1998 force 75hp electrical issues. Please help

98 75ELPT . Ser # OE325369

Hello all gonna be a longish post to give recent history
Had an issue after running boat for about 6 miles motor started sputtering and running very rough and lost speed quickly boat stayed running very rough at idle but got me back to the ramp. I did some inspecting of wire connections etc all was well. thought maybe fuel related replaced/inspected fuel lines drained fuel and put fresh in all that is well. Next trip out I noticed my volt gauge was up around 18 volts wich got me concerned. I then had the battery for outboard, fish finder etc die on me after only 2 hours of trolling in the dark with finder and bow and stern light on. Obviously engine was not charging batt. Got motor jump started off of trolling battery and ran it for a few miles at WOT to attempt to charge it seemed to work as I shut motor off for a few mins and it fired right back up. checked battery and was very hot as was wire with fuse on positive side going to dash somewhere. So I decided the voltage regulator/rectifier was bad. Got a new one and installed it and this trip engine ran awesome again but the voltage reading on my finder was only at 11.5 and staedily dropped as day went on with use, didnt go up as it used to when engine speed increased also when trimming motor the tach would jump around with every push of trim button and volt gauge just staying right around 14.
Got boat on trailer and one of the yellow wires from stator to regulator had got hot enough to start to melt electical tape on connection and connectors from stator to top coil also looks burnt/black. But like I said the engine was running great but not charging and burning wires is not good obviously.

Im looking for some advice where to go from here. any help is very appreciated.
Thanks in advance.

Usually when a wire gets hot enough to melt, the connections, ground aren't right.
Check them.

What type battery? Deep Cycle? Regular starting battery?
Deep cycle's aren't recommended for regular use.

I am using a dual purpose deep cycle 27 series battery. I have checked all connections and re checked them and all is well with them. Never had an issue with anything for 2 plus years of use at least once and lots of 2 weekly fishing trips.

Ok as for the charging issue I had some time to look at it more this morning and with my handheld volt meter at the solenoid where the cables from battery attach to engine I am getting up to 14.5 volts when engine gets up to around 2500 rpm but only getting up to 12.6 at battery. even getting 14+ at cable 6 inches from battery but not at battery and volt gauge on dash is not moving.

What DC battery do you have?
I'd like to research it.

From my experience the DC won't cause a problem as soon as you hook it up but over time is when it causes problems.
Your motor isn't designed to work on them.

Any soft spots or bulges?
Try replacing the cables.
You need at least a 4g wire.

The motor might not produce power until it reaches above 2000.

You load test the battery?
Harbor Freight 25$

been busy with work so havent had chance to reply with info.
I have a Deka master marine deep cycle/starting battery.
yes I load tested battery and it tests fine.
the cable from battery to engine is also in good condition with good connections.

Just remember your charging system isn't designed to charge DC batteries.