Reversing Battery Polarity

[VWGirl]

So I moved my bus last night to my new house, but my new battery was dead so I needed a jump. I recruited someone to help me jump start my bus. I hooked up my side and he hooked up his. Then I tried to start my bus. No go. He went to check my connections and then told me to try again. Viola! My bus started right up! Then he exclaimed that I had connected my terminals wrong on my end. Wha? He went on, yeah, you had the red cable on this black cable here instead of that red one in the back. You mean that copper ground wire in the back??!?? It was red, he said. *sigh* The art of explaining why the positive cable on a VW is black. Too late for this poor bus. :(

So my bus was running. I just hoped and prayed that whatever he did didn't mess anything up, but what's this? I have a full tank of gas? Odd, because I don't remember filling the tank and can't find the receipt for it. Oh well, the gas gauge has never fooled me before. Let's get going.

So 50 miles pass and everything is fine. I think the gas gauge is dropping quite fast, but must have been a false reading from the jump start. Uh oh, my lights are flickering, there is an exit right here, let me pull off. Uh oh again, the dash lights come on and the bus is dead. I bet those battery terminals just aren't on tight enough. Sure enough, they aren't! Let's tighten those down. Now let's start her up again, eh? No go. I have a half tank? Maybe it needs another jump? Polarity correct this time. It's turning over fast, check. It's got spark, check. What about gas? I'm not laying in this mud to look at that clear filter I put in there last month. I'd rather spend the $5 on a gas can at the gas station sitting behind me. When i rock the bus there is no sloshing.

O.k., gas in the tank, check. Start her up, check! Whew, bus is on the road again. Now with a full tank, my gauge reads zero. The only other thing that seems to be affected is the cd player which will only light for a second and shut itself back off. I think it is fused, but with it doing that I think it might be toast. I don't really care about that as I don't listen to the radio anyway, I only turned it on to see if it was fried.

I was a tad concerned about the speed of the bus. It didn't seem to want to go faster than 60, which is unusual for this '78 stock FI (minus the EGR) bus. It likes to cruise at 70 and has been known to catch me off guard in the 85 mph range. Granted, I do have a bunch of stuff in it because I am moving, but I think my normal camping stuff weighs more than these boxes of VW toys and clothes. Is something else wrong? The ECU? The AFM? The fuel pump? Am I just imagining it? I did get it up to 70 going down a hill, but I should have been able to do so on a straightaway too.

I can't believe this happened to my poor bus. NO one touches my jumper cables ever again... on either end! In the mean time how do I track down these nutso electrical issues? Is there a way to tell whether my gas gauge in the tank is bad or if it's the one on the dash? Anyone have any spares?

[Manfred]

I was a tad concerned about the speed of the bus. It didn't seem to want to go faster than 60, which is unusual for this '78 stock FI (minus the EGR)

That's one of the first things I learned about the FI systems. You should never jump start them. Always charge the battery. I know it sucks. I wonder if there is any work-arounds? Sometimes you just can't do it.

[VWGirl]

To add to this, the entire 100-mile trip after the reverse-polarity jump was in the dark. I think the alternator is charging, but haven't actually gone out and checked today because it's been raining. A friend had someone do this to her bus once and it only fried the alternator. I think I am luckier with only my radio and gas gauge... if that's all it did.

[dtrumbo]

That's one of the first things I learned about the FI systems. You should never jump start them.

Do you have any reasoning behind this? I've jumped both of my FI VW's with no problems. Maybe I'm just lucky.

VWGirl, sorry to hear about the trouble. You might want to invest in one of these to eliminate any further confusion.


http://www.wolfsburgwest.com/cart/Detai ... 111971235C

I think you're on the right track, check the alternator first and then go from there. The fact it still starts and runs is encouraging. Just check everything one thing at a time.

[Manfred]

That's one of the first things I learned about the FI systems. You should never jump start them.

Do you have any reasoning behind this? I've jumped both of my FI VW's with no problems. Maybe I'm just lucky.

