BBS02 just died, any pointers?

[Akerhage]

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.

FQzHpBv.jpg

Thanks, I will take that picture to work tomorrow. However I cannot get the bike to work now
But maybe I can borrow a multimeter and measure myself somehow?

Im thinking that its not the display? Because I got it working for about 30s a few days ago. Display looked as ususal. And when turnnig the throttle on it did die. Also the display lights up 1 second now (HELLO-yellow-screen) and dies when trying the first time after the battery has been charging a while. If trying again after that, all black.

This is how the battery is mounted on the bike now. It has worked without any problems 8 months for me.

 

[Akerhage]

Also if buying a new battery, will this work? Is the same connection? Can I put them in my yellow one? (Doesnt look so). Maybe some adapter needed?
Also Im thinking if its better to install the battery on the opposite side where the water bottle is mounted?
https://boxbike.se/sv/48-volt-batterier/516-48v-batteri-powerpack-elcykel-14-ah-672-wh-samsung.html

 

[dahondoug]

docw009, thanks for your reply and tip. I feel like I already tested for battery sag with the load test I described and found no voltage drop that could explain tripping a low voltage protection circuit. But you've given me some ideas for further tests. Do you know what the style of connectors between the various components are called and where I can order them? I'd like to make up some testing cables.

 

[tomjasz]

All BBSxx versions use the same harness. All Higo connectors.

 

[Akerhage]

I have just detatched the pins and metal clasps now. I will try to solder the cords together to see if this works. I have today measured again the battery. Giving 41v.

I have drilled a hole in the case for the cords as well

I noticed this red cord was loose. Is this just to the battery-level-display? Or is it needed for something else?

Sorry for spamming, but I am really bad at this and dont want to ruin everything. Thanks for all help!

 

[fechter]

I think bypassing the cradle contacts will be good. I've seen lots of those things fail before.

The small red wire appears to only go to the level meter. Looks like it might be pretty scary to re-attach at that end as it's very close to the black wire. If I was going to reattach that one, I would cut it a few inches away from the meter, attach to the meter, then splice back the place where it was cut. This way there is less chance of shorting something out.

 

[Akerhage]

I think bypassing the cradle contacts will be good. I've seen lots of those things fail before.

The small red wire appears to only go to the level meter. Looks like it might be pretty scary to re-attach at that end as it's very close to the black wire. If I was going to reattach that one, I would cut it a few inches away from the meter, attach to the meter, then splice back the place where it was cut. This way there is less chance of shorting something out.

Thanks, my colleague here told me that the battery should give me 48v out and not 40.8v? He told me that maybe some cells in the battery may be dead? And that it is not working because of that? Hovewer, the display should maybe go on even with 40.8v?

 

[fechter]

Hmm...

Yes, 41v would be pretty dead for a 48v battery. Is that immediately after charging? A 13s pack should be like 54v after fully charging.

A really good test would be to measure each individual cell group. A little tricky but since you have it apart, not really hard. I do it by unplugging the big balancing plug with all the red wires from the BMS board. Then I use a pair of solid strand wires to insert into the plug and run those to my voltmeter. Between each pair of adjacent holes, you should see one cell group voltage. Ideally, all of them should be the same voltage. If you have a bad cell group, it will read different than the others.

You have to be careful when you plug the connector back in to the BMS. Try to make contact on the battery negative end of the connector first by slightly angling the plug as you plug it in.

 

[Akerhage]

EDIT!
NO LUCK WITH THE NEW WIRING Nothing at all happend when plugging it into the bike like that.

Ah, sweet! So I cannot measure in that BMS instead of trying to dismantle the batteries?

Yes, I have had it in the charger yesterday and some whole days in the charger without use. But it has not been directly hit with the charger...it has been standing 24+ hours since last time I removed the charger.

I hope someone here at my work understand how to make a wire to be able to measure, I have printed your description. Thanks for a nice picture!

Btw, with solid strand wire, you meen this one to the right?

 

[fechter]

Correct on the wire. It also has to be the right diameter to fit, but not so tight it bends the contacts.

Try measuring the voltage on the controller connector while it's on the charger.

 

[Akerhage]

I have the charger with me today. When removing that bms Contacts last time the cord to the right got loose, but it could snap in but maybe something got broken when it was loose also? I hope they know how to measure with charger in. I just measure the xt60 contact while its charging?

