Small outboard charge question

[thaaland]

I recently picked up a sailboat - 26' Grampian - w/ outboard, and I'm starting to plan how to go about the electrical system, but I'm very new to all of this!

I've got a 10hp Honda outboard (I'm thinking a BF100 variety) with a charging system.

I've also got a new 200A/h AGM group 4D house battery. I've no plans for a starter battery (the engine doesn't support it.)

I'm interested in charging this battery from the outboard, possibly supplementing the charge from solar/wind, but that's further down the road.

Should I expect to require a charge controller for this setup? I'm looking at: http://www.defender.com/product.jsp?path=-1|328|51495|1031713&id=6501 however upon further investigation I'm a bit confused as to whether or not I even require this.

Thanks!

 

[sailingdog]

You want a good charge controller or three-stage regulator for your charging system. If you're just trying to charge the battery with your outboard, get a Flexcharge NC25a instead of that. It's a lot less money and far more useful a device... good for up to 25 amps, more with optional accessories.

 

[druid]

You won't need any kind of charge controller for the output of a 9.9 outboard. They put out 10A on a good day (usually more like 6) so going into a big battery like yours is no problem. In addition, the o/b almost certainly has a regulator of its own.

Once you get into a more complex system involving wind and solar, you will need a controllor of some sort, more to choose what charging system is working (an to avoid duelling regulators!) than to avoid overcharging.

druid

 

[Clark]

druid hit it. . . AND the output is only as rated when at (near) full throttle. It would take 1 hour of near full throttle running to get ~ 6-8 Ah. For a frugal overnight, it would take about 6 hours of runtime to recharge the battery. In reality, the alternators were designed primarily to cope with running lights only.

 

[thaaland]

Thanks for the responses. Very helpful.

I figured the motor would be on the weak side for such a large battery...

My primary concern here is the outboard outputting > ~14.1v (whichever is correct for AGM charging) and ruining / shortening the lifetime of the battery. It seems I shouldn't have to worry about that at all?

 

[Benny]

No, you will not need a controller as the output voltage of the outboard engine is rather weak. Perform a power survey about the anticipated amps usage in a 24 hour period and go from there.

 

[Clark]

It is very unlikely that the outboard would do any harm to that battery. IIRC, the bulk charge on most AGM's is in the 14.3 VDC range anyway.