Fiat 500 - Battery Drainage

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Fiat 500 - Battery Drainage

garydpoole

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My wife has a 2014 Fiat 500 1.2S which has for sometime, suffered battery drainage issues if left for a few days.

About a year ago, we changed the battery (start, stop version), but the problem never really went away, and now, it can fail to start Monday morning if not driven over the weekend. But will always start without hesitation when jumped.

I've measured the battery consumption with the car locked and once all the systems settle down, the parasitic current is around 150mA - which seems way too high to me, but I've got nothing to reference this against.

I've traced the drain to Fuse 36 inside the interior car fuse box (Red 10A), which according to some research is Diagnostic Socket, Car Radio, Climate Control System (car doesn't have climate control). If I remove the fuse, the current drops to virtually 0mA.

I'm no expert on car electronics, but I just can't see a radio that's switched off drawing 150mA. So that leaves the Diagnostic socket. And now I'm lost :(

So If anyone can help then I'd be much appreciated !

Regards
 
Last edited:
I can't specifically comment but would add.

You measured 150mA. Now a fully charged 60AH battery will be able to sustain 150mA for 400 hours / 16 days.

So you have either a not measured battery drain or the battery is self discharging due to age and battery plate shoring due to lower level deposits at the bottom of the battery.

Batteries that self discharge can seem to be 100% alive after a good charge but some time later will wither away but then recover after another good charge.
 
So you have either a not measured battery drain or the battery is self discharging due to age and battery plate shoring due to lower level deposits at the bottom of the battery.

Thanks for the reply.

I also think that the battery is probably no longer in the best of health. However, I believe that this has been exacerbated by the continuous 150mA current drain that I suspect has been occurring since it was replaced (and may have even been the reason why its predecessor died). Hence, I could replace the battery, but would end up eventually killing the new one.

For the last few days, the car has been running with Fuse 36 removed (no radio, but apart from that, no big deal) and the battery voltage has stayed nice and high at ~12.5V, whereas the same situation with Fuse 36 inserted would give a reading of ~11.6V.

I'm sure that the car will now be fine and will probably start without fail. However, pulling Fuse 36 out doesn't really solve the problem - it just sticks an Elastoplast over it.

My big problem is why the radio / diagnostic port seem to want to pull 150mA. Is there any way to isolate further the supply to the diagnostic port ? At least that way, I could isolate whether it was the radio or the DP that was responsible for pulling 150mA.
 
Well your next step is to remove the radio and see if the power/current drops?

Just because you do not have aircon does not mean that your non aircon climate controls do not draw any current.

The diagnostic port should not be involved unless you have some other device/diag kit plugged in. May seem stupid but if you have a dash cam which was not fitted by you then some fitters will use the diagnostic port as a convenient source of power.
 
Thanks for the reply.

My big problem is why the radio / diagnostic port seem to want to pull 150mA. Is there any way to isolate further the supply to the diagnostic port ? At least that way, I could isolate whether it was the radio or the DP that was responsible for pulling 150mA.


Years ago the panda CD:radio used to give issues..
the fix was to leave a CD in it.. :)


Agreed disabling the unit is relatively simple..

Is it a stock FIAT unit?

Charlie
 
Well your next step is to remove the radio and see if the power/current drops?

Just because you do not have aircon does not mean that your non aircon climate controls do not draw any current.
.

Removing the radio for me is a bridge too far - I can't help feeling that starting to strip out the dashboard to get to the radio could be opening a real Pandora's Box !

Looking into the DP a bit more, I also can't see any reason why, without anything being plugged into it, it should pull 150mA.

The car does have aircon, just not climate control. Does Fiat differentiate between the two or do they consider them the same thing ?

Years ago the panda CD:radio used to give issues..
the fix was to leave a CD in it.. :)


Agreed disabling the unit is relatively simple..

Is it a stock FIAT unit?

Charlie

Yes, it's the standard unit. The CD 'fix' sounds bizarre, but I'm gonna try it !

Regards
 
Hi sorry for hijacking your thread, but I have the identical problem.
Just wondered if you got it sorted out, if so what was the solution
Cheers
 
The diagnostic port often had its own fuse next to the port you could try removing that


But the most likely cause would probably be the blue and me system perhaps that's keeping the radio awake
 
Hi and thanks, I’ve disconnected the blue and me the draw has dropped to 0.09 from 0.20 I could pull the fuse at side of d port?
I don’t really know what the correct draw should be with everything working correctly. When I pull fuse F36 it drops to 0.00
Cheers
 
0.09 should be a perfectly fine current draw
So it looks like you have found your issue the common fault of the blue and me module draining the battery if you get very little current loss with it disconnected
 
Hi and thanks for your help
yes I’ve checked battery today and still holding a 12.4 volt charge after about 32 hours
 
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