battery - reverse hook up

[colonel33]

what will happen if i hook up my battery in a reverse manner?

i've taken the battery out and when i to put it back in it doesn't seem right. I have a 92 911 C2, looking at the battey cables I would assume the one furthest from the front of the car is the positive and the closest is the negative but when i put the battery in the posts line up the other way.

thanks for helping this idiot (me!)

[charlesbahn]

I definetely would not hook it up backwards. Delicate electrical devices generally do not like reverse current flow (reverse polarity). Some things will work OK, others will blow. I don't know for sure if all the Porsche components are the former or the latter, but it could be an expensive experiment. Maybe others on the board will know for sure.

[Formerly Steve Wilkinson]

Is it not possible in a '92 C2 to tell which of the battery cables goes to ground? It will, of course, be cable that is attached to some part of the chassis--the cable that in effect "dead-ends." That cable attaches to the negative post (marked with a - ) of the battery, and the other cable attaches to the positive post (marked with a + ). Definitely do not hook up the battery backward, even just as an experiment. You will do considerable electrical-system damage.

Stephan

[rbcsaver]

DO NOT hook up your battery with reverse polarity.

Your car should have one red cable and one black. Red is positive, Black is negative. The 2 battery poles are usually different sizes too. The positive pole is marked with a (+) and the neg. (-). The ground cable connects to the car body. Also use anti-corrosion battery preps, available at your local automitive store.
regards,
Steve

[david914]

STOP!!! Don't assume anything! If you connect the battery backwards you're likely to do all sorts of damage to your car's electronics, particularly if you turn the ignition key on. The negative cable should be fairly easy to identify. It should be bolted directly to the car's chassis close to the battery. If you can't find it that way, use a meter to check for continuity from each cable to a known ground on the chassis. The cable that shows the lowest ohm reading will be your negative.

P.S. Besides, if you connect the battery up backwards, your engine will turn the wrong way and you'll wind up with 1 forward gear and 5 reverse! (just kidding, of course)

[Brent 930]

Don't hook it up backwards and get an ohm meter and check the terminals. The one that is dead short to the chassis is your neg.

[Erakad]

All is true. I had a 77 Honda CVCC years ago. The battery died and I had a friend jump it. I dutifully noted positive/negative terminals on my end, noted red and black cables on his end and hooked up the jumper cables. He turned on his car and phoomph (yes that's a technical term) smoke on my end. WTF! I checked my connections...OK, but his...oh yes, he had put the battery cables (when replaced) on backwards! Ouch...but not the end of the world, I blew the fusible link (not sure where this is on a 92 911) and once replaced all was well. Warning: Big difference in the electronics between a 92 Porsche and a 77 Honda. Don't do what I did....check the cables very, very carefully!

Good luck

[chrispizza]

colonel33 - Last I checked batteries were rectangle. If stuff doesn't reach you might think about turning it 180 degrees, or if you like the backward look, buy an Austin Healy 3000. They have a pos ground. Otherwise, set it up correctly.

[raceman]

the ground(-) cable is easy to follow and confirm it`s secured to the chassis.Spend a few minutes

[Joe Bob]

SMOKE.....buy new electrical stuff.....

Ground is attached to the body....most likely a BLACK cable....

[TimT]

the pos and neg are also different diameters...

You kinda have to WORK to put them on wrong.

[vash]

it would be exactly like a welder, at least for a few seconds.

[304065]

A very bright, expensive welder. Followed by replacement, of Alternator, DME, CCU, Spoiler Control Unit, Alarm. . .

[SpeedracerIndy]

Originally posted by TimT
the pos and neg are also different diameters...

You kinda have to WORK to put them on wrong.

I have seen it done, and it ain't pretty. This is a post I made in another thread a long time ago:

I had a friend of mine try to replace a battery in his 86 Jeep CJ7. He used a suitable wrench to replace the battery cables. But, when he put the cables on the battery he could not figure out why one cable would not fit over one of the terminals on the new battery. Most people would step back and say, what am I doing wrong here, this shoud fit easily. But what does he do??? gets a HAMMER out and pounds the cable onto the new battery!!!!! Then the other cable clamp which is now way to big for the other battery terminal had to be bent so that it would make contact with the terminal. Now, before you go and say, well some cars are postitive ground, blah, blah, blah... The cable for the positive terminal was a RED cable, and the terminal on the battery was RED. I asked him if he noticed that there was a red cable, and a red terminal and he said yes but he didn't make the connection (no pun intended). Anyway, he left the battery connected backwards overnight and came out the next morning to various relays in the engine bay clicking spontaneously. Now, if you hook up the battery to the jeep (correctly) it literally starts on its own!