Battery Problem question?
First I am new to RC Boats and new to this site.I am just getting back into RC Cars also after being out of the hobby for a long time.I just got an Aqua Craft Brush less that I run 2 NIMH in.The other day after I was done running it the battery had become really hot and split the shrink wrap on it.Are these batteries old to were they are no longer good? I bought the whole setup used.
Whatever the battery, confirm output capacity
What ever you are running (even though brushless has way more amp draw capacity, ususaly) make sure your battery can put out the power that is being demanded by your ESC and your motor setup.
Once your battery is pushed past its discharge limit, it will heat up. The longer and harder you push it, the faster it heats up and the hotter it will get. Eventually, the heat will build up internal resistance in the batt. and you will melt components. Heat inversely effects conductivity.
Other issues that can cause heat in the battery department are poor connection in your electrical components, small gauge wires, corrosion, and back or inadequate battery to ESC connectors, etc. Maybe convert to dean's plugs if you are running lesser grade plugs.
So check on the discharge capacity of your NIMH's. They are most likely not up to the task of the brushless.
hope this helps.
Sean