How hot is normal for rectifiers?

[SeaKaye12]

I just installed a new rectifier on my Merc 850. Everything seems OK as far as it working and all...but I notice that it gets rather hot to the touch after running the engine for only a few minutes.

Of course on the old one, I never paid any attention...so I don't know if this is normal or not.

In looking at the mfg's spec sheet
http://www.nteinc.com/specs/5300to5399/pdf/nte5340_44.pdf

I see that they rate it at a maximun operating temperture of 175 degrees....which in itself seems to be pushing it for something that lives mounted to the block of an outboard. Oh; wait a minute...that says 175 degrees Celsius...that's what; 347 degrees fahrenheit....

Do you think I have an issue? Is it normal for them to get pretty hot?

Thanks, Chuck

 

[Fuzzytbay]

Re: How hot is normal for rectifiers?

Yes some of them can get hot. Most are mounted to something metal as a heat sink, but somehow mounting on an engine block would defeat that..

 

[Barnacle_Bill]

Re: How hot is normal for rectifiers?

Its normal for them to get hot. Make sure the mounting screws are good and tight. The block acts like a heat sink for them.

 

[j_martin]

Re: How hot is normal for rectifiers?

If you can light a cigarette on it, it's too hot. They can run hot enough to take some skin off your finger. Bolt it down tight where it's supposed to be and don't worry about it.

Voltage drop across it is close to 1 volt. Amps is about 16. That's 16 watts of heat to get rid of, or about 53 BTUH. That's about like a soldering pencil.

hope it helps
John