Hi fellow FD owners,

So I have an Apexi PFC, a brand new Alternator from Atkins Rotary and at idle I see on the PFC about 13.7-13.8V, idles around 900-1000 RPM. However, driving in higher RPMs I am seeing as high as 15.9V

What could be causing this jump in Volts?

Appreciate any advice or help.

Cheers

 

If you can make the problem happen by just revving the engine in neutral, try measuring the actual voltage at the battery with a multimeter to confirm the PowerFC readings are correct. The factory service manual has a troubleshooting section for the alternator / charging voltage, page G-7. It claims 16.1V is acceptable but 16.2V is not. The alternator has just a few wires that connect to it, and all the pins/wires should be pretty easy to access if you need to measure them. My best guess based on your description is a weak connection between pin 'S' on the alternator and the battery (white/green wire, or the pins on the connector itself).

 

Thanks Scotty305, I will do a multimeter check tomorrow and also check the wires as you suggested. Appreciate the help.

Cheers

 

Yeah max you should be seeing is 14v and change. That could be a problem with the voltage regulator.

You may want to look through the troubleshooting in the shop manual too. I want to say there's something dumb like if the battery warning light is burned out it can cause problems.

Dale

 

Thanks Dale, I will check the shop manual. I did notice last night that when I turn the ignition on, I didnt see the Battery light come on. Maybe a burnt out bulb.

Is there a way to change this bulb without ripping out the entire cluster?? Did that before and was an absolute nightmare. Many of the plastics are so old and weak everything breaks easily 😣. Maybe from beneath the dashboard ?? 🤷‍♂️

Will be making some more checks today and report back on this.

Cheers

 

Update

I was able to swap around some bulbs from under the dash 🙌. The bulb is fine and isn’t blown or damaged. I have a RHD efini and not sure if the battery light comes on with IGN on, I’m trying to remember ever seeing it light up. maybe someone can correct me if I am wrong. It did light up once when I had a bad alternator and it went away after changing the alternator.

Will do some more trouble shooting.

Oh, I also had the car engine on and disconnected the negative battery terminal and the car didn’t shut off or the battery light didn’t come on. I assume that’s a sign the alternator is working properly.

Cheers

 

94 Efini R - my ABS, Exhaust Heat, and Charge lights say on (seat belt light turns off after a sec)

 

Only my heat light stays on, but it’s disconnected due to an upgraded exhaust.

Placed the multi meter on the battery and revved to 3500RPM and the voltage went to 15.8 as the PFC indicated. So the PFC is accurate.

Cheers

 

Sounds like the alternator isn’t working properly and internal voltage regular is bad. You want to be careful not to shorten the life of the battery.

 

Thanks Sgtblue. Sounds like I need to pull the alternator and get it tested. It’s less than 8 months old but things can go bad.

Appreciate the feedback from everyone 👍

Cheers

 

My response was assuming you battery is fully charged.

 

Yes the battery is in good working order and fully charged.

Cheers

 

Most likely the regulator is bad. I would not advise driving the car with the voltage that high. If you want a repair/upgrade I offer this https://www.irperformance.com/produc...mp-alternator/

 

Thanks IRP, I will check out the link. 👍

Cheers

 

Hi all,

Update: It seems the Voltage Regulator was bad. I swapped it out at an Alternator repair shop with a useable regulator and now at about 5500RPM I am getting around 14.1V

When idling (no fans on, no radio, no lights) I see about 12.8V. When the fans come on it drops to about 12.4 / 12.5V, sometimes slightly below 12.5V

Thanks again for all the input.

Cheers