earlier than expected when I was stationary and never turned back on. it didn't seem obviously damaged when I took it off and removed the potting. it was also a later controller with good quality fets which is slightly concerning but I did push the motor pretty hard before it went.

Hi Neil, this is the curious thing, I had just left the house and it was only about 1/2 mile on the flat, the motor was barely used before I stopped to collect something. When I got back on the display was dead.

Today I did some more checking and there is full voltage to the display but it doesn't come on so I'm assuming the display has broken.....unless anyone knows better or can suggest a fix? I held the 'on' button down for a fair time to see if that assisted a reboot. Couldn't spot a reset button or fuse.

KingKey said:

Hi Neil, this is the curious thing, I had just left the house and it was only about 1/2 mile on the flat, the motor was barely used before I stopped to collect something. When I got back on the display was dead.

Today I did some more checking and there is full voltage to the display but it doesn't come on so I'm assuming the display has broken.....unless anyone knows better or can suggest a fix? I held the 'on' button down for a fair time to see if that assisted a reboot. Couldn't spot a reset button or fuse.

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Displays die, not unusual or a high rate either, but it does happen. Repairing is usually futile. I keep a spare. I've had a C961 fail with a bad display, and a C965 just dropped dead. I have a color display but found it to be a useless and expensive upgrade. I found a C963 for a backup for my 01's and 02 currently using C961's. Simple easy programing and just no fluff.

I wish the conversion to a CA3 wasn't so spendy! BUT that IS a sweet do=isplay option that actually adds useful CA3 utility. But it's kinda like lipstick on a pig.

I might do it for my last BBSHD....if I keep it...Wishing I had gone MAC or EZEE....

I have the very same behaviour now. Yesterday it was a bit cold here, and slippery. So on the way to work I fell with my bike.
But it was just a scratch for me, so I biked the way to work. Then after work I went home with the bike. No problem at all. The bike is standing inside during night. And now this morning it doesnt start at all. I´ve had it for 8 months now, no problem with it. So maybe something happend when I felt after all?

I dont understand the electrics at all, but when trying to power it on now, nothing happends? The display is dead and the motor is not giving power at all. Can it be that the display got hurt somehow? And is a broken display making the bike not to work at all?

I have tried to remove the battery, it is fully charged, and the battery and bike has been well mentained. Kept inside all the time. Charging 3-4 times a week.

Any ideas, or any tips on where to look, for a real noob in this.
I think I have this display now, looks the same,
Bollfit Bafang LCD Display 850C Colour Screen

Most likely a wiring issue. Check all connections. Activated brake sensors and speed sensors out of adjustment can prevent startup. Try unplugging them and seeing if it will run.

Check ALL connections again if you can't isolate the problem.

If the display won't power on, it hasn't got to the stage where it would check sensors yet. Trace all the wires and look for damaged spots. Unplug the display from the motor and reconnect. Unplug the battery from the motor and reconnect. Measure the battery voltage if you have a voltmeter (every ebiker should have a voltmeter).

Akerhage said:

I have tried to remove the battery,

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"tried to" implies, with no further info, that it will no longer come off the bike. that implies there coudl be damage to the battery casing, or the mount on the bike, and that means there could be a problem with the connection between battery on the bike, where it is not fully seated.

to verify this you'd have to disassemble the battery case enough to get it off the mount and then examine case and mount for the damage that is causing it to not remove. once that is fixed you could remount it and retest. if the problem still exists there are other possibilities.

it is fully charged,

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does this mean you've actually verified the output port has full voltage, with a load on it? or does it just mean you've plugged the charger in and the light goes green?

the former means the battery is unlikely to be the source of the problem. if you haven't done this test, we can figure out how you can.

the latter doesn't tell you if the battery works, it only tells you the green led on the charger does.


so once we have complete details on exactly what you've already tested and how youv'e tested it, we can try to figure out what else you can test without replacing parts.

The battery is taken off. Sorry for not being able to sort that out. I did measure the battery at my work. (Not me, but a guy there helped me). He did however not noticed anything wrong with the battery or charger.

So I have mounted the battery again on the bike if that was unclear. I do remove the battery every time I charge it, and then put it back on again.

How do I check the wires? I did buy this bike from another guy almost 8 months ago. Im not that familiar with wiring. I have tried to plug out every peace I can and plug it back in again. I did plug them out when battery was removed from the bike.

I have a speed sensor I know, I dont know what the break sensor is however.

