Over 50 years of working on cars, and never saw this untill last year. Now find it again. Friend asked me to hook up the ign on a non slant boat engine to see if it would run. Got the ign done, and went to start it. Starter would "throw out" and spin, but would not turn engine. After checking for a bad bendix (was OK), put a volt meter on the battery. Positive terminal was negative, and negative terminal was positive. This was causing the starter to spin backwards.

http://www.slantsix.org/forum/viewtopic ... ity#279690

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Is it possible that the boat is actually positive ground? I know there were quite a few older cars that were, but don't know about boats.

OH....wait.....I just re-read the post. You're saying the BATTERY polarity is somehow reversed? You suppose somebody hooked it up backwards at one time, and that's the way it got charged?

Roger

Weird.

Roger, the way pretty much all batteries are made, there is no way in the universe to "reverse charge" them.

Lou

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Home of Slant6-powered fun machines since 1988

Lou, the first time I ran into this, I called Johnson Controls. They were the maker of the first battery. Their tech guy told me if the battery is completely discharged, and then connected to a charger "backwards" it can happen. That battery was bought from a salvage yard. I was also told that I could most likely not do the same thing to bring it back to normal. He was correct, I could not.

The battery that we just ran into, had been on the charger for several days, so I am assuming it was completely discharged, also. I cannot verify whether is was connected to thecharger properly, or not.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Hmm. OK, I was thinking about other types of rechargable batteries. My apologies for the faulty statement earlier. There is a nice page on the "lead acid battery" on Wikipedia. Thanks for bringing this up, Charlie!

For a car battery (lead-acid), in theory you could reverse charge it once it was charged in the "normal" direction, but I'm pretty sure it would not be servicable. It would give you 12V reversed, but I believe the electrodes would be permanently damaged by the forward and then reverse charging processes. So, it would just give you a very small amount of power and stored charge, so wouldn't be able to drive a significant load for any amount of time.

In order to reverse charge it, it would have to be close to fully discharged before putting the charger leads on reversed. If it were charged normally, charging in reverse would make a lot of heat and likely damage the battery even more severely (and maybe you).

The reason you can reverse charge it at all is that both electrodes can be converted to (and start as) pure lead, and become PbO2 and PbSO4 at different points in the charge/discharge cycle.

Best,

Lou

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Home of Slant6-powered fun machines since 1988

That is just about exactly what Johnson Contols rep told me. If you screw it up, don't try to unscrew it. It could be hadzardous to both person and property.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I don't know all the details of your friend's boat, but 2 things come to mind that strike me as being a bit "off". First is if battery polarity is reversed, the alternator diodes should've fried, burned up the wiring, etc.

The other point is that as I understand, the stock type starter can't spin backward unless you somehow assemble it wrong. Most older starters are "series-wound", ie. the stator/field coil feeds through the armature. So if you reverse electrical leads, both electro-magnets reverse polarity & the starter still spins the same as before.

Modern "mini" starters use a permanent magnet field, so they can spin backwards if power is reversed.

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63 Valiant Wagon
225 - 4 bbl

Since marine batteries have screw terminals on them, and only SOME manufacturers use a different size for the terminal posts, it is very possible for someone to hook it up wrong. I have not seen this condition, but I have seen several batteries with the same size (small) post.

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Chuck Rivers, Webmaster

Let me clarify, a couple of things. The engine is a 350 chevy mercruiser inboard. It was purchased used, condition unknown. It was in the back of a pickup truck, when I worked on it. My friend just wanted to see if it would crank over, and maybe fire. Just hooked a Car battery positive terminal to the starter cable. The battery was one that was just sitting in his garage. The bat neg terminal to the block. A clip lead from the large stud on the starter to the coil positive (after we corrected the battery problem).
PS: the engine did crank and run, after the battery was swapped out.

WRC, This engine did not have the alternator wired up. My previous experiance was with a jeep, and it did take out the alternator diodes, and partially melted the alt "hot" wire. On both ocassions the starter did spin in reverse, and the started pinion did engage the flywheel, but the starter just freewheeled.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Very interesting thread. For some reason, my Miata battery has both leads in black. It would be very easy to hook a battery charger up backwards, especially since the battery is tucked back under the fender in the trunk. And to make things worse, it is a tiny little thing that will run down pretty fast if you leave the dome light on. I have done it may times. And I have put the charger on it multiple times.

This thread has put some serious caution in me on the subject now.

Sam

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