Charge kit on 30hp Merc outboard

[Mickldo]

I have a 30hp Mercury Lightning 2 stroke outboard (rebadged Tohatsu) on my 4.1m Quintrex Tinny. I have never had a charge kit on it but I was chatting to the local Tohatsu dealer today about getting a charge kit to keep my battery charged. He said the genuine charge kits are about $120 but there is a cheaper way.

Under the flywheel there is an AC coil already and there is two spare wires in the harness ready to go. A yellow wire and a white wire. All that is needed is a bridge rectifier. He told me the local electronics store sold them. So I went down and got one of these http://www.dse.com.au/cgi-bin/dse.storefront/46e8e4b8058bb620273fc0a87f9c074f/Product/View/Z3336

It is a bit hard to see in the photo but there is four male spade terminals. I assume two for the AC voltage in and two for the DC voltage out. Would I be right in assuming the two on the right side next to the AC mark would be for the AC in side? Does it matter whether the yellow or white wire goes on which terminal? I also assume the DC out side is on the left and the one marked + is for the DC positive and the unmarked one is the DC-.

I don't have my multimeter at home here ATM but hopefully the outboard is only putting out 12-15V and I wont need a regulator as well.

Does anyone have any experience with fitting charge kits to small outboards? Are all of my assumptions correct? Can I really **** things up by hooking the wrong wires to the wrong terminals? The bridge rectifier was only $5 but I don't want to wreck the outboards charging coils or whatever.

Gratuitous pic of my boat

 

[Mickldo]

I forgot to add in the OP that I am also not 100% sure whether this bridge rectifier is suitable for this application. The girl that served me at the electronics store knew about as much as me on the subject (ie nothing).

The one I got is 400 V 35 A. Is this suitable for the application? The guy at the boat shop said it would be about $16 so when I only paid $5 the doubts started to whether I got the right one or not. At least this one will be easy to mount on the outboard with the mounting hole in the centre.

 

[yooper]

You don't carry a multimeter in the Cruiser?

Yeah I got nuthin'

Let us know if it works. I wouldn't mind doing the same thing on my outboard, a Mercury 9.9HP 4 stroke. I'll eye the electricals in there this weekend....

 

[Mickldo]

You don't carry a multimeter in the Cruiser?

Yeah I got nuthin'

Let us know if it works. I wouldn't mind doing the same thing on my outboard, a Mercury 9.9HP 4 stroke. I'll eye the electricals in there this weekend....

Hey Yoop

The multimeter lives in my carry tool box which lives at work all week, I only bring it home on weekends.

I'm going to check it out this weekend. I got a bilge pump today too that I have to fit.

 

[fsusteve]

I don't have an answer either, but I don't think it matters which way you hook it up, I'd still try and verify that though. I was given an old merc years ago that had elec start on it, the guy had crossed the battery cables on it and left it, fried everything and I mean everything, so be careful with it.

on a side note I have a 9.9 Tohatsu, I love that motor, what a torquey little monster.

 

[Brindleboxer]

Mickldo,

Before hooking up the bridge you might need to do a little more research into your circuit and the bridge that you have purchased.

Most bridges have marking for the negative input but you do not state yours has a marking. The basic concept is that the positive and negative are opposite on the bridge so if your + terminal is marked then theoretically you would go cross corner and that should be your - terminal. This leaves the other two post as your input/ouput for the system.

I cannot get really techincal and would probably bore people if I could (I am not an electrical engineer or anything) but the whole purpose of the bridge is to allow an AC system to have DC capability (this is the shortend version). So your motor seems to already be wired to accept this you just need to add the brdige and exploit the existing wiring.

Glen

 

[Mickldo]

I don't have an answer either, but I don't think it matters which way you hook it up, I'd still try and verify that though. I was given an old merc years ago that had elec start on it, the guy had crossed the battery cables on it and left it, fried everything and I mean everything, so be careful with it.

on a side note I have a 9.9 Tohatsu, I love that motor, what a torquey little monster.

Mickldo,

Before hooking up the bridge you might need to do a little more research into your circuit and the bridge that you have purchased.

Most bridges have marking for the negative input but you do not state yours has a marking. The basic concept is that the positive and negative are opposite on the bridge so if your + terminal is marked then theoretically you would go cross corner and that should be your - terminal. This leaves the other two post as your input/ouput for the system.

I cannot get really techincal and would probably bore people if I could (I am not an electrical engineer or anything) but the whole purpose of the bridge is to allow an AC system to have DC capability (this is the shortend version). So your motor seems to already be wired to accept this you just need to add the brdige and exploit the existing wiring.

Glen

Thanks guys for your replies. I didn't get a chance to do anything on it this weekend as I had a Bucks Party to go to and the hangover was a doozy.

Brindleboxer, are you saying you believe the - post to be diagonally opposite the + post? I will have to confirm this before I try and hook it up. I was thinking it would be the one next to it but what you are saying makes sense. Time to do more research.

 

[Mickldo]

Ok I finally hooked up the rectifier. I checked the layout of the rectifier with my multimeter and figured out that the way Brindleboxer descibed was the way to do it. The two AC wires get hooked to the post marked AC and the one diagonally opposite it. The DC + gets hooked to the one marked + and the DC - gets hooked to the remaining post, the one diagonally opposite the +. I hooked it up and then started the outboard up on the muffs. Without the battery hooked up the voltage coming out of the rectifier was about 11V DC at idle and quickly came up in voltage as I revved it. I think it maxed out at about 50V DC during one blip of the throttle. I hooked up the battery, which had been sitting for a while and was reading 11.6V at rest. With the battery hooked up at idle it read about 11.8V and as I revved it came up to about 13.8V but I didn't let it run for too long as I didn't have enough water flow through the muffs and the tell tale wasn't working so I shut it down before it got to hot.

Will I need a regulator fitted to ensure the battery voltage doesn't get too high?

The 50+ VDC that I got with no load is scaring me a bit. I remember a few years ago a mate was having problems with his sounder that apparently were caused by excessively high voltages (18VDC + IIRC). A motorbike I had once had a really small regulator that might be able to be fitted, hopefully I can still find ithe spare one I had for it down the shed.

 

[yooper]

Mick I would try to find a regulator. Any automobile regulator for a 12V system should work. It will keep you from frying whatever else you hook up to that battery and keep you from overcharging it.

 

[Mickldo]

Mick I would try to find a regulator. Any automobile regulator for a 12V system should work. It will keep you from frying whatever else you hook up to that battery and keep you from overcharging it.

I think the little regulator I have down the shed is a 6V one the more I think about it. It is a nice compact unit with good heatsinks. I think it would withstand the marine environment a bit better than an automotive one. I might have to visit the bike shop (you know how much I hate going there) and try and find a similar one in twelve volts.

 

[semlin]

mick

i did what you did with a suzuki 55dt manual start commercial skiff motor on my old boat. there was no charge kit indicated but an obvious spot for one on the side. I bought a stock suzuki rectifier off an old dt65 hulk at the dealer for $50 then installed it in the spot it fit perfectly and hooked it up to matching wires in the harness.

it worked fine but i had a voltmeter and the voltage was unstable and often over 14 volts. by the time i sold the boat 7 years later I had put in two more rectifiers and two batteries. I actually disconnected the third rectifier and would only hook it up once every couple of weeks to charge the battery. it took me that long to discharge the battery using a fish finder and nav lights.