2021 Mercury pro xs starting problem

[bolton_brian]

So here is the scenario. Went to the lake this weekend and motor started right up. Ran to my first spot, fished and then decided to move. Got a low voltage alarm on my garmin graphs and when i went to start the motor it clicked, clicked like the battery was dead. Trolled back to the ramp and decided to try and start it before i tried to load with the trolling motor. The big motor started. Took it home and put it on the charger. Battery was low but not dead.
Charged all night and the next day all of the batteries were charged fully according to the minkota 4 bank charger. Took it to the lake and lauched, it started as it should. Ran about 10 miles and fished for an hour and a half. Went to move and same thing, it wouldn't start. Thought must have a low battery so i used a handheld quick charger pack and it started right up. Ran back to ramp and decided to shut it down to see if i could reproduce the no start issue. Motor started right up, repeated this several times and motor started right up. Took it home and all batteries were very low after just a few hours on the lake. Charged it all night at the cabin and then drove 3 hours home. Went directly to my guy who does all of my graph and trolling motor installation and he check the batteries and the charger and everything was good.

Could this be an ignition switch or starter problem? Would either cause the batteries to drain while sitting in the driveway?

HELP!

[mactlman]

alternator maybe? many have failed? or alt ground? bad battery?

[Jbass123]

Your starting battery AND your trolling batteries are dying quickly? If so, that’s very unusual. Ignition switch or starter would have zero to do with your trolling batteries. Possible faults shared by all your batteries are age/condition [although unusual, if all batteries are 4 years old, all could be weak now] and the battery charger. Your guy checked the charger, but it still could have a problem, and determining precise condition of batteries can be tricky. Cranking battery and trolling batteries are on completely different circuits, so a common fault that weakens both is hard to see.

[bolton_brian]

Crankin battery was new in march of 2022 and all 3 trolling batteries were replaced last year. Thinking maybe the trolling batteries were fine, the gauge upfront showed 38.5 volts and i had no power loss. Maybe a bad ignition switch or starter?

[xxstang90]

Ran to my first spot, fished and then decided to move. Got a low voltage alarm on my garmin graphs and when i went to start the motor it clicked, clicked like the battery was dead. - Bad battery

Thought must have a low battery so i used a handheld quick charger pack and it started right up. - Bad battery

Took it home and all batteries were very low after just a few hours on the lake. - Bad battery

Ran back to ramp and decided to shut it down to see if i could reproduce the no start issue. Motor started right up, repeated this several times and motor started right up. - Alternator is probably doing its job

Motor always starts when batteries are freshly charged or using a jump pack. - Bad battery

Just my .02 cents. Best of luck!

[EuropeanAM]

If you would, please take a moment to review the Forum Announcements, and be sure to provide the Required Info (serial number). Thanks!

Get that cranking battery load tested: Really needs to put out 975 CCA (Cold Cranking Amps).

[bolton_brian]

Don, i apologize for not posting the serial number, i didn't have it at the time. i will get it and edit my post.
XXstand thanks for stating the obvious. my initial post states that i had the batteries and the charger checked when i got home.

[EuropeanAM]

Bolton brian: It says your electronics guy "checked them and they were good". They need to be tested with a carbon-pile LOAD tester to confirm they exceed the capacity required for the engine (plus all of your boat accessories).

[bolton_brian]

Don, i will ask him when i see him this week. he is installing a spotlight for me to so i can ask then. The motor has ran/started flawlessly until this last weekend.