Hi, I’ve been using this forum today to help me fix an issue with the battery going flat on my 2015 twinair dualogic panda (not many of these cars in New Zealand, and the nearest fiat dealer 2 hrs away). It has start/stop. It’s done a bit over 40,000 km, and in the last 6 months has failed to start 3 or 4 times. I thought due to the hatchback door being left slightly open and the light being on (I just fitted an LED bulb inside the boot to help with this issue, but then the car again failed to start so that’s ruled out as a cause).

I was pretty sure the battery was at end of life but after much messing about I’m not so sure now. All I’ve got is a cheapish volt/ammeter but after much experimenting this is what I found.

1. Battery was at 12.2v (when it would not start) but after charging was at 12.8v, it dropped to 12.6 after 5 mins powering the lights etc.

2. With engine running fast tickover (it’s cold) and battery fully charged the battery was at 12.8 with all lights and everything else on, revving the engine made no change in volts. I thought maybe these special EXIDE stop/start batteries are charged at lower than normal volts than what I’m used too, or maybe the car “knew” the battery was fully charged.

3. The battery drain with everything off dropped to 30ma after a couple of mins, so the battery was not going flat due to bulb being on, or a short etc.

4. By putting one end of the ammeter to earth and other end on the battery negative then removing the snap on earth lead (after the engine started) there was NO current going through the battery. :bang:

This completely confused me, as it indicates the alternator was powering all the electrics but NOT charging the battery.

It also means that the battery was only starting the car and so could go many weeks before going flat.

So I read threads on this forum and the issues with batteries failing early and stop start issues and also that to charge the battery, and jump start the car the Intelligent Battery Sensor (IBS) must be disconnected to protect it from damage, and that has not been done on my car during charging or it’s first jump start last week (when the wife was stuck in town and rescued by Good Samaritan).

I’ve never heard of an IBS before

So I thought the IBS must be toast, I disconnected it and plugged it back it in, and checked the battery voltage again .....MAGIC...13.5v at tickover, 14.2v at 3000 rpm, all appears normal.

I don’t know why removing/replacing the IBS connector seems to have fixed the charging problem, dirty connector contacts? Reset of the ECU? Reset of the IBS? But I’ve got my fingers crossed the battery is still ok after being nearly flat a few times, and I’m very relieved the charging system is ok as the alternator looks very hard to get at.

Some threads say disconnecting the IBS cures stop/start issues, I’m wondering if the owners actually had a charging issue like mine ?

I’ll still be checking the charging and battery state for the next week, I can’t have the wife breaking down again (and there’s also a spare battery and jump leads in the boot) but fingers crossed the not starting issue is fixed

Batteries these days seem to go flat without much provocation. My boot and interior lights go off automatically after a few minutes so unlikely to be this. Plenty on here about batteries.

I had my radio on for a couple of hours recently while cleaning the car and this was enough to prevent starting. The battery also read 12.2v. I charged it and normal service restored.

From the many expert comments on here batteries seem to be suspects. I would however firstly check the charge rate is good to avoid changing a battery that's not at fault. Recommend Gunson's Test Tune as a very decent diagnostic tool with volts low and high and ammeter all in one.