Backwards Battery

[BigMacDave]

Hello all,

1978 124

So my brother hooked the battery up backwards. And of course now i have the lovely one click on the starter. I checked all the fuses under the dash and they are all good. Lights come on, yada yada. Before i take the alternator and starter out to go get tested, is there anything else (any fuse or such) i should check first? I might add, it started and ran fine a week ago, before we put a new battery in for the summer ;( The service manual doesn't mention fusible links or monster 40amp fuses so I'm not sure what to look at next.

I also noticed lots of places sell just the starter solenoid. Is that a smart route to go if it IS the starter, or should i just get a whole new one and be safe. I can't imagine the alternator would prevent starting, but i suppose that is a possibility as well.

Thank you as always,

David

[spider2081]

There is a good chance the alternator has been damaged. Connecting a battery to an alternator for only an instant can cause a diode in the alternator to short.
I would try: Disconnect the battery negative terminal
remove the wires from the alternators output post.
connect the wires together with a bolt and tape or insulate somehow.
reconnect the negative battery cable
Try and start the car.
If it starts chances are the alternator needs to be serviced.

Connecting the battery backwards usually does not damage a starter or solenoid.

[stuartrubin]

First, start with a new brother.

Just kidding, but I do have a question. Last summer when I put my winter-stored battery back in, I put it in backwards, too. Luckily, the battery was so dead, that even having been maintained electrically over the winter, it still had virtually no capacity. So, when I connected it (backwards) I got VERY faint sparks, but no damage.

In my trunk, the chassis connection cable (ground or negative) was RED in color. The positive side was BLACK. To me, even being colorblind, this was totally bassackwards! The PO worked mostly on MGs, which are wired "backwards" with the chassis being hot. (I know, physicists; this is just a matter of convention. But conventions matter!) So, maybe he used red on the chassis as a matter of habit (or just happen to have the right length cable in the wrong color).

So, as long as we're talking about backwards batteries, my question is: normally, is the chassis cable from the battery BLACK or RED? And the battery to the main electrical components in the hood RED or BLACK?

This is really just to satisfy me that I'm not an electrical idiot. And, BTW, right or wrong, I have since swapped the cables, so on my car, the chassis connection is black!

Thanks

Stuart

[Nanonevol]

To confuse the issue even more - I think my positive battery cable is green!

[stuartrubin]

To confuse the issue even more - I think my positive battery cable is green!

To confuse things EVEN worse, in retrospect, maybe the "red" wire was actually green. I really am pretty badly color blind, and red and green are the worst!

So, what are the correct colors? (I know, the electrons don't really care...)

[BigMacDave]

ok, just because i hate when I'm following a thread and people NEVER report a solid outcome.

Took the starter and alternator off and down to the local starter/alt/battery shop, thats all they do. The starter was fine, the alt was shot. I went ahead and purchased a new (referb) starter anyways, since mine looked like hell and it was only 75 bucks, and they are referbing my alt.

It will take a few days, and it will look "brand new" plus a 2 year warranty. bonus!

After i put them in next week, ill give you a final outcome. hopefully thats it. Also, before i hook the new alternator back up, I'm going to try the trick spider2081 suggested, just because it has me curious

Thank you all,

David

[DieselSpider]

So far all the positive main battery cables I've seen on the 124 Spiders are green which to someone used to working on Alternating Current 110 and 220 volt systems screams ground wire. Then neutral is white and hot is black on 110 volt systems while black is ground and white is hot on DC unless.....

Now I play it safe regardless of what I am working on checking polarity and verifying ground with a meter just in case some free thinker worked on it before I did. Better to be safe than that other thing.

[BigMacDave]

There is a good chance the alternator has been damaged. Connecting a battery to an alternator for only an instant can cause a diode in the alternator to short.
I would try: Disconnect the battery negative terminal
remove the wires from the alternators output post.
connect the wires together with a bolt and tape or insulate somehow.
reconnect the negative battery cable
Try and start the car.
If it starts chances are the alternator needs to be serviced.

Connecting the battery backwards usually does not damage a starter or solenoid.

Just wanted to verify, this in deed works

I tried it before i put the new alternator in, and it is a good test for sure. Thank you

[TJenkins]

I've been having issues with my solenoid going so in the process of tracking down the problem I purchased a new battery and yes connected it in reverse. Had the alternator rebuilt and the starter checked (it was fine). Put everything back together and nothing. Cleaned the connections at C6 (two bullet connectors by the alternator). At least now I was getting a click when I tried to start it. Pulled the hot wire going to the solenoid cleaned it and yes it started!! Started it a few times and worked perfect. Ok so renewed the license sticker, put insurance back on it and jumped in to take my first drive in almost two years and nothing but a 'click'. Checked all connections good. Voltage going to the solenoid 12v. Charged the battery thinking it could be a parasitic drain, still nothing. Really at a loss. One thing that I am thinking is to install a new ground cable from the motor to the body... grasping at straws. Or on second thought maybe a can of gas and a match.

Thomas