I have a 270a Mechman that I purchased this spring. Not a month after I bought it it had charging issues and was repaired under warranty. Well now I have another problem and not sure where the problem is. My system is NOT installed right now and hasn't been since the repair of this alt. I have two 3yr old Redtops under the hood now. The batteries rest at 12.6 with the truck off and hold that way. When the truck truck is at idle my voltage is at 12.9. As all. As I give throttle is goes to 13.6 but doesn't go higher. When I come to a red light it's back at 12.8-13.0. Again No radio at all. I'm thinking it has to be the alt again but I have two new xs3400's that could go in place but don't see how that will help since these are holding voltage above 12v.

Any suggestions or just send this back again. Twice in 3-4 months is alittle frustrating

I'm not sure about your issue but I still have a low idle issue with my Mechman alt (same model as yours)... But since it's a daily driver and I don't have the original alt since it was bad .. I'd have to buy a new factory alt just so I could use my car... it also doesn't help that I am unemployed... They were nice at Mechman so hopefully you can get it resolved

I say swap the batteries first then go from there. Since you already have them.

Yeah they are very nice and fast turn around, but........ I still have my stock alt but I now have a 1 inch shorter belt to help with the belt slip I was getting from the Mechman. Maybe it will still fit the stock but unsure. I sure would like to install the 3k worth of stereo equip I have but sure as hell can't do that until I have sufficient charging power. :/

I say swap the batteries first then go from there. Since you already have them.

I will check the batteries in the morning, if they are still holding at 12.6 it can't be them. I would love for that to be it though.

Batteries can still show good resting voltage and not be worth a poop. I just went through this with my kinetiks.

12.6v is LOW for an agm battery.

For the size you are running, they should be at LEAST at 12.9v or better.

You need an AGM battery charger and they need to be put on charge before placing a new alt in the car.

Whether this resolves the issue or not, this is crucial.

I use a Diehard battery charger for around ~$90 at Sears.

Next, You can also pick up a decent Load tester that is not electronic to save money.

For testing cell damage, most cheap load testers are 100-150A. That's plenty for quick testing batts that exhibit high voltage at rest.

I have this charger

http://www.centurytool.net/87151_Century_15_2_100_Amp_6_12_Battery_Charger_p/87151c.htm

charging bad batteries can cause an alternator to fail

Ok just went out and put in the two new D3400's, both sitting at 12.95. Well shall see tomorrow, I sure hope it was the Optimas going out.

Ok just went out and put in the two new D3400's, both sitting at 12.95. Well shall see tomorrow, I sure hope it was the Optimas going out.

Quick work... Keep up posted, I'm hoping that is your resolution man!

Maybe I should look into the resting voltage of my batteries ... although I think that isn't the reason for the car dipping into low 12's and high 11's at idle....

Possibly your Pcm is limiting your voltage and not allowing you to charge higher, an ext. regulated alt might fix your problem --its did for me. You also might need a smaller pulley if possible. But you may have to get a smaller belt size

OK,

Looks like it was the batteries. Truck sits back at 13.8-14.1 at idle like it should now. I am super glad its not the alt but now I have to go spend yet more money on another 1 or 2 batteries for the rear.

Thats very strange because both Optimas were sitting at 12.65 still this morning. I hate that I jumped the gun and was thinking it was the alt. But after all the trouble I have been through I just figured that would be my luck.

Thanks for the help!

Well, I guess I spoke too soon, when cold voltage is good but after the truck heats up it is dropping back to 13.2 at a red light or idle. Considering my stock alt will hold at 13.7-13.8 in the heat I think I'm gonna have to call Mechman and see what they think.

Possibly your Pcm is limiting your voltage and not allowing you to charge higher, an ext. regulated alt might fix your problem --its did for me. You also might need a smaller pulley if possible. But you may have to get a smaller belt size

This ^^

highly doubt its your batteries... your truck might charge 13.6v stock so you need a ext reg to raise the voltage...

also what do you idle at.... i know when my car idles at 800rpms it only charges like 13.8v but then once i rev to around 1.5Krpms the voltage raises up to 14.8v where i have it set....thats the bad thing about my mechman alt... needs to be revved above 1K for it to charge at its max...

Hmm, good thinking. Since my rebuild my idle may be a hair lower than it was before. I will go into my tuner and raise it 100rpm and see I that helps. My truck sits low at maybe 650-700. That may be the whole issue....

I just ordered two more D3400's today so I will have a total of 4 of them. I will have plenty of battery power that's for sure.

Looks like this ones going back , great customer service though. Should be another fast turn around

Ok just went out and put in the two new D3400's, both sitting at 12.95. Well shall see tomorrow, I sure hope it was the Optimas going out.

It sounds to me like a battery not that i know a whole helluva lot but if your battery is resting at 12.6 thats pretty low especially for running the sp4's with it. im sure you have more than one battery hooked up tho. But if you change youre bat to one of the 12.95s and try to put some music to it while it runs i would hope its up in the mid 14.- whatever voltage mine is at 14.2 or so i think for my voltage at an idle on my ap1500.1 and GCON ported. at rest its 12.8v when its on at idle its about 14.2v. and im running a stock alternator in my E-150

But i would make less of an ass of my self if i would have read that you fixed the problem haha. sorry swift

Edited August 16, 201213 yr by Austin863

Its dropping down to 12.9-13.0 at idle and red lights with the sound system OFF. This is with the 2 new XS d3400's under hood. They agreed its something wrong and said send it back.

Okay and yes if it isnt the batteries then i would say check the alt its an obvious problem that you have already found out being the alt. but sorry i couldnt help. but i hope everything gets back up and running well.

Alt is at Mechman now so hopefully when it gets back I can see good steady voltage. The stock 130 in back in and doing much better than the 270 was. Can't wait to get it back, gonna be adding some more 2/0 runs to back and may add my Optima's back in up front and have 4 d3400's in the rear since the optima's are still resting at 12.75 after sitting out for over a week. Maybe I will have them load tested just incase.

Alt is at Mechman now so hopefully when it gets back I can see good steady voltage. The stock 130 in back in and doing much better than the 270 was. Can't wait to get it back, gonna be adding some more 2/0 runs to back and may add my Optima's back in up front and have 4 d3400's in the rear since the optima's are still resting at 12.75 after sitting out for over a week. Maybe I will have them load tested just incase.

I would have them charged up over night ya know.

Alt is at Mechman now so hopefully when it gets back I can see good steady voltage. The stock 130 in back in and doing much better than the 270 was. Can't wait to get it back, gonna be adding some more 2/0 runs to back and may add my Optima's back in up front and have 4 d3400's in the rear since the optima's are still resting at 12.75 after sitting out for over a week. Maybe I will have them load tested just incase.

I would have them charged up over night ya know.

I did and this is where they sit now. I did find a killer local spot for power wire, custom rca's or any other audio gear. getting 2/0 600v jacket super flexible for 3.35 per foot.