Thanks for trying to help, I am not that good at all with either bikes or electricity

For the battery testing he did put it to some tests with a multimeter and some other things. He did measure the output from the battery to 42V I think. And the charger was also verified giving the correct ampere and other stuff it should.

Im thinking of trying to buy a new battery after all. But maybe then its not the battery and I throw 400-500 usd away for nothing.

Update, I have it plugged in now the whole night, and it did turn on. The throttle worked for about 10-15s then it died again. So seems that it is working, but then dies. I did clean the speed sensor, dont know how to remove it? Is it just to screw it off?

Check to see if the battery contacts are making a good connection with its mounting rail. Sometimes the clips widen until they fail to make contact with the blades.

Balmorhea said:

Check to see if the battery contacts are making a good connection with its mounting rail. Sometimes the clips widen until they fail to make contact with the blades.

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This is my guess also, can this be fixed? I can bring it to my work and probably I can ask for help here. They do work with electrics and soldering stuff here. But I dont want to waste their time to much so I want to limit down the possibilities first

Can I try to put this (see picture) alone in the battery without the mount maybe? and then plug the yellow side to the bike and see if its easier to spot contact issues?

It does sparkle a bit when trying to fit it to the battery however. Also maybe I can just buy a new one of this? Dont know the name of it though.

The sparks are normal when connecting the battery. The battery wire looks OK in the picture.

It almost sound like the battery failed and is cutting off as soon as you apply load. The best thing would be to measure the battery voltage just after it cuts off without disconnecting the battery. This may be a little tricky depending on whether you can reach the battery terminals with the meter probes. When a battery BMS "trips", it cuts off the voltage to the controller. As soon as you disconnect the battery, it resets.

I guess one other test would be to lift the bike off the ground so you can run it stationary, and try running it slowly while the charger is connected vs. not connected and see what happens. Another test would be to run it until it cuts off, then connect the charger for a few seconds and see if that makes it turn on again.

fechter said:

The sparks are normal when connecting the battery. The battery wire looks OK in the picture.

It almost sound like the battery failed and is cutting off as soon as you apply load. The best thing would be to measure the battery voltage just after it cuts off without disconnecting the battery. This may be a little tricky depending on whether you can reach the battery terminals with the meter probes. When a battery BMS "trips", it cuts off the voltage to the controller. As soon as you disconnect the battery, it resets.

I guess one other test would be to lift the bike off the ground so you can run it stationary, and try running it slowly while the charger is connected vs. not connected and see what happens. Another test would be to run it until it cuts off, then connect the charger for a few seconds and see if that makes it turn on again.

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Its not turning on again after the 20s when it works. Somehow maybe that says something about the battery. I will try it again now when its been charging the whole day.

Can I put some copper paste or something maybe on the battery where the pins is inserted or maybe sandpaper the pins or tighten the gap so that the pins maybe gets closer?
Sorry for bad english.

Got a small glitch from the display when coming home before, a second only.

This is how it looks while plugged in now when testing. (I have removed the battery now and opened it up to be able to provide pictures on how it looks while the battery cord is mounted in with the pins in the battery. Should this connection be enough you think?

If you see any discolored metal from heat tempering, or melted plastic and/or wiring insulation, all would indicate connection issues. But with slanted knife connections not parallel with the mating surfaces. And what appears to be broken, cracked and repaired connectors.... Take a look at this thread for possible fixes...

https://electricbike.com/forum/forum/knowledge-base/batteries-aa/12542-luna-hardcase-battery-documentation?p=35701#post35701

TommyCat said:

If you see any discolored metal from heat tempering, or melted plastic and/or wiring insulation, all would indicate connection issues. But with slanted knife connections not parallel with the mating surfaces. And what appears to be broken, cracked and repaired connectors.... Take a look at this thread for possible fixes...

https://electricbike.com/forum/forum/knowledge-base/batteries-aa/12542-luna-hardcase-battery-documentation?p=35701#post35701

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Thanks, I will check that out tomorrow.

I think you're on to something there with the battery connector. I see a crack in the plastic next to the + which might make the contact loose. I'm not familiar with that exact battery connector, but if there is any way to tighten the contacts it will help.

Hmm, look at this, this does not look that great?



Im thinking if I can bypass the pins? If so, do I need to buy something?

It did broke even more now when I was trying to get that pin-plastic thing of the battery.

