Helmer 0 #1 Posted September 10, 2010 I have a bad rectifier on my C-101 and am getting ready to replace it. I see that there are finned rectifters with three in a row terminals, finned with the "L" shape plug and small style with no fins and three terminals in a row. I have the plastic plug for either style so that is not an issue, but what is the difference between the big ones with the fins and small ones? I believe that my K241 has a 15 amp stator and it is putting out 30+ VAC. Any reason I have to stay with the original style big finned rectifier? Thanks for any advice on the mystical (to me) rectifier. Share this post Link to post Share on other sites
buckeye 2 #2 Posted September 11, 2010 My dad and I were asking ourselves the same question last week. It would be nice to know some information about the differences between the two. I'm sure SOI will have the answer. Share this post Link to post Share on other sites
Save Old Iron 1,563 #3 Posted September 11, 2010 Well, thanks for the vote of confidence guys, but I think I'll offer up some valid observations instead of guessing at answers. The good solid answers will eventually come from the construction and use of the Board Of Education currently under design and construction. http://www.wheelhorseforum.com/index.php?...topic=21252&hl= Here is what I do know. If you look at the offset terminal regulators, they occupy a slot in history in the late 1960's into the late 1970's. This generation boasts a fairly large block of heavily finned cast aluminum, mounted on the tractor chassis and cooled by outside air passing over the massive fins. The "straight" terminal RR units, are "modernized" versions of the previous models of RR's. They have more compact aluminum bodies with few if any "fins", mounted with one side of the RR exposed to airflow in the cowling of the engine and are force cooled by air flow created from the flywheel. There are other "Deere" RR's which have the straight terminal arrangement also. I am not sure from your original post if we are comparing the original WH RR to the "Deere" or "Modern" RR units. A few thoughts .... I would consider a few things when looking at interchangeability. All regulators have a amperage rating. Attempt to match the original rating with the rating of the substitute. Yes, a 20 amp unit will work in a 15 amp system. It will NOT PRODUCE an extra 5 amps - the amp limit is set by your stator design. A 15 amp stator will not produce enough current to "fry" a 20 amp RR. Yes, it is POSSIBLE to use a 15 amp RR with a 20 amp stator IF the total amperage draw thru your electrical system remains at or below 15 amps ! Your just not using the total capacity of your stator. Think about it as the weakest link in the chain argument. Think of it like fusing a 20 amp circuit in your house with a 15 amp fuse. You will not burn up the wiring (stator) by drawing 18 amps but you will burn out the 15 amp fuse (RR) if you do draw the 18 amps thru a 15 amp fuse (RR). The other major consideration would be a caution if you plan on just bolting a "modern", flat, no fins unit to replace a heavily finned unit on say a C series tractor. The "modern" RR depends on forced air cooling which would no longer be available if you just bolt it to the ammeter bracket of a C Series. Other than these few considerations, from an electrical standpoint, all the above mentioned RR units are the same. They are all powered off the stator AC voltage thru 2 "AC" terminals on the RR and provide a preset DC voltage output from the "B+" terminal to the tractor electrical system. The notable differences are all in capacity, mechanical configuration and method of thermal cooling. Hopefully I will have the Board Of Education partially constructed in the next week or so to continue on with more discoveries in the autopsy of my own C-160 RR unit http://www.wheelhorseforum.com/index.php?...topic=19973&hl= Share this post Link to post Share on other sites
Helmer 0 #4 Posted September 13, 2010 Thanks SOI, great explaination. It all makes sense now. Based on that I will use one of the large finned units since the airflow is limited where the rectifier is mounted. Now that I have attended your university do I get a degree?? :) Share this post Link to post Share on other sites
HankB 16 #5 Posted September 13, 2010 Yes, it is POSSIBLE to use a 15 amp RR with a 20 amp stator IF the total amperage draw thru your electrical system remains at or below 15 amps ! Your just not using the total capacity of your stator. Think about it as the weakest link in the chain argument. Think of it like fusing a 20 amp circuit in your house with a 15 amp fuse. You will not burn up the wiring (stator) by drawing 18 amps but you will burn out the 15 amp fuse (RR) if you do draw the 18 amps thru a 15 amp fuse (RR). That makes perfect sense to me. However, I think the biggest draw on a many vehicle electrical systems is recharging a battery that has been drawn down. I don't think that most people understand that a car battery, for example, is designed to be fully charged virtually all of the time. The alternator keeps it topped up while the engine is running as well as supporting all electrical loads. The only times the battery discharges is when running accessories with the engine off or when starting. Following start, full alternator output (minus house loads) is available for charging and if the battery has been drawn down significantly, it will be produced. With that thought in mind, I would be concerned that if a tractor with an undersized rectifier were started with a low battery, it could deliver enough current while recharging the battery to damage the rectifier. I think if I were to try to do that, I would put a fuse in line with the rectifier to protect it in that circumstance. If the fuse blew, I would know I would need to recharge the battery before replacing the fuse. Does this make sense to you or am I overlooking something? -hank Share this post Link to post Share on other sites