I havent really understand, if 40.8v is not enough to even power it on? I am thinking of buying a new battery. But it would be a shame it it turns out that a new battery doesnt solve it. Im not sure how to rule out the other problems. Could it be the display? Could it be some other wires on the bike? Could it be the controller? Its really hard for someone with no knowledge to try to determine this

EDIT: With Charger connected, I get 54V out of the battery.
So i should be able to start the bike with the battery connected to the bike and charger right?
Then maybe its not even the battery after all? Maybe some of the connectors instead? Or the controller?

 

[Akerhage]

Correct on the wire. It also has to be the right diameter to fit, but not so tight it bends the contacts.

Try measuring the voltage on the controller connector while it's on the charger.

Its 54v with the charger connected. So wouldnt I be able to start the bike then with the charger connected?
I´m guessing its not the battery after all?

 

[fechter]

If the voltage immediately jumped from 40.8v to 54v when the charger was attached, there is something wrong with the battery.

Yes, you should at least be able to get the display turned on if the voltage stays at 54v. The charger won't have enough current to run the motor though. It's also possible the actual voltage is dropping out as soon as you try turning on the display.

One more test: try measuring the battery voltage while placing some kind of load on the battery. If the display won't turn on, you might be able to use any load, like a 120v incandescent light bulb or heating element, hair dryer, etc. You want to see if the voltage just drops to zero with a load, indicating the BMS is tripped.

If the BMS is tripped, it won't pass significant current but it may pass enough for the voltmeter to get a reading. The voltmeter draws very little current so won't be like a load. If the BMS is tripped, it would indicate one or more cell groups is outside the allowable voltage range or something on the BMS failed.

 

[Akerhage]

If the voltage immediately jumped from 40.8v to 54v when the charger was attached, there is something wrong with the battery.

Yes, you should at least be able to get the display turned on if the voltage stays at 54v. The charger won't have enough current to run the motor though. It's also possible the actual voltage is dropping out as soon as you try turning on the display.

One more test: try measuring the battery voltage while placing some kind of load on the battery. If the display won't turn on, you might be able to use any load, like a 120v incandescent light bulb or heating element, hair dryer, etc. You want to see if the voltage just drops to zero with a load, indicating the BMS is tripped.

If the BMS is tripped, it won't pass significant current but it may pass enough for the voltmeter to get a reading. The voltmeter draws very little current so won't be like a load. If the BMS is tripped, it would indicate one or more cell groups is outside the allowable voltage range or something on the BMS failed.

Thanks, so if the BMS is tripped, then the battery is not able to fix? It could still be a battery fault then?
I will try to figure out how to put the battery on a load while still measuring it. Now the XT60 connection is hardwired to the cords.
Im guessing I have to remove that connection to try to put a lightbulb on with a load?

 

[Akerhage]

It works again! I was able to charge it at work before and measured 54v after charging.(which it hasnt showed before) So maybe if Im lucky the BMS did something and has repaired itself? Maybe some cells that recharged now, that did not recharge before?

I have only tried to start it and used the throttle some seconds. But looking good so far =)
I will try to take it to work tomorrow, and see if it is running the whole way.

Question. The XT60 adapter now is outside any protection from rain. Will this be a problem? Or can theese be located "in the free" if raining?

 

[fechter]

Question. The XT60 adapter now is outside any protection from rain. Will this be a problem? Or can theese be located "in the free" if raining?

Good news. It would be nice to know why it didn't work before though.

I wouldn't worry about the XT60 getting wet too much. They are exposed on all my bikes, but I don't ride in the rain. But I do occasionally wash the bike. Anyway, it shouldn't be an issue. If you expect a lot of rain riding, you might consider some kind of rubber boot that goes over the top of the connector that will act like an umbrella in the rain. Dielectric grease on the contacts will help prevent corrosion also.

 

[Balmorhea]

For what it’s worth, I do more transplants of bad BMSes on batteries than any other kind of battery repair. Today I ran across a failure I hadn’t seen before.

The battery was tagged for BMS replacement. It was a 16S LiFePO4 pack and it showed 51.3V, which implies just over 3.2V per cell. I connected it to a known good motor and controller, and it ran normally on the bench (which isn’t how bunk BMSes usually behave). I opened it up, disconnected the sense wire plug, and started probing the plug contacts with a voltmeter. They all showed about 3.42V, except one which was 0.0V.

