Is my secondary battery defective?

[voidedwarranty]

The bike is a Juggernaut HD Duo. Primary battery is 52v 17.5ah and secondary battery is 52v 14.5ah.

Recently I went on a few long rides using both batteries. Had great range pedalling out and used the throttle liberally on the way back. By the time I was done I was reading around 45% battery. When I went to charge the batteries, the primary took a good 5+ hours but my secondary stopped after only 40 minutes.

I thought this was odd, I figured both batteries would drain at a similar rate. So I decided to take the secondary battery to the bike and see if it would turn on and read what percentage and voltage it was at. Well the bike will not turn on. The gear shift sensor receives some amount of voltage to light it's little LED but the screen never powers up. This bike was advertised as being able to run off either battery. So it seems something may be amiss. Has anyone encountered this problem? I'm hoping it's a mere poor connection in the frame somewhere and not an issue with the battery.

 

[roshan]

The bike is a Juggernaut HD Duo. Primary battery is 52v 17.5ah and secondary battery is 52v 14.5ah.

Recently I went on a few long rides using both batteries. Had great range pedalling out and used the throttle liberally on the way back. By the time I was done I was reading around 45% battery. When I went to charge the batteries, the primary took a good 5+ hours but my secondary stopped after only 40 minutes.

I thought this was odd, I figured both batteries would drain at a similar rate. So I decided to take the secondary battery to the bike and see if it would turn on and read what percentage and voltage it was at. Well the bike will not turn on. The gear shift sensor receives some amount of voltage to light it's little LED but the screen never powers up. This bike was advertised as being able to run off either battery. So it seems something may be amiss. Has anyone encountered this problem? I'm hoping it's a mere poor connection in the frame somewhere and not an issue with the battery.

Depending on the state of charge of the cells, one pack may have gone through the balancing cycle which will take much longer than if it didn't.

 

[voidedwarranty]

Depending on the state of charge of the cells, one pack may have gone through the balancing cycle which will take much longer than if it didn't.

Well after several tries of cycling the switch on the secondary battery pack, I was able to turn on the display. At first I got it to turn on and it immediately shut off. A few more tries later and I got it to stay on. So is this a BMS issue? There is never a problem turning the bike on when the main battery is installed.

 

[roshan]

Well after several tries of cycling the switch on the secondary battery pack, I was able to turn on the display. At first I got it to turn on and it immediately shut off. A few more tries later and I got it to stay on. So is this a BMS issue? There is never a problem turning the bike on when the main battery is installed.

The second battery has a switch - if that's in off, then you will see the display come on and then turn back off.

 

[voidedwarranty]

The second battery has a switch - if that's in off, then you will see the display come on and then turn back off.

Thank you. That is exactly what's going on when my battery switch is in the on position. The switch must be defective. That would also explain the short charge times as the battery is basically not turning on while I'm riding. I'll make an official service ticket today.

 

[Gionnirocket]

The switch works through the BMS, it does not directly break the current.
So yes, switch or BMS seems to be your problem.

 

[roshan]

Thank you. That is exactly what's going on when my battery switch is in the on position. The switch must be defective. That would also explain the short charge times as the battery is basically not turning on while I'm riding. I'll make an official service ticket today.

Send us an email and they can help you with further debugging.

 

[voidedwarranty]

Send us an email and they can help you with further debugging.

Thank you. I have made a service ticket.

 

[voidedwarranty]

@roshan
I am still working with the support team about this. They have been great and the only reason it has gone on this long is my own lack of time to perform the tasks they asked for. I have attached 3 photos of the battery voltage readings using a multi meter. If you zoom in you can see that with the battery switch in the off position there is about 3.6v at the terminals. When switched on in the next photo you can see the voltage still reads 3.6v. only after toggling the battery switch on/off several times do I eventually get a reading of 55v.

