1991 mercruiser 502 can't charge battery

[Tahiti warrior 502]

So I'm stumbling onto this boat it's been sitting for a few years they apparently had some alternator issues. The alternator has been replaced however the batteries are not taking a charge I was trying to figure out which wires charge the batteries??? Maybe they didn't hook it up right or something. Any help would be great

 

[alldodge]

ALT has 3 wires

Orange (main output) - goes to 90 amp fuse which is connected to the starter post
Red/Purple (Sense lead) - which comes from the 50 breaker
Purple (excite) - which comes from the key switch

 

[Bt Doctur]

Do you have battery voltage at the Orange wire?

 

[Tahiti warrior 502]

Ill have to check tomorrow and let you know about voltage on orange wire... I have 2 purple wires just laying in the floor that run to my dual battery switch.. could that be part of it?

 

[Bt Doctur]

shouldnt, alt is wired direct thru the engine harness unless its be fubar`d

 

[Tahiti warrior 502]

Ok ill check voltage on orange wire tomorrow and go from there