GsDAteg

I was wondering how many volts there should be when a alternator is charging properly? My battery light and ABS light are going off on on but everything else seems to be normal. Car is a 90' Integra if it matters.

ken9

It should be around 14.7 volt on alternator.

imadigitalgod

Id say 13.5v - 14.5v, most likely in the high 13's tho

fcm

At batt. the voltage should be 12.5 when not running and at least 13.5 when running at idle. 94

twentyhurtz

yep, float without car on 12v plus or minus half a volt, idle - car warm... 13.8ish, full limitation of voltage regulator- 2k rpms or so... 14.5v ish..

twentyhurtz

but don't tell my local advanced autoparts i said that, they will get pissed, cause according to them the alternator i bought from them, which DOESNT WORK, should idle at 14.5v all THE TIME! - advanced autoparts... idiots..

willforest

I think a fully-charged car battery, in good condition, with no load on it, will measure about 13.2 volts. With the engine running, if the alternator and voltage regulator are working correctly, you should measure about 14 to 15 volts at the battery.

GsDAteg

So what voltage makes your charging light and ABS lights go off then? Mine reads about 14.6 when cold and between 13.3 and 13.4 when warm. Sounds pretty on to me from what you guys are saying. I mean my idle voltage when warm might be a little low but as soon as I turn my car on when cold the battery/ABS lights go on, even though at cold idle it was reading 14.4v.

I was thinking I needed to replace my alt. but are there other reasons for this? I mean if I'm getting a reading of over 14v when I first start up, why is my battery light coming on?

ken9

Could be your battery having some issues.

twentyhurtz

usually on most dc devices there is a solid state limit switch, i know here at work i deal with many devices that i have to put on a test bench to find the preset voltage point to where something trips into protect mode or shuts off, usually on dc devices that setting is at 10.99 volts or 11.49 volts, i guess it all depends on the unit, some even as low as 10.49 volts.

willforest

The alternator's voltage output depends on air temperature. When it's really cold the battery becomes more resistive and requires a higher voltage to get charged. The regulator typically puts out a slightly higher voltage then. If it's hot then the voltage out of the regulator may be less, maybe in the 13's.

Something like 14.3V sounds normal, but part to part or car to car, typical difference 0.3V in comparison is possible. The real goal is to ensure the regulator is working, it means putting out a voltage higher than 13V and lower that high 14's. If the regulator puts out 15V or more then it can overcharge the battery.