Adding a charging system to a Mercury 15hp EFI

[Steve509926]

Hi all,

I'm lining up a few projects to do during the winter months or 2nd covid lockdown period as it will become known!

One of them is to retrofit a charging system to my Mercury 15hp EFI to charge a 12v 20AH L-ion battery so that I can run a mobile, GPS, FishFinder, radio, lights etc The intention is to spend a few nights at a time wild camping in Anglesey and Scotland, so having a bit of electrical power would be useful.

I'm ok with the battery, w/proof battery box, external outputs USBs etc
What I need to check is the charging system. Is it as simple as retro fitting a new ignition / alternator coil and a regulator? or is there more to it than that?
If it is that simple, has anyone got the part numbers I would need?

Thanks in advance.

[Pikey Dave]

Originally Posted by Steve509926

Hi all,



I'm lining up a few projects to do during the winter months or 2nd covid lockdown period as it will become known!



One of them is to retrofit a charging system to my Mercury 15hp EFI to charge a 12v 20AH L-ion battery so that I can run a mobile, GPS, FishFinder, radio, lights etc The intention is to spend a few nights at a time wild camping in Anglesey and Scotland, so having a bit of electrical power would be useful.



I'm ok with the battery, w/proof battery box, external outputs USBs etc

What I need to check is the charging system. Is it as simple as retro fitting a new ignition / alternator coil and a regulator? or is there more to it than that?

If it is that simple, has anyone got the part numbers I would need?



Thanks in advance.

Dunno about your specific engine, but I’ve just done something very similar with my pull start DF20a & used a 20Ah Poover Lithium battery. The battery is fussy about its charging voltage, so I added a Buck regulator between the engine & battery to maintain the charging V at 12.7V.

[jeffstevens763@g]

You get a charging kit with regulator/rectifier plug in then you need a cable to the battery cost about £100 for the kit 10 mins to fit

[smallribber]

Originally Posted by jeffstevens763@g

You get a charging kit with regulator/rectifier plug in then you need a cable to the battery cost about £100 for the kit 10 mins to fit

Don't you have to already have an additional set of wires off the Stator in order to connect the regulator/rectifier to ?

[jeffstevens763@g]

Originally Posted by smallribber

Don't you have to already have an additional set of wires off the Stator in order to connect the regulator/rectifier to ?

not sure if the new ones have a charging coil the old ones didnt and was part of the kit

[Steve509926]

I'll find out if I need charging coils or not when I start the project. It's 3rd on my list of things to do.
Nearly finished the 1st project - a bow box/seat, just needs another coat of paint. I didn't like the builders bucket full of ropes, anchor and bits at the bow. I could never secure it down properly, and this adds a bit more weight to the bow if I'm on my own.
Started number 2 - a couple of seats with back rests to attach to the SIBs benches, I find my back is getting a bit stiff sitting 2 or 3 hours without a back rest.

[jeffstevens763@g]

found this on ebay


https://www.ebay.co.uk/i/322886968602?ul_noapp=true

[Steve509926]

Thanks Jeff, it says its for 2 stroke OB, but I will email the seller to see if he's got one for my 4 stroke.

[Steve509926]

Originally Posted by Pikey Dave

Dunno about your specific engine, but I’ve just done something very similar with my pull start DF20a & used a 20Ah Poover Lithium battery. The battery is fussy about its charging voltage, so I added a Buck regulator between the engine & battery to maintain the charging V at 12.7V.

Hi Dave, did you fit the Buck regulator in the battery box?

[Pikey Dave]

Originally Posted by Steve509926

Hi Dave, did you fit the Buck regulator in the battery box?

Yup, I think there’re some photos on my Volaire build thread. If not I’ll get some tomorrow.

[jeffstevens763@g]

Originally Posted by Steve509926

Thanks Jeff, it says its for 2 stroke OB, but I will email the seller to see if he's got one for my 4 stroke.

Not sure there's a difference but worth a call

[smallribber]

I still think that kit assumes that your Stator has a separate take off for a charging (or Lighting coil). That is just the wireing and rectifier that converts the AC from the stator to regulated DC at 14ish volts to charge a battery. You need an AC Source and that can only come from the Stator

[smallribber]

This is an example with the Stator included. If of course your outboard already has the 'spare' take of from the Stator that will be ok. If not you would need to have a new stator with such a take off.

https://www.ebay.co.uk/itm/Alternato...QAAOSw5BNeWVD0

[smallribber]

To be honest given that a small 7 amp hour battery will run a chart plotter for quite a long while I feel that this type of conversion is not money well spent

[Steve509926]

Originally Posted by smallribber

To be honest given that a small 7 amp hour battery will run a chart plotter for quite a long while I feel that this type of conversion is not money well spent

You obviously didn't read the beginning of the thread properly!

[chipko]

Must admit, I also thought the same, and did indeed read the start of the thread.

We have a small 20ah 12v li-ion (Poover) battery which runs the Garmin chart plotter for 65+ hours. Located in the obligatory under seat sarnie box with usb and 12v accessory sockets, we’ve recently done three full days boating on one charge, and it’s nowhere near dead yet. This included running plotter, charging phones and topping up tubes.

Am I correct in thinking, if your motor has a charging circuit, you should not ever run it without a battery connected.

[Pikey Dave]

Originally Posted by chipko

Am I correct in thinking, if your motor has a charging circuit, you should not ever run it without a battery connected.

Nope, you can run the engine “sans batterie” what you mustn’t do is connect/disconnect a battery with the engine running.

[Steve509926]

Hi Chipko, did the 3 days boating also include 2 nights wild camping? That's where I think I would use most of the battery power.
However, maybe 2 batteries may be the answer to what is yet a non existant problem!

[chipko]

Ok, thanks PD.

Steve, no didn’t include nights....tent on a campsite with electric hook up....too nesh at this time of year for wild camping.

We also have two batteries. Very light at 1.2kg so no bother carrying a spare in the kit bag.

[Steve509926]

"too nesh at this time of year for wild camping"

So am I !!!! I'm talking about April 2021 at the earliest.

At that weight, 2 or 3 battery's may be the easier way to go.