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rectifier vs regulator

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mike Brehmer

New member
'94 merc 60 hp voltage regulator was fried. just replaced it witha rectifier from a '92 merc. seems to be working fine. anything I should watch for or worry about?
 
I was horrified to lately measure the voltage coming out of my 70 Merc triple: 17 volts! Gaaa!

I've since learned that this is common to these non-regulated set ups and does not cause problems. Hell, I ran it that way (apparently) all last summer without boiling the water out of my lawn mower type battery.

Jeff
 
your lawnmower type battery is the reason you didnt have problems jeff....it normally takes time to fail anyway..for some unknown reason once you drop one rectifier it gets more frequent after that...i suspect its when a person goes to a new battery....most of us go to buy a battery and get the best in the store for the boat.....thats exactly the opposite of what we need to do with the rectifier only system...
 
it's a choice.

If you use a rectifier then your battery acts as the voltage sink and does not last as long. If you use a regulator then your regulator acts as the voltage sink and does not last as long. Rectifiers only fail when you hit them with a hammer and break off the connection tabs. Regulators overheat and melt. Radio Shack rectifiers cost $3.50, good regulators cost $60, and Wallymart marine batteries cost $40

That said ... the real benefit of regulator is that it protects electronics against bad battery connections. As the engine revs, the output from your stator increases. If the battery has a corroded or loose connection then the over-voltage is not controlled and can cause damage to computers, electronic ignition, gps, depth finders, stereo, etc. The benefit of rectifiers is that they never break and when your battery cable is going bad it gives you ample warning (weeks, if not months). Consequently, the chances of ever needing a tow home due to dead electricity are significantly less with rectifier. The cost of disconnecting the battery with engine running are significantly less with regulator.

IMO, which choice is best depends upon the boat and the boater.
 
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This is all great information. I just rec'd a price for a new voltage regulator which is on back order. 193.00 plus tax. With no guarantee it will last. A new battery each year cost 100$. I like to replace them every year or so. I just want to go fishing without that stupid alarm going off. I will hook my fish finder to my other battery if I have to. My fish finder does have a fuse though. won't it blow before i ruin the fishfinder? You guys are great. tks for all the info.
 
A new battery each year cost 100$. I like to replace them every year or so.
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There are good wet cell (add distilled water as needed) batteries available for $69 and up...3 years is the avg. life span of a good battery; why spend the extra money? Each season check each cell w/a 5 ball glass tube battery charge tester when the charger says it is fully charged. With 4-5 balls floating in each cell the battery is still good enough. If you find one cell w/darkened acid containing cell fragments, get a new battery because it is going to crap out soon.

I will hook my fish finder to my other battery if I have to.
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Excellent choice...it is isolated from the perils of the OB charging system and won't discharge the battery due to low current consumption.

My fish finder does have a fuse though. won't it blow before i ruin the fishfinder?
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No, just the opposite...the fuse protects the boat wiring and battery from an internal short or increased current draw from the fish finder. Since FFs are solid state, integrated circuits they are quite reliable.
 
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the rectifier is fed by a separate winding in the stator and has nothing to do with the running of the boat...its purpose is strictly to charge the battery....and feed the tach.....the sealed and the gel batteries have no internal discharge as did the older type batteries...so they will accept a higher charge..thats putting it simple....there are more sophisticated explanations out there.....and if the owners manual is read the rectifier only motors call for a battery that is hard to find now... ....to run an expensive hi amph battery is the kiss of death for a rectifier....it just dont happen overnight but if you look at your voltmeter and it is running 16-17 volts it is going to happen....the only good thing about is that it is not going to strand you because the battery is fully charged when the rectifier blows..
 
guyjg said:
Correct, they usually just short out and send AC volts everywhere.
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not true. a square bridge rectifier is one of the most bullet proof electronic devices ever made. The forward voltage drop is only 0.7V so it takes an incredible amount of current to overheat one. Your stator will melt before a decent square bridge even starts to get warm. If a rectifier "breaks" it can usually be traced back to bad wiring or physical abuse.
 
mike Brehmer said:
This is all great information. I just rec'd a price for a new voltage regulator which is on back order. 193.00 plus tax. With no guarantee it will last. A new battery each year cost 100$. I like to replace them every year or so. I just want to go fishing without that stupid alarm going off. I will hook my fish finder to my other battery if I have to. My fish finder does have a fuse though. won't it blow before i ruin the fishfinder? You guys are great. tks for all the info.
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that's a good question about fishfinder fuse. i would guess probably not. You can damage sensitive electronics with too much voltage even at low amps. However, most electronics should have some form of voltage regulation between the 12VDC and the circuits. Cheap electronics would probably skip the regulator in order to cut costs.
 
guyjg said:
There are good wet cell (add distilled water as needed) batteries available for $69 and up...3 years is the avg. life span of a good battery; why spend the extra money? Each season check each cell w/a 5 ball glass tube battery charge tester when the charger says it is fully charged. With 4-5 balls floating in each cell the battery is still good enough. If you find one cell w/darkened acid containing cell fragments, get a new battery because it is going to crap out soon.


