Voltage questions

[Frijolito1988]

Hey guys been playing around with this multimeter gauge .

I have a known good battery that looses all its juice.

I charged the battery up to about 12.5 volts and the truck barely started.

Once started the volts dropped to 11.6 and im sure if i left the truck on longer it will drop and drop.

Now. I am working out some problems with the internal alternator conversion and my alt is reading 16.1 volts at idle ?? Whats wrong here ?


To recap .

Battery looses juice really fast, and alt is reading 16.1 volts at idle.

Hope you guys can leed me in the right direction.

[mechanicalman]

Originally Posted by Frijolito1988

Hey guys been playing around with this multimeter gauge .

I have a known good battery that looses all its juice.

I charged the battery up to about 12.5 volts and the truck barely started.

Once started the volts dropped to 11.6 and im sure if i left the truck on longer it will drop and drop.

Now. I am working out some problems with the internal alternator conversion and my alt is reading 16.1 volts at idle ?? Whats wrong here ?


To recap .

Battery looses juice really fast, and alt is reading 16.1 volts at idle.

Hope you guys can leed me in the right direction.

How do you know the battery is good?

[Frijolito1988]

Ok so the battery either needs a good charge or to be replaced.

I fixed the problem . I was using 12v coming from another source in the truck instead of the one that comes from the external regular .

Now with truck off battery at = 12.2

With Truck on battery at = 13.2

Alternator with truck on = 14.4



I have a few questions.

The red post on the alternator always has 12v even when the switch is off , is this normal ?


Also I do not have anything wired to my BAT gauge in my truck is this necesary ? I read about a brown wire needing to go to the battery gauge but i do not have this installed.

[mechanicalman]

Originally Posted by Frijolito1988

Ok so the battery either needs a good charge or to be replaced.

I fixed the problem . I was using 12v coming from another source in the truck instead of the one that comes from the external regular .

Now with truck off battery at = 12.2

With Truck on battery at = 13.2

Alternator with truck on = 14.4



I have a few questions.

The red post on the alternator always has 12v even when the switch is off , is this normal ?


Also I do not have anything wired to my BAT gauge in my truck is this necesary ? I read about a brown wire needing to go to the battery gauge but i do not have this installed.

Yes 12v always at the alt red wire. No, you don't need a BAT gauge if you don't want one. Sounds like it's fixed.

[Steeveedee]

Originally Posted by Frijolito1988

Ok so the battery either needs a good charge or to be replaced.

I fixed the problem . I was using 12v coming from another source in the truck instead of the one that comes from the external regular .

Now with truck off battery at = 12.2

With Truck on battery at = 13.2

Alternator with truck on = 14.4



I have a few questions.

The red post on the alternator always has 12v even when the switch is off , is this normal ?


Also I do not have anything wired to my BAT gauge in my truck is this necesary ? I read about a brown wire needing to go to the battery gauge but i do not have this installed.

1. A fully charged battery reads 12.6 on a good meter.

2. Not sure what you mean by " With Truck on battery at = 13.2", is that with the key on but not running? If so it would not be right.

3. "Alternator with truck on = 14.4" This may be a little high, but it depends on what you had running as far as accessories at the time.

4. The alternator red post should read battery voltage, it connects directly to it.