I found this on Ratwell's site. I think I also read it in Muir's book

Muir says not to jump start a fuel injection bus but the owner's manual makes no mention of it unless. I finally located some information in the Bosch L-Jet manual and in the safety instructions it clearly states: Never jump the battery to start the car."

We'll, you can do it safely. Just use the technique to jump modern FI cars:

1. Keep cars insulated from each other
2. Connect +ve jumper cable from good battery to dead battery
3. Connect -ve to the engine block or a good ground away from the battery to avoid sparks.
4. Start the car with the good battery
5. Run the car for 10 minutes at 2000 rpm to invigorate the dead battery
6. Start the car with the dead battery
7. Turn on the headlights and fan on the car with the dead battery
8. Remove -ve jumper cable from good battery, then dead battery and repeat with +ve

The whole point of this exercise is to keep the other car's alternator from potentially frying your electronics during the jump start. If the other car's VR puts out more voltages than the typical VW you should disconnect the positive cable from the dead battery during the invigorating period. Muir must have had a bad experience with a D-Jet FI VW he worked on once that was jump started by a GM truck with a 14.5V electrical system.

[dtrumbo]

I found this on Ratwell's site. I think I also read it in Muir's book

Muir says not to jump start a fuel injection bus but the owner's manual makes no mention of it unless. I finally located some information in the Bosch L-Jet manual and in the safety instructions it clearly states: Never jump the battery to start the car."

We'll, you can do it safely. Just use the technique to jump modern FI cars:

1. Keep cars insulated from each other
2. Connect +ve jumper cable from good battery to dead battery
3. Connect -ve to the engine block or a good ground away from the battery to avoid sparks.
4. Start the car with the good battery
5. Run the car for 10 minutes at 2000 rpm to invigorate the dead battery
6. Start the car with the dead battery
7. Turn on the headlights and fan on the car with the dead battery
8. Remove -ve jumper cable from good battery, then dead battery and repeat with +ve

The whole point of this exercise is to keep the other car's alternator from potentially frying your electronics during the jump start. If the other car's VR puts out more voltages than the typical VW you should disconnect the positive cable from the dead battery during the invigorating period. Muir must have had a bad experience with a D-Jet FI VW he worked on once that was jump started by a GM truck with a 14.5V electrical system.

Sorry, don't buy it. He's parroted a blanket statement with no supporting statements from the L-Jet manual and then followed it with a procedure on how to do the opposite. The procedure is sound except I don't get step 7. I also don't get how disconnecting the positive cable during the "invigorating" period will invigorate anything unless you find watching your watch, with absolutely nothing else happening for ten minutes invigorating. Further, on Mr. Atwell's site, the paragraph below the one you've quoted says that the alternator in a bus will put out somewhere between 13.8 and 14.2 volts. This is based on his actual experiments. Back up to the original paragraph, he hypothesizes that Mr. Muir might have been spooked by a 14.5 volt GM truck and a D-Jet system. 14.2 and 14.5 is close enough in my book. I think he's confusing the issue by speculating on too many things that have been heard and not proven. Richard Atwell has a fantastic site and it's a hugely valuable resource to us all. I just think he missed the mark on this topic and is causing more confusion than he clears up.

[Amskeptic]

I found this on Ratwell's site. I think I also read it in Muir's book

7. Turn on the headlights and fan on the car with the dead battery
The whole point of this exercise is to keep the other car's alternator from potentially frying your electronics during the jump start. If the other car's VR puts out more voltages than the typical VW you should disconnect the positive cable from the dead battery during the invigorating period.

Sorry, don't buy it. He's parroted a blanket statement with no supporting statements from the L-Jet manual and then followed it with a procedure on how to do the opposite. The procedure is sound except I don't get step 7. I also don't get how disconnecting the positive cable during the "invigorating" period will invigorate anything unless you find watching your watch, with absolutely nothing else happening for ten minutes invigorating. Further, on Mr. Atwell's site, the paragraph below the one you've quoted says that the alternator in a bus will put out somewhere between 13.8 and 14.2 volts. This is based on his actual experiments. Back up to the original paragraph, he hypothesizes that Mr. Muir might have been spooked by a 14.5 volt GM truck and a D-Jet system. 14.2 and 14.5 is close enough in my book. I think he's confusing the issue by speculating on too many things that have been heard and not proven. Richard Atwell has a fantastic site and it's a hugely valuable resource to us all. I just think he missed the mark on this topic and is causing more confusion than he clears up.

