Voltage Drop as Engine Warms Up

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Oct 21, 2010 | 09:10 PM

84Elky

Thread Starter

Senior Member

Joined: Jun 2010

Posts: 580

Likes: 32

From: Montgomery, AL

Car: 84 El Camino

Engine: 360 TPI

Transmission: 700R4

Axle/Gears: 3.42 + Truetrac, Moser 28 Spline

Voltage Drop as Engine Warms Up

Have 105 amp CS130 alternator. Monitoring with TunerPro RT, when cold it shows 14.2 volts at the battery and 14.3 at the fuel pump. As car warms up to operating temp, the voltage drops to a range of 13.2-13.6 at the battery and 13.4-13.8 at the fuel pump. Have solid 0ga grounds (one from battery to engine and one from battery to frame), 8ga wire from Alt post to battery and 10ga sensing wire.

Two questions:

What could cause the voltage drop from cold to hot (195* F)?
What would cause more voltage at the fuel pump than at the battery?

Thanks!

Oct 25, 2010 | 10:11 AM

NINÅ

Supreme Member

Joined: Jan 2006

Posts: 3,341

Likes: 10

From: Mooresville NC

Car: LOWERED ♦ CRIMSON METALFLAKE

Engine: ► 400 KUBES ◄

Transmission: 765R4

Axle/Gears: EATON POSI 4.56

Drop The Subject

It’s normal for the voltage to reduce itself from 14½ to 13½ after warmup to prevent shortening the life of the battery and alternator.

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