Running an outboard motor that has a generator without a battery is bad?

[tenuki]

i'm kinda embarrassed to admit this, cause I have a degree in Electrical Engineering, I just wasn't thinking...

I ran my outboard all summer without connecting it to a battery. It's a Yamaha 8hp electric start and alternator, with pull start too, so I've just been pull starting it and had the leads that would normally connect to a battery just covered and isolated. duh.

When I pulled it this fall for maintenance, I started thinking.. you know, it probably is very damaging for that alternator to run without a load of any kind. I'll know if I did any damage when I do the maintenance and then re-install it with a battery but it sucks I didn't think of that earlier.

What is everyone's opinion on this, I was pulling it out when it dawned on me, don't know if it's common knowledge or not.

[artbyjody]

You are ok....


The starting energy is mechanical to electrical and honestly - you would be better off having a battery system for it to tie to.. but in a generic sscenario you have a lawn mower.. you yank it starts...


If you want the ability to be more self sufficient get the interface kit and install batteries and you can begin to9 enjoy extended cruising...

But as it is - you are ok..

[tenuki]

That's the thing, it already has an alternator built into the motor. Running it open circuit without load means the voltage can float and get out of hand, burning it out. I hope that hasn't happened yet, I'll let you know what the yamaha dealer says. 2006 yamaha T8h

[artbyjody]

But its not hooked to anything.. so what is the issue

[tenuki]

Here is a discussion of the issue. and again here.

Basically the alternator is running when the motor runs, so either the diodes or the stators are in jeapordy because it can develop high voltage spikes in open circuit mode. If it has a battery the battery acts to regulate the voltage by providing a load, so no spikes or floating.

I was planning on just adding a battery anyway, so just crossing my fingers that there hasn't been damage.

[artbyjody]

if you haven't had problem...you are probably ok... it is shunting the energy one way or the other but if an alternator is not connected to something - nothing is happening...

[tenuki]

Originally Posted by artbyjody

you are do have Electrical Degree right?

Yes, which is why I understand that it may be a problem. What about you?

[haffiman37]

There should be no problem.
The generator system on outboards consists of 1 or more seperate charge coils under the flywhel. Total output at max rpm is probably no more than 8amp, and drastically reduced at lower rpm's. Most outboards with pull and el starts may run not connected to any battery, BUT b sure the battery cables have isolated ends. Only if the + and - gets together the diode and coil will be dammaged. Open loads should be no problem.

[artbyjody]

was idiot and post reflects that - my apologies

[tenuki]

Originally Posted by artbyjody

I don't own a degree just worked on nuclear submarines with them thinking I had some semblance of understanding I understood electronics .... but your degree trumps my experience - kudos...see you next year at the north pole...

hmnn, somebody got up on the wrong side of bed today.