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Old 03-04-2016, 00:38   #1
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Battery terminal melted?

I have newish twin 150 hp Iveco engines in a 1967 classic Hagg 36 MY. Last week I had little life in my 4 batteries wired for 24 volts. On close examination the positive terminal on one battery was found to be "melted" and the battery has been replaced. I have asked my engineer (French) to find out if this was a battery defect or a fault in the charging system. The batteries are 2 years old and kept on a voltage sensitive charger when not in use. Any ideas why this has happened? I am worried in case it happens again.

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Old 03-04-2016, 00:48   #2
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Re: Battery terminal melted?

could be caused by high resistance in the terminal clamp ,either dirty or corroded wire .
corroded swage fitting,loose connection ,dirty terminal etc

you will probably find their was lots of life left in your batteries,just a bad connection,with resulting meltdown when you tried to start the engine,ie draw a high amp load via a bad connection,resulting in heat build up.

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Old 03-04-2016, 03:19   #3
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Re: Battery terminal melted?

Greetings and welcome aboard the CF, kyanos.
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Old 03-04-2016, 04:25   #4
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Re: Battery terminal melted?

Another good case for fuse protection of the positive conductor.
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Old 03-04-2016, 18:39   #5
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Re: Battery terminal melted?

+1 for Atoll. I've seen that here, once. (Not twice!!)
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Old 03-04-2016, 19:06   #6
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Re: Battery terminal melted?

Originally Posted by boatpoker View Post
Another good case for fuse protection of the positive conductor.
If the heating was due to a high resistance connection at the terminal, as has been suggested, no overcurrent would have been involved, and a fuse would not have changed the outcome.

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Old 03-04-2016, 19:17   #7
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Re: Battery terminal melted?

Dirty connection. My machine operators would come in and say they heard a buzz in the battery box and no start.

Opened it up and a post was melted. This was more common in 24 volt systems.
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Old 04-04-2016, 13:30   #8
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Re: Battery terminal melted?

I still have a set of post molds for replacing post when this happens. I would clean the surface screw a short screw part way into what is left of the old post and melt lead into the mold. A lot of times I used the battery voltage with a jumper cable and a carbon rod to melt the lead in the mold to be sure the old and new bonded.

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Old 04-04-2016, 13:34   #9
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Re: Battery terminal melted?

When I was looking for a bad connection in the wiring between my battery and starter, I was able to find it by feeling for the hot terminal. Do this with caution, though!
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Old 05-04-2016, 09:21   #10
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Re: Battery terminal melted?

While a dirty or corroded terminal could be the cause, most likely it was a loose terminal. If the terminal got that hot the cable probably needs to be replaced for some distance from the melted terminal, that is, don't put a new terminal on the old cable end. The battery or a charging device or a heavy use of the battery would not cause a terminal to melt. The battery would go first if the battery got that hot - expand and burst, explode, etc.

Also, make sure the terminal always is put the first thing down at the battery with any washers on top of the terminal. Stainless steel washers are not good conductors of electricity and can get very hot if between the terminal and the battery. Stainless steel is okay for this use - on top.
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Old 05-04-2016, 20:11   #11
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Re: Battery terminal melted?

I have had two experiences in the last few years with stainless steel washers causing very high resistances under high current loads.

The first was with an anchor winch motor which persistently melted the solder from the field coil terminal on the up side. The motor was second hand and the original chrome plated brass washers and the brass nut on the terminal had been replaced with SS washers and an SS nut.

The second was with new cranking batteries which came with washers and nuts. When the battery voltage was down at all these would not crank the engine. I removed the SS washers and replaced the nuts with brass ones and have not had a problem since.

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