In my case low temperature seems to accelerate the rate of Batt.Kapa decrease. But the latter never picks up in summer. Check my stats here, I have a chart with Batt.Kapa over months later in the thread viewtopic.php?t=16253
In my case low temperature seems to accelerate the rate of Batt.Kapa decrease. But the latter never picks up in summer. Check my stats here, I have a chart with Batt.Kapa over months later in the thread viewtopic.php?t=16253
My understanding is that Batt.Kapa shows the kWh that the battery is either able or allowed to accept during charging. At least that's been happening in my case (I checked this assumption many times, including after almost complete battery depletion and charging up to 100%).joni3s wrote: ↑Fri Jan 03, 2020 9:44 am
I'm curious if an easy way to check battery capacity more accurately is to just fast charge to known values a couple times and see how much kwh are able to be used. Or is this that wildly inaccurate? Isn't that what BMW is doing more or less when they discharge and then recharge (from what i think I remember reading).
I've read that the i3's nominal battery capacity is determined by charging/discharging at a C/3 rate. That means for a 21.6 kWh battery pack (60 Ah), the charge/discharge power would be 21.6 kWh / 3 h = 7.2 kW. That's the maximum single-phase AC charging power, so measuring the kWh vended when AC charging at 7.2 kW would be a good start. However, the Idaho National Lab measured the AC charging efficiency as 93.8%, so the energy vended would need to be multiplied by 0.983 to calculate the energy added to the battery pack.joni3s wrote: ↑Fri Jan 03, 2020 9:44 amI'm curious if an easy way to check battery capacity more accurately is to just fast charge to known values a couple times and see how much kwh are able to be used. Or is this that wildly inaccurate? Isn't that what BMW is doing more or less when they discharge and then recharge (from what i think I remember reading).
MKH, what do you mean by registering the new one? I have a 2015 i3 with a lower than expected Kappa that had the 12v replaced not too long ago. Wondering if I can try the registering to get the capacity to normal. The help would be appreciated.MKH wrote: ↑Thu Aug 01, 2019 4:54 amAn odd factoid. On another board several i3 owners experiencing noticeable range degradation said that after replacing their (aging) 12v battery and registering the new one, their range went back to near normal. One of the owners this happened to mentioned that when their Dealer was apprised, was told was some sort of GOM/ECU software glitch.![]()
Registering a new 12 V battery is telling the module responsible for charging the 12 V battery about the replacement battery including its type (e.g., AGM, flooded cell), capacity (e.g. 20 Ah), and replacement date. If the battery is the type and capacity of the original battery, only the replacement date need be registered. According to a BMW i mechanic, the replacement date tells a mechanic in the future when the battery was last replaced but doesn't do anything else. So registering a 12 V battery won't affect the usable capacity of the high-voltage battery pack.panamamike wrote: ↑Wed Feb 05, 2020 2:04 pmMKH, what do you mean by registering the new one? I have a 2015 i3 with a lower than expected Kappa that had the 12v replaced not too long ago. Wondering if I can try the registering to get the capacity to normal.