I plugged the battery the wrong way!!! What now?

[farleyd]

Hi, an idiot (not me) put a BIG RED and a BIG BLACK wires. I had to unplug the battery, but when time was to replug it, i tought that the RED was hot and black not. Wrong!!! Results?

A puff of smoke when cable touched the pole which i took off instantly. The red generator light is permenantly on.

Have i fried the alternator?

Thanks for helping.

[304065]

You probably destroyed the battery and fried the alternator diodes.

[sammyg2]

You let the magic smoke out. Never, ever let the magic smoke out.
Sorry, I couldn't help myself.

I agree with what was posted above, except the battery is tough and may have survived.
Prolly have to replace the diodes in the alternator but let me ask this question, is this thing externally regulated? Is it possible the external voltage regulator took the hit?

[farleyd]

Hi guys, yes it is externally regulated, as all 1978 are. And the car is still cranking fine, so the battery (Optima) should be good.

Why the hell is that negative cable red??????

So, how to test if its the regulator OR the alternator.

[farleyd]

I might add that my generator light is dimming depending which RPM the engine goes.

Idle = full red
4K RPM = mid-red

But it never goes out.

Does that help diagnosing alternator OR regulator?

Thanks!

[Early_S_Man]

Sabin,

You probably blew a couple of main rectifier diodes with that giant spark ... maybe more, but it should be repairable at a local motor/alternator repair shop.

The red cable was probably a replacement aftermarket ground cable ... but, as to why someone would pick red over black, brain fade would be the obvious excuse ... or maybe just lack of good judgement!

[farleyd]

Hi Warren, any change that the voltage regulator blew also OR that it contained the damage to itself?

As i said, the red light is dimming vs RPM. Does that mean something?

Also, does ANY alternator shop could fix a Bosch alternator?

Thanks!

[keagy]

I have a related question. Is it possible for a car to continue running with the negative cable disconnected? I swear my ground came loose while the engine was running. The engine did not stop and the only indication was a wild RPM gauge. Does this make sense? Don’t many cutoff switches disconnect the ground wire to make a car inoperable?

[filou]

Can you start the engine ???? If you can start engine, check voltage BEFORE you start at the battery. it's best if you use digital voltmeter.
once engine running, Check your voltage again. If is higher at battery before engine was running, your alternator is OK.
According to the symptoms, it looks that you fried one or more capacitors more likely to located inside voltage regulator.
To make sure your alternator is not dommaged, disconnect it from the car electrical circuit all together (mark wires before you do so) before you start the car. Once the engine is running, check voltage out of the alternator. If you have no voltage at all from alternator, i am afraid it is gone. Basically, the only elements sensible to reserve voltage are diodes
and capacitors. Even diodes can survive reverse voltage sometimes.
If you could remenber the location from where the smoke came out, it may help to look in the right direction.
Let us know.
Truly, Phil.

[filou]

regarding, Keagy question: well for engine to run you need sparks to fire the mixture air + fuel. If your battery is disconnected, from where do you think the juice is coming from ???
You all guessed it right: form the generator/alternator (while engine running)
Truly, Phil.

[keagy]

Phil, for some reason I thought if you remove the negative to the battery while the car was running the alternator would blow. I guess not. Or at least I got away with it once. These cars can take some abuse.

Keagy

[farleyd]

Me again. I put an analog tester, not an automotive one tought, on the battery. On the DCV scale set to 50 sensitivity, i have a steady reading around 140-150 ma. Same before cranking AND engine running.

Does it mean that the system is charging? Anyhow...

OH! And the smoke came from the battery pole, and not much i might add.

And yes the car is cranking fine!

[filou]

If you put your meter on DCV, then you should read the Voltage range in Volts. Anyway, For a battery to charge the output of alt/generator HAS TO BE GREATER that battery at rest. If you don't have that condition, battery will not charge. Can you borrow a digital one ?
So the engine is running ???? Do the same test, disconnect the battery briefly and see if you still have a voltage reading at the wires going to battery (not the battery itself). You are trying to found out if the Alt/generator is giving you a output voltage.
Truly Phil.

[RoninLB]

Originally posted by keagy
Phil, for some reason I thought if you remove the negative to the battery while the car was running the alternator would blow. I guess not. Or at least I got away with it once. These cars can take some abuse.

Sometimes,
You can disconnect the ground at 3k rpms and the engine will still run. It'll probably shut down at idle.
You can survive the disconnected ground.

[Gunter]

Do not disconnect the battery with engine running!!!!!!Leave the battery cables connected. Before start, test the battery across the terminals with a DCV meter for 12V. Start engine. Now the meter should read about 13.5V across the terminals. If not, there is damage to the alternator and your battery will drain. A repair shop can test at your regulator for more details. Since the terminals are a different size (diameter), how was it possible to connect the wrong cable?

[farleyd]

Since the terminals are a different size (diameter), how was it possible to connect the wrong cable?

How can i possibly answer that one without feeling like an absolute idiot...

BECAUSE THE DAMN NEGATIVE WIRE WAS RED!!!!!

[on-ramp]

Originally posted by Early_S_Man


You probably blew a couple of main rectifier diodes with that giant spark ...

man, that sounds kinky

[Gunter]

At the worse scenario, the alternator comes out. Search this board for details on how to remove it. Phone around for the best price on a rebuild with new bearings, etc. You have a choice on keeping the external regulator but most likely they will recommend an internal one. When you put the right neg. cable in, clean all the rust from where it connects to the body and use a di-electric grease (or Vaseline) on all electrical connections. I use it on any connection like the 14 pin, or the 6 pin injection plug. At least you have a rebuild alternator. Cheers.