Hot battery terminal and solenoid

[Dom08]

Hey guys
We ran into a problem with my 03 outback. The terminals on the battery (dual battery) have gotten extremely hot to the point of remelting the soldier on the terminal connectors! We have also found the solenoid is running extremely hot. We have disconnected the aux battery. Our battery gauge shows 12-14 volts

We have ensured the bilge and blower are working.
Any tips?

[mmandley]

If your battery terminals are hot and melting things, then you have a short, and you might find it before its a Fire or the battery explodes.

Seriously....

Things can be warm to the touch, but never hot enough to melt things.

When you say Solenoid, are you referring to the starter solenoid? It can be warm and even slightly hot but since thats you main relay to tell the starter to engage, if its abnormally hot, its most likely failing internally.

[Dom08]

Sorry i should have been more specific
Its the battery isolator solenoid thats hot.
https://i.ebayimg.com/images/g/D~UAA...Wu-/s-l300.jpg


If we have a bad isolator solenoid could this csuse the battery to over charge hence reading up to 14 volts? Or a potential shorted battery?

[zabooda]

Either worn internal contacts or loose wire connections. Clean the wire connections and retighten. If it continues to heat up then replace the solenoid. RV stores have them for slightly more than a dime a dozen.

[web]

Sounds more like something is loose. Loose connections = hot connections. If your switch has copper points make sure they are not discolored, if so change it

[Dom08]

I went through and checked all connections and ohmed out the battery wires at .3ohms. The connections that hook up to the battery are discolored. Ill clean them and change those wires out along with the solenoid for the price of one



Thanks guys

[Dom08]

Quick question.
Is there anything that will stop the batteries from being charged from the altrrnator when they are fully charged? I'm thinking the battery may be shorted internally, maybe over charged?

[MLA]

Is that solenoid factory? Is it up the task in its rated amp capacity duty cycle or is it too light?

That solenoid will not cause an over charging of the battery(s) as it just controls the distribution to one back likely. The solenoid does not create the level of charger, or voltage if you will. The alternator controls the level of charger. However, that solenoid could allow one bank to be undrcharged.

Ohm on a large cable is not the best test for a bad connecting, poor terminal or bad cable. I would suggest a voltage drop test. Can be done with the same meter you used to ohm them. Much more telling then a single ohm reading.

Heat is typically a result of a loose connection or excessive current draw.

best advise, I would remove that solenoid and go with a much better auto combiner setup that IS properly rated for the loads.

[zabooda]

Is that solenoid factory? Is it up the task in its rated amp capacity duty cycle or is it too light?

That solenoid will not cause an over charging of the battery(s) as it just controls the distribution to one back likely. The solenoid does not create the level of charger, or voltage if you will. The alternator controls the level of charger. However, that solenoid could allow one bank to be undrcharged.

Ohm on a large cable is not the best test for a bad connecting, poor terminal or bad cable. I would suggest a voltage drop test. Can be done with the same meter you used to ohm them. Much more telling then a single ohm reading.

Heat is typically a result of a loose connection or excessive current draw.

best advise, I would remove that solenoid and go with a much better auto combiner setup that IS properly rated for the loads.

Those solenoids are rated between 50 and 80 amps and work well connecting two banks of batteries. They are used on motorhomes where the batteries are connected when the engine is running and then disconnected and the batteries are isolated when the engine is shut off. The application doesn't work so well when someone wants to switch batteries and that would require another solenoid as in motorhomes for backup starting. Another issue is the solenoid is not intrinsically safe so they can be a hazard in enclosed areas and require some continuous air flow. The failure points are the coil eventually failing, the contacts failing through repeated cycling or the contacts fusing due to excessive loads.

power for the coil

https://www.grainger.com/product/6C0...180801145508:s

[MLA]

Zabooda,

I am well aware of how the solenoid works and how its used in this application. This is why I suggest to remove them, for a much better setup using a auto-combining relay/voltage sensing relay.

There are places to use a heavy duty, continuous duty solenoid/relay in boats. Ive come across them before. Ive even used one in a work van, of mine, to charge a house battery used for an inverter for powering lights, laptop, printer and solder iron. However, using them in this scenario for battery bank isolation and combining, is less then ideal, compared to whats out there.

Is the relay in your link the exact model in the OP's boat, or just one grabbed off the net for an example?