Technical HELP !! Battery warning light and High Voltage

[maycool]

Hello fellow Fiat enthusiasts,

I hope this message finds you well. I'm in a bit of a predicament with my beloved Fiat Bravo 2011 1.4 Tjet 120, and I'm seeking some expert advice and guidance from the community.

Recently, I noticed that my battery warning light on the dashboard has been illuminated. Concerned, I decided to investigate the issue further. Using a voltmeter, I measured the voltage across the battery terminals and was shocked to discover that it's reading a staggering 20 volts when the engine is running, instead of the expected 14.2 volts. Even with the ignition turned off, the voltage remains abnormally high at 19 volts.

This abnormal voltage reading has also led to a power steering error, rendering my power steering system non-functional. I'm now faced with the dilemma of whether this is a problem with the alternator or the battery itself.

I've tried to do some research online, but I couldn't find a definitive answer, and I certainly don't want to make the wrong diagnosis and end up with costly repairs that might not even solve the issue.

So, I turn to this knowledgeable community for guidance. Has anyone experienced a similar problem with their Fiat Bravo or any other Fiat model? What could be causing this high voltage reading, and is it related to the battery warning light and power steering issue?

Your expertise and advice would be greatly appreciated. I'm hoping to get my Fiat back to its optimal condition as soon as possible, and your insights will undoubtedly help me in making an informed decision on how to proceed.

Thank you in advance for your assistance.

 

[The Panda Nut]

The alternator should has a voltage regualtion function so it would be my first choice. Im cant see how a battery could cause this issue. I would get the alternator checked. You could remove the drive belt which would enable a short trip to a garage to get it checked / replaced if you dont want to do it yourself.

 

[varesecrazy]

Hi @maycool.

There was a long thread on here about another Bravo alternator problem ( member @Arvid)

The Bravo and Grande Punto seem prone to strange Alternator issues

But.. Probably best to just change the regulator (and brush pack while it's accessible.. )

Do let us know what you discover

 

[vexorg]

I'm amazed it hasn't fried anything, including all the bulbs. The battery should have been bubbling away like a kettle stuck on.

 

[bugsymike]

I'm amazed it hasn't fried anything, including all the bulbs. The battery should have been bubbling away like a kettle stuck on.

I agree.
I had a customer many years ago with a Bedford Midi van, he had already fitted a new battery because the old one had gone flat, but was still having issues.
I put a meter on it and it was charging at 19 volts and had boiled all the water away in the cells resulting in not enough electrolite so very weak battery amps.
In his case a new alternator and topping up battery fluid solved the problem , charging was now 14 volts. So if he had come to me first he would have saved the price of the battery.
I believe on newer alternators the ECU can control the output of the alternator to match the load conditions, it is well worth a auto electrician familiar with that to confirm whether it is an alternator which is most likely or a ECU signal fault.
There is some data online regarding this to do with the signal going to the alternator thin wire.

 

[varesecrazy]

Back 40 years ago I had a mk1 fiesta (my 1st car..)

The Headlights 'Pulsed' .. I asked my mate who I saw every weekend..
Between asking and the next weekend I needed a new battery..
Got 3 days.. I MELTED THE LEAD TERMINALS of the new battery and
" cooked it"

Saw my mate...
He had asked his foreman and was told its an overcharging alternator

Great advice.. But a little late

 

[bugsymike]

In the days of dynamos we used to be able to adjust the output of Volts and Amps at the regulator box.
I even had a BSA 650 Road Rocket with a 6 volt dynamo that by fitting a 12 volt regulator, battery and bulbs, could convert it.
I would say my first attempt burnt out the dynamo as I had simply fitted the battery and a 12 volt regulator from a Wartburg Knight that I had available without adjusting it.
So the second one I considerably reduced the output Amperage whilst still keeping a steady 13 volts going to the battery.
The advantage of the conversion was Quartz Cibie headlamp and a pair of 12 volt air horns for those on four wheels who objected to me passing them!

 

[vexorg]

At 20v the bulbs (and most other things) will be running at near 3 times their rates power

 

[bugsymike]

At 20v the bulbs (and most other things) will be running at near 3 times their rates power

Don't suppose the ECU was too impressed either.

 

[Derbyfella]

At 20v the bulbs (and most other things) will be running at near 3 times their rates power

Sorry not meaning to be rude ( I think you know this but just slightly wrong terminology
but watts is power
amps is current
volts is……volts

 

[g8rpi]

For a fixed resistive load, say 1 ohm, the current would be 12 A at 12V so 144 watts. At 20V it's 20A so 400 watts so 2.7 times, close to 3 times. The only flaw with this simple assessment is that there are very few purely resistive loads on a modern car.
The root problem with the OP's car is a faulty alternator. This is likely to have caused other issues. For starters the battery needs replacement as it will be damaged.

 

[vexorg]

Sorry not meaning to be rude ( I think you know this but just slightly wrong terminology
but watts is power
amps is current
volts is……volts

Not rude, just missing the point. Power is related to the square of the volts or current. So your 60W headlight will be something like 160W at 20v. The point was that a relatively small change in voltage is a huge change in power for devices.

Thinking about it, it's hard to believe the car would survive 20v, are you sure the meter was right?