Charging System Output

[scatgo]

Got myself a boat a few months ago and after installing a new battery I hooked up a volt meter to the battery with the engine running and the meter did go up but only a fraction of a volt. I did this in my driveway with the garden hose hooked up to the engine so I didnt rev the engine much above idle. It has a 1980 johnson 35 HP on it. Just how many volts should the charging system on this motor give up?

 

[GA_Boater]

What is the voltage you read with the motor running?

 

[scatgo]

About 12.010 volts

 

[scatgo]

Anyone have this information?

 

[tblshur]

scatgo either your battery is bad or your voltmeter

 

[achris]

scatgo either your battery is bad or your voltmeter

Nope. Old 'unregulated' charging system.

The maximum output is only about 6 amps, and under normal conditions the output at idle is very very low, less than 1 amp. At idle, it would take HOURS to recharge the battery just from the power drawn to start it.

Check the voltage again after you've been running around for a couple of hours at 3 or 4 thousand revs. And don't be surprised if the voltage is up over 15 volts. That's normal for an unregulated charging system, and why you should only ever be using a proper MARINE battery on older outboards. Use a car battery and you'll find it'll overheat, buckle plates, develop internal shorts, and explode! Not a good way to end the day...

Chris.......

 

[scatgo]

Thanks. We did get a new marine battery when we got the boat. The person we got the boat from said he switched it over to electric start with the charging system that would come with it. It has a rectifier. Would that still be unregulated? If so are there any upgrades that would help?

 

[achris]

Rectifier only converts AC to DC, it's an unregulated system. That's how they came. Not sure what sort of upgrade you want to do. People have been using outboards with unregulated charging systems for over 50 years, and as long as you have a proper marine battery, they aren't a problem.

Chris....

 

[scatgo]

Thanks for the information. Found this. https://www.boatingmag.com/convertin...arging-system/ Not sure if I will bother getting there rectifier every thing is seemes to be ok as is. And I installed a voltage stabilizer for my radio and fish finder. Just dont want a dead battery at a bad time. Looks like from all I am getting overcharging is more of a problem than to have a dead battery.

 

[achris]

Just read the document. I can tell you, the only way their 'regulator' can work is by dumping the excess current off as heat. That little box of theirs is going to get mighty hot! Even at 6A, that's about 85W, and it has to go somewhere. As it's a stator winding and magnets, there is no way to reduce the output, as a car style alternator does. It can only be dumped. Merc used the same sort of thing on the old 470 4 cylinder stern drive engine. Those regulators were water cooled, and still managed to fry themselves on a regular (and expensive) basis.

A nice big battery, or 2, and anything you can add as a load. You should also install a voltmeter so you can keep an eye on it.

Chris.........

 

[sam am I]

Just read the document. I can tell you, the only way their 'regulator' can work is by dumping the excess current off as heat.

In regards to perm mag (magneto) charging systems, if it is SHUNT type rec/reg, yes!! you're quite correct but, this is pretty old school though. Not really done so much anymore..See old mercrusier perm mag water cooled rec/reg stuff.

However with PHASE CONTROLLED type rec/reg's (used by Merc, Yamaha, Honda, Polaris, etc, etc ), this is not true. With phase controlled rec/reg (1 or 3 phase), the perm mag output is only electronically connected (thyristor/FET) to the load (battery etc) on a phase by phase basis(quite similar to squirrel house heater controllers....lol, funny that!!). With the addition of a battery (and feedback) now connected through this type of rec/reg, this integrates to a smooth varying regulated DC output dependent on load, no shunt needed., thus no real appreciable heat.

CDI has always touted themselves as some sorta Masyiah of all things stator, switchbox and rec/reg (and even DVA meters) but, IMHO is no more then a reverse engineering over priced Pariah. Here again, they've merely copied(re-branded) what has been being done for many many years ahead of them but, claim(imply) they have some new magic YOU need and can only get from THEM!! Not even close........

 

[achris]

In regards to perm mag (magneto) charging systems, if it is SHUNT type rec/reg, yes!! you're quite correct but, this is pretty old school though. Not really done so much anymore..See old mercrusier perm mag water cooled rec/reg stuff.

However with PHASE CONTROLLED type rec/reg's (used by Merc, Yamaha, Honda, Polaris, etc, etc ), this is not true. With phase controlled rec/reg (1 or 3 phase), the perm mag output is only electronically connected (thyristor/FET) to the load (battery etc) on a phase by phase basis(quite similar to squirrel house heater controllers....lol, funny that!!). With the addition of a battery (and feedback) now connected through this type of rec/reg, this integrates to a smooth varying regulated DC output dependent on load, no shunt needed., thus no real appreciable heat.

CDI has always touted themselves as some sorta Masyiah of all things stator, switchbox and rec/reg (and even DVA meters) but, IMHO is no more then a reverse engineering over priced Pariah. Here again, they've merely copied(re-branded) what has been being done for many many years ahead of them but, claim(imply) they have some new magic YOU need and can only get from THEM!! Not even close........

I'd love to throw my oscilloscope on one of those. Even with a big battery, it's going to be as noisy as all get out!

 

[sam am I]

Differently do!! Grab just about any OB from the 80's forward and yes, they are very noisy but only visually. The switching is primarily the highest contributor of the noise but has such very fast rise times (nano seconds) "spikes", it's usually not an issue. These spikes are periodic obviously because it switches cycle by cycle, to which translates to just a ton of high freq hash on the screen.

Your electronics on your boat would typically have/be the only issue BUT rarely cares, every once in a while though you'll read of someone hearing whining in a amp or vhf or something or sees crazy crap on a FF screen but it's rare.

As stated, we've been and are running this technology rec/reg on perm mag charging systems in our OB's, motor cycles, ATV's, side by side since perhaps back to the 80's.

The primary heat these type devices generate is just the junction of the electronic switches (Thyristor/FET) getting heated due to the junction's resistance when turned on when careering higher current (charging low battery etc). However with the super low R-on we have today's in our FET technology, the heating is so low it's almost become non-existent. See Shindengen's FET phase controlled rec/reg's....

An analogy here that might help is switching power supplies........For example, in most of these kid's high power audio amps (or DAC's) they use switching power supplies to boost 12V up to make +/- 30, 40, 50V rails for the audio drivers. These have hella-tons of high freq switching noise/ripple on the switched DC side of the amp's rails but its so freaking high, the speakers electromagnetic conversation can't respond to it, human ears can't respond it, thus they don't even know/can't hear it and thus, don't care.