Battery Charging voltage

Ian H

Member
Messages
167
My battery charging voltage on the dash always seemed a bit low (indicated ~11-12 volts) and wondered around a bit based upon load but never caused any issues.

After a major service it now seems even lower. With Air con and full lights on it is indicated ~10 volts but with no discharge warning light.
This wander back up to 11-12 volts when power load is taken off - interestingly the engine idle temporarily shifts a few 100 rpm when A/c is turned on/off before going back to 1000 rpm.

Based upon multiu meter readings at the battery terminals:

On idle and no electrical load it reads 14.3 volts
On full load (air con. /lights rear window) at idle this drop to 12.8 volts but picks back up to 14 volts at higher RPM

The Bosch battery is only a couple of years old. The car has been infrequently used but most of the time it is plugged into a battery conditioner.
It did go flat during service. Have fully recharged but doesn't seem to have made any difference.

Should I start getting worried that the alternator is on way out / regulator wrong or is this another fine Italian design feature with the dash gauge more closely indicating the weather than the state of the battery?

Many thanks

Ian
 
Last edited:

midlifecrisis

Member
Messages
16,102
It's also predicting the lottery numbers.

Seriously, it's always been wayward. It's probably accurate when the engine is off, but otherwise not. I once saw it plummet from a healthy 14V to 10V then 30mins later it popped back to 14V... That was a long while ago and I've done a fair few miles since.
 

conaero

Forum Owner
Messages
34,594
Ignore the gauge it’s garlic powered.

With the engine running put a volt meter across the battery terminals, your looking for over 14v....14.5 preferably. If it’s lower your alternator is failing.
 

babel 101

Junior Member
Messages
253
Ignore the gauge it’s garlic powered.

Con el motor en funcionamiento, coloque un voltímetro en los terminales de la batería, busque más de 14v ... 14.5 preferiblemente. Si es más bajo, su alternador está fallando. [/ QUOTE]
IT´s right