Can I use a 10 amp rectifier in place of 35 amp on crossflow V6?

[cleger]

Hi, long-time lurker and beneficiary of the invaluable info found here. Thanks. This is my first post.

I've read many posts on the subject of tachs, rectifiers, etc. I have a 1985 Johnson GT150. I believe my water-cooled regulator/rectifier is blown. Tach doesn't work, and last year, I was having charging problems.

I bought a new regulator, but haven't had a chance to install it, and now I'm afraid I'm out of time. We leave tomorrow for 2 weeks on the lake, and I'm reluctant to start on pulling the flywheel, etc. Also I'm a little worried I'll disturb something under there (magnets, stator, etc) that might lay the boat up for more than 2 weeks.

So, I've seen it posted elsewhere that in some cases (different engines) folks can get away with installing 10 amp external rectifiers? My main concern is that I'm going to burn up the harness & more if I leave my blown regulator in place. Can I put a 10 amp rectifier on for a couple of weeks? I swear I'll install the proper one when we get back! My boat is a 17' Baja and the only electrical accesories on it are the tilt/trim, lights and horn.

Thanks in advance!

Chris Leger

 

[Joe Reeves]

Re: Can I use a 10 amp rectifier in place of 35 amp on crossflow V6?

If you're speaking of the small three wire rectifier that attaches to the engine with two screws.... No you can't do that. It's been tried and that 35 amp stator will actually melt it within seconds.

 

[cleger]

Re: Can I use a 10 amp rectifier in place of 35 amp on crossflow V6?

Argh. Just as I feared. Yeah, I meant the little rectifiers.

Thanks very much for the quick reply, Joe!

 

[iwombat]

Re: Can I use a 10 amp rectifier in place of 35 amp on crossflow V6?

Well . . .

You could if you put some current drains between those yellow wires and ground. Three resistors and and a capacitor for each one is all you'd need.

But, I don't think you really want to go there.

 

[cleger]

Re: Can I use a 10 amp rectifier in place of 35 amp on crossflow V6?

Well, let me put it this way... which approach presents less risk of fire or other catastrophic failure: leaving the burnt regulator in there, and keeping my fingers crossed, or cobbling together what you're describing?

Radio shack is nearby and has drawers full of big wire-wound resistors, etc.

Thanks!

 

[iwombat]

Re: Can I use a 10 amp rectifier in place of 35 amp on crossflow V6?

A fried regulator poses no safety risk, you just won't charge the battery.

I'd need good specs on the stator output and some quick arithmetic to put down a wiring plan for you. I'd just run the bad regulator and charge the battery at the dock until you can do it right. Might want to carry a portable jumper on the boat just in case.

 

[cleger]

Re: Can I use a 10 amp rectifier in place of 35 amp on crossflow V6?

Ah, OK, thanks very much. That's what I've been doing (well, minus the jumper.)

Last year I was just charging the battery every couple of days, as needed.

I was basing the whole safety question on posts I thought I remembered reading here where people were being warned not to postpone replacing failed rectifiers, as they could catch fire, etc. That was the main source of my concern. (Though how mine could catch fire from inside the water jacket & under that plate is beyond me... maybe those posts were refering to the very 10 amp external rectifiers I was asking about. Still, I was concerned about cooking the harness.)

As far as charging & so forth goes, that's not a problem. It isn't far from the dock to the deck!

Also thought I understood from my reading that my failed regulator might be the cause of the "high speed miss" I've been experiencing, but that doesn't concern me too much, as it only occurs intermittently at full throttle, but seems fine at about seven-eighths. Frankly, 60+ mph in my 17 foot boat is a little spine-tingling on Lake Winnipesaukee anyway, so no big disadvantage there.

I should mention again, I've netted a lot of benefit from lurking here for the past couple of years. This forum has been of very real help to me troubleshooting a number of minor problems. My thanks to you and Joe, as well as all the folks who have posted in the past asking and answering questions about problems analogous to mine! I guess there's nothing new under the sun.

Many thanks, and best regards.

 

[Silvertip]

Re: Can I use a 10 amp rectifier in place of 35 amp on crossflow V6?

Those better be big resistors if you plan to waste 25A across them.

 

[HighTrim]

Re: Can I use a 10 amp rectifier in place of 35 amp on crossflow V6?

There is always solar power, lol

 

[iwombat]

Re: Can I use a 10 amp rectifier in place of 35 amp on crossflow V6?

I actually started designing a circuit for you, but soon realized radio shack wasn't going to have any capacitors capable of shunting 35amps and surviving the heat. I can do it with only three caps, but they'd be d-battery sized.

Best laid plans of mice and men and a' that.

 

[iwombat]

Re: Can I use a 10 amp rectifier in place of 35 amp on crossflow V6?

Solar isn't a bad idea, really. I have a solar panel I use on the battery for my electric motor. I can get back about 1/4 charge over the course of an afternoon. The panel is about 20"x20" or so. You can get 'em at any outdoor/RV/camping type store.

 

[cleger]

Re: Can I use a 10 amp rectifier in place of 35 amp on crossflow V6?

Ha! I'm just afraid once I set down a path like that one, there's be no turning back... next thing you know we'd have a 2-stroke cook stove hanging off the transom.

Thanks for starting on that circuit. The charger is already packed away. I think we'll be good for the 2 weeks.

 

[iwombat]

Re: Can I use a 10 amp rectifier in place of 35 amp on crossflow V6?

I don't know about a cook stove, but a 2-stroke washing machine might be handy.