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  Topic Review (Newest First)
08-10-2012 10:19 AM
Re: Honda 8HP outboard to charge 12V

There is a principle to remember here which is that the current a battery will accept decreases at it charges up. The last 10-20% or so takes an hour + regardless of your charging source. This is what makes the solar panel great for a mooring boat.

Even if you run the engine enough to supply plenty of energy on paper it won't run long enough to top it off. So even your lightly used battery will spend all season at 60%-80% instead of 100%. Not a huge deal but it decreases the life of the battery. Even a 2W or 5W solar panel, I have this one, could probably keep your bank at 100% all season.

I literally just throw this panel on the cockpit seat and plug it into the cockpit lighter outlet when I leave the boat (the outlet has a diode wired for this purpose). So far it's kept my group 27 and group 24 at a good 12.5V.
08-10-2012 07:49 AM
Re: Honda 8HP outboard to charge 12V

I too have an 8hp honda for my boat. Like you no nav lights and I have a bilge pump and depth sounder fish finder combo. I make sure that my battery is fully charged at the begining of the season. I have yet to take my battery out to recharge it. The fish finder draws very little and the bilge pump is used occaisionally. I have to motor out of the dock and into the harbour were I am about 10 mins at most, same on the return trip. So I find that the motor charges the battery OK. If that is what you have to do or there abouts then I would not worry about it.
08-10-2012 07:41 AM
Re: Honda 8HP outboard to charge 12V

While and outboard will charge the amount of time the motor needs to run makes it a bad pick for a sailboat as a stern mounted 20 to 40 watt solar pannel will just sit there and take care of it
08-10-2012 06:22 AM
Honda 8HP outboard to charge 12V

For the 9.9 and the 15 hp (bf15a) it is possible to upgrade the charging coil to produce a higher amperage. I am not sure if that is available for the 8 hp version. Something to look into. I think it almost doubled the amps.
08-10-2012 12:20 AM
Honda 8HP outboard to charge 12V

Right, even a small 5w solar panel is going to be better here than the motor with a 5a alternator.

Definitely go LED. No Nav lights? I love sailing at night.
08-09-2012 11:10 PM
Re: Honda 8HP outboard to charge 12V

I have a Honda 8hp with the plug. Honestly, I have never really used it. The problem with outboards and sailboats, they aren't usually run long enough to really charge much plus the rated amps in the book is it full throttle, which they are rarely run at. Of course it depends a lot on your usage.

Sure it could help but it's not like a little fishing boat where you might be running it all day. I did the charger thing with an extension cord for a while, then switched to solar instead of installing a proper shore power system. Shore power can lead to other issues especially if not done correctly and some others even if done correctly.
08-09-2012 10:35 PM
Honda 8HP outboard to charge 12V

I only have DC on Edel 22'. No shore power. Minimal requirements: interior lights that I will update to LED. Doubtful I will ever be in a situation where I am sailing in dusk or dark and in need of nav lights. No radio. No bilge pump.

The previous owner is storing the Honda 8hp (BF8A) until next spring. In reading its manual I noted that it comes with a cord and outlet that allows the Honda to charge a 12V. (12V/ 5amps)

As I was considering getting an intelligent charger to hook up to shore power being able to top up my 12V with the Honda is another option.

Has anyone used this type of charging set up? How long do you charge? How often?


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