Technical Battery woes (need quick reply)

[Dreddfan]

I've been having a lot of trouble with our 99 1.2 Brava over the last couple of weeks, see here https://www.fiatforum.com/bravo-brava/312483-temperature-gauge-issue.html
It is very reluctant to start but I put this down to lack of driving.
Last week it died completely (no lights on dash or anything) so I installed a new battery but I still have the same trouble.
Is there any way to test the altinator to make sure it's charging the battery?

 

[PuntoFXF]

Connect a multimeter across the battery terminals set the multimeter to read voltage DC with nothing turned on the meter should read around 12v. With the engine started and alternator running you should see around 13.5v - 14V on my car on others up to 16v

Ensure your multimeter is set right if your leads are in the current hole it will blow your meter up

Any reading below 13.5V wont charge your battery adequetly

 

[Dreddfan]

Thanks Putno, I'll give that a go.

 

[Dreddfan]

Ok, looks like my altinator is allright. I've a reading of 12V when off and 14V when running.
Looks like I've a current drain on the battery, any ideas on whats the best way to trace this?
I've done nothing major electrically to the car except:
Disconnect the sunroof switch ( all wires taped up and should be ok.)
Replace the headlight bulbs with Ultra bright bulbs but problem was there before this.

I get the feeling that this is going to be a nightmare :yuck:

 

[Neverth]

Does it starts fine with charged battery?
Interior lights on, glovebox light, etc?

You can test the current drain when off if you do it carefully.
Working from the highest range down (10A -> 200mA/whatever) on the multimeter, doors closed and ignition off.
Disconnect negative from battery, clamp the other lead from meter to the negative cable with alligatorclip or something. Push the negative cable against the negative terminal and let the car do its stuff (mine cycles power locks and electronics start up and go to sleep). After that put the other lead against the negative post and then diconnect the cable from the terminal. At that point the drain current flows trough the multimeter (10A range might show nothing due to inaccuracy if there is almost no drain).

If you got no drain, the fault is elsewhere, otherwise start pulling fuses and see when the drain stops.

 

[Dreddfan]

Ok, I have this solved and it was something I should have checked out a bit better

My mechanic found that the switch running the light in the boot wasn't working properly, the light was either staying on or just going very dim when the boot lid was closed so was draining the battery.
He replaced it with one from a scrapped Bravo he had for free but I should have spotted this myself

Thanks for all the suggestions.