Voltage at battery

[RUSSELLM]

When ticking over I'm getting 12.25 volts at the battery, put a few electrics on & this is obviously going to drop. Took the car in & was advised that a new battery was required. Cars back & I'm still getting the same voltages. When i give it a couple of extra revs (200) the voltage is more like i expect it to be (13.8 volts)
This shouldn't cause a problem normally, however the missus has had me sitting outside sainsburys for an hour & to avoid hypothermia I've put the heater on presuming tickover would charge the battery, doh !
New alternator, faster tickover, new missus ?
Which is the cheaper.
Do not suggest helping with the shopping ! Tried it once & to avoid falling out It's not going to happen again.

[bilton_d]

i was told by my dealer that the battery doesn't get charged at tickover.

[RUSSELLM]

Is that perculiar to cerberas, as we have another 3 vehicles here & they're all giving the battery 13.8v at tickover.
**** me, I'm a mile from where the M5 meets the M6, I could be on that junction days.
I know the answer is to sit there with a few revs, but what a ball ache.
Is the dealer right anybody ?

[Julian64]

Some cars just maintain at tickover but shouldn't. You should be getting a good charge even at low revs.
If you load the car electrics headlights, heated windscreen, window wipers, you shouldn't see the voltage drop at all. Cos the regulator on the alternator compensates doesn't it?

How low can you get your tickover voltage to go?

I'll try mine tomorrow for a comparison.

[Julian64]

Normal voltage after a night in the garage 12.1.
Car started and at tickover a consistent 13.2.
Tickover and headlights heater etc, 12.6.

Any comparisons?

[RUSSELLM]

Hi Julian, just re tested, 12.8 at tickover, 11.8 at tickover with a few electrics on, 13.8 with an extra 200 revs.
mystified, starting ok with new battery so i'll try & ignore it.

[olly]

Sounds like it could be your altenator then....

OR, it could be the 100Amp fuse is on it's last legs, or even is cracked, so isn't letting all power from altenator through ?