How does BMW perform the Battery Capacity Test?

[EVBob]

Greetings All,

Both our i3(s) are still at the shop :-/

On the last status call they said they are doing a battery capacity test on both of them (one with 49.5K miles, the other with 21K miles)...

Checking on both of them via iremote - I see both are 100% charged, but one of them (the one that I assume is in their garage and not parked outside, since iremote is telling me the windows are down and the side lights are on) I see that the status keeps updating the time roughly every 25-35 minutes, but the charge indicator never switches from green. I assume they are drawing a very small load - enough so that the battery doesn't dip below 99.5 to trigger the iremote to say it's charging, but enough to get power from the evse every 25-35 minutes so that it shows as an update on iremote.....

Seems kind of a weird way to do a capacity test? I would think they would drain the battery to a certain voltage and recharge it and see how much went back in?

 

[i3Houston]

Following!

I thought I read somewhere dealership works with folks in Germany for that but only after someone really complains about the battery. And Dealership might just do for i3s with Battery Kappa thing drop below certain level.

 

[EVBob]

Looks like they switched cars - the one (49.5K) that was updating the time overnight, stopped, and the other one (21K) is doing the green light/plugged into the EVSE and time update thing now (and notifications windows down, doors open, side lights on)...looking at it again the last time it updated the last update was an hour ago....vs 25-35 minutes in the other i3....I wonder if the time to discharge/recharge is tied to figuring battery health...or they are just working on it....

 

[EVBob]

Talked to them again today - they were a bit baffled when I asked if they were running the battery drain tests last night - as they said they were only charging the vehicles - I suppose they must have left the side lights and interior lights on, and maybe that drained the battery ever so slightly (enough that that an update happened every 30 minutes or so) Turns out in order to test the batteries - they make the i3 use it's accessories to drain the battery then figure the condition of the battery when charging it back up....

 

[i3Houston]

Thought the accessories run on the 12V battery. :?:

 

[alohart]

Thought the accessories run on the 12V battery. :?:

They do. However, the 12 V battery is charged by the Li-ion battery pack. When the 12 V battery begins discharging due to 12 V loads, the Li-ion battery pack begins charging the 12 V battery which discharges the Li-ion battery pack.

 

[i3Houston]

Thought the accessories run on the 12V battery. :?:

They do. However, the 12 V battery is charged by the Li-ion battery pack. When the 12 V battery begins discharging due to 12 V loads, the Li-ion battery pack begins charging the 12 V battery which discharges the Li-ion battery pack.

Thanks!!