Battery light on, then off....

[Max527]

Hi there.
2007 310,000km yaris.
Just today, after a blustery very cold day, the battery light has just started coming on, then off, then on, then off. The fm tuner I have connected oddly shows 11.5V-11.8 when the battery light comes on then goes away when the light turns off.
Would this be a battery issue? It stops after driving for 30 mins more or less.

Thanks for any help. Merry Christmas

[bronsin]

Healthy battery voltage is at least 12 V, actually slightly more than That 12.5 really I’m afraid your battery is shot!

Merry Christmas and happy new year!

[bronsin]

With the engine running and voltage measured it at the battery The reading should be more like 13 V definitely more than battery voltage measured without the alternator running. If this is the case it could be your alternator and the battery could be fine just not charged.

If you don’t know how to do this or don’t understand see your local mechanic. You wouldn’t want to buy a new battery for the alternator was really the problem!

[mitch9521]

Healthy battery and alternator should be 13-14v when running. Battery time, this bastard of a cold snap really takes a toll on old batteries.

My OG Toyota battery is approaching its ninth year of service and still cranks fine, knock on wood.

[IndestructibleYaris]

LOL "battery time" what on earth....these people have no clue what they're talking about! The alternator puts out around 14v even with a dead battery in the tray and is engineered to run every accessory on the car and still remain at a charging voltage above 12.8v. Read the service manual or the alternator rebuild guide in the search function. Good luck

[WeeYari]

Voltage regulator inside the alternator is starting to fail.
I can also say with absolute certainty that your brushes are pretty much at end-of-life.

[mitch9521]

LOL "battery time" what on earth....these people have no clue what they're talking about! The alternator puts out around 14v even with a dead battery in the tray and is engineered to run every accessory on the car and still remain at a charging voltage above 12.8v. Read the service manual or the alternator rebuild guide in the search function. Good luck

Not everybody is all-knowing as you, Your Highness. :smile:

[Compeer]

LOL "battery time" what on earth....these people have no clue what they're talking about! The alternator puts out around 14v even with a dead battery in the tray and is engineered to run every accessory on the car and still remain at a charging voltage above 12.8v. Read the service manual or the alternator rebuild guide in the search function. Good luck

By "battery time" he meant the cold snaps during the year are when the most batteries fail and are sold. Maybe hes not the only one who needs a clue?

A rebuilt/rebuilding the alternator should be pretty cheap. We used to sell refurbished units for under $100usd for a common car like this. A decent sparky will have a stack of them ready to exchange with you or will take an hour to rebuild yours.

Check anc clean all your earth connections when you replace the alternator, Clean the terminal end on the alternator, battery and any other earth leads going to the engine (unbolt them clean corrosion off with light sand paper and reinstall). Bad earth connections cause the voltage reg to run hotter and eventually burn itself out and you dont want a repeat.

When ever you have charging problems you should always check all the electrical connections and clean them, This is always the first step in diagnosing a charging fault.

[WeeYari]

In the North American market, 2006-2008 have a known design flaw with the voltage regulator. He is showing the exact early warning signs that the regulator is failing. Frankly I'm surprised he's gone this long without symptoms presenting themselves.

[BLH]

Technical Service Bulletin EL002-07
The one I saw. Was corrosion on the regulator connections inside the alternator. Made things like the warning light to turn on.

[Compeer]

In the North American market, 2006-2008 have a known design flaw with the voltage regulator. He is showing the exact early warning signs that the regulator is failing. Frankly I'm surprised he's gone this long without symptoms presenting themselves.

Could be as simple as a loose/frayed battery terminal. Always worth starting simple first and if it is the reg the terminals are all nice and clean to help them eliminate a future issue.

[WeeYari]

Could be as simple. Highly doubt it. I've lived it, been here long enough to see countless others through it. It'll trace back to the regulator.

[RedRide]

FWIW.....
The cold can reduce cold cranking power.
However, it is actually extreme heat that can kill it quicker than cold

[Max527]

In the North American market, 2006-2008 have a known design flaw with the voltage regulator. He is showing the exact early warning signs that the regulator is failing. Frankly I'm surprised he's gone this long without symptoms presenting themselves.
Car eventually died then revived itself in time for me to get home. Changed alternator and all is well. Thanks

[bronsin]

:bow: