BBS02 750w dead after 1 sec

[Dannydonghi]

I already replaced battery bms, controller and display, but problem still exist. My bafang 750w shuts completely down after 1 sec, just a flash on the display and that's it. Problem occurred 1st time after 18 km and when using throttle for 200m (first time so long). Now, at mornings, it starts up for about 1 min, than shuts down, no error code, no display. Usually I can get it Back started when using the charger and/or disconnecting the battery, but only for about a minute. After 30 min I get it back on for 1 sec.
It seems that something got some power, gets overheated and fails, when removing power completely, it gets a small reset, but immediately overpowered. When charging it the reset is bigger, but failure again.

 

[AHicks]

There's only 2 things I know of that require a hard reset like you're describing, the BMS and the controller. If you've already replaced those, I'm wondering about your display? I know that when working with the KT Systems components (35a controller and LCD3 Display in my case), that the display holds all the setting for the controller. When changing controllers, your original setup will remain in effect. However, if you change displays, you will have to re-enter everything.

Thinking about it, wondering about the potential for a dead cell somewhere in your battery pack that's failing under load?

 

[Dannydonghi]

There's only 2 things I know of that require a hard reset like you're describing, the BMS and the controller. If you've already replaced those, I'm wondering about your display? I know that when working with the KT Systems components (35a controller and LCD3 Display in my case), that the display holds all the setting for the controller. When changing controllers, your original setup will remain in effect. However, if you change displays, you will have to re-enter everything.

Thinking about it, wondering about the potential for a dead cell somewhere in your battery pack that's failing under load?

 

[Dannydonghi]

Batterypack has just new bms and fully checked.
I switched the display c961 with c965 that I use on same type bafang 750w on another ebike.
I am going to switch the battery and try again.

 

[Dannydonghi]

After testing with other battery it seems OK, but when wiggling the bike, power is cutoff. This only happens when charger is not connected, with charger on, power stays on, even with wiggeling. Any idée?
Same result on both battery's, with charger loading, everything stays good, without charging, wiggling does cutoff the power completely. Than impossible to reignate, only whe' charger put in, restart is possible.

 

[AHicks]

It sure sounds like the battery(s) are at a voltage level that's too low - unless/until boosted by the voltage the battery charger adds.

Still think it's something to do with the BMS, the controller, or the battery

 

[Dannydonghi]

I used another working battery with same result.
I will disconnect the controller once again to check?

 

[rich c]

Try using a multimeter to measure with some accuracy instead of just switching around components and charger.

 

[tomjasz]

I used another working battery with same result.
I will disconnect the controller once again to check?

If the battery pack is one of the older Hailong, "Shark", packs you may have bad connections between the battery and the case. Wiggling should be a clue. What is the battery voltage? The BBS02 like and needs to be ridden like an acoustic bike. Shifting up and down and not lugging the motor. Coming to a stop and not shifting as you would with a non-electric bike and taking off with the throttle will overheat the motor. Using a large, 48T or 52T chainwheel and being lax about shifting will quickly overheat a BBS02.

Pictures of the base? Checked the wiring in the base?

 

[tomjasz]

Try using a multimeter to measure with some accuracy instead of just switching around components and charger.

Not to beleaguer the OP, but gosh... I spend an hour a day on the phone explaining to customers that they NEED to use a multimeter and offer some real numbers. Lots can be learned. Learning to check for continuity as well as voltage in various states is an invaluable trouble shooting tool. These days an auto off (batteries get expensive), auto ranging multimeter can be had for $10. Good enough for us!

 

[Dannydonghi]

I used another working battery with same result.
I will disconnect the controller once again to check?

Not to beleaguer the OP, but gosh... I spend an hour a day on the phone explaining to customers that they NEED to use a multimeter and offer some real numbers. Lots can be learned. Learning to check for continuity as well as voltage in various states is an invaluable trouble shooting tool. These days an auto off (batteries get expensive), auto ranging multimeter can be had for $10. Good enough for us!

I know, but I don't have the knowledge, and I don't find shops who wants to work on ebike, not bought there or really going on a deep search, so I have to follow suggestions of forummembers

 

[tomjasz]

I know, but I don't have the knowledge, and I don't find shops who wants to work on ebike, not bought there or really going on a deep search, so I have to follow suggestions of forummembers

Many here were once in the same position, and are very willing to help.

So, my questions are,
what is the pack voltage?
what kind of battery case and base? Pictures would be good.

I help BBSxx customer by phone, text, and email all day every day M-F 11AM-7PM CST
[email protected] remove MYPANTS.

But best to use the forum and we can all learn something. I learn something new nearly every day here.

 

[Dannydonghi]

Many here were once in the same position, and are very willing to help.

So, my questions are,
what is the pack voltage?
what kind of battery case and base? Pictures would be good.

I help BBSxx customer by phone, text, and email all day every day M-F 11AM-7PM CST
[email protected] remove MYPANTS.

But best to use the forum and we can all learn something. I learn something new nearly every day here.

It is 48v lifepo4 25a pack custom made 3,2 v batteries

 

[tomjasz]

48v lifepo4 25a pack custom made 3,2 v batteries

Well I missed that one...

if as you wrote

when wiggling the bike, power is cutoff. This only happens when charger is not connected, with charger on, power stays on, even with wiggeling

THIS is the key I think. So when the charger is plugged in all is well?
But wiggling the bike when not power cuts out. That is acting like a bad connection. Poorly wired BMS? Sorry, I'm guessing this one has me confused as to how that can happen. But you alsosay another battery does the same thing. That starts pointing back at the controller or harness....

What are the connectors between the battery and the motor? Have you checked them?

FELLAS?

BUT as Rich S mentioned, battery voltage?

 

[tomjasz]

Facebook has a good endless_sphere page. There are other Belgians there from time to time. Maybe you can find someone local. EU Pedelec forum too, for local hobbyists. We all like to help!

 

[AHicks]

I think the erratic behavior while moving the charge jack is key as well. The problem is I'm not clear on how our OP's bike is wired up because it's homemade. Knowing exactly what has been swapped with the use of different battery packs, controllers and BMS is impossible.

I think we need more detailed info to proceed. I'd like to know more than we are working with a 48v pack built from 3.2v LiFe cells for instance. I'm curious regarding the EXACT voltage of this pack when it's fully charged, and where we are at right now? I'd like to know what the low voltage cut off (LVC) is for the controller?

 

[Dannydonghi]

Plan for tommorow;install my battery on my wife's 750w bafang, than recheck the new installed controller and wiring, than throw the bike away??

 

[Dannydonghi]

OK, problem was a loose welding in the battery with on/off contact so difficult to pinpoint.
This explains the wiggling.
Also, the light up after about 15/30 min for a glimp, was the internal battery from the display.
Thanks everyone for the inputs?

 

[tomjasz]

That is acting like a bad connection.

 

[AHicks]

OK, problem was a loose welding in the battery with on/off contact so difficult to pinpoint.
This explains the wiggling.
Also, the light up after about 15/30 min for a glimp, was the internal battery from the display.
Thanks everyone for the inputs?

That's where I was confused. You did say you changed the battery with no difference.