Good afternoon/evening,
2008 Mercury Optimax Pro XS 250HP
1B550013
Battery - X2 Power (Northstar?)
Group 31M
CCA - 1150
RC - 220
I will try to keep this short with major bullet points I feel are relevant.
November 2020
Running back to weigh in on Chic. (15 miles or so) and got the voltage alarm when hitting the trim switch. Limped back to ramp. 1 week later I changed alternator (cheap one from Amazon) and everything ran fine.
July 2021
Running back to weigh in and hit trim switch and motor completely shut off. Was able to start in back up and idle to ramp. Took it back out following weekend and same thing. Got quoted $600 for OEM alternator from local mechanic but decided to try another $80 one from Amazon thinking I may have gotten a bad one. Installed it and everything ran good no problems.
Fished almost every Thursday night tournament on local lake with no issues until the last one in September. My buddy was in the boat and I launched him. He tried to start the motor and heard multiple fast beeps and clicking from around the dash. I got in the boat and it started fine and we fished as usual. Fished a few times for fun with no issues.
October 10th 2021
Fished a regional tournament. Launched boat fine and took off fine. Ran to first spot no issues. Fished for about 3 hours. Went to run to 2nd spot and noticed the voltage dropped to almost 9V when cranking. Motor cranked but died when I would hit the trim. Sat there for a few minutes and was able to idle back close to the ramp to finish out our fishing day. During the day I tried multiple things to figure out what was going on. I finally heard the clicking/fast beeping (not like a normal alarm beep) when trying to start that my buddy had heard a moth before. When I would hit the trim switch, I could hear a buzzing sound from under the dash. The battery would jump from trolling motor battery but I could only idle.
Today
I read some old forums to check some stuff. Here's what I have done...
Charged battery fully
Load tested battery at Batteries + Bulbs (load tested good according to tech)
Checked 100 amp fuseable link for resistance. Checked good.
Decided to remove panel that has Blue Sea switch panel on it and check connections. On the back on the switch, one of the post was just a tad "wobbly" and the battery cable was the slightest bit "loose".
I then decided to remove the switch completely from the equation. Cleaned and connected battery cables from motor directly to battery. Connections were good and tight. No wing nuts.
Put a meter on the battery and read 12.8V
Hooked up muffs and started motor. Battery read 13.8 after 5 mins.
Check voltage at alternator on red output lead. Read 13.8 with motor running.
Turned off motor and checked voltage at red and purple wire at the alternator. Both read 12.8V with the key on motor off. Check them with key off. 12.8V and 0V respectively.
What am I missing here. I cannot believe that I have yet another bad alternator. I know I went the cheap route but that would be 2 bad ones in a row. What else can I do to troubleshoot this. Any help is appreciated.
Thanks