Battery shuts off after successively shorter time
This seems like the right thread for my question. I have 2 ebikes with identical setups. Bafang BBS02 motors, standard LCD display from Luna Cycles, a battery cradle mounted on each bike. I only have one 48v-13s-4p shark battery pack which I switch between the bikes. Combined I have 2,000 miles on the battery, 1200 on one bike, 800 on the other. The 1200 mile bike was assembled 2 years ago, the 800 mile bike one year ago. I go 10 to 20 miles between charges so between 100 and 200 partial discharge-recharge cycles. My range is about 45 miles to shut off discharge. They both worked perfectly until last week.
Last week I was riding the 800 when the power shut off after 5 minutes of use with an 80% charged battery. Turning it back on worked for about a minute, then shut off again. Two or three more off-on cycles, each shorter than the last, then it wouldn't come back on at all for several minutes. Reading from ebike forums I decided the display was the likely culprit so I put the battery in the 1200 bike but it misbehaved in exactly the same way. Thinking I might have a bad cell group I checked the partially discharged battery voltage at the bms 13s connector. There was either a 3.69 or 3.70 reading between each post with 48.1 volts overall read at the battery case contacts. I charged the battery up and got a reading of 4.19 or 4.20 between the posts and 54.6 overall. The bike ran a little longer with a full charge but misbehaved the same way after about 10 minutes. So I ordered a new bms and soldered it in. Hit the power button and the LCD lit up just as it should. Went for a ride, but within 10 minutes, same misbehavior.
I then read that a display might be the problem, so with one bike, then the other, I disconnected the display and plugged in my programming cable. The behavior of shutting off persisted with both bikes with the battery pack at 52 volts.
Next I took a 12 ohm heating element from a kiln and an ammeter and put a 4 amp, 200 watt load on the battery. It ran for half an hour with a steady, slow voltage drop overall and between cell groups. Cell groups stayed within .01 volts of each other, never shut off during the load test. Put it back on the bike and it shut off within 5 minutes. I put a load on the battery with the case on then off, it performed perfectly in both cases.
I haven't considered any component other than the battery since that's the only common component and for two bikes to fail in exactly the same way, on the same day, after one and two years respectively of perfect service is statistically highly improbable unless it is the common component.
Do the BBS02s have a low voltage or high temperature shut off down in the motor case? What have I missed?

When it occurs simultaneously to two different systems that had been operating perfectly, doesn't it have to be the battery? Batteries can show appropriate charge with no load, then misbehave when stressed.

I described the load test I did. When riding the battery shuts off in very light use situations, even standing still at a red light. I should think a 200 watt load should be enough to simulate light riding.

fechter said:

If the display won't power on, it hasn't got to the stage where it would check sensors yet. Trace all the wires and look for damaged spots. Unplug the display from the motor and reconnect. Unplug the battery from the motor and reconnect. Measure the battery voltage if you have a voltmeter (every ebiker should have a voltmeter).

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There are definitely versions that will not power up if the brake cutouts are activated. My early version BBSHD absolutely did that.

Interesting.

If the battery connection goes bad for even a split second the display will turn off. If you can turn it back on without having to disconnect the battery first it probably means the BMS didn’t trip.

Akerhange, Does your battery go into a working cradle? How does that funky XT90 adapter get used in your bike? WHat you show in your pictures makes me doubt that battery power even gets to your display.

Here's a wiring diagram someone kindly provided for the BBSHS, but I believe it matches the BBS02. FOllow the wire out of the display to where it meets the main harness. If you unplug it, the harness side will show a round connector with 5 pins, a male connector. Bummer. Female is better.

This part is not easy, because of the darn pins, but battery power and ground are available there. If your buddies at work have clip-on probes for these pins, it's an easy thing to measure, but for us folks at home with blunt probes, it takes care, as we can fry an adjacent pin if the probes slip. In any case, if it can be measures, and if battery voltage is present, then the display got whacked when you fell.

You could also look at the harness connector coming out of the motor and check there for battery voltage, but I think the motor side is also pins.

dahondoug, if you got time, pick up a $12 RC wattmeter. Put it between the battery and BBS02. You also need to power the wattmeter off a 9 volt battery. It will tell you the minimum voltage seen by the system. Then you will know hiw nych your battery sagged.

The wattmeter can run off the bike battery, but if it resets, so does the wattmeter. I've found the parasitic drain on mine is significant, so I don't leave it on my e-bikes.