Something weird happened

[Neo]

Hi All,

My OB is 2004 Mercury BF50 50EFI. It's a great fourstoke OB but it has a bid Achilles Heel. The standard Mercury electrical Regulator is underrated low quality junk and will blow up if I do the wrong thing .... I know because I have been through 3 of these now.
They will (sometime post event) self-destruct if ... they get even split second reverse polarity or a split second heavy load, like charging two low batteries turning through 1+2 on the switch.... Learning from my past experiences I now always turn through zero (never 1+2) on the switch.
But today I had the engine ticking over. I saw there were charging volts on battery 2 (so the regulator must be working) and while the engine was still running I turned the switch to zero and the engine stopped
I can't recall ever doing this in the past but I was kinda expecting it would keep running under it's own charging current? .... Could some confirm if this is normal for my OB?

I plan to upgrade the Regulator (when this one goes again) and I have already identified a much better (self protecting) alternative.

[Jimmyt]

You probably should NOT turn your battery switch while the engine is running. The switch may not provide continuous contact with a battery during switching. I have heard that this can cause damage to the charging system on some outboards. Can't verify, because I don't turn my battery switch while running, and don't have the same outboard as you. Just throwing it out for you to check...

It wouldn't surprise me at all if your motor won't run without a battery.

[NiceAft]

In the instruction manual for my battery switch, it explicitly says to not turn the switch to zero while the engine is running.

[Tomfoolery]

It wouldn't surprise me at all if your motor won't run without a battery.

In the instruction manual for my battery switch, it explicitly says to not turn the switch to zero while the engine is running.

It's an EFI system, so no surprise that it doesn't run without a battery. Can't pull start one either, if the battery is too low, from what I've read here.

But as the guys above said, don't turn the battery switch with the engine running. If you want to charge both batts, set it to 'both' before starting the engine. Shut it off to change the setting, then restart.

I just alternate batteries with each excursion. That way I know if one is getting weak, from how it cranks the OB. At the dock, I use a 2-channel charger, so each batt gets it's own charge, with the battery switch off. The charger is the only thing direct-wired to the batteries, via inline fuses of course.

[Neo]

Hmmm ... I wondered about the EFI system ... It's a bit crazy because Mercury actually provide an emergency starter pull-cord which is presently in the cowl.

Thanks for your help guys

[Jimmyt]

You may be able to pull start it with a weak battery. No battery, or a shorted or dead cell, will likely be a problem.

[Tomfoolery]

You may be able to pull start it with a weak battery. No battery, or a shorted or dead cell, will likely be a problem.

That's what I was thinking - not enough juice to spin it, but enough to run the fuel pump (if any) and electronics. I remember a discussion about pull starting back a year or two, which is where I heard about the need for at least a little battery power. Might have had to do with the Evinrude E-Tecs.

[Neo]

When I upgrade the regulator I might install a super cap to get around this issue.