Mercury Optimax 200 battery issues

[agdave112]

i suspect I may have an alternator issue. Serial ot271351
2001 mercury Optimax 200.

I bought a new exide xmc-31 first of December and now even straight off the charger it’s slow to start. I had to jump it off the trolling batteries twice. I used my ohm meter on the red terminal of the alternator and touched a ground and have a resistance reading of 37.8. Any input would be greatly appreciated


Thanks in advance

David

[Savage]

Sure, what is the output of the alternator in Volts tested at the alternator.

[tomloans]

Tighten up all connections at the engine. Be sure to unbuckle your battery before u check connections though. Very important. Then buckle up the battery again and be sure it is tight. If it really is the alternator, u can have it rebuilt. All my comments are from experience.

[SilverFox579]

Sure, what is the output of the alternator in Volts tested at the alternator.

^^^^

[agdave112]

I’ll check this morning and get back with y’all. I appreciate the help

[agdave112]

I may have found my issue. I went to run it on the hose and when I tried to crank with fully charged battery showing 13.5 v it was slow to turn over and I noticed the red power cable going to the starter getting hot as I saw some light smoke. What kind of tests can I run on my starter to see if that’s the issue Shows 13.5 v at the solenoid

[agdave112]

I’m still wondering though why my voltage drops later in the day. Possibly I have both going out. I can tell you what the ohms are through the alternator right now. 30.8 is what I measured as the resistance

[Savage]

If you saw smoke, then you have a large amp draw, which could be internally corroded cables, or bad connections. Check those items first.

[agdave112]

Connections have been cleaned and I tried to start again. Wires running from starter are war to the touch

[agdave112]

More info to add. My fish finders have been shutting off when trying to start up but not otherwise and not the first time of the day. I checked my voltage before trying to start after charging overnight and it was 13.5v on the battery. The fish finder said it pulled the battery down to around 11 v but the starter never spun fast at all. I even tried to jump the battery with my other vehicle and still had a slow spinning starter and got positive cable attached to starter. I’m thinking maybe my starter has been the problem all along just pulling down my battery when trying to start and getting too hot. After sitting not charging the battery it’s back up to 12.6 v.

[EuropeanAM]

Very likely the cable you saw "smoking", a connection on that cable, or the starter itself.

[agdave112]

I finally got it to turn over fast enough to crank after it warmed up outside. I was able to check the positive on the back of the alternator and the battery. 14.2 volts there. Going to replace that cable first then see if that cures the problem

[agdave112]

Replaced the cable to the starter and so far it cranks right up even in the31 degree weather this morning.

[tomloans]

Could you please take the bad cable apart and take a picture. I would like to see what you are speaking of? Why would this happen? Curious....

[EuropeanAM]

"Bad" cable could mean any number of things. More often than not, the best method to determine a cable is bad is by performing resistance, voltage drop, or loaded testing.

In this case, it's probably a "burnt" cable (partially melted due to high resistance and resulting heat).

[agdave112]

Corrosion over time would
be my guess. It’s a 2001 model. Already chunked the wire before a picture. It was crunchy feeling up and down the cable and stiff. Melted throughout the entire length

[Savage]

Replaced the cable to the starter and so far it cranks right up even in the31 degree weather this morning.

Glad post #8 fixed you up.