hot rectifier

funin the sun

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Nov 3, 2015
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Hello. I just replaced a bad rectifier due to the old one burnt up. Well i ordered a new rectifier and put it on. One day i was running my boat and it just died and would not start back up. Well i was able to locate the issue and the switchbox was shot. So i order a new switchbox and bang. Motor fired up and seems to be running great. Well after about 10-15 mins of just letting it run at idle in my driveway i noticed the rectifier ( the new one i replaced) was kinda hot. Now i know that shouldnt be hot. I know my battery is a little low on charge. When i was looking for the problem when my motor wouldnt start at all i tested trigger and stators resistance and voltage and all checked out to be good. I was wondering if having a low charge battery could be the reason why rectifier is getting hot. Correct me if im wrong. I think with the battery being low on charge the rectifier is over working trying to charge a low battery. Just wanted to get some information on why rectifier is getting hot.
 
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gm280

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funin, hard to tell not being there and testing things myself. But you can read the voltage before and after the engine is started to see if the battery is being charged. And even riv up the engine while reading the battery voltage to see if the voltage goes up with the RPMs. JMHO!
 

funin the sun

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Ok so to do this test i check the battery voltage while the motor is off. ( not running) correct. Then read meter. What should i get for good voltage with motor not running. Then start the motor and check the voltages again. And then rev motor up to what recommended rpm and then i would check the voltages again. Is that the correct way of doing this test
 

gm280

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Ok so to do this test i check the battery voltage while the motor is off. ( not running) correct. Then read meter. What should i get for good voltage with motor not running. Then start the motor and check the voltages again. And then rev motor up to what recommended rpm and then i would check the voltages again. Is that the correct way of doing this test

Funin, you are correct. The initial "engine off" battery reading should be ~12.6 volts or better (if your battery is good and charged). After the engine is running, you should read a little higher then that at idle. And as you run the RPMs up, the voltage should track it for the most part. There really isn't any set RPM to voltage output per say other then the voltage should raise slightly with the RPMs and then you know both the rectifier and stator are good.
 

funin the sun

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Ok i just checked the volts with motor not running and i got a reading of 12.55 i will have to do the test tomorrow to have help reving motor while i check volts.
 

gm280

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Is the rectifier suppose to get hot or even alittle warm when the motor is running

That really depends on what the rectifier is passing through to the battery at the time. As with any electronic component, the higher the current flow, the hotter the part becomes. So if your battery is taking the max output from the stator after it is rectified and passed to the battery, yes, it will get hot. But hot is a relative term. Electronic parts can easily handle hotter temperatures then we can touch without burning ourselves and still work. It is when the temperature exceed the components ability to dissipate the heat, does the component get destroyed. So the answer to your question yes, it can get hot and not burn out. But how long can it do that and how hot can it get is in the rectifier's specifications. JMHO!
 

jbcurt00

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Fun, a note about the posting in old or other members topics:
The reason we discourage it is that although your problem may be similar to someone elses, the details of your problem, how it occured and its possible solution may not be. Things get complicated w motor work, and the process to fix your problem may involve multiple lengthy posts. By piggy backing onto an old topic, what may have been done on the other motor may not be what needs to be done on yours and some (or all) of that info could be irrelevant to your problem. Talking about your motor in someone elses motor topic also changes their topic away from what needs to be done on their motor.

After 90+days w out any posts, consider okd inactive topics closed and for research only.

Also understand that there are significantly fewer experts on iboats w vast knowledge about Chrysler outboards compared to other motors, so it may take longer then you think it should to get good help w your motor.

Frank A is a frequent poster, very experienced and is very helpful w Chryslers, there are a few others as well.

Good luck and dig deep into the archives at iboats and read as many topics as you can as research, just try to take notice of who started a topic and when they last posted to their topic.

If its been over 90days you can use the @ symbol directly infront of their user name, in a post to your topic. Like I've done below w mine:
@jbcurt00

This sends me a message indicating my user name was used in the topic it was posted to.

The other choice is to click their user name and when their profile page opens, you can click to send them a Private Message. Then you can send them a message and question directly.

