Newbie question about running Mercury 9.9 outboard

[gerolamo]

Can you run a Mercury 9.9 outboard without connecting it to a battery?

Sorry for the newbie question, but I read somewhere that if the angry pixies generated by the alternator have nowhere to go it will blow the alternator fuse.

To be fair, the article was referring to blowing the alternator by switching between battery banks, which is somewhat different and makes sense.

But I have to move the boat on short notice, and won't have time to re-install the batteries.
I thought it wouldn't hurt to ask. I plan to just isolate the cables and pull start the motor. I don't need to run it for more than 30 minutes.


Thank you,

[dfloeter]

If it is not the electric start version, as mine is, I don’t believe there is an issue with being disconnected from the battery. On the electric start version, the directions implicitly state the warning about never disconnecting while running or starting without a battery.

[a64pilot]

I believe that it most likely doesn’t have an alternator and has a charging coil like a motorcycle and a rectifier like a motorcycle.
The difference is with a lighting coil and a rectifier the voltage output is always at max, if not used the rectifier just wastes it to ground, the battery is constantly trickle charged.
It wont hurt anything to run it without a battery, but oddly it’s harder often on the rectifier if there is no load as it’s gets hotter, it’s supposed to handle that, but bikes etc’s rectifiers will last longer if the headlight is always on, but without a load it still should last years so no worry.

However even if it has an honest to goodness alternator, and maybe a new motor does? It should hurt nothing if there is no battery, there just will be no voltage made cause there is nothing to provide power to the exciter field to the alternator, it will just spin and make no power.

[gerolamo]

Thank you for your replies. The motor does have an electric start option. I think it should be OK to run it without battery but maybe I'll just borrow one to be sure

[Lake-Effect]

Originally Posted by gerolamo

Can you run a Mercury 9.9 outboard without connecting it to a battery?

Sorry for the newbie question, but I read somewhere that if the angry pixies generated by the alternator have nowhere to go it will blow the alternator fuse.

I was expecting that it wouldn't matter, but according to this Mercury 9.9 manual, it might:

NOTE: Electric starting outboards must have the battery cables connected to a battery whenever the engine is running. Even if started manually, as damage to the charging system could result

Please check the manual for your actual outboard model before proceeding without the battery.

[wayne.b]

Originally Posted by gerolamo

Can you run a Mercury 9.9 outboard without connecting it to a battery?

Sorry for the newbie question, but I read somewhere that if the angry pixies generated by the alternator have nowhere to go it will blow the alternator fuse.

To be fair, the article was referring to blowing the alternator by switching between battery banks, which is somewhat different and makes sense.

But I have to move the boat on short notice, and won't have time to re-install the batteries.
I thought it wouldn't hurt to ask. I plan to just isolate the cables and pull start the motor. I don't need to run it for more than 30 minutes.


Thank you,

===


If it has an alternator the diodes will be toast within a split second with no battery attached. All it needs is a small motorcycle or tractor battery that you should be able to hook up in a minute or so.

[malross]

I have a Mercury 9.8 with electric start.
I have starter issues quite often and have No problem using the pull start other than I'm getting too old.

[Mike Banks]

Don't run it without a battery.

[a64pilot]

Originally Posted by wayne.b

===


If it has an alternator the diodes will be toast within a split second with no battery attached. All it needs is a small motorcycle or tractor battery that you should be able to hook up in a minute or so.

If it has an alternator, since there is no power to energize the field it won’t hurt, what will hurt is to suddenly disconnect the battery with the alternator working.

However I doubt it has one, I bet it’s a lighting coil, and how it could be hurt is that the power that will be generated may be too much to be shorted to ground and overheat the rectifier,easily replaced and not usually expensive, but why burn it up when you don’t have to?

The difference between an alternator and a lighting coil is the alternator is an AC device and has to have power to energize the coil, a lighting coil is a permanent magnet generator and will make power as long as it’s being spun.

Now I’m going back to my days of working on old bikes and outboard etc, but usually you had two coils, one was to power the ignition, and if you ordered it with an electric start, then it has to have a way to charge the battery, so another coil was put under the flywheel.

Bottom line, if the manual says don’t, then don’t.

I keep meaning to add a charging circuit to my Suzuki 20 HP as I’m sure it can be done and shouldn’t be hard, just haven’t gotten around to it yet. I’d like to power a depth sounder.

[TampaTom]

Google it, but, believe you can do this if you disconnect the lead from the charge coil to the rectifier. Otherwise, you might toast the rectifier.