PIM Battery Rebuild Resource

Wow! Kevin at Northeast Battery Systems has been very responsive. He responds within minutes. He quoted me $419 to rebuild my Polaris battery, using 21700 cells. Claimed they would give 15ah, as opposed to my current 6ah batteries. Sounds good to me!

New Polaris/PIM topic:

I was on a bike ride today. Everything was going fine while pedaling on a flat paved (ex railroad) right-of-way when my Polaris Aapex ebike suddenly went into "-2" regen mode all by itself. Pushing the control buttons on the handlebar display/controller did not make any difference. I finally stopped, shut off the battery and turned it back on. This cleared the condition and my ride resumed in normal operation. The battery still had 3 out 5 bars of power left. Has anybody had this issue before? Any idea what might have caused it. I have owned the ebike since 2017 without any operational issues before.
I recently had 2 of my Polaris ebike 44v/6ah batteries rebuilt by Northeast Battery Systems LLC in CT. They are now 44v/15ah. They used 36 LG 21700 batteries that fit within the same Polaris battery case. Due to recent Seattle weather, I haven't been able to get a full range test. My 6ah batteries were only reaching about 10 miles per charge. I currently have 24 miles on a new 15ah battery and it is still going strong. My new problem is that the handlebar digital display (and the 3 LED lights on the battery) still act like I'm on the old battery. The display & lights still expire around 10 miles, but the new battery still keeps on going. I'm thinking of maybe adding a handlebar digital voltmeter and using that as a replacement. I'm pretty sure I should be able to tap some electrical points in the wiring (or battery) that would allow the voltmeter to work correctly. Wondering if anyone as ever successfully done that on a Polaris/PIM ebike before? Mike
Update on new battery monitoring. I added a voltmeter on my bike handlebar, an on/off switch on the frame tube and a wire tap connector on each battery pack (tapped at the "+" wire of the fuse). The meter will display up to "99.9" volts. I tried it out on a test ride. I started out (fully charged) around "48" volts and the battery pack shut down exactly at 30 volts (cell cutoff is 2.5v) using 12 cells in series 12x2.5=30v.
For maximum battery life, I plan to charge no higher than 85% of battery capacity, stop using the battery around 32v, and charge to 50% capacity for storage.
Well, it appears I am completely screwed now! I have 2 Polaris/PIM bikes and several batteries. Two of my batteries were rebuilt by NorthEast battery Systems ( into 15ah batteries) and I also had an original 6ah Polaris battery and an 8ah Polaris battery. Everything had been working fine until my 3rd Polaris bike motor stopped working. It tries to run but it was having stiff hesitation rotating, with a heavy shudder in the motor. Even when turned off, the motor resists rotating. It feels like the internal magnets are trying to prevent the motor from rotation. I junked that bike and continued to use my remaining 2 bikes. Yesterday, one of my 2 remaining bikes had that same behavior, I was using the 8ah Polaris battery (which showed a full charge). I moved that 8ah battery over to the remaining bike and now that one is toast too. Both motors do not want to turn (whether they are on or off). I can only guess that the 8ah battery is the cause of the problem, even though the display panel lights up fine when the system is turned on, the motors will no longer function. There are many very powerful permanent magnets in the Polaris/PIM motors but somehow I suspect their polarity is now all screwed up. Not sure that this is fixable, as the problem exists whether there is power to the motor or not. You can barely crank the pedal even when the system is shut off. Looks like my bikes are junk now.