If you find and inactive topic that you think might be relevant, just copy the topics url from your web browsers address bar and paste it into a post in your topic. Something like:

I found this voltage regulator topic, is my rectifer problem the same:
http://forums.iboats.com/forum/engin...1996-force-120

Then maybe someone can answer why your problem is the same or different from the old topic you found.

HTH

Good luck w your project
 
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Jiggz

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I'm not even sure what year or HP is the motor we are talking about hence not sure if it is just a plain rectifier or one of those with rectifier/regulator. Regardless, yes, the rectifier do get a little warm but not hot to the touch. Hence, the heat sink it is encased in. This is also independent of the state of the battery charge. Note I am talking about a plain rectifier one that DOES NOT HAVE A REGULATOR. Since there is no voltage regulator, a rectifier will always put out its maximum voltage/current (generated by the stator) to the load (which is the battery). It is rated higher than the maximum current and voltage rating of the stator to keep it from failing which usually results in open circuit.
 

pnwboat

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I would echo the comments by GM280 and your statements regarding a battery that is not fully charged. The lower the battery voltage is, the more current it will draw from the battery charging system. This will generate more heat. Not sure how this will impact your Regulator/Rectifier set up, but it wouldn't surprise me if it got hotter. Most of the failures that I've seen with the Regulator/Rectifier set-up like you have appear to have some type of heat damage as you showed in the picture you posted on your original "No Spark" thread.

On a side note, the charging system on the Force outboard is not a powerful as an alternator in an automotive application. The most the 1991 - 1998 3 and 4 cylinder Force charging systems will put out is about 16 AMPs. The earlier systems were around 9 AMPs. Most automotive systems put out a minimum of 40 AMPs. It will take longer to charge up a low battery in your boat than in your car. If you have a battery that is really low, it's probably better to charge it up with an external charger before you take the boat out.
 

funin the sun

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Well battery is fully charged. And i took my boat out in the water today and ran it around in the lake for about 30-45 mins and ran it mostly wide open. Boat ran amazing. No issues. However once i pulled back up to the loading dock. I shut the motor off and took the cowling off to see if rectifier was hot. Rectifier was alittle hot. I was able to keep my hand on it but it was almost as if was to hot to touch. Again i was able to keep my hand on the rectifier without it burning my hand but i was close to being hot to the touch. I understand it will get warm or slightly hot. So does it sound like my rectifier is normal or maybe getting to hot. It just concerns me because this rectifier is brand new and i dont want it to burn out on me again and have to buy another one. Now before captain pinpointed that my switchbox was bad. I went through all the wires and connectors. I even took alittle wire brush and cleaned off all terminals and connectors. I cleaned all the ground wires on motor block. I even squized the little plugs were all the connectors plug into each other so they would plug together tightly. I put new terminals on the battery along with new terminals on the other wires that connect to the battery and made sure everything was tight with a good connection. I even took all the coil pack wires off one by one to clean the terminlas and made sure they were all tight. So im positivly sure all the wires and connectors and terminals all have good connection. Now that being side let me mention this. The battery in my boat is a car battery. This is the battery that came in the boat when i bought the boat. The battery thats in my boat is a exide and is a 800cca. Should i consider getting a regular marine deep cycle battery or is this battery ok for me to use. The only accessories i have on my boat that run off the battery is the radio a horn witch i never use. The lights on my boat work but i dont use them. Only thing i use is the radio. So having this car battery not good or is it ok.
 

pnwboat

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Sounds like it's probably OK. Just as an added measure of safety, you can put some thermal grease on the back of the Rectifier/Regulator so that you get maximum heat transfer to the mounting plate. If you don't already have one, you should have a ground wire from the regulator case to the mounting plate. You can use one of the Regulator mounting bolts if needed to add a wire. Thermal grease is available at any computer store. It's stuff that is used on computer CPU processor chip heat sinks.

One thing that I've noticed on many of the Regulators is that the tubular barrel connectors on the Yellow wires seem to show signs of overheating. The clear plastic cover on the connectors is discolored and sometime brittle. I replace the connections with a two position terminal strip with eyelets crimped and soldered onto the Yellow wires (both stator and Regulator wires). I've never seen any evidence of overheated connections since I've been doing this.

