alt is killing me

[dohckiller808]

my new mechman 300 alt drops to 12.5 on idle, but on rev using their voltage boost controller ramps up to 14.6 where i set it to at 1000rpm.

this does not seem normal...

my car idles at ~600rpm, pully is smaller than stock and the belt is tight enough.

any input on this would be appreciated.

[Red-navi-916]

what car? and do you have the big 3 done? and most importantly how good are your grounds? with a 300amp i would think youre looking at over 15v at idle, my dc 270 idles at 15.4 15.3 warmed up but as soon as i gas to 1k rpm goes back to 15.4

depending on the year of the car maybe the computer wont process it,

so here is a few things you could try

1* go toautozone get a load test(could be a bad alt, a company wont have perfect luck with every single alternator they make)

2* get a multi meter and stick it on the battery with the vehicle running

but like i said only thing i would guess is bad grounds because that is waaay too low

[dohckiller808]

It's an 01 Sequoia. Did run a neg cable to the chassis. Never test the resistance on the ground yet.

[crunkjuice1]

From the but I have learned the setting depends on type of batteries your using like AGM or what. I'm still learning on mine also, your going to have to set it around 14.9v at 1000rpm at start up that way when it warms up the voltage will drop down a bit but should stay in lower 14v range if using AGM batteries.

To some this seems so easy but I know me and you as well all the new mechman adjustable voltage boost module owners are in need of help on this topic.

[crunkjuice1]

That most likely is your problem Matt himself had told me to connect ground on alt directly to negative on battery.

[dohckiller808]

Yes. Running 7 agm batts. I'll try setting on cold start like you said. I hope that's it.

Edited February 26, 2011 by dohckiller808

[UnderLoK]

Are you saying it drops to 12.5 under load or this is just under normal operation. Meaning you stop at a light (no stereo) and it does it or is this under a load?

As far as wiring goes (all 1/0, this isn't optional). Alt to ground (frame or strut tower if unibody), ground to batt. Alt power to batt.

On a related note, if you have that many batteries you really should get a charger.

Edited February 26, 2011 by UnderLoK

[fr34kout]

I told him he needs to top off his batteries to start.

He's got a Stetsom 11k with 6 blue tops and idk what battery in the front. Batteries have got to be drained from all the sampo's you've given ryan lmao. Throw them bitches on a charger and once they're topped off THEN check your voltage. If it's still low, do your whole big 3 cheapass XD

[crunkjuice1]

Call Matt he will recommend connecting alt ground directly to battery negative.

[Dr. Johnson]

I run a mechman 250amp alt and mine does the same thing as the op. I have everything set up with big three and xspower batts. I idle very low too especially when the vehicle is warm.. sometimes down below 500 rpm. I dont think anything is wrong with the alt at all.