Car dies after jumping when I remove the cables - no idea...

[uhhair]

So I went to start my D after a few weeks and it was completely dead. Not sure how that could have happened as I didn't leave any lights on but I just assumed shit happens. Went to jump the car last night...went well until I disconnect the jumper cables. The car then completely stops running. I tried this a few times, even letting it sit with the cables connected to the other car for a few minutes to try and charge the battery a little. No dice. Same result every time. Volt gauge also was really low during this time (around 8-9 volts). My first test is going to be getting a new battery. Mine is already pretty old so it was on the list anyways. I also suspect it could be my alternator has died as well, however I am wondering if anyone else has had this problem before and what their issue was? I'd just like to get an idea of some other things to look into in case sticking in a new battery does not work, or if this is an issue someone else may have had and could provide some insight. I'd prefer to not replace my alternator if it is in fact not the issue, but I don't know a way of eliminating it as a problem short of replacing it. Any thoughts here? Thanks in advance for your help, I really appreciate it!

[Jonathan]

Start with a battery you know has a charge on it. Like you said, get a new one, or charge your old one outside of the car on a workbench with a car battery charger.

Then when you put it back in the car, turn the key to accessories and ensure the battery warning light comes on as part of the start-up sequence. If it does, then try to start the car. If that light doesn't come on, then you get to find out why because the car won't run without it.

[OverlandMan]

Sounds like your battery is for sure dead. With the car running, put a multimeter on the battery. You should get upwards of 14V, indicating the alternator is working. If not, your alternator needs replacing. You'll want to fix that first otherwise you'll keep draining new batteries.

If your battery is somewhat new, you can load test it and see if it will take a charge. Autozone can do this for you if you don't have the tools. Also, check into battery warranty.

[Bitsyncmaster]

When your battery is completely dead, it puts the highest load on the alternator when you start the engine. I think your correct in replacing the old battery first and then see if the voltage is about 14 volts with the engine running.

[OverlandMan]

When your battery is completely dead, it puts the highest load on the alternator when you start the engine. I think your correct in replacing the old battery first and then see if the voltage is about 14 volts with the engine running.

If you have a fully charged jump-pack you should be good though, until you remove the jump pack...

The battery on my 308 was completely dead a month or two ago so I jumped it. As soon as I took the jump pack off, it would die... at first until the alternator could charge enough of the battery to keep it running. At idle, the pully-driven alternator was cranking out minimal voltage so when the cooling fans kicked on (with the jump pack disconnected) the engine would die. I literally had to keep it around 2k RPM or higher to keep it running for the first several minutes. Of course, I turned all non-essential electrics off to lighten the load.

A new battery fixed this problem but I did check the alternator just to make sure I wasn't going to drain another battery.

[uhhair]

Sounds good guys, I am going to replace the battery tonight and see what happens from there. Hopefully that's all that is wrong with it!

[DMCMW Dave]

If the battery has failed (internally shorted cells) this is a good way to smoke the alternator too. Always better if possible to charge the battery first, jumper cables should be an emergency thing.

[Parzval]

Most cars (not sure about a D... yet ;) ) will run on the alternator alone if you jump it. A shorted battery or a weak alternator can kill it though. SOOOO If you disconnect the "dead" battery from the circuit after you get it jump-started but before removing the cables....and THEN remove the jumper cables and it keeps running... then it's your battery. If it still dies, then it's either the alternator or in your wiring. Hopefully your alternator and wiring is still fine. Battery is the easy part!

Good luck!

[Bitsyncmaster]

Most cars (not sure about a D... yet ;) ) will run on the alternator alone if you jump it. A shorted battery or a weak alternator can kill it though. SOOOO If you disconnect the "dead" battery from the circuit after you get it jump-started but before removing the cables....and THEN remove the jumper cables and it keeps running... then it's your battery. If it still dies, then it's either the alternator or in your wiring. Hopefully your alternator and wiring is still fine. Battery is the easy part!

Good luck!

Not a good thing to disconnect the battery with the engine running. Most alternator manufacturers say not to do that. It also can put high stress on other electrical devices in the car.

[uhhair]

Well, it turned out to just be a bad battery it seems. I took the old one out and down to the store to be tested and they couldn't even get a reading off of it. So I bought a new one, took it back home, and the car started right up! Volt gauge was reading around 13 volts even after letting the car run for about 20 minutes. Once I get my multimeter back this weekend I'll check the current on the battery when running, but I'm pretty confident it was just a bad battery. Thanks for your help guys!

[David T]

Well, it turned out to just be a bad battery it seems. I took the old one out and down to the store to be tested and they couldn't even get a reading off of it. So I bought a new one, took it back home, and the car started right up! Volt gauge was reading around 13 volts even after letting the car run for about 20 minutes. Once I get my multimeter back this weekend I'll check the current on the battery when running, but I'm pretty confident it was just a bad battery. Thanks for your help guys!

