Battery Charging Issue

[six_sigma 12]

Hey guys I have an issue that has come up.

 

I pulled my car out of winter storage reconnected my battery and the car fired right up, great! A few days later I went to go for a drive and the car was completely dead not even a click click click. So I jumped the car and at started right up. Took it for a long drive got it home turned off and then tried to start it again and dead.

 

So here is what I've done:

 

Took the battery to verify that it was still good, it was.

Checked the voltage at the battery while the car was idling no accessories on. 12.2V

Checked the voltage at the alternator 13.5V.

Cleaned up the positive and negative battery terminals remeasured the voltage at the battery and it went down. 11.8V

Changed the voltage regulator and the voltages went down again. 12V at the alternator and 11V at the battery.

 

I'm confused... :confused1:

 

200CI, C4, no power anything.

 

Thanks for any insight.

[Lemon Owner 11]

Alternator should be charging around 16volts prior to regulator. May be a problem with the alternator?

[six_sigma 12]

Thanks Lemon Owner, I didn't think that the alternator was supposed to be pushing out that many volts, if thats the case I think I'd much prefer replacing a bad alternator than tracking down a short or corrosion in my wiring harness.

[Lemon Owner 11]

I wouldn't quite rule out bad connection yet. It could be a poor earth to the alternator causing it not to reach full voltage. With all problems always start with the cheapest solution. :)

[Angel 24]

The voltage at the battery should be between 13V and 14.6V max. Ideally, the voltage at the alternator should be 13.5-14.5V. 13.5V at the alternator is ok but it shouldnt drop by more than .3v at the battery. Take your alternator to Autozone and have it tested. Its free and it isolates the alternator so you know the condition of if without being influenced by other things.

[Boogerschnot 12]

I would take the alternator in to your local parts house and have it tested, If it works then check your wiring and possibly get another new regulator. I went through a phase where I was killing regulators left and right every few months. Replaced the alternator and regulator and then it was good.

[DRASTiK 22]

If alternator checks out, then you may have a voltage drain somewhere in the car. Since the battery was disconnected for winter storage, you wouldn't have noticed this issue until after hooking it back up, then letting it sit long enough for the battery to be drained.

[six_sigma 12]

Thanks guys, I'll do that this weekend. I've actually been looking forward to getting my hands dirty.

[six_sigma 12]

Well, pulled and tested the alternator, turns out it was bad. Replaced it with a new one and still only 11V at the battery. I pulled out the alternator wiring harness and inspected it and it seems all right, now I'm wondering if it might be the connection into the voltage regulator.

[Lemon Owner 11]

Next bet will be the regulator. My mach 1's alternator died about the same time as the regulator. Or maybe the alternator took out the regulator or vice versa.

[six_sigma 12]

Regulator was actually the first thing I replaced after I inspected the battery and cables.

[Powershift 19]

That seems a little odd your Alternator tested bad, but nothing seems to have changed when installing a new one.

 

You are checking the Batt voltage while the engine is at idle, with accessories turned off, correct? Just ensuring you are checking it that way... should be between 13.5 and 14.5v at idle.

[six_sigma 12]

Yup, all off engine at idle, 11.2V at the battery. I watched the alternator test and the voltage that the alternator was kicking out was inconsistent. One sec 14, another 12.

[Boss302 22]

that mustang restore guy, the doc, he has a few videos on this same issue,

testing the alternator, egine on and running, put in park,open the hood, disconnect the NEG cable from the battery, if the car stays on, then the alt is working...

 

to check the regulator, he mentioned jumping some power pins...i didnt want to risk it..but since these are Not new cars with ECM or any computers in them should be fine.

 

 

recently i had the same issue, didnt drive for over a week, battery was dead.

charged it...for a couple hours, at the battery terminal i used a multimeter, it read 17.5v then it started Right up.

the next day it was 17.4.8- so theres a drain, but soo small, its hard to find.

everyone says 13-14v, but this is what works.

ill end up replacing the alt and voltage reg. ive heard in the past, replace ONE, mise well replace the other...one bad could make things worse for the other.

[Powershift 19]

Is the Alternator harness the original?

[six_sigma 12]

Actually I have no idea, I've only had the car 10 months. The alternator harness and the voltage regulator plug were the next things on my list to replace.

[Powershift 19]

If you can't tell by looking at the wires, and they don't appear to be new, it would seem like cheap insurance to replace them. I would suggest replacing them just to be safe. With a known good Alt, and Reg, the wires really are the next critical item.