I drove my slash through some water and now there is water and sand in the case by the way the battery is a 4200 nimh series 4
Don't worry about it. It won't hurt it at all.
"I like rc cars"....."WHAT? YOU'RE KIDDING!"
I have the same problem, I got condensation/water in the plastic wrap of my 7 cell hump pack. I know upbasher said don't worry about it but is there any issue or risk in charging the battery with this moisture in there?