The car battery is OK, but when it eventually goes bad, you might consider getting a dual purpose (starting and trolling) Marine type battery.
 

funin the sun

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Yes i forgot to mention. I did add a extra ground wire for the rectifier. I used the rectifiers mounting bolt and connected it to the mounting plate. However i will track down some of that heat grease and put some on the back side. Thanks captain for all your info. I have really learnt alot from your info and if it wasnt for your help my boat would probley still be sitting broke down. Thanks. Your a hero
 

gm280

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I see you are still concerned with the rectifier heat. I can say that if you can place your hand on the rectifier and not get burnt, your rectifier is no too hot. And since that rectifier is mounted on the engine itself, some of that heat is from the engine heating the rectifier up as it runs. It is part of the typical setup. And your battery choice is not bad. Your starter doesn't know the difference. If you were using a trolling motor as well, then I would get a deep cycle battery, but for general engine starting, not a problem. JMHO!
 

funin the sun

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Yes gm280. I just want to make sure the rectifier is ok. However the last one i just replace burnt up pretty bad. You could tell it was heating up bad. The hole front plastic cover was just melted and all the plastic that melted just ran down the side of the mounting plate. I just want to make sure that the rectifier is suppose to be warm or sightly hot but not hot to the touch to burn your hand. Just want to make sure my boat is operating properly. Like i said when i ran it out in the lake yesterday for about 30-45 mins when i got back to the loading dock i checked to see if rectifier was hot and yes it was alittle hot but not so hot it burnt my hand. I was able to keep my hand on the rectifier and not get burnt or have to tske my hand off becuz it was to hot. But it was pretty warm. Just want to know and make sure that its ok and normal for it to get like that. After taking the advice that you experts have giving me im pretty confident everything is good and in normal operating mood. I would like to thank you all for the info and advice. I would still be lost with out yalls advice and info. Thanks
 
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funin the sun

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Nov 3, 2015
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Yes gm280. I just want to be sure that the rectifier is working properly and that with it getting hot like it does is normal. It doesnt get hot to were it burns my hand. But it does get slightly hot. However like i said i can keep my hand on it and it doesnt burn but it is quit warm/hot. Just want to make sure that is normal tempurture for the rectifier. I just bought this rectifier brand new and dont want to have to buy another one. After taking you experts advice im pretty confident everything is all in proper working order. I am going to do as captain mentioned about the thermal grease on the back side and hopefully that will help. Other then that the boat ran great yesterday out on the lake. I do have a few maintance things that need to be done and the motor should be in almost perfect condition. I would like to thank all you experts for all the advice and info. Thank you
 
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gm280

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funin, yes thermal grease is used to help dissipate heat from electronic parts! But you have to remember it is a two way transfer as well. Meaning the engine heat will also transfer to the rectifier. But either way not an issue if you can hold you hand on any part. And one reason your boat is running so well is because you took the time to remove and clean all those electrical connection. That is always a good thing to do. Wish more folks understood that. :thumb:
:
 

funin the sun

Seaman
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Nov 3, 2015
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One more thing gm280. The rectifier does sit on the motor block witch im sure you know that. It has a mounting plate that bolts to the motor that the rectifier bolts to. So the rectifier sits about a inch in half off the motor so would it still get that heat transferr
 

gm280

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One more thing gm280. The rectifier does sit on the motor block witch im sure you know that. It has a mounting plate that bolts to the motor that the rectifier bolts to. So the rectifier sits about a inch in half off the motor so would it still get that heat transferr

It would get some but not much. Of course air really doesn't flow around it being in the cowl like it would in open air. But again, I really don't think you have an issue with it. If you already verified the wiring to and from the rectifier to the battery and there are no pinched wires or such, then I think you will be fine.

If you are really worried, you can take a true heat sink type plate and install it behind the rectifier and it will dissipate more heat because of the fins. But personally I would just enjoy the boating now. JMHO!
 
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