Max charge keeps dropping

[hlivkopj]

For the past month or so have had some odd behavior. Interested in any insights. It’s a 2008 Roadster.

First, when I change the charge mode from storage, standard, performance... etc the mileage number for amount of charge I have changes instantly. For instance, now I’m charged at 96 miles but on range but changing to standard instantly drops it to 64.

Second, right now my car thinks it’s done charging at full for both of those numbers. And the total amount was 184 until a few months ago and then slowly started dropping as to where it thinks it’s full.

Finally, it sort of feels like it might be full but something about the measurement device is the issue. Just a guess as I don’t drive it much and it’s always plugged in.

Thanks for any insight / ideas / help.

Paul

 

[slcasner]

The range changes instantly when you switch between standard and range mode because the display is scaled differently for the two modes. The simple way to think about it is that standard mode chops off the bottom 10% and the top 10% of the battery capacity (approximately). That is, charging in standard mode leaves the top 10% of the battery capacity empty. Similarly, when driving in standard mode 0% on the display really means there is 10% of the battery capacity left. These reductions on both ends reduce the stress on the battery to extend its lifetime. I would have preferred a user interface where the scale did not change but just the top and bottom 10% of the battery icon would be shaded in some way.

Have you tried changing modes while driving by tapping on the battery icon? When I go on a long drive I charge in range mode but then switch to standard mode before starting out because I want to have full power available if I need it, and I prefer to not run the battery down to the bottom. So that means the battery display would show greater than 100% if it could and it doesn't drop below 100% until I have driven for a while.

You are right that changes you see may simply reflect inaccuracies in measurement rather than real change. It is difficult to truly determine the full capacity of a battery without filling it all the way full and then running it down to empty. But that is not good for the battery, so the car tries to estimate from conditions in between those extremes.

 

[gregd]

If it thinks 96 miles is "full", your battery is probably unbalanced for having been in storage mode for a while. Leave it plugged in on Standard mode and see what happens over the next few days' of daily top-off charging.

 

[hlivkopj]

Thank you both! So now I get the difference by mode so that’s not an issue.

My only and big problem is what it thinks is full keeps dropping and as of right now on standard mode it stopped at 50 miles. It was 184 in the spring time, 96 maybe a month ago. I’ve tried switching chargers to the remote one, doesn’t seem to change. Normally I use the model S charge cable with CAN adapter.

I leave it on standard plugged in all the time.

Paul

 

[gregd]

50 full is not right. I recommend you get in touch with either Carl Medlock or Peter Gruber for a diagnosis, and quickly. If it gets bricked, it's a big (bad) deal.

 

[ML Auto]

If you read the min and max brick voltages from the service menu, you can see if you have a really bad problem. It doesnt sound good. When you get a bad cell that discharges faster then the car can balance the pack, it eventually will become a brick.

 

[hlivkopj]

50 full is not right. I recommend you get in touch with either Carl Medlock or Peter Gruber for a diagnosis, and quickly. If it gets bricked, it's a big (bad) deal.

Thanks! Not too familiar with them, contact on forum or elsewhere?

 

[hlivkopj]

Thanks! Not too familiar with them, contact on forum or elsewhere?

Nevermind, got them.

 

[Gabner]

Update?

 

[Botbldr45]

Alcasner: what’s your status now?