 

[Gionnirocket]

Then I would suggest as the next step is to bypass the switch to determine if it has failed or if the problem is the switching circuitry on the BMS. You can also do a continuity test on the switch.
Another less evasive and less reliable test for the switch is to very slowly operate it applying a bit of pressure to the switch as you toggle. This bit of pressure sometimes is enough to allow the contacts to make if that's the issue. . if so, then it's most likely the switch. Do it several times for more information.

 

[voidedwarranty]

Then I would suggest as the next step is to bypass the switch to determine if it has failed or if the problem is the switching circuitry on the BMS. You can also do a continuity test on the switch.
Another less evasive and less reliable test for the switch is to very slowly operate it applying a bit of pressure to the switch as you toggle. This bit of pressure sometimes is enough to allow the contacts to make if that's the issue. . if so, then it's most likely the switch. Do it several times for more information.

Fiddling with the switch does change the output voltage. I'm expecting at this point though that Biktrix will just send me a new battery. It's covered under warranty. Unless they want to start paying me hourly to continue diagnosis, I'm not interested in going much further. The battery has a problem. It's been proven. Hoping to hear back from them today or from @roshan on here.

 

[Gionnirocket]

Fiddling with the switch does change the output voltage. I'm expecting at this point though that Biktrix will just send me a new battery. It's covered under warranty. Unless they want to start paying me hourly to continue diagnosis, I'm not interested in going much further. The battery has a problem. It's been proven. Hoping to hear back from them today or from @roshan on here.

I concur.
But I like to tinker and sometimes a solution can be had quicker doing so.
Understanding that battery shipment is expensive and how much you're able/willing to do on your own are all important factors.
In all I'm sure my friend Roshan will take care of you. . . He's the Man!!

 

[voidedwarranty]

I concur.
But I like to tinker and sometimes a solution can be had quicker doing so.
Understanding that battery shipment is expensive and how much you're able/willing to do on your own are all important factors.
In all I'm sure my friend Roshan will take care of you. . . He's the Man!!

I would certainly hope they don't expect me to cover the shipping on their defective and warrantable part. That's ridiculous.

 

[roshan]

I would certainly hope they don't expect me to cover the shipping on their defective and warrantable part. That's ridiculous.

Just contact support, they will go through next steps with you. From your post above it seems that either the switch or the wire between the switch and the bms is the culprit. We'll likely need to ship your battery back and ship you another.

 

[voidedwarranty]

Just contact support, they will go through next steps with you.

Yeah already done. Waiting for a response. Your support team has been awesome so far through all this

 

[voidedwarranty]

I'm back to update this thread. Biktrix has been excellent throughout this whole process especially given how much time had elapsed from start to finish (any delays were all on my end. Not much free time these days)

They asked me to package up my battery and send it to them with shipping and invoice labels provided by them. All it took from me was a trip to a UPS store and off it went back to Canada for inspection. Tracking said it would arrive today. I wasn't expecting a response until maybe end of the day tomorrow.

They responded today, about an hour ago confirming the failure as a bad switch, it has been repaired, everything working perfectly and shipped back out to me. I'm guessing I'll have it in about 7-9 days from now.

@roshan your support team and technicians did a great job. All responses were timely and professional. All requests were reasonable and easy to understand and/or perform. They deserve a Pizza party lunch break.

 

[roshan]

I'm back to update this thread. Biktrix has been excellent throughout this whole process especially given how much time had elapsed from start to finish (any delays were all on my end. Not much free time these days)

They asked me to package up my battery and send it to them with shipping and invoice labels provided by them. All it took from me was a trip to a UPS store and off it went back to Canada for inspection. Tracking said it would arrive today. I wasn't expecting a response until maybe end of the day tomorrow.

They responded today, about an hour ago confirming the failure as a bad switch, it has been repaired, everything working perfectly and shipped back out to me. I'm guessing I'll have it in about 7-9 days from now.

@roshan your support team and technicians did a great job. All responses were timely and professional. All requests were reasonable and easy to understand and/or perform. They deserve a Pizza party lunch break.

That's awesome. We do have pizza parties pretty much every Friday