....i meant to attach a .png to previous comment, but it appears I cannot delete or modify the comment.  I've attached the screenshot with a highlight outlining the warm area.

Sorry for the delayed update  - life keeps interfering with my goal of messin' around with this battery. I have installed the new BMS and it is a little warm (in the area highlighted in attached screenshot).  Is this something I should be concerned about?

TL;DR

I Trickle charged the cells from the tabs - they seemed to be fine - and so I installed the new BMI.  The new BMI is a bit warm still, after 12+ hours.  My initial thought was that the BMI might be balancing the batteries - so I waited ~12hrs thinking it might complete the balance and cool down.  Alas, the BMI is still warm, hence the question.


Any thoughts on why the BMI would be warm without any load and no charger plugged in?
Also, Any suggestions as to next steps?  I'm thinking I will:
1. Let it sit for another 24 hours and see if it's still warm.
2. try charging after 24 hours - see what happens.
3. test output voltage ---see if the same problem (~21 volts instead of 48) presents.

Inoxa - ahhh thx gotit. Now that I understand you were suggesting to tear it down far enough to remove individual battery cells, I'm sure I can find something (with some searching).  First, Im going to try DickB's suggestion to charge at the tabs.

DickB - I ordered some parts - a female 5.5 x 2.1mm DC charging port and a 1k ohm resister.  Once that arrives I'll piece it together.  Once assembled I'll post a pic of both the charging circuit with the resister *and a pic of the tabs across which I believe I should charge.  If you'd help validate my plan at that time (before I do anything stupid) I'd be grateful.  Prolly be a cpl days.

Really cannot overstate my appreciation. Thanks again to you both!

Since I have the new BMS I may just go ahead and replace it.  See if I can then use the charge port.

I can't find anything on bypassing BMS to charge battery pack cell groups (or individual cells) - seems like to do that I'd have to disconnect the tabs anyway.

DickB: Correct, the battery will not charge - with the charger, through the charging port.  I tried some other troubleshooting steps as well and posted it here:  https://www.radowners.com/index.php/topic,9624.0.html#msg23799.  Sorry for hijacking this thread - happy to continue here or in the other (and grateful for all ur thoughts!)

Inoxa - I've spent some time on youtube:  This is the closest I've got -https://www.youtube.com/watch?v=hv1DXRRmqB8.  He is testing through a BMS connector cable.  Attached is me performing - what I believe to be - the same test for the RAD BMS.  As I mentioned there is ~0volts when measured at the tabs.  Somehow my google-fu is failing me (there's a lot of videos out there, struggling to piece together enough tidbits from the different videos. Sifted through 100 videos of 'change the fuse' etc ) ----Really hate to ask, but if you have any links describing testing the cells (in some way other than I have done at the top tabs) *and any links that show how to try bypassing the BMS to charge (if that is what you are suggesting I might try) I would be super grateful. 

Thanks again folks - I obviously have alot to learn and really appreciate your time/thoughts :-)

Finally getting around to poking at this.  Looks like all the cell groups are registering zero (or, more accurately per attachment, between 30-1800mV) volts.  I wonder if this is because I've left the key in the on/lock-engaged mode and the batteries might have trickled out?

The replacement BMS has arrived, but I'd like to dive into the battery-group voltage issue.

* Does anyone have any suggestions for troubleshooting zero voltage? 
* Is there a way - or is it even wise - to charge the battery groups one-by-one and see if any of the cell groups are damaged?  Would this introduce a threat of unbalanced groups?

Thanks so much for your awesome walk-thru on drive.

I believe I have a BMS issue described here: https://www.radowners.com/index.php/topic,9624.0.html#msg23799 described



I've just ordered the controller you mentioned from green bike kit..... wish me luck!

@inoxa - thanks for the confirmation.  Looks like I may want to add 'how to make and repair battery packs' to my bag of tricks. 

I'm hoping someone might help troubleshoot my Rad battery issue - I've gone pretty far down the rabbit hole and I *suspect I have a bad Battery Management System (BMS) 

If anyone has any knowledge to confirm (or discount) this theory - or even point me to further troubleshooting steps - I would be most grateful!   I found this video on replacing the BMS - so if one of you battery gurus agree that the BMS is the problem and that there are no secret tricks to *reset the BMS, I'd love any feedback you have on the video: https://www.youtube.com/watch?v=wJyFALSY9Dk&t=934s. 


Below I've described the issue and my troubleshooting steps (with pics). Thanks In Advance!

• The issue occurred while I was pulling my 70lb dog in her trailer.  We were cruising some decent hills - I'm sure everything was hot - and then we hit a big construction pothole.  The power gave out.  The battery has not worked since. (attachment 1)
• I have two ~2019 Rad Citys.  This made troubleshooting easier as I have two batteries to compare. By switching batteries between bikes I was quickly able to isolate it was a battery problem.
• On the good battery fully charged with the key in the on position, I get 53 volts.  This is slightly over 48, as expected when fully charged. (attachment 2)
• On the bad battery charge status kinda unknown with the key in the on position, I get ~21v.  Pretty sure that's why it won't power the motor. (attachment 3)
• On the bad battery, if I plug it in to the charger, I see the proper voltage ~54v.  In the last bullet I will show you that the charger doesn't turn red on the bad battery (to indicate charging) as it does on the good battery. (attachment 4)
• On both batteries I have the lock in the correct position.  On the bad battery I checked continuity - the lock behaved correctly in that when unlocked there was no continuity, but when in the position showed in the picture the continuity was good. I think that rules out the lock (attachment 5)
• On the bad battery I replaced and validated the fuses.  When I looked at the fuses I could tell that the plastic mold was broken.  When I opened the battery case I used some plastiweld to 'fix' the mold.  I replaced the fuse and validated continuity at the wire. I think that rules out fuses - despite the wonky repair job. (attachment 6)
• On the bad battery I validated that the voltage at the wires leaving the battery and going to the bicycle connector.  It matched the connector - ~21v.  The connector looks pristine.  I think this rules out the connector (attachment 7)
• As mentioned above, when the rad charger is plugged into the good battery, the charger reads 'double red' for charging.  When the rad charger is plugged into the bad battery it remains green and red ---as if it is not plugged in or not communicating with the BMS.  I think this is an indicator that the issue is the BMS. (attachment 8 Bad Battery charger indicator lights,   attachment 9 Good Battery charger indicator lights

Really looking for any thoughts at all on this one.  I'm definitely out of my wheelhouse, but I'm a techie.  Soldering and battery spot welding are not out of my realm of capabilities - in fact, seems like understanding how to make/repair battery packs will be an increasingly useful skill so I welcome the learning.

TIA!