Voltage Regulator Rectifier--Hot to Touch

HelmetHead

I've got a 94 with no electricity-drawing farkles. Come to think of it, I'm the only farkle on the machine...

I've read a lot here about the 28 amp alternator problem, so I've checked my voltage a few times, and checked the 6P connector last weekend.

Voltage is fine, and the 6P connections were so clean I wondered if someone replaced the 6P before I bought the machine at 67K (now 77K) miles. For minor reasons unimportant here, I have not yet checked the 3P or 2P connectors from the alternator.

The machine runs fine, but I am concerned about the VRR. After running for about five minutes, and continuously thereafter, the VRR is hot enough to touch that you will instinctively take your finger off in about a second or less. I can gauge oven temperatures pretty well by sticking my hand in, and I know water temperatures from baby-bottle-is-ready to hot tubs and hot springs that take highly experienced enthusiasts 15 minutes to get into.

I'm guessing the temperature on the VRR plastic cover is about 115 ~ 120F. Pretty hot.

Why is my machine OK? Or am I just Wile E. Coyote about to look down?



If it weren't for this forum, I'd be riding a bicycle...
 
If I'm not mistaken, all rectifiers run hot... and yours doesn't sound like its too hot to me... (but I'm not a rectifier expert either)... :D
:cool:
 
The regulator part dumps extra electricity as heat, it's gonna be hot. Add a couple running light and convert it to lumens instead. :D
 
It is normal for the regulators to get pretty warm. It might be a good idea to check the ground wires coming from the regulator. If you have a weak ground the regulator can get too hot. Also make sure the three wires coming from the alternator to the rectifier have a good solid connection.
 
Think of it like this... The alternator produces X amount of electricity... the battery (and other electrical stuff) needs Y amount of electricity... When X > Y, then the EXTRA electricity has to go somewhere... The rectifier turns the excess electricity into heat (which it dumps into the atmosphere via a heat-sink)... :D I still don't think I'm an expert, but I think I do understand the function... :D (and it IS a little more complicated than that...) :D
:cool:
 
Thanks a million y'all...I do understand that the process of regulating and rectifying (do church rectors rectify?) should yield some excess energy, and I wondered if I might be encountering excessive excess enroute to the occasionally mentioned "fried VRR."

I'm feeling rather better after reading everybody's responses...which means I now have to go further in trying to find the hot plastic smell that arises about two minutes after start-up, then mellows out, but doesn't seem to go away completely, at least not until I've been riding for at least 30 minutes. I'm afraid it might be a tick-tock-troubles-a'comin' situation. I'm going to work up a proper description of facts and start a thread related to that...thanks again...
 
The connector for the alternator wires (4 pin) can get hot enough to melt if the connections are weak. This may be where the melting plastic smell is coming from. Also you may be smelling coolant from minor leaks on the hoses or hose fittings under the carbs. I have seen leaks that are minor enough not to drip on the ground but will seep onto the top of the engine and then when you startup and ride the coolant evaporates and causes the smell. After riding a while the smell goes away or is reduced until the next startup. Twice now I have had someone think this was an electrical smell when it was coolant.

Dan
 
They do get hot... that's why the police-spec 1100s with the 28A alternator had an uprated VRR with cooling fins.
 

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What Tom said! (Tho many 28s go well beyond 100,000 miles.)

The 40 amper works differently, produces more energy on demand, less energy when not needed so the heat isn't such a big factor. One down-side, tho, since it's air cooled (with slots open to the environment), it's more subject to corrosion damage than the 28.
 
George said:
The regulator part dumps extra electricity as heat, it's gonna be hot. Add a couple running light and convert it to lumens instead. :D
Click to expand...
Rectifiers do run warm, but regulators generally don't

There is no 'extra electricity' in the system. The regulator senses the need for juice and energizes the rotor so that the alternator stator will output exactly as much juice as the system requires. When the need (load) goes down, the regulator outputs less votage into the rotor so the alternator stator outputs less current . . . . no 'extra electricity' anywhere to be wasted as heat. Adding extra lights will just cause the alternator to work harder, get hotter and you'll get worse gas mileage because your electrical plant is working harder . . . . no such thing as free energy

The main advantage to the 40 amp alternator is that the rectifiers (which do get hot) are located inside the alternator, which is fan cooled. The lesser (but still important) advantage is that with the rectifiers and regulator located within the alternator there are fewer external high power electrical connections to get dirty, hot, melt connectors and fail

If you have an alternator which is converting 'extra electricity' into heat, get if fixed . . . . you'll get better gas mileage by generating only as much electricity as you need . . . . which is the job of the regulator - Plus, everything will last longer

Don
 
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