Outboard Battery Charging II

[goodrun11]

Hello to all,

I've read the posts on "small" alternators charging batteries, essentially w/o regulators. And this makes sense if the power useage on the boat has the battery constantly requiring recharging. And I also understand that the actual current output of the alternator will decrease as the battery terminal voltage increases to 14.5 volts or so, at full charge.

My question is how small is "small"?

I have a Honda 9.9 HP electric start motor that is equipped with an alternator (or magneto?) that is advertised to put out 6A at idle and and 12 A at cruising speed.

The battery I plan to use is the Seavolt Dual Purpose Group 24 model from West Marine.

In the use I plan for the boat there may be long periods (4-6 Hr or more) of operation, in which I expect the battery to reach the fully charged condition.

Does the Honda electric start motor have a built-in regulator? Or should I plan on adding a regulator? If so, what type and model would you recommend? Or would I just be wasting money?

[goodrun11]

It seems unusual for me to be the first to comment on my own post.

So far, I have found out that the Honda 9.9 electric start outboard Does have a built-in regulator.

I bought the service and installation manuals for the motor. These show the regulator, but do not seem to show the control voltage setting. In other words, what the high limit on charging voltage might be.

As I currently understand the battery technology, AGM batteries are very sensitive to overvoltage charging. Other posts seem to indicate that they function best if they should only be discharged to 50% of capacity, as judged by terminal voltage under moderate load.

Honda seems to recommend a two battery installation. One battery is to be used as the starting battery, and the other as the house battery. They also recommend a combination switch and control device made by BEP marine (Model 716SQ).

The BEP device is an automatic switch relay. And it seems to have isolation switches for ewach battery and a third switch that can be used to emergency overide the dropout of the automatic relay.

With a very small charging alternator, BEP recommends that each battery be limited in capacity to about 60 AH, "to avoid chattering of the relay"

Has anyone out here had any experience and/or comments or success with this combination?

I have used dual bank flooded cell "marine grade" batteries controlled only by a Perko 1-Both-2-Off switch on other boats with reasonable life (5-7 years between replacements)

[camaraderie]

I think the Honda/BEP suggestions are appropriate and reasonable and I would only use a flooded battery in this situation as you cannot provide proper charging for an AGM (I am assuming the outboard alternator is your only choice for charging.)
Of course this only leaves you with about 30ah's usable on the "house" battery so you'll need to watch your usage.

[brian1]

I have had two Honda outboards (9.9 & 15 HP) and have has problems with over-voltage with both. I have found that the charging voltages can exceed 18.0V. My current work around is to monitor the voltage on my GPS when I am motoring & switch on enough appliances to suck up the charging current when it gets to 14.1V for gel batteries. I have called Honda & they only can refer me to their authorized service centers. I am scheduling an appointment with one who claims that there is a voltage regulator on the engine. I am skeptical. Does anyone have any info on this issue? If I cannot find a better solution, I plan to design & make my own shunt regulator which will monitor the voltage & provide a variable load to use up the excess current.

[GMac]

I've got a Yammy 9.9 which puts out 60W's I'm told, the newer version does 120.

I've wired it direct to the battery through nothing. When motoring for a while, which isn't that often as I sail a pile faster, the volt thingy gets up to 13.5 odd and seem to flatten out there. Seems to work and doesn't have appeared to have hurt the battery. 120Amp sealed black one I'm not to flash on some technical terms as you have noticed.

When parked up I put a 5W solar panel out just to trickle or hold charge up. Again that runs through nothing and seems to be fine.

[marting]

It sounds like you have a faulty rectifier/regulator. I would try and remove it so you can take it to someone for test/repair
Martin

[marting]

Sorry wrong thread
Martin