https://community.electricforum.com/t/re-2012-gem2-lithium-conversion/17850/37
Hi:
I am having an issue with the charger. It will not charge the new FeLi battery after reprogramming. When I connect the charger, it reads the battery state then turns off after a few seconds (I can hear a faint click). Any suggestions?
Need more information.
Source of charger and programming.
Sorry to leave you hanging. I started too many threads and got lost.
Update: This is a Gem2, 2012 conversion from the original sealed lead acid batteries to FeLi 24s, 72 V , 105 Ah system. The batteries arrived some time ago but I had to order a beefier BMS to handle 300A. I also ordered a balancer. You reprogrammed my DeltaQ for lithium.
Then Covid, and now my mom was ill, so I finally got to installing the charger, battery, BMS and balancer this weekend. Incredibly everything worked (with a few adjustments to the BMS) except the charger was not staying on. KingHappy was kind enough to point me in the right direction by pointing out that I had not dealt with the temperature sensor.
I am having an issue going down steep hills, where the recharging is overwhelming the system and causing a shutdown. Code 76 appeared on the dash, and the BMS reported overcurrent protection.
Do you think there is something going on with the controller?
I forgot to mention that after a few seconds the system restarts and I am able to drive away (much slower)
You can lower the regen to limit charging current below the 50a rating of the bms.
Or you can set the bms charge current limit over specs.
Say to 100a.
As the bms is opening the power to the Gem, the regenerated power has no place to go. Controller will shut down to protect itself. Capacitor volts will go through the roof.
Once you get the charge limit raised it should be ok.
Need to take this public so others can benefit.
I did not consider reprogramming the regen limit in the controller. Is the procedure documented already? Does that mean getting a reprogramming kit for the controller?
Our hills are very steep and the amount of current generated going downhill is substantial. Frankly, this has been an issue from the beginning, even with the lead-acid batteries. I found the motor “smoking hot” after the first descent to our house, applying the brakes to slow down the vehicle. Later I learned that going down the hill using only the motor to keep the car at speed (full acceleration), I avoided any heating problems, but it was a harrowing descent.
I had already set the BMS current limit to 75a. I will try 100a. Just checking, do you think it is safe for the BMS? The electronic module looks frail…
Bms is a low cost part. I would take a chance. Do you monitor regen current in app?
There is also a delay setting. I was sure it was regen current being the issue, as 50a was the most I saw. It would trip after the delay.
You might try bypassing bms for a test.
You are right, it is a low risk item to set it at 100 a, since it is rated at 300 a.
Yes, I can monitor regen current in the app (it is a phone app) and there is a log of the vent to check. Correct, there is a delay setting as well (default 5 s).
Yes, I’m not sure why the conservative rating for charge current.
The control mosfets for charge and discharge are identical. Connected back to back.
Unfortunately I won’t be back on the island until tomorrow, but will report on the results. Thank you again.
The controller has shunt braking built in . If you Gem starts going over 25 mph down a hill the controller reverses voltage to the motor using it to slow the Gem . This is VERY hard on motor and controller . You can easily program it out but your gem will lose its ability to slow itself . I take it out of all my Gems .
At that time lower your regen amps under 100
Can you help me program the shunt brake out of my Gem? It feels like a liability and I experienced overheating of the motor and the controller shutting down with code 76. I increased my BMS amps to 100.
you can send it to someone to do it or buy the cable and software and do it yourself . There is a learning curve but if you have time it is not that hard .
FYI Gem refers to it as plug braking . If you go to flight systems website you can download your controller manual that will show you which parameter it is .
https://www.shop.fsip.biz/Image/GetDocument/en/291
This is the T4 manual .setting #5 is the one you want to adjust
Sounds like a challenge that is worth taking.
Thanks again
So cable is $73 plus Century software for a one-time change of one parameter does not make sense. Could I ship you the controller for reprogramming? How much would you charge to turn off the motor braking?
I was running around the campground last night. Was a the top of a steep hilltop and was creeping down the hill not touching the accelerator and it held us at 1mph. After a few minutes we smelled smoke. Stopped at the motor was to hot to hold my hand on. Need this feature gone as soon as I get home.