I have a 220a MechMan alternator with two runs of zero going to the two XS power S3400s in the back. Nothing except the alternator is connected to the cars main battery but yet my cars battery is running at 16.5+v. The voltage jumps around like crazy to, no predicting it. Why is it doing that and what can I do to get it to sit at a stable 14.1-14.4v?

What are you using for a voltage meter?

Stinger, and my regular car battery warning. When it sits above 16.5 it throws the battery warning.

Try a dmm to confirm the voltage.

sounds to me like your voltage regulator has gone bad.. check it with a DMM and if indeed it is spiking contact mechman.

oh, and dont drive it anymore ... high voltage can kill your cars computer. your head unit, and some amps

Sad day. I'll check it with a ddm in a second, I'm actually out right now but I'm headed back. Thanks for the heads up though! I already had one new computer put in this car, don't wanna do it again.

Stupid question, but I got stinger zero and I ran out of zero Ga when installing it so I used some thick 4 Ga, could that be it by any chance? ( 4Ga on the extra batts and amp grounds) it's stupid I know, but zero is hard to come by down here.

if your away from how now.. if your alternator is PCU controlled then check your connection to the alternator.. if it has come lose or a wire has got snagged some how the voltage can not be controlled by the PCU there for it will spike..

so check your connection plug too

Stupid question, but I got stinger zero and I ran out of zero Ga when installing it so I used some thick 4 Ga, could that be it by any chance? ( 4Ga on the extra batts and amp grounds) it's stupid I know, but zero is hard to come by down here.

no chance.

Alright, that might be it because I heard Mech Man is pretty good. I can't see it being bad already. And that's good news too. Thanks a lot man, I'll double check the plug and wires of the plug and if it's all good give him a call.

update?

I haven't done anything yet. I'm active duty military and my alternator is under my car so I have to lift it up and fight with three huge bolts. Not to mention the garage that has lifts is only open Thursday through Sunday . My car is running at those voltages though, dmm tested. I started my car and it idled at 16.5 and my windows wouldn't roll down for some reason, maybe a protect? I'll definitely get it fixed and send the update in case other people have the same problem.

no luck with the pigtail being lose? or wires being messed up?

Everything checked out fine. I reinstalled the stock alternator and it's holding a more stable voltage. My batteries need a charge since the incident but they aren't dropping below 11.9 or rising above 14.1 anymore. Checked the wires everywhere for lose or cut or unplugged and no luck. Contacted MM, they said box it up and ship it back and they will fix it. Hopefully they can fix it and I can get back to pumping out the higher amps.

good stuff.. let us know what was wrong with it

As soon as I can. It's crazy though, I thought MechMan wouldn't have this issue. It could be my car, seeing as the computer had been replaced before but I've got a feeling it's the alt.