Well, yesterday we boated up river to our spot, turned off the motor (Briggs 36) and when we went to start it again a minute later, the battery was d - e - a - d, dead. We'd been running an LED light bar and a hand held spotlight, running for 30 minutes or so.

Not having a jump pack or spare battery, we thought we were SOL until we decided to take the 6V batteries out of a couple of spinners, wire them in series (creating a 12V battery) and voila! Got 'er going. So we decided to hunt. After the hunt, had to jump it again with the spinner batteries. So the moral here is that a couple of 3.5 amp hour spinner batteries will indeed get a big block Briggs started. We even googled how to wire batteries in series (vs in parallel) to make sure we were doing it right. https://www.batterystuff.com/kb/article ... orial.html

Now to troubleshooting my problem. Looking for input as to possible causes:
1) Bad alternator on the Briggs not charging the battery as we draw it down with accessories?
2) Corrosion at terminals preventing proper charging? They weren't exactly clean but they weren't massively corroded either.
3) Bad battery even though it is only a year old?
4) Low charge on the battery just enough for one start, but wouldn't the battery charge as I was running the motor at high RPM?

If any of the brain trust wants to give your opinion, I am all ears. I am going to get the motor started today and remove the battery leads, putting my multi-tester on them to see if I am getting a charge back toward the battery from the alternator. I also charged the battery when I got home yesterday, it began with only a 38% charge on it.

Thanks for any constructive advice.

Pm sent

Try this to troubleshoot! The rectifier/regulator is connected to the battery at the hot side of the solenoid on the starter. Check that side for 12 VDC then Start motor and get the rpms to at least 1100, you should see an increase in voltage to at least 13.5 or better, this means charging system is working. The stator under fly does not generate enough to charge battery unless at around 1100-1200 rpm. If you don't get voltage increase, check at rectifier/regulator the yellow wires(on most motors) for at least 35 volts AC(my motor outputs 42 Volts AC), and output of rectifier, Red and black wires should be at least 13.8 Volts DC(mine does 14.2). Now what could effect output is bad battery, shorted wire, or bad rectifier.

You should charge your batteries when the boat is parked at your house. Don't rely on the charging system by itself. It is not an alternator and not really designed to keep the battery full like what you have on your truck. Your truck is designed to run off basically just the alt, only using the battery to crank. Your boat is not. It's not really designed to keep a battery charged that's doing a bunch of other jobs other than starting the motor.

Thanks to all for taking the time to reply!

And Russ, nice to talk to you this morning.

Gotta wait now to troubleshoot. It's 7:40 a.m. out west here and I don't think the neighbors would like to hear the boat fired up in the driveway just yet.

I don't know what MM you have but I was told by KP at Prodrive that the alternator/charging system on their motors was not enough to keep up with the drain placed on the battery by high-power lights for extended periods. Better off running those lights off smaller rechargable 12-volt batteries.

Chased it down to a bad rectifier. Thanks all.