Excellent choice...it is isolated from the perils of the OB charging system and won't discharge the battery due to low current consumption.

No, just the opposite...the fuse protects the boat wiring and battery from an internal short or increased current draw from the fish finder. Since FFs are solid state, integrated circuits they are quite reliable.
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a guy in the battery business told me that there are really only two or three companies that make batteries and everybody just puts their private label on the same battery. So I asked him the obvious question - "you mean the walmart special is the same battery as the pep-boys deluxe? just a different name on the sticker?" He said "yup". I've been buying $40 wallybatts ever since.
 
I was a buyer for a municipality that ran its own utilities...gas, water, sewer and electric...and mass transit system and ran its own fulltime police and fire depts. I was involved in the procurement of everything from AAA batteries to fleet vehicles that included cars, trucks, buses, firetrucks, and everything needed to run the utilities including coal fired steam turbine generators and hydro generators.

My point is there ARE differences in similar products especially batteries. Manufacturers require explicit specifications to build items for different segments of the market. Not ALL batteries are made to the same specifications...albeit many are branded differently off of the same run/mfg. line...i.e...Wally-World, Ace Hdwre, JoMommas Batteries, K-Mart, etc. One example is battery plate size...if Wally-World can shave off 2MM of every battery plate purchased they have made a savings of X amount. The buyer shares in the savings and also returns millions of failed batteries. They did not fail prematurely but did so based upon their design standard. If your Wally-World battery lasted longer than 24 months then it surpassed the designed lifespan.

I have seen Ford batteries last longer than 60 months, Toyota batteries last 60 months, AC Delco batteries last 84 months and my current Snapper Mower battery is in its 7th year. I've also seen the same batteries fail within one year or last any number of months. Battery lifespan is dependent upon how the battery is designed, manufactured, packaged, shipped, handled, installed and maintained. A simple cushion of 1/4" rubber bushings installed under the battery on its corners can extend its life by reducing vibrations that damage cells. I can continue but have made my point. If you are happy w/a certain battery...enjoy it but always carry a quality set of jumper cables.
 
agree guyjg....the rectifiers used on these rectifier only systems run so hot when everything is running normal that they use the motor block for a heat sink.....we not talking cape canaveral quality here on these rectifiers......i am outa here on this discussion...enjoyed and always learn something.....
 
a battery on the old submarines lasted forever....had a designated guy to care for them....one battery failure was bad...2nd one someone lost a stripe...
 
I just rec'd a price for a new voltage regulator which is on back order. 193.00 plus tax.
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Make sure you apply the heat sink dielectric grease to the base/back of the regulator when you install it. If the seller did not include a small foil pack of it w/the regulator you can buy it at any electronic store.
 
It's all in not letting the water levels get too low--which means your battery HAS to have removable caps. Running them down too far, too often, is another battery killer--you need to maintasin at least 75 % full charge at all times (except for deep discharge batteries).

Overcharging is NOT a major problem IF you keep the water levels up, for overcharging boils the water away. Took me a while (and $$$) to learn that!

jeff
 
papyson said:
agree guyjg....the rectifiers used on these rectifier only systems run so hot when everything is running normal that they use the motor block for a heat sink.....we not talking cape canaveral quality here on these rectifiers......i am outa here on this discussion...enjoyed and always learn something.....
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you are confusing rectifiers with regulators.
Power = voltage x current

a silicone rectifier can only have 0.7V. That is it's "turn on voltage".
if your stator puts out 20A at 18V then the rectifier must handle (0.7v) x (20A) = 14Watts

For a regulator, the voltage is (input - output)
if your stator puts out 20A at 18V then the regulator must handle (18v-13.5v) x (20A) = 90Watts

90watts is a lot for any single electronic device to dissipate without damage.
Your regulator is going to need BIG heatsinks to survive. maybe even water cooling.
14watts is hardly anything for the module package (1" square with four tabs).

if your rectifier is running hot then it is either getting hot from the engine heat or has been ineptly installed.
 
Regulators regulate bringing voltage down to 14.7 ish volts rectifiers rectify (change ac alternating current to direct current dc) running open voltage can increase with speed and can fry electronics. change with right parts and save yourself the cost and head ache of future problems and then having to replacing it with right part later
 
As I said before My regulator on my 94 merc. 60 hp. was fried. I had a rectifier from a 92 Merc 60 hp. It fit in the same slot which had the holes for either. I ran it on the weekend and the voltage varied on the meter form 14.5 to about 16.5.

The alarm went off after a while which drives me nuts. its the steady alarm, not the intermittent one for the oil. I guess I will change the module. I have a manual. Thought the rectifier installation would have gotten rid of the alarm. I guess not. Dam!
 
I believe this over heat could be the cause. maybe thats why the regulator fried???? the alarm only starts after ten minutes or so on the water. I am using oil, I watch my oil resevoir steady. I replaced the gasket on the water pump. the water coming out is warm but not hot. what else is there? I checked the manual and did a test (removing a blue/gray wire to check for a faulty module. I'm just not sure if they mean the module at the bottom of the oil resevoir or elsewhere.
 
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