charging woes partII

[tim eh?]

i'm going nuts help me please

There is a big background to this but the thread is long and full of stuff that doesn't matter anymore,
I think all the relevant stuff is here.

I am using the obc test#9 for these tests... I compared it at idle to readings with the voltmeter and it seems to be pretty reliable.

The system runs at 14.2V at idle when cold with nothing on.
.... >13.4V at idle when cold with everything* on.
.... <12.0V at idle when warm with everything* on.

*highbeams, stereo, blower, rear defrost it's all i've got! The rear defrost really kills it.

Battery is new December/07 - it passed a load test at the shop yesterday.

Battery is at 12.50V after driving, 12.62V if I remove the neg terminal.
No change to this if i disconnect the main terminal at the alternator.

Goes to around 12.15V the next morning.

Using a new multimeter I got the DCamp test working... but the static draw test blows the 315mA fuse every time (even with alternator disconnected).
What's with the 10A setting? That looks scary but I'm so tempted.

I replaced the original alternator (which just crapped out... the symptoms weren't the same) with a rebuilt (not bosch) one during the summer. I didn't notice these problems until recently but they might have been happening since i replaced it. When i first noticed this I thought it was the alternator and took it back but I get the same symptoms with a different (still not bosch) one. The belt is brand new it's tight I'm pretty sure, I've checked it plenty.

So I guess there is a definite >315mA drain somewhere. But if it's just an accessory could it be enough of a load to kill the system voltage like it does?
And why oh why does it only do it when the engine is warm???

Can a faulty alternator drain a battery like that just sitting there?

I have removed the main terminal from the alternator and will test the battery voltage tomorrow morning (will suck in the dark) , will that tell me anything(?) or should I do something useful, like start pulling fuses.

The parts store will send it in for testing if i take it to them should I just do that?

help meeeeee!

[Claude]

Q1:The system runs at 14.2V at idle when cold with nothing on.
.... >13.4V at idle when cold with everything* on.
.... <12.0V at idle when warm with everything* on.


Q2: So I guess there is a definite >315mA drain somewhere. But if it's just an accessory could it be enough of a load to kill the system voltage like it does?
And why oh why does it only do it when the engine is warm???

Q3: Can a faulty alternator drain a battery like that just sitting there?

Q4: I have removed the main terminal from the alternator and will test the battery voltage tomorrow morning (will suck in the dark) , will that tell me anything(?) or should I do something useful, like start pulling fuses.

--------------- ----------
E1: 12 v at idle warm or cold not normal (should stay 13.5 v and a up) bad battery or bad alternator. But you say battery load test passed OK, so suspect the alternator.

E2: 315 ma drain is not very high, should'nt be the cause of voltage drop you report, but such a drain is not normal (should be lower) otherwise if the car stay unused 2-3 days that drain is enough to drain the battery flat

E3: Yes a bad alternator (shot inside diodes in the regulator) may drain a battery

E4: Very good idea to isolate the alternator from the battery to night to see if it's the alternator itself that drain the battery... can't wait to see the result.

[tim eh?]

thanks++++ guys

E4: Very good idea to isolate the alternator from the battery to night to see if it's the alternator itself that drain the battery... can't wait to see the result.

kinda dumb i only disconnected the main terminal should i disconnect also the small alt terminal also (i didn't ) or does it matter?

Start pulling fuses Tim. It's not the alternator, two in a row?

that's what i thought but it's weird i was pretty sure i had my wiring figured out. everything i mean everything electrical works perfectly except the a/c and the fog light cluster light (it's not the bulb and the foglights work... weird)

Wait a while to watch the draw, it takes time for everything to go sleepy.

I don't understand... you mean disconnect battery->wait->test or wait->disconnect battery->test.

i would get split second readings for a draw but then the fuse would blow.

with alternator connected 70mA
with alternator main terminal disconnected 20mA ...
i dunno if it was just the wire melting or what...

yeah... fuses are next... starting with IHKR i think - what a pain one test/night!

