NEED SERIOUS HELP!!

I have a 1998 mercury 200 hp motor, last weekend on the lake when I put the boat in the water the battery was dead which is very rare. So we switch the batteries just to start the motor then put the other back on. We proceed to go to our spot then I noticed smoke coming from the motor cap. I pulled the motor cap off, all the wires from the wire harness was glowing orange and nothing would work anymore. The bilge, trim, air aiader, and live well pump stopped.does anyone know what might have happened or if there is a way to fix it a new wire harness or somethong. Thank you

sounds like the battery wires were hooked up backwards or the stator went south

My mechanic told me that you can't crank a boat and switch batteries with it running like a car. He told me that I'd fry the electronics. I have no reason to question him and judging by your experience, it must be true. I think you'll need to go see a mechanic and how much damage is done.

I've run into this trouble before with both automotive and marine systems. Many will disagree, but here it is; your alternator, whether car or boat, CAN NOT charge a completely dead or bad battery. It will, however, work itself to death trying to. The charging system was designed to top off a serviceable battery, putting back the relatively small amount of power that was used to start the engine, if the battery is completely dead, or bad, say with shorted plates, it will quickly overload and burn or short itself out. What you describe fits this scenario perfectly.

Hope you can get going without too much expense.

Start looking for a blown 200 to use as a parts motor.

Disconnecting the battery from a running outboard is a big no-no! More modern outboard manuals even warn against adding a jump battery then removing it while the engine is running - they don't want the change in load.

Leaving the replacement battery in place for the day would have been the right thing to do. Note for the future....

Thank yall I think Im just going to put it in the shop and let them do it