Outboard voltage output regulator

diver 1 · 21 February 2011, 02:11

I have an early 90´s Mariner 40, 2stroke outboard, serial number 6EM...

The voltage output varies from 8volts at low revs to 16+ volts flat out.

I´ve been reading lots of posts on here regarding similiar stories.

I´ve re-wired my boat so that the feed from the engine goes to a large 75amp 12volt car battery then an isolator switch, then a fuse box, then feeds off to the instruments.

I still not that the voltage reading on my Lowrance equipment varies significantly at different engine speeds and I´m sure this can´t be good for the fish finder / gps etc..

Would a standard voltage regulator such as this on on Ebay Item no. 310281692683

Fitted in line with the positive lead from the engine, stabilise the voltage to more consistent 12 ish volts, or do I need something else?

Thanks

jyasaki · 21 February 2011, 07:52

Don't think a 12V regulator would work, as it won't have enough input to give you an output when the motor's not running.

Lowrance stuff is supposed to work from 10 to 17VDC, so as long as you stay within that range, your Lowrance unit should be happy (if it doesn't, I think the unit simply shuts down.)

jky

DJS · 21 February 2011, 10:02

[QUOTE=diver 1;389686]
Would a standard voltage regulator such as this on on Ebay Item no. 310281692683

Fitted in line with the positive lead from the engine, stabilise the voltage to more consistent 12 ish volts, or do I need something else.

Hi There

Voltage in this range (16V) may be a little high and I would check this independently with a multi-meter as normal voltage is between 13.5 and 14.5/15V. If the voltage is too high it will eventually damage the Battery.

If you were only putting in 12 volts into your battery it would eventually become flat. Therefore the system has to generate more voltage than the battery's rated voltage to overcome the internal resistance of the battery and thus permit charging. The variance in the regulator is there to take account of the draw you are putting on the battery and the residual level of charge. In essence if you are drawing significant amps form electronics or draining the battery from constant short stop starts, this will result in a higher charge rate. It would also be useful to check the condition of the battery by using a high rate discharge or specific gravity test for each cell.

Ill hang up my cagoul now and all the best

donald463 · 21 February 2011, 10:22

I had this problem with a Suzuki 15 HP outboard causing Plotter to display overlaod voltage. I fitted a 24v to 12v regulator designed for lorries etc between outboard charger lead and battery. Ran all electrics directly from battery. Problem solved never more than 13.8volts. More than enough to keep battery charged.
Item number: 170447617324 is similar. Also check out solar/wind regulators.

DJS · 21 February 2011, 10:34

[QUOTE=donald463;389707] Ran all electrics directly from battery. Problem solved never more than 13.8volts. More than enough to keep battery charged.

All electrics should be from the battery-perfect

donald463 · 21 February 2011, 16:55

All electrics should be from the battery-perfect

[/QUOTE]

Manual start outboard and only nav lights and fish finder NO battery fitted when purchased.
Not the best way to make newbies welcome!!

DJS · 21 February 2011, 17:24

Quote:

Originally Posted by donald463

All electrics should be from the battery-perfect

Manual start outboard and only nav lights and fish finder NO battery fitted when purchased.
Not the best way to make newbies welcome!! [/QUOTE]

I think something has got lost in translation here as I was agreeing with your previous post!

Oh and welcome:

jwalker · 21 February 2011, 20:11

Check your wiring harness. The charging output on some of those engines was simply AC and intended for powering nav lights. From memory, the AC output was via a pair of green cables which came down from under the flywheel. If this is the case, the output needs to be rectified to convert it to DC (though it will be bumpy DC) then it requires a voltage regulator for battery charging. The fluctuating DC will be smoothed by the use of a battery.

Vandad · 24 February 2011, 00:24

DO NOT TRUST YOUR lowrance!!!!

I had exactly similiar problem! On the screen it was showing random number up to like 18V! and I thought my regulator is dead! It was just loose connection in the actual device NOT the main electrics!

Buy a voltmeter, check your battery voltage when the engine is off. It should read between 11.5V - 13V. (11.5 means your battery is not fully charged).

Once you switch on the engine, it should go up to about 14V (or even 14.5V)

ANDDDDD

You must see a difference between low idle voltage and when you rev the engine.

Hope it helps.

diver 1 · 16 March 2011, 16:37

The engines have the pre-described green wires coming out from beneath the flywheel these then link to a black box of electronic wizardry on the engine then continue to the battery...

When I use a voltmeter to check the voltage I get a reading of 26volts for AC and 14 volts for DC at fast tickover.

What is the best way to determine if it is DC or AC voltage? I only have a basic voltmeter...

Thanks

donald463 · 16 March 2011, 19:51

Would expect output to be DC but you can only be certain with an Oscilloscope.
Can you see that output is coming from a rectifier? this would make it DC.
Is there not a circuit diagram in your handbook?

doggypaddle · 16 March 2011, 21:56

Measure the leads with the diode test function on your digital multimeter. you should measure open circuit one way, and about 1.2volts drop the otherway. this proves the presence of a rectifier voltage drop. if you get continuity both ways then its an AC output and needs a Rectifier adding. If its a low wattage output called a lighting output, then a regulator isnt nesscesary as the battery will clamp the voltage down to 15 volts maximum, as the battery reverse impedance falls rapidly at over this voltage.

Turbodiesel · 16 March 2011, 22:14

You have AC power coming from under the flywheel, and (as i have not read all the answers etc) im guessing manual start engine? If its manual start you will have no regulator/rectifier fitted which you will need.

Outboards do have a very low output at tick over so to get round this you can fit a large capacitor to give you a better constant power. Really the best way to get regulated power would be to get the engine to charge a battery and run everything from the battery.

jwalker · 17 March 2011, 02:02

Quote:

Originally Posted by diver 1

The engines have the pre-described green wires coming out from beneath the flywheel these then link to a black box of electronic wizardry on the engine then continue to the battery...

When I use a voltmeter to check the voltage I get a reading of 26volts for AC and 14 volts for DC at fast tickover.

What is the best way to determine if it is DC or AC voltage? I only have a basic voltmeter...

Thanks

I suspect you've got rectified AC but not voltage regulated. The rectifier effectively inverts the negative going part of the AC waveform so you have pulsing dc current. I think your meter is reading the peak voltage of the wave when set to AC and reading more of an average when set to dc. Since I have no knowledge of your meter, that's a best guess.