Also check the current when the motor is NOT running and the doors are closed. If it is over 50 MA you have too much drain and the battery will go dead in less than 2 weeks. It is very detrimental to the health and longevity of any lead-acid battery to be drained completely flat.

[uhhair]

Will do! I do have a cutoff switch installed on the battery, and I use it every time I turn the car off.

[DMCMW Dave]

Not a good thing to disconnect the battery with the engine running. Most alternator manufacturers say not to do that. It also can put high stress on other electrical devices in the car.

Yeah - especially the ECUs. The don't like voltage surges.

[David T]

Yeah - especially the ECUs. The don't like voltage surges.

Light bulbs too. They may not die the day you do that but you took a LOT of life out of them and many will soon blow. The battery acts like a "sink" absorbing surges and holding the voltage steady. Without it the alternator can put out over 100 volts! I have seen a lot of mechanics doing that "test". NEVER try that on newer cars chock full of computers. It can be VERY expensive!

[Parzval]

Light bulbs too. They may not die the day you do that but you took a LOT of life out of them and many will soon blow. The battery acts like a "sink" absorbing surges and holding the voltage steady. Without it the alternator can put out over 100 volts! I have seen a lot of mechanics doing that "test". NEVER try that on newer cars chock full of computers. It can be VERY expensive!

Ok then! Let me delete or modify that post so nobody does that. It's been some time since I've done that under the advice of a 70's repair manual for my beetle... which had pretty much none of these newfangly things like... ECUs and LEDs and... heat.


(ok..... I guess I can't mod that post... never tried that before.)

[uhhair]

Ok so it turns out whatever is going on is not my battery. After I installed the new battery the next day the problem returned. Last night I also replaced the alternator and I am still having the same issue with the car. I am not getting any current to the battery from the alternator/rest of the car (at least it doesn't appear that I am). Anyone have any idea what I can chase down next to try and resolve this issue? Is there a way I can test the volts coming right off the alternator itself so I can at least rule that out? My guess is that there has to be a bad electrical connection somewhere, I just have no idea where to even start now.

[dn010]

Go back to post #2, second paragraph. Did you do that?

[hmcelraft]

Sounds to me like one of the main cables from the battery to the car is "open". I say that because I assumed when you "jumped" the start you connected the ground directly to the engine and the positive to the post in the engine compartment. That by-passed some major wiring to the battery.

Most likely the ground connection at the trailing arm bolt. Could be the ground strap from the frame to the engine - maybe the grounding harness behind the interior rear panel. Some major wiring junction is corroded, loose or broke I suspect.

[DMCMW Dave]

Take a common jumper cable and connect it to the negative terminal of the battery. Clamp the other end to the engine block. See if that makes any difference, then go clean your grounds.

[uhhair]

I did try the jumper cable to a ground trick, didn't make a difference. However, if my battery wasn't grounding right the car wouldn't work at all, right? I can still start the car and everything runs, but it is running off the battery not the alternator. Also, I did not check the previous suggestion but I will tonight when I get home. I do believe the battery light is working correctly though. Are there any electrical connections inside the engine bay that might be causing this issue? Maybe back by where all those large plugs connect to everything inside the car (I apologize, I forget the proper name of them).

[dn010]

I had all kinds of problems with the original cluster of brown wires (I am pretty sure they were brown) that hook to the main post on back of the alternator and runs to the bulkhead connection area by the coil. I cut open my wiring harness and removed the whole 3 brown wire strand, and instead, hooked up a battery cable from the alternator directly to the bulkhead connection. I had to shrink wrap the ends a bit because there is much more metal exposed on a battery cable than those connectors on the brown wires. This, and new ground cables /bus solved a lot of my electric issues.

Also - you can try this without doing anything with the brown wires except disconnecting them and taping the ends so they don't touch anything. I ran the battery cable along the pontoon to the bulkhead connection - still like that to this day too. Once I knew it worked and all was well, I cut the brown wires down to the harness and taped them. At a later date when I had the harness out, that is when I cut the harness open and removed the remains of the brown wires.

[uhhair]

Would you happen to have any pictures of what you are talking about? I'm not so good with the electrical side of things at all, and have no idea where those wires go other than the connection on the back of the alternator. If I can see what I need to do I think I can manage, I'm just not sure where anything you mentioned is.

[dn010]

Would you happen to have any pictures of what you are talking about? I'm not so good with the electrical side of things at all, and have no idea where those wires go other than the connection on the back of the alternator. If I can see what I need to do I think I can manage, I'm just not sure where anything you mentioned is.

