Upsizing mercury stator

Hi, all, I was wondering what the downsides to upgrading the output of the stator in my motor would be?

It's a 115hp mercury thunderbolt 1972 model.

Current output is 9 amps.

I would like to upgrade to maybe 15 or 20 amps.

I want to run a radio and gps and lights and such. Plus keep the battery fully charged.

So what would that do and is it even possible??

Re: Upsizing mercury stator

Average GPS uses about 0.5 amps, a lamp about 0.5 each (total 1.5A for a set of nav lights), a VHF radio about 1A, FM radio about 0.5A. Combine total of about 3 or so amps. The current stator will handle that easily. Apart from the fact that you can't get a bigger stator for those engines, if you managed to wind your own, you would run the risk of boiling the battery and destroying the voltage sensitive devices on the boat....

Chris.........

Re: Upsizing mercury stator

achris said:

Average GPS uses about 0.5 amps, a lamp about 0.5 each (total 1.5A for a set of nav lights), a VHF radio about 1A, FM radio about 0.5A. Combine total of about 3 or so amps. The current stator will handle that easily. Apart from the fact that you can't get a bigger stator for those engines, if you managed to wind your own, you would run the risk of boiling the battery and destroying the voltage sensitive devices on the boat....

Chris.........

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I tend to disagree with you on the boiling the battery and destroying the voltage sensitive devices on the boat, if there is a stator then there is also a regulator or rectifier to control the volt/amps to the battery and anything else as the draw requires. This was one great topic that was discussed more then not in a motorcycle forum I am a member of and the particular stator is marginal for the bikes we have/had in my case, sold bike to buy boat, rewinding isn't an option with larger wire, but if our rectifier is possibly a shunt type then there may be options to help save the stator from over use by replacing the rectifier with a non-shunt type, but first we need to determine if in fact we have a shunt type rectifier, but this is another topic...I have a 75 hp merc so this would be of interest to me as well...This is/was a major problem for the Suzuki Intruder motorcycles in keeping a good stator..The one thing I keep reading on charging systems is to have /keep a fully charged battery and not let the outboard motor be the sole charger for the battery, this is suppose to give the stators much more life to enjoy..

Re: Upsizing mercury stator

beardeddone said:

...if there is a stator then there is also a regulator or rectifier to control the volt/amps to the battery and anything else as the draw requires. .....

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Not on early era outboards.... AC straight out of the stator into a full wave bridge rectifier, into the battery.... NO regulator...

And the stators didn't suffer the same fate as the bike stators you talked about. You can use the outboard as the only charging source with no problem. But unless you have a constant current drain, the battery voltage will continue to rise. I have seen it as high as 17 volts. This is not a fault, it's just the way the system is designed. And it's not unique to Merc's, OMC has the same system. I think the first regulated systems appeared in the late 80's... On the bigger engines, on boats that people had other (electrical) stuff on....

Chris......

Re: Upsizing mercury stator

Welcome to the forum Topic Mercury outboards. Knowing that having a full charged battery by you when setting out is first key in the fact that you do not need a stator with more amperage. Most people don,t even pay attention to that really important detail. Therefore if you (Knowingly) have a fully charged battery when setting out there should be ample current from the stator to handle your extra componants with a deep cycle heavy duty battery as a good regulator.Better yet run two batteries with a battery switch to charge both when running then switch to Batt #2 reserve for radio etc etc, when sitting or fishing. Then switch to Batt 1 to start you engines!!!!!!! Nascar Pun then switch back to charge the two btteries while running and hit the throttle. This would be an even better regulator as one battery is fully charged and the current will balance out between the two batteries while recharging. It may be a bit more work but you will always have plenty of power and an assured battery for starting. cheaper than trying an unproven idea that may cause damage to other electrical companants I,d say. Just My opinion. If your dead set on that idea and I am in NO WAY suggesting trying it to anybody including you then you would need the companants from a newer say 97 4 stroker being flywheel startor 16 amps all the goodies that attach to that including but not limited to the regulator etc etc, that would bolt up to your upper endcap and flywheel hub unless the hub from the newer componants was compatible with your crankshaft as well as make supporting brackets wiring posibly more I,m no technician.

Re: Upsizing mercury stator

t's a 115hp mercury thunderbolt 1972 model.

Current output is 9 amps.

I would like to upgrade to maybe 15 or 20 amps.

I want to run a radio and gps and lights and such. Plus keep the battery fully charged.

So what would that do and is it even possible??

Click to expand...

Back to the original question....not with OEM or aftermarket parts. You may be able to send it off to CDI and see if it can be rewound/poles increased to up output. Also Max 4 stroke parts wont fit/interchange with this.....

Re: Upsizing mercury stator

Thanls Fastbullet thats kind of what I thought when posting it. I just wondered if there was that option