Full wave or half wave rectifier

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Streffpilot

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So...... Wondering if my rectifier is half or full wave. It's a 1973 mercury 1150.

Thanks
 
Texasmark

Texasmark

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Re: Full wave or half wave rectifier

Only difference is average current output. Half wave, using only one diode sends half the input signal since it only conducts when the AC input is in the positive cycle, in direct current (DC) and yes it is pulsating. Full wave uses a bridge rectifier of 4 diodes rather than 2 and captures both cycles and the output current is doubled for the same stator winding. Obviously the wire size has to accommodate the current, but the number of turns and inductive pickup laminations are the same.

I don't have a clue as I never dismembered a rectifier on an OB but I will bet you that they wouldn't fool around with a half wave rectifier. You get half the current for the same amount of stator capacity and that just doesn't make sense from an engineering economy sense. The diode pack costs pennies, as does a small increase in wire size, and the difference in loading 1 vs 4 diodes into it and changing wire on the winding spindle is immeasurable.

Just curious, why the question?

Mark
 
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Dave1027

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Re: Full wave or half wave rectifier

wired247 said:
Half wave. Pulsed DC,
Click to expand...

Are you sure? That does not sound right. How many connections does it have? A half wave would only have two as it's only a single diode.
 
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wired247

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Re: Full wave or half wave rectifier

Three and a ground on that one if I am not mistaken. Your'e probably right. Probably full wave PDC from zero. The battery acts as the sink and stabilizes the pulses instead of a capacitor.
 
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Chris1956

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Re: Full wave or half wave rectifier

It is a Full Wave bridge rectifier. 4 diodes, 4 connections.
 
Texasmark

Texasmark

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Re: Full wave or half wave rectifier

wired247 said:
Three and a ground on that one if I am not mistaken. Your'e probably right. Probably full wave PDC from zero. The battery acts as the sink and stabilizes the pulses instead of a capacitor.
Click to expand...

True but the battery doesn't care that the input is pulsed like a piece of electronic gear would care. You are just pumping energy back into it and the pulses will do that just fine.

Mark
 
mercurymang

mercurymang

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Re: Full wave or half wave rectifier

My 650 had no VR on it and the rectifier crapped out. I was putting some equipment on it and wanted a regulator on it. I bought a generic one and I now where in the documentation did it state whether it was full or half wave. :confused:
 
S

schematic

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Re: Full wave or half wave rectifier

Other than Noa's Arc, I doubt you'll ever find a half/wave charging system on marine. Some air cooled small engines (lawn tractors etc.) used it, but I've never seen one on marine.
- 2 wire stator + 4 diodes = full wave
- 3 wire stator + 6 diodes = full wave
- 3 wire stator + 2 diodes = full wave (one stator lead goes to ground)

Half wave rectification would use 1 diode and would take twice as long to charge a battery comparing to full wave. Half wave rectification was used years ago in old battery chargers. It took longer to charge, but the pulsing effect helped break down sulphation.

I'm sure that all regulator/rectifiers used on marine are full wave.
 
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Streffpilot

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Re: Full wave or half wave rectifier

ok, so just for kicks, (and cuz it only cost $4.50) I put on a full wave, 25A, 50V rectifier from Radio Shack. WORKS WONDERFUL!!!!!

Have yet to test it on a lake, but I am expecting it to work well. Only time will tell if it lasts a while, but at $4.50, who cares if it has to be replaced each year.

I am expecting more felt power too, as It now will have 13.5+ volts vs the 12.5 or less from the battery. I hope to gain another mph or three. :D

let me know if I am expecting too much.
 
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wired247

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Re: Full wave or half wave rectifier

Streffpilot said:
ok, so just for kicks, (and cuz it only cost $4.50) I put on a full wave, 25A, 50V rectifier from Radio Shack. WORKS WONDERFUL!!!!!

Have yet to test it on a lake, but I am expecting it to work well. Only time will tell if it lasts a while, but at $4.50, who cares if it has to be replaced each year.

I am expecting more felt power too, as It now will have 13.5+ volts vs the 12.5 or less from the battery. I hope to gain another mph or three. :D

let me know if I am expecting too much.
Click to expand...


Yeah, I used one for a few years on a Johnson 140. Worked like a champ.
 
GA_Boater

GA_Boater

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Re: Full wave or half wave rectifier

Put the same one on my motor a few months ago. Charges the battery better than my old half broken Merc rectifier and the tach works all the time instead of just higher rpms. For less than 5 bucks, how can you go wrong. I think you choose well, Streff. :D
 
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Chris1956

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Re: Full wave or half wave rectifier

Streff, You did ground the -DC post on the rectifier, right? Your battery will certainely charge better, but don't expect any other changes in the motor.
 
mercurymang

mercurymang

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Re: Full wave or half wave rectifier

Technically with a half wave as opposed to a full wave you would see more voltage drop as load increased. That doesn't necessarily equate to a performance boost though.
 
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Chris1956

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Re: Full wave or half wave rectifier

The way I understand a rectifier is the diodes allow current to pass only one way. Alternating current moves a "short" distance in both directions. Call those directions North and south. So alternating current in the "north" direction passes thru a diode, but the AC going "south" passes thru another diode. Each of these current directions are fed to the battery, north to positive and south to negative (ground). You need one diode pair for each side of the stator, to capture the full voltage and current.
 
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Imjus4u2nv

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Re: Full wave or half wave rectifier

Can anyone provide specific details on how to hook up the full wave bridge rectifier? I have a traditional three post rectifier (mercury 90hp 1986). I am sick of paying 30 bucks for a rectifier and want to switch over to the "radio shack" method, going to purchase a full wave bridge rectifier, guessing the 25a, 50v? Do I also need a voltage regulator with this rectifier?
Thanks in advance!
 
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wired247

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Re: Full wave or half wave rectifier

Yellows to the AC terminals and (-Neg) to ground. Batter Positive to the (+Pos) terminal. Pretty straightforward. You do not NEED a regulator.

FWIW a late potted V6 regulator/rectifier combo can be had under $40 and will last until you are tired of looking at the motor. Easy to hook up and makes your battery last a lot longer with a lot less maintenance.
 
GA_Boater

GA_Boater

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Re: Full wave or half wave rectifier

Two connectors are marked AC, the two leads from the stator are connected to these, makes no difference which lead. One is marked - or ground, this is connected to ground. The remaining one is marked +, is connected to the +12v lead (red?)

You don't need a regulator, but it wouldn't hurt.

EDIT - Wired got you the wire colors.
 
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