Actually, Ratwell's Step 7 came from me via a post on theSamba many years ago re: my BMW's owner's manual. You must apply a load to the electrical systems of any electronics-equipped car, donor or recipient, before disconnecting jumper cables! This prevents the alternators from spiking their respective electrical systems when the jumper load is suddenly stopped. That bit about invigorating batteries. . . I don't get.

[VWGirl]

That's one of the first things I learned about the FI systems. You should never jump start them.

Do you have any reasoning behind this? I've jumped both of my FI VW's with no problems. Maybe I'm just lucky.

VWGirl, sorry to hear about the trouble. You might want to invest in one of these to eliminate any further confusion.


http://www.wolfsburgwest.com/cart/Detai ... 111971235C

I think you're on the right track, check the alternator first and then go from there. The fact it still starts and runs is encouraging. Just check everything one thing at a time.

That is the copper ground wire that I was referring to as the ground wire on my bus. It's not in bad shape. The confusion lies in the stock black POSITIVE cable. Really I don't see the confusion anyway, just look at the battery, it is clearly labeled. *sigh*

As far as jump starting a fuel injected car. If you weren't supposed to do this, then I think the jumper cable companies would be going out of business these days.

[chitwnvw]

I jump start my FI bus daily. Well almost, before I, well actually Randy, figured out my DR ground issue. Never, ever had a problem.

[Hippie]

I jump start my FI bus daily. Well almost, before I, well actually Randy, figured out my DR ground issue. Never, ever had a problem.

Me too. Not the Bus, but I've jumped and been jumped in FI cars so many times over the years. Now maybe I'm not doing it right to play it safe, but no problems so far.

Might be a good idea for VWgirl to wrap some red electrical tape around the + cable to avoid confusion from roadside helpers since pretty much all modern-ish cars have a red cable.

[dtrumbo]

You must apply a load to the electrical systems of any electronics-equipped car, donor or recipient, before disconnecting jumper cables! This prevents the alternators from spiking their respective electrical systems when the jumper load is suddenly stopped.

This makes sense to some degree. I would think the dead battery on the recipient car would be plenty of load for the recipient alternator. Providing a buffer load for the donor car makes sense.

That is the copper ground wire that I was referring to as the ground wire on my bus...

Sorry, I misread your original post. I thought you said the ground wire was red when in fact the dolt "helping" you with your bus interpreted the copper strap as "red". Oh geez. You're plan is sound, the only person who touches your bus is you!

Have you made any progress testing the alternator?

[Manfred]

Please see page 131 under Safety Instructions item number 2.

http://www.vaglinks.com/Docs/VW/Misc/VW ... Manual.pdf

[Randy in Maine]

Gee my new battery + cable is red, just like it is supposed to be.

http://www.busdepot.com/details.jsp?par ... =111971225

I think someone put a generic black battery cable on there.

Is your alternator still charging?

[germansupplyscott]

Gee my new battery + cable is red, just like it is supposed to be.

Randy,

Original battery "+" cables are black, so they are "supposed" to be black. The battery ground is always uninsulated copper. All hell breaks loose as soon as people start changing the wire colours. That, coupled with how difficult it is to see the top of the battery when it's in the engine compartment. I think people around here regularly try to jump start their buses backwards - we're forever jump-starting cars here because it's so bloody cold.

Anyhow, red is good for the battery + cable, but technically on a VW, solid black is always a + wire. All the wires on terminal 15 (+ ignition switch) are solid black, for example.

[Amskeptic]

Gee my new battery + cable is red, just like it is supposed to be.

http://www.busdepot.com/details.jsp?par ... =111971225

I think someone put a generic black battery cable on there.

Is your alternator still charging?

Typical American generic positive is red (+).
Honest OEM German Positive is black (+).
Typical American generic negative is black (-).
Superior and correct German Negative is brown, like Earth (-).
Colin