LP928

I've been having some problems lately with my alternator not charging, the volt meter on the dash reads nothing (I know its not accurate) however it used to read about 11.5V, still low but it kept my car running. My battery went totally dead a week ago and my car wouldn't crank so I had it tested and ended up buying a new battery which worked fine for a week and then again last night, no crank just a click. I charged it for half an hour and it started, but ran itself dead after about 5 - 10 min in the garage. I charged it overnight (with a battery tender, my real charger was at my grandfathers house) so I could get to swim practice in the morning. Got there fine and on the way home it started stuttering and stalled down the street from my house. So I called my mom and and she came and I jumped it got me home then it stalled in my garage. I've been wondering for a while why there is no ground strap on my battery, could that be the problem?

thanks

Kyle

LP928

Picture: WONT LOAD!!!

Alan

Err - yes that would be a problem - but if your car ever starts you must have a ground strap - its not possible for the car to start without one (so what do you mean - picture?) Sounds like your voltmeter also died - but this is unrelated. Your alternator is not charging your battery at all. 11.5 v (if true) means the bettery is running everything - so no wonder it doesn't last long.

Alan

LP928

Where would the ground strap be so I can check it, I thought it would be in the battery box? When my car used to run without charging it, the voltmeter read about 11.5V, never higher. Now it doesn't read anything. When I turn my key the voltmeter needle pops up a little bit, but the charge light doesn't light up on the gauge.

LP928

Just found the ground points on the new user forum. I can't find a battery ground strap! The only things connected to my battery are the positive and negative wires. The ground strap connects to the chassis at on the battery box, right?

blitz928

Ground strap will be a flat strap about 2 feet long from the battery to a post behind the tool kit in the hatch.

Landseer

The negative wire "is" the groundstrap as Matt says, flat braided (unless somebody replaced it). Follow the negative, where does it go?

LP928

There is no flat braided strap. The negative goes grounds where it should. Now I feel really stupid. OK then, what should I check for my charging problem first?

Lizard928

Yes the negative lead is the ground strap.

Confirm that you have a ground strap from the engine block to the chassis. This will be on the passenger side of the engine block just behind the cross member. It will be a braided copper looking wire.

Then if it still is not charging ensure that the belt is on the altenator and is tight. Sorry but it needs to be checked. We just had a member asking about PS issues and the belt had broken.

Then pull the cover off the back of the altenator and verify that all the wires are connected and the connectors havent broken off.

As well charge the battery and start the car. Once the car is running rev it up to 4000rpm and let it fall back to idle. If the voltage increases to 13.5V or higher then the exciter wire is not activating the starter and you will have some electrical things to fix.

I am not sure what year your car is so I will end this here.
But I would strongly recommend that you fix this before driving the car anymore. Running the fuel pump and other componants at low voltage can have negative effects.

Alan

Well - first buy a digital multimeter and check the voltage on the front jump post with ignition off and also with the car running. The dash voltmeters may not be accurate even when working so you need to do this.

The "charge light" (really a no charge light) comes on if the connections to the alternator are good but the alternator is not generating. If the connections to the alternator are not good the charge light may not come on even if you have a problem.

You need to verify if the alternator is generating - if when runing your voltage is below 13v you are not charging properly (or at all). The at rest voltage will indicate the basic battery condition.

You should investigate the alternator initiation via the excitation circuit. This is what makes the dash light come on. has any work been done recently? clean the 14 way connector near the front jump post.

On the alternator see if you get any voltage on the smaller connector when the ignition is on? if you ground this small terminal with the ignition on - does the charge light in the dash come on?

Do you have other instrument problems in the dash? - maybe your pod connectors need to be cleaned since possibly several things already have issues...

Alan

sharknoob

Take that download of the ground points and clean them all

LP928

OK. I got a multimeter and measured voltage at the jump start terminal with the car off: 12.51 V. This is after its been charging all day. Then I tested at idle: 11.8V At 2000: 11.8 3000: 11.8 4500:11.8 So it seems that the alternator is not charging whatsoever.

Lizard928

Alt is not charging is correct.

Pull the back cover off and verify that the cables are all connected. If they are remove the altenator and have a shop check to verify that the diodes are ok. If they are then replace the voltage reg and reinstall.

Alan

Don't foget to first do the checks I noted on the exciter circuit. Not all alternators self excite at high RPM's so your symptoms could all be related to a disconnected exciter circuit - a break anywhere along the path - the 14 pin connector, pod connections to the bulb circuit or the connection to the alternator itself are the most likely (there are other connection locations but these are the most common).

Usually if the alternator alone has failed - the charge light should come on... However it is still possible the alternator is at fault - you'll know this if the exciter circuit checks out OK otherwise - as noted.

Alan

Bill Ball

Alan:

If it were an exciter problem, wouldn't it still begin to charge once you get over 2500 RPM or so? That's what I have seen. He isn't getting anything regardless of RPM.

Parenthecally, I had an interesting exciter circuit fault recently. Normally you suspect the 68 ohm resistor in the instrument panel, but in this case we had 12V from the exciter ciruit all the way to alternator. This alternator was a freshly rebuilt one. Anway, I opened it up and found that the exciter wire inside the alternator which is brazed on the backside of the wire post, had broken off. Somebody snugged up this post and turned it, breaking the wire off. So, be careful tigtening this if the nut securing this post comes loose. The wire is rather stiff and will not flex but rather breaks off.