Hey gang, last night for the first time i noticed my battery light coming on when under a hard pull and close to top of RPM band. My alternator is a Mechman billet 240S with only about 1,500 miles on it. I refreshed my entire motor 1,500 miles ago and went fuel return also. I’ve never noticed this battery light issue before . It did it so bad one time all my lights dimmed in the car. The Mechman i have do not have an external voltage regulator. My setup is Fuel return, KB 2.2 with a 3” pulley, stock lower pulley . Any help or advise would be appreciated. Thank you
Battery light coming on when in high RPM
- Thread starter Nervouswreck
- Start date
It's a known issue with Mechman and some other aftermarket alternators. Did Mechman supply you with an adapter harness? Call them and they'll send you one.
It has an additional wire that you connect key-on ignition power which solves the issue. It does basically disable the battery light in the dash so having an aftermarket voltage gauge is recommended.
It has an additional wire that you connect key-on ignition power which solves the issue. It does basically disable the battery light in the dash so having an aftermarket voltage gauge is recommended.
They did supply me with the harness and when i asked them what the extra blue wire was for they said it might not be necessary for me to hook it up so i didn’t
Did you log voltage during the run?
If all your lights dimmed then it is a voltage issue. So hooking up that extra wire to "disable" flickering battery light won't fix the problem.
I personally would datalog voltage. I also wouldn't keep seeing full boost until the problem is fixed.
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I personally would datalog voltage. I also wouldn't keep seeing full boost until the problem is fixed.
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The extra wire connects to the "exciter" wire that turns on the alternator. For whatever reason the +12v signal through the factory exciter wire becomes unstable or weak at high RPM causing some aftermarket alternators to malfunction. Connecting the extra wire to a reliable +12v power source solves the problem and the alternator will function properly at all RPM. The one side effect is that if the alternator dies, your battery light in the dash won't light up. This is what I was told by another Cobra owner, I haven't tested it myself.
No it came out of nowhere
Thank you
Good to know. I was under the impression it was for the battery light.
My Nations alt sometimes makes the battery light flicker at high rpms, but after datalogging my voltage is still good.
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