Ebike shuts off as I ride over bumps

Blinding_Light

New Member
Region
Europe
Hi. First of all sorry If my english is bad.

So I recently built my own custom ebike with Bafang BBS02B 750 W motor kit with battery. Everything is working very well and I've had a lot of fun riding it, except the battery seems to lose contact and because of that the ebike shuts off and I have to detach and reattach the battery. It happens when I ride over some bumps. Can it be a battery connector? Everything is brand new and my battery has this connector which is praised by all that it's much better for keeping contact in bumpy terrain
con_dt_silvblt.jpg


I would replace it right now but my only option is to order it on aliexpress so it'd take months to arrive I suppose. Did someone experience this issue? I don't know, this is weird... Like i've seen that people have problems with this type of connector but not when it's brand new and unused :/
 

JES2020

Active Member
Bypass the connector and see if it still happens. You can also just jerk and wiggle the connector and see if you get the same problem.
You diffidently have a loose connection somewhere, test all your joints to verify.
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
I had the same issue as you and many others have had... Even with the so called improved connector. I saw no logic in replacing it with the same so I opened up the battery, eliminated the connector and extending the discharge wires so that they were long enough to reach as needed. I passed the new longer wires through the area of the removed discharge port and silicone'd the opening. I do have a fuse added before the motor for safety, but that was there from the beginning. I also have a switch on the battery from the manufacturer so it was safe and easy to work inside on the discharge wires. This does makes it a little more difficult to remove the battery, but I rarely did anyway so it worked well for me.
 

indianajo

Well-Known Member
Those green things in the back are .177" bullet connectors, and if they won't pull off (properly installed) they are more reliable than most any push in connector. The US made ones (AMP, TE conn, Ideal, T&B, Panduit, 3M) are extremely reliable over 30 amps. Dorman from Taiwan are okay. I've dumped the XT90's that came with my battery & use the bullet connectors exclusively. Or insulated .250" flag terminals, also good to >30 amps. Use a Klein or Ideal tool to install, and pull test before using. Reverse sex on + and - to avoid cross wiring them and shorting the battery. 12 ga in a blue connector may require peeling back a few strands & cutting them off, as blue connectors are for 14-16 gauge wire.
 

Blinding_Light

New Member
Region
Europe
Very good idea to bypass the connector. I opened the battery mount bracket and removed the connector, then I tried to wiggle the connector a little bit with multimeter and indeed I'ts a loose connection. I have the switch too, but still a little bit scared to open the battery. I think that's my only option tho :(
 

Blinding_Light

New Member
Region
Europe
Those green things in the back are .177" bullet connectors, and if they won't pull off (properly installed) they are more reliable than most any push in connector. The US made ones (AMP, TE conn, Ideal, T&B, Panduit, 3M) are extremely reliable over 30 amps. Dorman from Taiwan are okay. I've dumped the XT90's that came with my battery & use the bullet connectors exclusively. Or insulated .250" flag terminals, also good to >30 amps. Use a Klein or Ideal tool to install, and pull test before using. Reverse sex on + and - to avoid cross wiring them and shorting the battery. 12 ga in a blue connector may require peeling back a few strands & cutting them off, as blue connectors are for 14-16 gauge wire.
That photo I sent is just as an example of the battery 5 pin connector. It's not the same as mine. But I have a question, is it a problem if there's XT60 instead XT90? The xt60s came with the battery. And it's 48 V and 17,5 Ah capacity.
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
Very good idea to bypass the connector. I opened the battery mount bracket and removed the connector, then I tried to wiggle the connector a little bit with multimeter and indeed I'ts a loose connection. I have the switch too, but still a little bit scared to open the battery. I think that's my only option tho :(
Well if you want to replace the connector you'll have to open the battery as well as it should be replaced as a set. Xt60 is just fine. To make it easier to pass the wires you may want to go with bullet connections as @indianajo suggests. I used Xt60 and had to grind the opening at the end of the baseplate to pass the wire more easily.
If you open the battery work slowly and carefully. Everything is tucked in just right and there's not much room to get sloppy with wiring. It wasn't hard to do, but patience is key.
 

indianajo

Well-Known Member
I find with XT60 and XT90, if I add enough heat to provide a proper solder connection, the plastic connector body melts and the pins go out of line. Stupid ****ing design. XT60 is probably good for the 20 amps of a 500 watt motor. Since it is of oriental origin, no looking up a datasheet for specifications.
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
I find with XT60 and XT90, if I add enough heat to provide a proper solder connection, the plastic connector body melts and the pins go out of line. Stupid ****ing design. XT60 is probably good for the 20 amps of a 500 watt motor. Since it is of oriental origin, no looking up a datasheet for specifications.
They are difficult to solder.
The tricks I use is as you solder have a spare matting connector plugged in the other end to keep everything aligned properly.
Wrap a small wet rag around the plastic to keep it cool.
Tin the wire well and loaded with solder before you add the XT60.
Use additional Flux to speed up the soldering process.
Use a large tip @ 500°c

XT30 - 30a
XT60 - 60a
XT90 - 90a
All rated continuous
 

Blinding_Light

New Member
Region
Europe
Okay guys. The issue is solved! If anyone is interested in what caused the power to cut out - It was VERY BAD soldering. I opened the battery case and immediately noticed that red cable was very loose and poorly soldered to the connector. Little did I know what fight this was gonna be. Soldering was fine but the cable management was a nightmare! It took me like 3 hours just to figure out how to put the cables so I could close the battery case. I ended up extending both power cables so I could route them correctly. But after all of this I'm so happy that it works :)

The funny thing is, I already ordered a new connector and managed to fix the old one beforehand XD But having a spare one is always a good thing :D

Thank you guys and I hope this helps others with the same problem!
 

JES2020

Active Member
Okay guys. The issue is solved! If anyone is interested in what caused the power to cut out - It was VERY BAD soldering. I opened the battery case and immediately noticed that red cable was very loose and poorly soldered to the connector. Little did I know what fight this was gonna be. Soldering was fine but the cable management was a nightmare! It took me like 3 hours just to figure out how to put the cables so I could close the battery case. I ended up extending both power cables so I could route them correctly. But after all of this I'm so happy that it works :)

The funny thing is, I already ordered a new connector and managed to fix the old one beforehand XD But having a spare one is always a good thing :D

Thank you guys and I hope this helps others with the same problem!
No problem, I am happy to help !
The connectors themselves are usually pretty fool proof, if undamaged and installed correctly.
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
Okay guys. The issue is solved! If anyone is interested in what caused the power to cut out - It was VERY BAD soldering. I opened the battery case and immediately noticed that red cable was very loose and poorly soldered to the connector. Little did I know what fight this was gonna be. Soldering was fine but the cable management was a nightmare! It took me like 3 hours just to figure out how to put the cables so I could close the battery case. I ended up extending both power cables so I could route them correctly. But after all of this I'm so happy that it works :)

The funny thing is, I already ordered a new connector and managed to fix the old one beforehand XD But having a spare one is always a good thing :D

Thank you guys and I hope this helps others with the same problem!
Glad you got yourself on the road quicker than anticipated.
Believe me... That new connector will come in handy, sooner rather than later.
In the meantime I suggest you check the existing one periodically and clean it with contact cleaner if you see any discoloration.