Within the curiosity of decreasing weight, I’ve purchased a LiFePO4 battery which is meant to work with BMW IBS and so far as {hardware} goes, be plug’n’play.
Nevertheless, I am getting “over voltage” errors with energy reduce to the modules that get the over voltage, like for instance, I misplaced ABS whereas cornering at 160km/h with a warning error pop saying “brake system failure”. Clearly not what you wish to see whereas gazing a wall in entrance of you at 160km/h.
After performing some analysis, plainly the issues is because of the regenerative braking and the lithium battery BMS that disconnects the battery to guard it from over voltage.
BMW regenerative braking can go as much as just below 16V. At 16+ V it’s thought of over voltage, beneath it’s regular. The lithium battery appears to disconnect at round 15.5V, however when doing so, since there isn’t a longer an inner battery resistance the voltage spikes in the entire automotive, with voltages as much as 18V.
My automotive got here with 80Ah AGM and I used to be instructed to code it to 80Ah “not AGM” for the lithium battery.
I attempted that, I attempted coding larger AH, decrease AH, AGM and non AGM. None of this codings have an effect on the regenerative voltage, solely the “regular charging voltage”, which is about 13.8-14V for non AGM and 14.1-14.8V for AGM.
For the reason that difficulty is simply on regen (elevate off or downshift engine braking) and since I am unable to change the voltage at which the battery BMS disconnects, I hoped to have the ability to possibly change the max voltage allowed in regen section. Does anybody know if that is doable, and if that’s the case how can or not it’s completed ?
It ought to be within the FEM, since it’s the one liable for charging .
That is the information log exhibiting AGM battery in regen section:
That is the lithium battery in regen section: