Adding charging system to 1986 Merc 9.9 2-stroke?

[zuren]

I'm looking for some advice. There is a potential for me to go on a week long remote fishing trip later this year where I would take my boat. It is drive-in camping, but the sites are rustic...no power or water hookups. It's the type of place that you need to make sure you have enough gas in the truck when you arrive so you can get back out to civilization. It has me thinking how I would keep a trolling motor battery from going completely dead over the week.

Currently, my manual start 1986 Mercury 9.9hp 2 stroke does not have the ability to charge.
I'm looking through the service manual and doing some searches, and it seems it had the option of an auxillary stator/"alternator" for charging a battery. It looks like the parts needed are:

- Auxillary stator - Mercury #86704A2
- Voltage regulator - (still confirming #)

Has anyone added this auxillary stator to a pre-1998 Mercury? Just curious how involved it will be and you felt it was worth it? From what I'm reading, once it is installed, it has to be connected to a battery any time the engine runs, otherwise damage to the stator will occur.

The other option would be a solar charger and/or old fashioned anchoring and less SpotLock.

Thanks!

 

[lightflyer1]

Unless you are constantly using the engine and charger it won't really help the battery that much I would think. Solar is also somewhat the same as it won't get you much charge unless it sits for hours during the day and you have enough panels. You really need a generator like a small Honda 2k or so and a battery charger. I found one of these years ago on Craigslist for $300. Cleaned up and fixed up it works well and is fairly light and powerful and quiet.

https://www.ebay.com/itm/296327313770

 

[LDUBS]

Those small Honda inverter generators are very quiet. They set the standard in the RV world. I've never done it but wonder if you can rent one for a week. Some folks say the Harbor Freight knock off is just as good. I can't say if that is true or if folks are just trying to justify their purchase.

 

[lightflyer1]

They are pretty pricey though. For the cheap price I found mine it can't be beat.

 

[Pappy]

All the comments above are spot on. Have you priced the kit plus labor and have you determined the total output of the Merc charging system and at what RPM it puts out peak amperage? I think you may be a bit shocked. Once answered you will see why it is not an acceptable solution. A 2000w (initial) and 1600w (continuous) inverter generator will also have to run quite a long time to fully recharge a dead or close to dead trolling motor battery as it should be hooked up to a dedicated battery charger at a reduces output but will be way ahead of the outboard alternative.

 

[flatheadsteve]

Wise advice above...the output of those tiny alternators is not worth the expense...take that money to harbor freight and check out the predator generators. They won't be as quiet as a Honda or yamaha inverter generator but they work and are a fraction of the price.

 

[zuren]

All the comments above are spot on. Have you priced the kit plus labor and have you determined the total output of the Merc charging system and at what RPM it puts out peak amperage? I think you may be a bit shocked. Once answered you will see why it is not an acceptable solution. A 2000w (initial) and 1600w (continuous) inverter generator will also have to run quite a long time to fully recharge a dead or close to dead trolling motor battery as it should be hooked up to a dedicated battery charger at a reduces output but will be way ahead of the outboard alternative.

From the info I'm putting together, cost will be $100:

- auxiliary stator @ $50
- rectifier/regulator @ $50
- wire to the battery @ (minimal, I may already have what I need)

I found some instructions and it's pretty easy, so would be doing the work @ $0.

Assuming I have a 2 magnet flywheel (there is a 2 and a 4 magnet model), stator output is 4A @ 6000 RPM (WOT) (according to the service manual). If I have a 4 magnet flywheel, it is 6A @ 6000 RPM.

My battery charger is a CTEK smart unit with a 7A max output. I do not own one of those little suitcase generators, and not sure the purchase of one is within the budget.

 

[flatheadsteve]

From the info I'm putting together, cost will be $100:

- auxiliary stator @ $50
- rectifier/regulator @ $50
- wire to the battery @ (minimal, I may already have what I need)

I found some instructions and it's pretty easy, so would be doing the work @ $0.

Assuming I have a 2 magnet flywheel (there is a 2 and a 4 magnet model), stator output is 4A @ 6000 RPM (WOT) (according to the service manual). If I have a 4 magnet flywheel, it is 6A @ 6000 RPM.

My battery charger is a CTEK smart unit with a 7A max output. I do not own one of those little suitcase generators, and not sure the purchase of one is within the budget.

Even at 6amp on a 100ah battery you would have to run full throttle for hrs on end to even replenish 50%. At 4amps full throttle wouldn't cover the draw of a 10" chartplotter. Your 7amp charger likely takes overnight to top off your battery your best bet is more batteries or a generator you dont mind listening to all night.

 

[airshot]

Running your OB all night to try and keep your battery up will use more gas than a stand alone generator...

 

[zuren]

Running your OB all night to try and keep your battery up will use more gas than a stand alone generator...

Running engines all night isn't what I'm going for.


Thanks all! I think the resounding message is that having a charging circuit on this outboard isn't worth the $100 or effort.

 

[MrGiggles]

Grab an extra battery and a 200 watt solar panel. Swap it when needed, the solar panel should charge it up in without issue during a day's worth of sunlight.

 

[thill]

Okay, I'm going to be the oddball here.

Mine was an Evinrude, but same concept. Parts were about $100. Needed a stator, a rectifier and a terminal strip. Was only a 4 or 6 amp stator, and everyone said it wasn't worth it.

Took me about an hour to install, and from then on, I NEVER had to charge the battery for that boat. In my personal opinion, that was a great upgrade! Whether I was trolling or doing a blast and cast, battery just wasn't a concern anymore.

So, if you ask me, I say go for it.

IF you want to go the generator route, the one I strongly recommend is the WEN:
The one I got for $209 has over doubled in price:
https://www.amazon.com/gp/product/B07XZX5FTR/

This one might get it done, but it's a 1200W unit:
https://www.amazon.com/GENMAX-Generator，Gas-Compliant-Lightweight-GM1200i/dp/B09GTKMG2F

 

[LDUBS]

Okay, I'm going to be the oddball here.

Mine was an Evinrude, but same concept. Parts were about $100. Needed a stator, a rectifier and a terminal strip. Was only a 4 or 6 amp stator, and everyone said it wasn't worth it.

Took me about an hour to install, and from then on, I NEVER had to charge the battery for that boat. In my personal opinion, that was a great upgrade! Whether I was trolling or doing a blast and cast, battery just wasn't a concern anymore.

So, if you ask me, I say go for it.

IF you want to go the generator route, the one I strongly recommend is the WEN:
The one I got for $209 has over doubled in price:
https://www.amazon.com/gp/product/B07XZX5FTR/

This one might get it done, but it's a 1200W unit:
https://www.amazon.com/GENMAX-Generator，Gas-Compliant-Lightweight-GM1200i/dp/B09GTKMG2F

I used a WEN generator when I had the travel trailer. Worked great for me. It was a larger output model.

 

[Pappy]

Okay, I'm going to be the oddball here.

Mine was an Evinrude, but same concept. Parts were about $100. Needed a stator, a rectifier and a terminal strip. Was only a 4 or 6 amp stator, and everyone said it wasn't worth it.

Took me about an hour to install, and from then on, I NEVER had to charge the battery for that boat. In my personal opinion, that was a great upgrade! Whether I was trolling or doing a blast and cast, battery just wasn't a concern anymore.

So, if you ask me, I say go for it.

IF you want to go the generator route, the one I strongly recommend is the WEN:
The one I got for $209 has over doubled in price:
https://www.amazon.com/gp/product/B07XZX5FTR/

This one might get it done, but it's a 1200W unit:
https://www.amazon.com/GENMAX-Generator，Gas-Compliant-Lightweight-GM1200i/dp/B09GTKMG2F

Thill.....am thinking you are referring to charging up your starting battery? Huge difference between that and a trolling motor battery.

 

[Pappy]

I used a WEN generator when I had the travel trailer. Worked great for me. It was a larger output model.

What was the output? Looking at a 3500W but know zero about WEN and reputation

 

[FuzzyGrub]

My 90’s Merc 25 came with elec start and charging stator. It is barely enough to keep up with charging for starting and the FF.

On my gps trolling motor they indicate not to have it plugged in while the battery is charging. There is no real off switch unless you installed one. Stator charging creates more electrical noise than a standalone charger. Unplugging and plugging it back in will be a pita, every time you move. I also believe a stator charger is not good for a DC battery lifecycle.

You mentioned having to always have to run with a battery once you added the stator. Without elec start, that sounds like just hauling around more weight than needed.

I think a generator is you best option. Barrow or rent. Even with two DC lead-acid, both will be exhausted in a weeks use. Maybe a solar panel will help, but I wouldn’t bet on a nice sunny week, especially during a planned fishing trip. That usually means rain for me . A pair of LiFePO4 would probably work, but costly.

 

[LDUBS]

What was the output? Looking at a 3500W but know zero about WEN and reputation

Mine was the 3800w model. Weighed about 100#. I would say the only negative was keeping a charge on the small starter battery. I used the pull rope most of the time. It always fired right up. Other than that, I never had a problem in the two years of use before I sold the travel trailer. The WEN is pretty quiet but won't compare with an equivalent Honda. I had mine mounted in a sound box on front of my travel trailer. Not really necessary -- I think I just wanted to have fun building a sound box.

 

[thill]

Thill.....am thinking you are referring to charging up your starting battery? Huge difference between that and a trolling motor battery.

Yes, you are mostly correct. I DID use it for the trolling motor, but it was a 14' boat with a little 30# Minn Kota, which doesn't use much juice, and I only used it to keep me on the edges of the reeds, which is very little use compared to many. I could go a couple of trips without charging even before the stator.

It's about a 5 mile run to and from my fav fishing creek, so the battery was always topped up after installing the stator.

With a foot-controlled TM of any decent size, no, that wouldn't work. I didn't catch that he was looking to charge his TM batteries, sorry.

 

[Billy H]

Lots of small compact inverter generators for sale on marketplace for around 200$. At least around here there are.

 

[thill]

By the way, my 2,000W Wen is very comparable in decibel level as a Honda. I think it was 36dB if I recall correctly. Really like that little machine. It stays in my truck wherever I go.