Did BIg 3. Getting less power.

[Dom8706]

Used 2 gauge AWG wire, 2 gauge AWG pure copper terminals and brass battery termianls

I did a replacement not an addition. Starter to positive, alternator to 100AMP breaker to positive, left white/tan wire to fuse box alone and just added it to positive as is. For the negative i did engine ground to negative and chassis to negative.

I have a little device that plugs into my cig lighter outlet that tells me the temp and the volts. Before hand i would stay around 13.8-14.0 most of the time and it was consistent while driving. When i first started it up after i installed everything it was at 14.0-14.1. I was happy and went on with my weekend. Now that ive actually drove it its dropped down to 13.8 and when i am at a stop it will drop to 13.5, maybe 13.4 if i have my blinker on.

Whats going on here? Does anyone have any ideas? I thought i did everything right. I also hooked up a additional fuse block for my accessories.

 

[TheDurk]

You know, it might be normal. You may have improved the alt/battery connection to the degree that it actually takes less voltage at the battery for the alt to think it is fully charged. Ignore that silly device for this purpose and take your readings directly at the battery with a real voltmeter before you go fixing what ain't broke.

Also check your Alt-S fuse and the condition of the wires at the oval plug on the alt., especially the white one.

 

[raKnizek]

Thinking out loud here, but since you have increased wire diameter but have not changed voltage or amps supplied to the system, your voltage reading at the cigarette lighter would be lower

 

[3bears]

when I did my big 3, I also put an extra engine ground going from alternator bracket to the inner fender , an existing bolt, right next to battery...prob overkill

 

[19963.4lsr5]

In 100 degree heat I see 13.5 to 13.6 if my underhood temps are really high.


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[gamefreakgc]

In 100 degree heat I see 13.5 to 13.6 if my underhood temps are really high.


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Bingo. As under hood temperatures increase alternator output at idle goes down. Mine will normally sit around 13.5V at the cig lighter at idle once warmed up but 14.0V at startup cold. Of course, that's also idling at 600 RPM vs 900 RPM+.

Based on my experience, your wiring is correct and the system is functioning as it should.

 

[19963.4lsr5]

Bingo. As under hood temperatures increase alternator output at idle goes down. Mine will normally sit around 13.5V at the cig lighter at idle once warmed up but 14.0V at startup cold. Of course, that's also idling at 600 RPM vs 900 RPM+.

Based on my experience, your wiring is correct and the system is functioning as it should.

Denso or GM Alt? The CS Alt in my Saturn never goes below 13.8. Normally it’s 14 to 14.2


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[Dom8706]

Bingo. As under hood temperatures increase alternator output at idle goes down. Mine will normally sit around 13.5V at the cig lighter at idle once warmed up but 14.0V at startup cold. Of course, that's also idling at 600 RPM vs 900 RPM+.

Based on my experience, your wiring is correct and the system is functioning as it should.

That's exactly what is going on with me. 14 volts cold start up. 13.5ish when idle at temp. It's also been hot as shit here the past couple of weeks. Pushing up towards 100 degrees.

Glad to know this is normal. Going to be making a cross state trip this coming weekend and want to make sure it's all in working order.

 

[gamefreakgc]

Denso or GM Alt? The CS Alt in my Saturn never goes below 13.8. Normally it’s 14 to 14.2


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GM Alt but the Denso unit acted similar. Those voltage readings are from the cigarette lighter which are lower than off the battery terminals but just sharing because that's what the OP also used to read the voltage. Off the battery it's 14.4 at startup, 13.8-14.0 when warm, and 13.4 when my 20 amp electric fan kicks on full blast on hot days.

 

[Dieselchessy]

Battery looks like the smaller size. Seeing the original battery clamp hanging there looks odd.

Maybe replace the brushes in the alternator. But like the others have said, heat and increased draw may be the cause.

 

[phattyduck]

Alternator output voltage is specifically reduced at high temps - it keeps the battery from boiling over (avoids overcharging).

It can be as low as 13.4V at very elevated temps, but 13.6V is a more normal 'minimum' voltage in more normal summer temps.

If your AC was on high, headlights, brake lights on and in gear, a slight drop in voltage is to be expected. Your battery isn't discharging until voltage drops below 12.7V or so - but it just isn't charging at that time.

-Charlie

 

[19963.4lsr5]

I determined the factory 70 and 80 alt’s can only push around 40a idling in gear at 600rpm.


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[ambush]

Your setup looks GOOD!! I should have gone 2 ga as well.
I agree with everyone, the idle voltage maybe fine versus cold and driving.
OR
just throwing a dart out, maybe your ground???
I dont know....

This is how I did mine...(KiTT)

The ground from the Alternator is connected to the side wall where the OEM ground was. Then I just added that to the battery. I hid that fuse and connected one from ALT --> FuseBOX --> Battery (the previous owner did a hack job i had to clean up). I have not checked the running voltage yet as my exhaust is completely removed at the moment (DAMN CLOGGED CAT!!)...

Plugs:
HighWire Audio Big 3 kit (4ga)
Battery tie and Fuse box cover courtesy [MENTION=78895]DeathCougar[/MENTION] parts

Just my $.14 cents.