# This can't be right!



## Rustyrotor (Nov 7, 2017)

Have had my new-to-me Mi Tide 1602 out for a week, all good, minor tweaks and adjustments ID'd and upcoming as soon as the budget allows. The big and cheap job will be moving the trolling batts into the bow. Must do. Just need to figure out exactly how to do a very sanitary install, including a built in charger.

The motor is a Yam F70 with unknown but very very low hours. Clearly high condition, seemingly perfect function in every way.

But.

On two occasions when I'm done charging the trolling batts, I've gone on to put the starting battery on charge to top and check it, and have found it low, my fancy automotive charger showing a 60% charge a couple days ago, and today 40%

Any connectors that didn't look perfect have been replaced. 
Have pulled the switch panel and it's all pristine. I make sure to leave everything off, and the three-position nav and anchor switch is kept in the middle when not in use.

So. As it seems unlikely that there's an alternator problem (will check output as soon as I can locate my good VMeter), that leaves a poor or absent connection, or a parasitic loss.

How do I troubleshoot this without tearing apart the harness?
Where could there be a parasitic loss in something so basic and simple?
Are the alternator connectors readily accessible? The manual doesn't even have the word alternator in it. (!)


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## Gatorgrizz27 (Apr 4, 2015)

If the battery switch is functioning properly and you are in fact turning it off after use, then there’s no chance of a parasitic loss. 

I don’t know about the F70 in particular, but I’d assume it has a stator that puts out around 60 amps of AC current when revving. This is converted to DC by the regulator/rectifier, which has likely burned up. Yamaha R/R’s aren’t fantastic, heat and vibration typically does them in. 

The other possible problem is just a bad battery. They can go bad and not hold a full charge regardless of what a voltmeter or even load tester says. 

The simplest thing to troubleshoot it would be to put a voltmeter set to DC current on the starting battery terminals with the engine running. It should read between 13.5 and 14.4 v depending on RPM’s. If it does, the entire charging system is working properly. If it does not, you can test the stator by measuring the resistance on the wiring harness. Unfortunately, I don’t know the measurement or which wires to test on that motor.


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## KCTim (Feb 7, 2017)

I would just pull the battery and take it to any local auto parts store and they will do a load test free of charge.


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## bryson (Jun 22, 2015)

Are you familiar with the rest of the boat's wiring? It's pretty common to see a bilge pump wired directly to the starting battery, and I'm (sadly) not surprised when I see other things hooked up to it as well, bypassing any sort of switch.

I'd start there before assuming there's a charging issue from the motor.


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## SomaliPirate (Feb 5, 2016)

I had a sort of similar problem about two months ago. Turned out I had a bad spot in one of the battery cables that I guess was preventing the rectifier from charging the battery like it should.


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