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With my new mechman 240amp alternator. Now I know this is no Bueno. And it is just on the stock wiring. So.....I ran to the store and dropped another $150 to do the "big 3" upgrade. And very nicely done IMO. Anyway, thinking maybe that was the problem.
Nope.
With 0 gage wire an extra battery ground and an extra engine ground and and extra power cable....she is still at 16 volts at idle. Checked by both the DIC and voltage meter. About 3 minutes of run time you can smell the battery starting to cook
At this point I got nothing. I have to call mechman in the morning.
Oh, I didn't have anything to really contribute today. Just socializing and sharing my struggles.
Yeah, that big 3 will just make sure the entire system cooks evenly. Man, this is a new one on me...I have no idea where that extra 1.5-2v is coming from.
Well this is the pulley that came with it. Id hate to think that a company that builds alternators would know.....ya know? Plus that small pulley is so pretty lol and has mechman lasered into it.
Why replace the pulley with something larger? The smaller pulley is designed to provide sufficient power at the lower RPM our motors typically operate at. Replacing the pulley will not change the output voltage--the regulator will adjust to maintain the commanded setpoint. The regulator on that particular unit just might be set too high for his system. There should have been a tag on the unit that identified the test voltage and power output.
My Mechman defaulted to 14.8V, hot, out of the box. Cold, it put out about 15.5V. Nothing wrong with that. Depending on the type of battery you're running, 16.0V may be fine for a minute or two while the system is cold, but for compact racing batteries, I believe that they recommend a maximum charging voltage of about 15.5V (check your manufacturer's documentation to find the exact value). I have mine set to put out 15.8V cold, and it drops to about 15.1V when everything has reached thermal equilibrium.
My suggestion would be to check with Mechman and see if they'll cut you a deal on their small inline voltage regulator adjustment module. The alternator is really designed to be used with that--you're supposed to tune the voltage output to a safe initial level based on your cable voltage drop and then leave it and let it do its thing.
Last edited by FuzzyLog1c; 08-29-2016 at 12:31 PM.
I called mechman and it turns out they put the wrong regulator on it. It has a 3 wire. Not the 2 it needs. great. Another freaking week minimum my car is down. SMH
Running the car for 2 minutes with the larger cables installed immediately started cooking the battery and had my garage almost intolerable smelling of hydrogen. It took about twice that time to even get a whiff of it on just the stock cables. So there is that!
Hydrogen doesn't have a smell by itself. Given what batteries consist of, I'd be concerned about what you ARE smelling...in addition to smashing the battery.
True, but the sulfate/sulfur is what you're smelling mixed with the hydrogen.
I hope my battery isn't toasted. It shouldnt be....For a short of time as I ran it.
I can tell you this, Once our cars hit about 16.2 volts a lot of weird crap started happening. Once I reved the car the dash lite up like a Christmas tree and EVERY warning I believe the car has cycled through on the DIC haha
True, but the sulfate/sulfur is what you're smelling mixed with the hydrogen.
I hope my battery isn't toasted. It shouldnt be....For a short of time as I ran it.
I can tell you this, Once our cars hit about 16.2 volts a lot of weird crap started happening. Once I reved the car the dash lite up like a Christmas tree and EVERY warning I believe the car has cycled through on the DIC haha
Really? Mine gives an overvoltage warning on the main navigation display if I exceed... something on the order of 17.0 VDC. But no other weirdness. Vehicular electrical systems are primitive but pretty robust, compared to most other consumer electronics.
Well, mine did. I only reved it to about 2 k with the new cables and the voltage climbs. So much so I can hear my spal fans getting faster haha and let me tell you they get loud!
NAF - suggesting a smaller pulley is a pretty ridiculous recommendation for this. The alt's regulator should provide relatively steady voltage whether you're at idle or higher rpms. That'd be like saying don't drive at 2k rpms cause it will provide too much voltage compared to 1500 rpm.
NAF - suggesting a smaller pulley is a pretty ridiculous recommendation for this. The alt's regulator should provide relatively steady voltage whether you're at idle or higher rpms. That'd be like saying don't drive at 2k rpms cause it will provide too much voltage compared to 1500 rpm.
Plz read my posts one more time slowly,
I did not recommend a smaller pulley, i recommended a LARGER pulley...
I did not recommend a smaller pulley, i recommended a LARGER pulley...
I know - I meant suggesting it was because of the smaller pulley. Larger or smaller is no different than different RPMs from the engine changing the alternator speed.
The alternator creates AC votage that the rectifier/regulator converts to DC.
08-28-2016, 10:51 PM
16 volts at idle! 
Man, this is a new one on me...I have no idea where that extra 1.5-2v is coming from. 
