Charge Gauge and Range Estimator Upset after Aux Battery Removed

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New member
Oct 16, 2021
Hello everyone. I’m another newbie on this forum, although I’ve been reading on here for some time.

I have a 2011 Ion that’s done approx 70k miles. It suffered from the blown 20A fuse and snubber capacitors recently. I managed to repair everything with the help of all of the useful information on this forum, particularly from Kiev and Coulomb. I also replaced the 12v auxiliary battery as well, which was still the original so could have been responsible for the failure.

Everything has gone fine and the car is up and running again but I have two things that I need to sort out:

The first is the fault light (“!” on car symbol). Do I need to reset this using an ODB2 with hobdrive software?

The second is to do with the charge gauge and range estimator. Whilst I was working on the Ion I disconnected the 12v auxiliary battery and left it off for what was probably close to a month (other than briefly connecting to open the tailgate when I needed to get in to work on it). I’m guessing the memory has been lost and it doesn’t know how much charge is in the main battery pack. I’m saying this because after putting the on board charger (OBC) back together and replacing the 20A fuse I fully charged the car (it showed about 3 or 4 bars before I charged it) and when it had charged the range estimator said 80 miles. Now because of its age and how I drive the car I normally get a predicted range of between 60 to 70 miles typically.

After driving for a couple of days and recharging the range went up to 88 miles, which I have never had in the four and a half years I’ve owned it. The next day I did a 43 mile journey to work and plugged it in when I got there. When I left work and turned it on the range now said 96 miles!

Now as much as I would like to think that the range capability of my Ion has miraculously improved I suspect I’ve upset it’s memory. Out of interest I drove it with heater, air-con and anything else I could think of to drain the battery to prompt it to do a balanced charge when plugged in. The charge gauge got down to 4 bars when the dreaded turtle/tortoise symbol appeared sporadically. It kept coming on and then going off dependant on how much power was being pulled from the battery pack. Eventually it stayed on and I crawled along until it died completely. Just before it died the charge gauge dropped a bar and started flashing, which is what I was trying to get it to do so a balanced charge was going to occur when I plugged it in.

I’ve recharged the car and today it’s saying the range is 68 miles. Now this maybe due to driving the car hard and running everything at the same time to drain the battery or it’s fixed the problem. I’m suspecting it hasn’t fixed the problem and I need to make sure my wife doesn’t run it down to 4 bars on the charge gauge.

So the question is how do I go about re-educating the car? Will it eventually learn or do I need to do something else?

Your thoughts will be very much appreciated.

Kind regards,