Light weight battery issue? - Ford Mustang Forums : Mustang Forum
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post #1 of 1 Old 06-30-2017, 02:21 PM Thread Starter
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Light weight battery issue?

I've been running an Odyssey PC680 (mounted passenger side due to turbo) on my turbo 2v. Starts the engine no problem. Only non-stock acc the car has is 3 Ford GT fuel pumps (running full time) and a BAP.

The problem I've been experiencing is a low charge voltage. I am using a Motorcraft reman'd alternator (130 amp) that I bought directly from Ford.

I am running underdrive pulleys if that makes a difference.

Here is what I see for voltages @ battery:

Cold start: 13.8 (DVOM)

Warm idle: 13.4 (DVOM)

WOT: 12.0 (via live link)

Voltage does not increase when I rev the engine. It is basically a static value.

I installed a brand new PC680 last night to see if that was the issue, results are the same.

I have checked the resistance for the alt charging wire and the comes within spec.

12v excite wire is intact and produces battery voltage when measured.

I have an overdrive pulley to install on the alt, but figured revving the engine should at least bring up the voltage, which it does not.

I've thought about going to a larger 200 amp unit with upgraded power and ground cables to see if that helps, but that is a $400 gamble at this point.

Any thoughts? I'm kind of stumped at this one and would rather not just toss money at it to figure out WTF is going on.



'91 GT: SOLD

'04 GT: Forged bottom end, MHS Stg 3 PI heads, Hi-Tech Custom Cams, MHS Vic Jr + elbow, custom turbo kit, Precision 7175, T-56 & 3.27's. 785rwhp/725rwtq @ 20 psi.
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