Smokin hot battery terminal?

[petemac]

The symptom starts with weak cranking power then the battery dies from heat exhaustion. Followed by extreme heat coming off the positive terminal/wire. We just had the Mercruiser Mech. look her over but could get it to repeat while in the shop. He checked grounds and sold us a bigger battery. My partner had her at Lake Meade and she did it again. Once the battery cool off the problem disappears but it isn't nice to have a BBQ from the battery. ANY IDEAS of the WTF this is?

[Bill_AirJunky]

Bad connections? Maybe the connection at the starter. Or maybe from the cable to the connector itself. I've had those bolt on connectors go south on me a couple of times. They get loaded up with corrosion inside the sheath & it was tough to see till I removed the connector from the battery & cable.

[uk_exile]

there's high resistance at the battery terminal. I'd cut the terminal off the cable and refit a new terminal.

Edited June 6, 2009 by uk_exile

[ucontrol]

there's high resistance at the battery terminal. I'd cut the terminal aff the cable and refit a new terminal.

I had a similar problem in the second year of my boat. When I tried to start the boat, the battey terminal would get very hot and if I kept trying, the terminal would actually smoke. All the starter would do is click. I checked all the connections and they were all good. It turned out that the battery had an internal short and it was exchanged under the warranty. It was good the rest of the season. The next year the new battery also went bad. I bought a new one at an auto parts store and since then there has been no problem. It has been 3 years now. I believe the factory batteries are only good for 1 or 2 seasons. Perhaps this is your problem?

[Pistol Pete]

there's high resistance at the battery terminal. I'd cut the terminal aff the cable and refit a new terminal.

Agreed.

[petemac]

Thanks all, took her back to the shop for my "mystery diagnosis" the battery terminal sounds plausible.

[WakingMeHappy]

I would not put her back in the water at all until this is fixed. If that battery gets hot enough it could easily explode.

[pup]

With a good battery, a bad starter will cause the terminal & cable to heat up due to high amperage. During cranking, voltage will be low at the starter & battery.

A bad connection or high resistance due to corrosion will show up as voltage much lower at the starter than the battery during cranking.