Topic: how hot is the regulator/rectifier supposed to get while running?

[fuzzybutt]

i have a solid state regulator/rectifier on the k4 750 and it got quite warm while the bike was running last night.

[mark]

spit sizzlin' is probably too hot.

 

[Steve F]

I would say that if you can place your hand there and tolerate it, you're fine (about 115* to 125*F)  If you get pain while touching it briefly, it's in need of some air, and could be a problem >130*F.  Modern electronics run quite a bit hotter and survive on a regular basis than a decade ago.  If you have doubts, find an infrared thermometer and call the manufacturer.
Steve F

[fuzzybutt]

i'd just never had a reason to touch it while it was running.its  hot enough that i dont want to keep my hand there too long but not spit sizzlin' hot

[Hush]

Does your reg/rec have an earth wire or take an earth from the bike frame?
I find if it's automotive electrical and not earthed it will heat.
Otherwise it's becoming toast inside the cover due to a fault or you screwed some wiring somewhere.

[seaweb11]

"If it was hot" .......Would heat generated effect the charging......if it wasn't getting enough air flow.

[Bodi]

The rectifier part makes a fair bit of heat in normal operation. The diodes have a characterictic "formard voltage" which is unavoidable. This is usually about 0.5 volt and is always there when the diode is conducting electricity. If the diode is carrying 10 amps, that 0.5 volt drop means there's 5 watts of heat being produced in the diode. The 3-phase rectifier has two diodes working to make every electricity pulse, so with 10 DC amps produced there's about 10 watts generated as heat.
The original silicon rectifier blocks on SOHC4 bikes run quite hot, and have a bunch of fins to get rid of the heat.
You can use diodes with lower forward voltage drops and reduce the heat generation but the minimum for power diodes is about 0.3 volts. They also cost more.
The regulator part can be designed in several ways, some make a lot of heat and some don't. I don't know what design this one uses. A reg/rect unit, though, will run pretty hot just from the rect function.