[Ross]

Start pulling fuses Tim. It's not the alternator, two in a row?
Wait a while to watch the draw, it takes time for everything to go sleepy.

[bubba966]

So your electrical system is pulling over 315mA, blowing the fuse in your DMM when doing a load test with the car off?

Car should draw under 50mA when everything is off. Need to find out what's causing the power draw by pulling fuses 'till you get normal readings. Set your DMM to a higher range so that you don't blow more fuses in it while doing this.

[tim eh?]

So your electrical system is pulling over 315mA, blowing the fuse in your DMM when doing a load test with the car off?

yes the fuse blows every time after about half a second, but it does flash those readings.

the max setting with the 315mA fuse is 200mA. there is no higher one maybe i shouldn't buy these at the dollar store... maybe i could use the 10A unfused setting. I only kind of half know what I'm doing so 'unfused' is enough to put me right off, whether it's me or the car I'm going to hurt I just don't like the 'unfused' idea...

I want to rule out the alternator first because if it turns out to be suspect I don't have to piss around with fuses and finding a decent DMM.
Ughhh I hope winter comes late this year...

[Scott C]

yes the fuse blows every time after about half a second, but it does flash those readings.

the max setting with the 315mA fuse is 200mA. there is no higher one maybe i shouldn't buy these at the dollar store... maybe i could use the 10A unfused setting. I only kind of half know what I'm doing so 'unfused' is enough to put me right off, whether it's me or the car I'm going to hurt I just don't like the 'unfused' idea...

I want to rule out the alternator first because if it turns out to be suspect I don't have to piss around with fuses and finding a decent DMM.
Ughhh I hope winter comes late this year...

You can always put an inline 5a fuse in series with your leads to protect your DMM

[tim eh?]

You can always put an inline 5a fuse in series with your leads to protect your DMM

i'm mostly worried about frying a circuit board in the car i don't care about the DMM and i don't think i can start any fires unless i really do things backwards but yeah i should just do that - thanks.

as far as the possibility of getting 2 bad alternators in a row goes... actually where i live that's not so improbable now that i think about it.... sometimes you're lucky to actually get the correct part even. PITA shopping here sometimes.
(eg i went to 4 stores today before I found 315mA fuses - i found them at a place where the guy told me they didn't have any)

[bad_manners_god]

i'm mostly worried about frying a circuit board in the car i don't care about the DMM and i don't think i can start any fires unless i really do things backwards but yeah i should just do that - thanks.

as far as the possibility of getting 2 bad alternators in a row goes... actually where i live that's not so improbable now that i think about it.... sometimes you're lucky to actually get the correct part even. PITA shopping here sometimes.
(eg i went to 4 stores today before I found 315mA fuses - i found them at a place where the guy told me they didn't have any)

You got 2 bad alternators tim, I'm 95% sure, IT'S A VERY COMMON PROBLEM HERE, we get alternators and starters at the garage that are rebuilt and are deffective.

Just return it and say it's deffective and get another one.

[Ferret]

Time to wade into this one I think...

Your multimeter can wage war on upto 10 amps, if you plug the black lead into the common/ground normal port, and the red lead into the socket that's labelled 10A (it's usually marked with small lettering) set the meter to 10A and you can get a decent reading.

Your car shouldnt be drawing a current of 2-300mA when stationary and everything's switched off. You've got a current drain somewhere that's abnormal.

With regards to the rear defrost causing the voltage to drop down to 12v, mine does this as well - I've never really been arsed eyeing up the alternator and trying to figure out if it's natural.

You need to wire up your meter in it's 10A configuration, and start pulling fuses until you figure out what's drawing the current when the drain suddenly drops off.

Dont forget the fuses under the rear seat either, they've got a lot of ancilliary crap running off them - drain could easily be in one of these.

If after you've pulled all your fuses you've still got a drain, then you've confirmed it's an alternator or starter fault. They're the only two systems that should be left connected. (Though, there's some fuses in the e-box which you may need to pop out first.)

Another thought that's just hit - you've not any 3rd party audio kit fitted like amps etc have you?