Running it without a battery

[Ladiesinpinknightshirts]

Why does the manual for an electric start Johnson two stroke state I must not attempt to run the motor (pull start with rope or jump off battery) without it being hooked to its battery? The manual even goes on to say 'even if the battery is dead it must be hooked up... you must not run the motor without it being hooked up.

It says, the electrical system will be damaged.. but why or how? What's going on?

has anybody else had experience with this..

LIPNS

 

[Silvertip]

Re: Running it without a battery

If they explained why, most people would not understand anyway! But since you asked, without a battery there is no electrical load on the charging system, charging system voltage spikes very high and pop goes the regulator and/or the rectifier. The engine runs without a battery because it uses a magneto ignition. The battery is used only to spin the starter and to power any accessories in the boat.

 

[Randybeall]

Re: Running it without a battery

The battery acts as a big buffer for the electrical system. The coils in the stator devolop a charge as the magnet of the flywheel passes them. They pass the charge through the diodes of the rectifier and into the battery which offers a slight resistance and capictance to absorb the electron flow at a controlled rate. Remove the battery and the electron flow stacks up to peak voltages till some part fails and lets the electrons go to ground. Diodes of the rectifier are usually the fall guys.

 

[Ladiesinpinknightshirts]

Re: Running it without a battery

Thanks to both of you guys.
Surprisingly enough it makes sense. (enough to hurt myself) Now I guess I know why a pull start motor will have a magneto and an electric start will not.

I wont run the thing without a battery in line.

thanks again.

 

[Ladiesinpinknightshirts]

Re: Running it without a battery

Just to continue this.. so anything with a starter has to have a battery in line while running or you're going to screw it up as stated. This also goes for my old truck. I've on occasion wondered if I had no battery could I simply jump the thing or roll it down a hill and get it going. I guess if I did I'd have burned something out.

LIPNS

 

[Tuna mad]

Re: Running it without a battery

Your truck would not start without a battery in it, even if you roll started it. But if you hooked up a battery and got the engine running you could then take the battery out and it would keep running, because the alternator would then be supplying voltage to the ignition. Eventuallly though, you would end up doing damage to the alternator and/or voltage regulator, which would be sensing 0 volts and making the alternator charge at full capacity.

The difference between an outboard and a car is that an outboard uses a magneto ignition, which generates its own voltage as the engine spins. Even cranking speed is enough to generate a spark and fire the engine. Most cars use a battery ignition system, which means if the battery is disconnected there is nothing to provide spark to the ignition, until the engine is running fast enough to give an alternator output.

 

[F_R]

Re: Running it without a battery

Just to continue this.. so anything with a starter has to have a battery in line while running or you're going to screw it up as stated. This also goes for my old truck. I've on occasion wondered if I had no battery could I simply jump the thing or roll it down a hill and get it going. I guess if I did I'd have burned something out.

LIPNS

One simply cannot make such blanket statements. Not all outboards are created equal, and not all trucks are created equal. Not all electric start outboards even have generators or alternators. And some outboards have automotive type ignition systems. Finally, some outboards have battery powered electronic ignition systems that will destroy not only the charging system but also the ignition system if the battery is not securely connected. Now those will cost you a few bucks if you disconnect the battery while running!!

Best policy is if it is supposed to have a battery, make sure it does, unless you know for sure that it's safe to run without it.

 

[Silvertip]

Re: Running it without a battery

And one last bit of clarification. Most outboards (electric start or not) have magneto ignition. Magneto merely means power for the ignition is achieved by magnets in the flywheel passing over a coil creates the electricity so a battery is not needed to run the engine. A charge coil is built into this system on electric start engines for battery charging purposes on those engines. But both pull start and electric start engines use a variation of the magneto system to actually run the engine.

 

[metriccrescentwrench]

Re: Running it without a battery

WHAT... nobody explained all about letting the smoke out!!!

 

[Mark_VTfisherman]

Re: Running it without a battery

WHAT... nobody explained all about letting the smoke out!!!

With all the new emissions regulations, manufacturers are installing much smaller (and even digital) factory smoke these days. If you let the factory smoke out, only a qualified dealer should be authorized to recharge it.

Seriously, though, what silvertip said is true: "Magneto merely means power for the ignition is achieved by magnets in the flywheel passing over a coil creates the electricity so a battery is not needed to run the engine"

...and what he implied and others have said and you have concluded, it ain't a good idea to run your engine without a battery. Some people do it (to newer outboards) occasionally, thinking there will be no harm, remembering the old outboards from the sixties or before which may not have had any charging system even if they had electric start. I had two different Johnson's like that- electric start, no generator; electric start, shift, and no generator. Had to charge the battery after every day on the water. Glad those days are over

 

[metriccrescentwrench]

Re: Running it without a battery

....I had two different Johnson's like that- electric start, no generator; electric start, shift, and no generator. Had to charge the battery after every day on the water. Glad those days are over

OK, so when are these smart manufacturers going to put charging systems on trolling motors so I don't have to charge that battery every time I get back from fishing?

 

[SuzukiChopper]

Re: Running it without a battery

OK, so when are these smart manufacturers going to put charging systems on trolling motors so I don't have to charge that battery every time I get back from fishing?

Once perpetual motion machines become a reality

 

[Mark_VTfisherman]

Re: Running it without a battery

OK, so when are these smart manufacturers going to put charging systems on trolling motors so I don't have to charge that battery every time I get back from fishing?

The old Johnson's I was referring to were 40HP- a '64 and a 70-ish. I guess I assumed all the new motors had alternators or magneto/field charging.

For whatever reason I never really thought about it- most of the little engines don't have electric start, either!