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  1. #1
    Seaman Apprentice
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    Default Do outboard motors charge batteries?

    This is probably a dumb question but i was wondering if my 1971 18HP Evinrude outboard will charge the battery while it is hooked to the motor. (it is electric start) In other words, do boat motors have alternators to keep the battery from dying?

  2. #2
    Petty Officer 1st Class cwhite6's Avatar
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    Default Re: Do outboard motors charge batteries?

    My 1993 Nissan does. If it is electric start and has some kind of alternator, it should.
    2008 Carolina Skiff J16
    1994 Nissan 25hp

  3. #3
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    Default Re: Do outboard motors charge batteries?

    Some older electric start OMC motors had alternators, some did not. Look for the rectifier on the motor (it typically will have a couple of yellow leads and one or two of another color coming into it and is usually on the top, rear of the block and is normally a watercooled device recessed into the block.

    Any BRP dealer could tell you after a quick look. The two 1971 18HP models shown on BRP's parts site don't show any sign of charging equipment for those motors, so I would say most likely no charging for you.
    Jim

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  4. #4
    Petty Officer 2nd Class tootallofwa's Avatar
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    Default Re: Do outboard motors charge batteries?

    Quote Originally Posted by Blake Hearn View Post
    This is probably a dumb question but i was wondering if my 1971 18HP Evinrude outboard will charge the battery while it is hooked to the motor. (it is electric start) In other words, do boat motors have alternators to keep the battery from dying?
    It will charge if it has the generator. You can tell easily because the gen is about the same size as the starter mounted on the other side of the carburetor and driven by a belt off the flywheel.

    Don't worry if it doesn't have one... The battery is only used to crank the engine. You may have lights, fish finder maybe a radio. Those don't use much power. You'll need to re-charge it periodically.

    The battery has nothing to do with keeping the engine running. It would be used also for electric shift also, but you have manual shift on that 18hp.

  5. #5
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    Default Re: Do outboard motors charge batteries?

    Quote Originally Posted by Blake Hearn View Post
    This is probably a dumb question but i was wondering if my 1971 18HP Evinrude outboard will charge the battery while it is hooked to the motor. (it is electric start) In other words, do boat motors have alternators to keep the battery from dying?
    Harken back to the year 1971. Back then, Evinrude made those great 18 and 25 horepower motors that had the OMC Universal Magneto (no room for an alternator). It was compact and carryable so no room for a belt driven generator either. It had a "real" choke on the carburetor. And they ran great because they weren't freaked out by a few drops of fuel getting in the water.

    Be glad you have what you have. They don't make them like they used to. If you freak out at the fuel in the water, use 100% Synthetic TCW-3 outboard oil. They claim it is bio-degradeable. Sure smokes less too.

  6. #6

    Default Re: Do outboard motors charge batteries?

    Outboard motors are used most commonly for boats and are developed as a self-contained unit with an engine. Outboard motors will usually provide a method of steering control. Not all outboard motors charge batteries only some motors do charge batteries. Today the outboard motors are designed to take on bigger boats and will provide more power than before.

  7. #7
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    Default Re: Do outboard motors charge batteries?

    Quote Originally Posted by Phillip001 View Post
    Outboard motors are used most commonly for boats and are developed as a self-contained unit with an engine. Outboard motors will usually provide a method of steering control. Not all outboard motors charge batteries only some motors do charge batteries. Today the outboard motors are designed to take on bigger boats and will provide more power than before.
    Lol, that read sooo like a straight copy/paste

  8. #8
    Petty Officer 2nd Class applebj8's Avatar
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    Default Re: Do outboard motors charge batteries?

    Not a dumb question at all. As mentioned, if engine has a rectifier then yes it has charging capability. However, you'll not have nearly enough fuel to really charge battery up.
    If for example, you have a 75 Amp-Hour battery, it would take 5 amps of charging for 25 hours to bring battery back from "dead". 10 amp source would charge it up in 7.5 hours.
    Practically speaking, you'll need to connect battery to a 110 volt battery charger and let it sit overnight...

  9. #9
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    Default Re: Do outboard motors charge batteries?

    Quote Originally Posted by Blake Hearn View Post
    This is probably a dumb question but i was wondering if my 1971 18HP Evinrude outboard will charge the battery while it is hooked to the motor. (it is electric start) In other words, do boat motors have alternators to keep the battery from dying?
    Your 1971 18hp has no provision for battery charging, nor was there any option to fit battery charging.
    I think even the electric starting has been added as an optional extra as it is not shown in the basic parts lists for the engine.

    As already explained generally some motors do have battery charging capability, while some do not.
    More modern electric start motors generally include battery charging, some small ropestart engines as well. It is available as an optional extra on most where it is not standard bar the smallest. No you cannot fit anything off a modern one!

  10. #10

    Default Re: Do outboard motors charge batteries?

    Another dumb question... What about the johnson 85hp 1976, I'm a newbie, as far as I know it doesn't have charging capabilities?

  11. #11
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    Default Re: Do outboard motors charge batteries?

    I don't know the official "rule," but at some point the engine becomes large enough where they always start putting a charging system on them.

    Your 85hp will definitely have a charging system. Even the old 90 hp in the 1960's did. I believe this "could have a charge system/could not" only applies to smaller kicker-style motors. Again I don't know the specifics or the cutoff, but I do know that people with engines of 85hp will have them on a large enough boat where that engine will also need to power all lights, accessories, etc. As such, it will have a charging system. Engines without charging systems I believe are intended for smaller aluminum (or the like) style boats, where lights and accessories are not abundant.

    Note - You could check this in about 2 minutes by checking the voltage at the battery while the engine is running next time you're at the lake. If the voltage while it's running is higher than when the engine is off, you've got some type of charging system.

  12. #12
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    Default Re: Do outboard motors charge batteries?

    Quote Originally Posted by magialatina View Post
    Another dumb question... What about the johnson 85hp 1976, I'm a newbie, as far as I know it doesn't have charging capabilities?
    The diagrams show that a 1976 85 hp has 6 amp stator coil and a rectifier for battery charging.

    As mentioned checking that the battery volts rises to well above its normal reading once the engine is running will confirm that all is well and that the battery is in fact charging ( it is not regulated so the volts may well rise much higher than you'd expect)

    For a little over $200 you can even obtain a 12 amp conversion kit. In addition to the more powerful coil and rectifier that also includes a regulator to control the battery charging.

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