Why does my battery keep going flat?

[Bibby]

I've just had to abandon my car half an hour away and walk home. Not happy.

The battery isn't even 6 months old but I had similar trouble with the last one. It;'s either not charging properly or it's losing charge somewhere.

How can I check for either case and why does it happen? The voltage gauge reads at about 13v when the engine is running.

[Greg_S]

Have you checked the cells to make sure they have enough fluid? Could it be an alarm draining the battery? also get a multimeter and check voltage when engine off and with engine running. when running it should be about 14.4V to charge the battery up

[Bibby]

When idle it's 13.4v-ish.

[4WheelDrifter]

Maybe it has something to do with this:



Try turning it down a bit Karlos.

[caterpillar]

14,4 volt at ca 2000 rpm( with lights and fan on) i use 15 volts gen regulator,( its only 14,7 volt) lower fuel consuptions and better lights.... have you big stereo units in,check out the batt taps there, and the main rad fan, they have some strange habbits some time,they startin up when the engine are cold......

[Bibby]

It was the same without the ice install...

I may just take it to an electrical fault finders around the corner.

[s2dude]

It was the same without the ice install...

I may just take it to an electrical fault finders around the corner.

Could be a faulty alternator possibly...
Have you checked the output of it with all lights etc switched on.....and with them off.
Ive got the same problem and have just rebuilt a spare alternator I bought to replace my current one. Symptoms are the battery warning light comes on sometimes on startup until you rev the car over 3k rom. Battery tested out fine.

Could be the voltage regulator on the back of it , or earth lead...or coil / brushes!

[Bibby]

I swapped over the regulator last night off my spare alternator. It was in much better condition that the one I took off as that alternator has only had about 12 months use since it was reconditioned. Only found that out yesterday.

Idle voltage is now 13.8v but I'm going to swap the alternators over at some point. I should have a go today, but I'm officially lazy on Sundays.

[Bibby]

Felt guilty for slacking so have swapped them over. Idle voltage still 13.8v so I don't know what that means, if anything.

We'll see...

[Greg_S]

The saga continues. hopefully its a cheap and easy fix

[caterpillar]

13,8volt are TOO low. by a new one . with 15,0 volt stamped on(or 14,7volt is an option) low cost( 20£) or so....if you not sure, check out the batt acids weight.... full charged batt are 1,275,or 1,280..... 1.25 are half full batt.
does you have trailer elecktric contact in the rear, they does have some bad habbit too.

[Bibby]

13,8volt are TOO low. by a new one . with 15,0 volt stamped on(or 14,7volt is an option) low cost( 20£) or so.....

Buy a new what? Voltage regulator? Can you suggest where I can pick one up for £20 that will fit my 110a alternator?

No idea what you're on about with battery weights, and I don't have a trailer.

[caterpillar]

you need another voltage regulator in your alternator with 15,0volt stamped on!!
the "FULL" battery arent full of liquid fluid; the only way to check this out are the mesuring the weight of differene between the vater and acid. havent you yhe clue how to do, go to a garage were they can do this.
the volt regulator in the generator are the piece who reg the volt in the system, to low volt crack the batt.
i have 14,9 volt in my car, no prob. but you HAVE to sort out the batteri leac, who flatten the batteri, the solenoid at the starter, the stereo,( have you a UGE condenser in the system) the main rad fan, who are startin up whwn the engine are cold,or have you sentral locin system, the vakuum engine in the trunk, goin, and goin, and goin......

[Bibby]

My Bosch alt is 0120468121 which says 110 A on the label, although it's listed as 120 A.

The regulator is 1197311027 which has 14v stamped on it. It's the standard factory fit one for that alternator.

I've made an enquiry as to whether I can get a 14.7v one to fit it. The extra would be good for my ice install to be honest, but if it's safe, why are regulators of this voltage level not fitted as standard?

[Bibby]

Just a little update... I'm picking up a 14.6v regulator tomorrow from a local company. They seemed quite helpful. Going to give me a price for upgrading my spare alternator to 200 A when I go in, which would be useful.

I've been doing a bit of testing today too. The bonnet switch (for the alarm) was reading almost 12v with the bonnet closed, whether the alarm was disabled or enabled.

Does that sound right?