Hi guys. I just purchased a voltmeter today. I bought it to test the charging system in my 1990 Bronco.

1990 Bronco
351W
New battery
75 amp alternator

All these volt measurments are based on a .5 volt scale.

Idle with all accessories off: 13.3 volts
Idle with all accessories on: 12.3 volts
1800-2000 r.p.m. with all accessories off: 13.3 volts
1800-2000 r.p.m. with all accessories on: 13.2 volts
Cranking volts: 12.1
Battery volts: 13.1

All these measurements were taken from being connected to the battery!

I just need to know if all this is normal for my truck or not. I really appreciate your help!!

p.s. When I say all accesories I mean, headlights, radio, and A/C on full blast!!!

 

Looks normal to me. Do you have any symptoms that suggest any problems?

 

Yeah, my voltage gauge in the dash reads extremely low. Also, it seems like my headlights are dimmer at idle than at 1200 r.p.m. plus! Maybe the lights are just my immagination. Though, the A/C definetly blows less air at idle!!

 

i agree with steve the readings seem normal to me also the numbers sugest that there should be no battery drain.art above idle speeds . has the truck ever left you stuck? it is normal for there to be battery drain at idle speeds with all accs. on .just hope you bought the best battery because this is all factored in with the calculation of the engineers.my 91 blows slower at idle than at off idle its gage also moves with blinkers on in time with the blinkers especially when lights and ac on.as long as you are inthe normal range i feel this is ok.

 

No, my truck runs fine. It has never broke down due to the battery problem Also my battery has 750 or so cca and 890 or so ca!! The reserve is like 225. Does this sound like a good battery to you. It is a duralast.

 

sounds like a more than suficient batery. cca is the amount the battery can put out in an instant at a 40 degree temp the ca is the amount of current the bat can put out at i believe its normal op temp of 75 degrees and i believe thereserve of 225 is what the bat can put out before the battery drops below the 12 volt threshold. maybe your gage is just getting worn out . is dura last a eveready bat or do i have it mixed up with something else.

 

I'm not sure, I think it is just a Duralast battery. I also think that maybe my gauge is just worn out! THanks for all the help.

 

why don't you check some ground wires.for the headlights and blower motor,could be at the bulk head connecter even.the voltage numbers all sound right,at the battery.

 

Next time, get a MotorCraft Silver Series.

I think it's a dash ground problem, too, but check the voltage at the headlights and at the blower motor to find out.