Wondering if there's any 12v specialists. I have a deep cycle leisure battery 110ah for my motor. The positive terminal has been getting really hot on discharge, as the motor is running. The negative terminal is fine. It doesn't seem to be doing any immediate damage, and has done it quite a few times over a few months. so... does anyone know what could be causing this, and would it be slowing damaging it? I have re-wired the connections and this changed nothing. I use the car battery type connectors and tighten them with a little adjustable, as i find it's much more efficient than crappy crocodiles.
many thanks for any help

chris

Sounds like a bad connection, despite your car terminals idea, high resistance results in heat.Check they are not corroded or oxidised.Same goes for the battery terminals.

As wee Jimmy says, best to keep the terminals and connections absolutely clean.
Gently scrape the terminals with a knife until you get nice shiny lead, then smear with a light coating of vaseline. Clean the car connections with first a scrape with the knife, then rub them up with with sandpaper, until they are like new. Put them on the battery, make sure that the wires are shiny bright as well. I am assuming that you have to pack the wire up with copper to make the connection tight, if not you really should do this, but make sure that it is clean as well.

You willl always get a certain amount of heat off the pos. terminal anyway, as long as you can touch it and it merely feels warm, you will have a good connection. I agree entirely with the croc. clips being ****, but you could also buy ones that are a lot stronger than the rubbish used on the motor. Croc. clips with teeth are the better optiion, if you think that the car connectors are not doing the job, although they should be fine.

I fitted heavy crocs. on my own engine, and it worked for quite a while before I sold it.

Sam

I have come across this a number of times on electrically powered plant/machinery.

For the connections I'd recommend using an "Anderson Plug" - cheap, safe, easy to self wire/install and the act of pushing on and pulling off at the time of each use helps to keep the connecting surfaces clean and fit for duty.





Aidan

Thanks for the responses guys. I thought it may have been resistance but i'm not an expert. I don't pack the wire up with copper, i just trim the plastic back and double the wire back on itself, this usually packs it up quite well. I go over the terminals with a stiff wire brush every couple of weeks. I don't do it with the connectiors though. They look fine from the outside but the inside of them may be slightly corroded, so i'll give it a go. As long as there's no damage being done, that's the main thing. I'll give the anderson plug a go too, if the problem persists.

Might be an English to American translation problem, but I don't follow.

At the point where the wire attaches to the battery terminals, how exactly is it attached?

My transom mount motors have always worked with alligator clips that just clamp on to the terminals with spring tension. HOWEVER, I have seen one of these clamps on someone else's motor that was melted because the wire became frayed right where it connected to the terminal. This fraying resulted in high resistance and heated the terminal to the point where the rubber coating insulator started to melt.

I suspect that this or similar connection issue between whatever means you're using to connect the motor wire to the battery could well be to blame.

Grouse

Sir Grouse, it's a standard connection that you'd find on a car battery, there's a nut which i tighten up when i connect it. I fold the wire back on itself, to double the thickness, for a better connection. The greasy stuff is, well, grease! Just to stop the wire rusting.
terminal picture by chrisontilt - Photobucket

OK, I'm with you and that certainly looks like it should be a solid connection. I was wondering if maybe your wire was breaking inside the insulation right at the flex point there the wire enters the connector, but it sounds like you've redone the connection so I'd think that possibility would have been eliminated.

I guess I'm out of ideas, maybe someone else will chime in.

Grouse

A heavier gauge cable might help reduce the problem.

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Not an expert but by any chance are the nuts that hold the cable in pressing down too tightly and squashing the cable. Just my thoughts.

Flyinghigh