I couldn’t know without tearing deeper into the pack whether the zero volts reading was a bad cell or a bad connection, but a quick calculation showed that 15 x 3.42V equaled the total pack voltage I was getting. I hooked it back up to the motor and found that it still worked... with all the sense wires disconnected. The BMS had failed with a closed circuit, and was allowing the pack to pump lots of juice through a zero volt cell.

I sure am glad that was a LiFePO4 pack. It had been sitting around my shop for weeks waiting for repair.

Now I need to bypass the dead cell and get a BMS that works with 15S.

 

[amberwolf]

first, make sure it really does have a dead cell, and not just a broken sense wire. the latter seems to be more common than actually dead-to-0v cells. (i've seen both, though).

fwiw, most cheap (common) bmses i've seen (and read of here), regardless of chemistry they're for, are designed so cheaply that with a broken sense wire, leaving the bms sense voltage floating, it reads 0v with a multimeter, but the bms doesn't detect this as a low cell and shutoff the output. this is dangerous enough, since the bms can't balance that group anymore, or detect if it's overcharged or overdischarged, but wait--it gets worse. :/

...the bms would work normally (shutoff the output) if the voltage was near enough to the lvc (but below it), but below a certain point, near or at zero volts, the bms simply ignores that channel, and operates as if the whole pack was fine. it can happen with actual dead cell groups, too, which is where it gets really dangerous.

this means that dead cell is getting current flowing thru it, driving it negative voltage during discharge, and then it's being recharged, and cycled like that....some chemistries kinda hate this, and object rather dramatically (or they can--it doesn't always happen).

better bmses do detect this situation and shutoff ability to use the battery or charge it. but i'd guess that most of the "generic" ebike batteries out there don't have this type.

 

[Akerhage]

Hmm so should I worry now about the BMS? Matbe it was a bad sensor? I measured 4.2v from each cell package from the sensor cords going into the bms. Bit I dont want to risk anything here. Maybe the battery will explode or something?

My guess is that I had a cell that would not charge before. Because the charger had a green light. But yesterday last charge gave me a red light indicating that it was charging and after the red light went green I got 54v instead of 40.8v.

Edit, the bike worked all the way to work for me today! Battery level at 88% when arrived, which is normal. So hopefully the BMS just needed some kind of restart and wire connection to work again as normal.

 

[Balmorhea]

first, make sure it really does have a dead cell, and not just a broken sense wire. the latter seems to be more common than actually dead-to-0v cells. (i've seen both, though).

In this case, the fact that the 15 cells that display a voltage add up to the measured total battery voltage would seem to indicate that 0V is truly zero. I’ll get to verify this when I go in to bypass the dead cell.

 

[fechter]

Edit, the bike worked all the way to work for me today! Battery level at 88% when arrived, which is normal. So hopefully the BMS just needed some kind of restart and wire connection to work again as normal.

Good news. Yes, sometimes the BMS might hang up in the tripped state and need a "reboot" to get reset.

 

[tomjasz]

Um, a pack with mismatched salvage cells. I'm not surprised there are problems. I'd expect more issues in the future.
That's a pack I'd definitely be charging in my ammo can!

 

[dahondoug]

docw009 and anyone else. This is in reference to my post on 2-29-20. Today I went out riding on pedal assist 1 on flat terrain. After 3 minutes the display shut off, no power. I rode the rest of the way, 3 miles, to my destination without power as it was downhill, no problem. When I started back I turned on the power and used full throttle for the steep initial hill. It ran great so I decided to see how far I could get at full throttle. 10 minutes later I was home going full throttle all the way, uphill, 15-25 mph. When I arrived the display was still on showing a full battery. It would seem that whatever is shutting off my system isn't triggered by either low voltage or high temperature protection. Since by passing the display doesn't fix the shut off problem I'm thinking something in the motor case is doing it. Using the throttle seems to bypass whatever is happening when I'm only using pedal assist.
Can someone point me to a discussion of the electronic components inside the BBS02?

 

[docw009]

Well, this picture says your battery connections are all messed up. You need to fix that.

 

[Balmorhea]

Luna sells a possible solution to that problem. There are probably other sources for the same item.