# Charging battery from old outboard engine



## 99miles (May 11, 2010)

I have an old Evinrude 6 HP outboard engine on my sailboat. Is there a way to rig this to the battery to charge the battery as it's running, or do I need a more recent engine with an output for this?


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## MARC2012 (Mar 17, 2008)

Most small outboards have small charging systems & not of much value as charging systems.Battery usage would help.marc


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## pedcab (Dec 4, 2008)

Hi

Have a look:

http://www.sailnet.com/forums/electrical-systems/49456-battery-charging-outboard.html

Cheers


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## AdamLein (Nov 6, 2007)

99miles said:


> I have an old Evinrude 6 HP outboard engine on my sailboat. Is there a way to rig this to the battery to charge the battery as it's running, or do I need a more recent engine with an output for this?


Do you know for sure that the motor doesn't already have a charging circuit? According to the SELOC manual, 6 hp (164cc) 2-strokes have a 4 amp non-regulated charging circuit.


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## mitiempo (Sep 19, 2008)

How old is the outboard? The older it is the less chance it has a charging system. I understand that if it is not there it would be an expensive addition. A small solar panel may be a better choice.


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## DropTop (May 7, 2009)

I have a 8hp Tohatsu OB on my boat, when running above idle speed it will output around 13.5-14 volts, but only a few amps. I replaced nearly every light in the boat this spring with LED bulbs because the draw from the old nav lights, steaming light, and chart plotter/sounder was more than the output of the engine.

Now with all the nav lights replaced, and the cabin lights replaced with LEDs, I can actually put a small charge into the battery when running the engine at night. 

I'm going to replace the steaming and anchor lights sometime soon as well. two nights on anchor coupled with the chartplotter being on (for the anchor drag alarm) combined with daytime use of the instruments pretty much killed my 2 batteries attached in parallel.


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## AdamLein (Nov 6, 2007)

Of course, it's important to have a well-tested energy budget before investing in any charging system.

Also, there's a pretty good post by Bene505 on his thoughts on upgrading to LEDs vs. buying a bunch of solar panels: http://www.sailnet.com/forums/electrical-systems/63690-how-much-watt-hour-per-day-worth.html

As he mentions, the important thing is not the numbers he's produced, but the planning and research that goes into making the decision.


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## pedcab (Dec 4, 2008)

DropTop said:


> I have a 8hp Tohatsu OB on my boat, when running above idle speed it will output around 13.5-14 volts, but only a few amps. I replaced nearly every light in the boat this spring with LED bulbs because the draw from the old nav lights, steaming light, and chart plotter/sounder was more than the output of the engine.
> 
> Now with all the nav lights replaced, and the cabin lights replaced with LEDs, I can actually put a small charge into the battery when running the engine at night.
> 
> I'm going to replace the steaming and anchor lights sometime soon as well. two nights on anchor coupled with the chartplotter being on (for the anchor drag alarm) combined with daytime use of the instruments pretty much killed my 2 batteries attached in parallel.


As far as I'm concerned yours is the right aproach to the question.

One can not rely on an outboard limited auxiliary electricity output to run everything like they do at home, nevertheless I always find very funny comments about the outboard motor's charger being useless...

I can say that on my trimaran I only rely upon my tohatsu M5, on a tiny 250mA solar panel and on an automotive 35Ah lead-acid battery to provide all the electricity I need on board. I sail almost every weekend and I only have to bring the battery home for a deep charge about two to three times a year (after long autopilot runs)....

But then again my electrical instalation resumes to an Autohelm bidata (~300mA), a pair of LED nav lights I retrofited from the standard ones (about 200mA both), an FM radio (about 500mA at low volumes) and two fluorescent lights, although these run very little time...

My VHF runs on AA cells as my GPS does and I use a DIY solar charger to manage them.

So, for coastal sailing and with frugal management of baterry consumption an outboard is a very usefull way to charge batteries...

Unfortunately not all of us can sail on super diesel powered boats in which the speed under motor often is higher than under sail. Probably that's the cause why they're most often seen motoring on beautifull sailing days...


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## JimsCAL (May 23, 2007)

If the engine wasn't originaly fitted with a charging feature, you really can't add it. A solar panel plus reducing DC loads to a minimum would make the most sense.


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