Sure! I do not have a photo handy at this time, but I will post one tonight of how mine is currently unless someone beats me to it. It's pretty easy though, if you have a cover over your coil/bulk head connections on the passenger side/rear portion nearest your rear windscreen in the engine bay, take it off and look for the cluster of brown wires attached to a post, and that's the wiring I'm talking about. I'll post a photos in a few hours.

[kings1527]

Would you happen to have any pictures of what you are talking about? I'm not so good with the electrical side of things at all, and have no idea where those wires go other than the connection on the back of the alternator. If I can see what I need to do I think I can manage, I'm just not sure where anything you mentioned is.

I have one handy...

33513

[dn010]

Need one of the bulkhead end.

[kings1527]

Need one of the bulkhead end.

The best I have

335163351533514

[uhhair]

Hey thanks, those should help a lot. The second series of pictures looks like it is on the inside of the car though, not the outside in the engine bay?

[kings1527]

Hey thanks, those should help a lot. The second series of pictures looks like it is on the inside of the car though, not the outside in the engine bay?

Correct. Just behind the rear speaker. In the back corner on the passenger's side.

[dn010]

He needs one of the engine bay bulkhead side, where the brown wires connect by the coil in the engine bay.

[uhhair]

Excellent, so I will need to remove that panel the speaker is under to get to it? Or is there a way I can get to it without taking that panel off? I only ask because I know those panels can be a bitch to glue back down where they wrap on the outside with the door seals.

[Jonathan]

Excellent, so I will need to remove that panel the speaker is under to get to it? Or is there a way I can get to it without taking that panel off? I only ask because I know those panels can be a bitch to glue back down where they wrap on the outside with the door seals.

You don't need to take that interior rear panel off to get at the bulkhead connections from the inside of the car. You only need to take out the rear carpeted backing board (the vertical one). The access to those connections is crap as it is, but going through the hassle of taking that panel off with the door seals you mentioned won't help.

See here in this photo. You can say the thick jumble of wires with the black wrap on it and the one ground there right beside it towards the centreline of the car.

33517

Here is a photo of the rear bulkhead connections in the engine bay with the cover removed.

33518

And the schematic for those connections:

33519

Please confirm your battery warning light in the dash is coming on when turning the ignition key to accessories before you get too much further ahead of yourself.

[David T]

You don't need to take that interior rear panel off to get at the bulkhead connections from the inside of the car. You only need to take out the rear carpeted backing board (the vertical one). The access to those connections is crap as it is, but going through the hassle of taking that panel off with the door seals you mentioned won't help.

See here in this photo. You can say the thick jumble of wires with the black wrap on it and the one ground there right beside it towards the centreline of the car.

33517

Here is a photo of the rear bulkhead connections in the engine bay with the cover removed.

33518

And the schematic for those connections:

33519

Please confirm your battery warning light in the dash is coming on when turning the ignition key to accessories before you get too much further ahead of yourself.

Take voltage readings on the battery with the motor off and with the motor running. Tell us what you get.

[dmruschell]

Some things in general to consider:

I have a 72 Buick with a ~6 month old battery that went to be painted. The painting took about 5 months, and the car wasn't run much, if at all. Before I picked it up, the battery needed to be replaced because it was shot. I've since bought float chargers ($20 at Harbor Freight and work great) for all of my cars that aren't driven on a regular basis. The batteries are always fully charged, the cars start up with more "pep," and the voltage readings are more stable. I'm also not straining the alternators as much since the alternators just have to maintain the battery instead of recharging it. The $20 HF Deluxe chargers have contacts that can be permanently installed at the jump points and then a connector along the wire is plugged and unplugged to make connecting the charger less of a hassle.

That same Buick started having electrical problems after an engine swap. After correcting some wiring issues, the voltage would still be very low at idle. It had a 12SI self-regulated alternator in it, but since the idle voltage was low, I decided to upgrade it to a CS130 style alternator, which is the same style as most alternators that are used on the DeLoreans nowadays. The first alternator died on the second drive. The second was DOA. I bought the third one from another auto parts store that must have used a more robust voltage regulator because it didn't die, but the idle voltage was still around 10 volts, and running volts was around 11-12.5, though it would sporadically jump up to 14 where it should be. It turns out the battery ground cable was corroded and not always making good contact with the battery. The increased load on the alternator killed the voltage regulator in 2 of the alternators fairly quickly (though my spare 10SI that I used as a band-aid to be able to drive the car handled it like a champ). The point is: check your grounds, as they can fry your alternator and cause some other electrical gremlins if they're not making good contact.

[opethmike]

Derrin is a horrible human being.

[Jonathan]

Derrin is a horrible human being.

Did the OP get this problem resolved or am I not realizing there is some inside joke to this?

[dmruschell]

Derrin is a horrible human being.

Yeesh, Mike woke up on the wrong side of the bed today. Crabby crabby.

:P