The Cessna 120-140 Association Forum

I am pretty sure my voltage regulator is going bad. I currently have an Electrodelta VR 300-14-50 installed in my 47 140, but I have a 20 amp generator. Should I replace it with the VR 300-14-20 or 14-50?

I was looking at the Zeftronics regulators. Anybody have experience with them?

Thanks in advance.

Mike

I replaced the old regulator in a 140 with a Zeftronics, been working just fine. It fit in the same bolt holes. I think I'd get a 25 amp regulator G1250N. There are places that still fix the old points type regulators.

I penned a little article for the NL a "few" years back (...30+ ) titled something close to: "The Next Best Thing to an Alternator". That was after some very positive experience with the Zeftronics regular "controlling" my 20 amp generator. It worked great and, as I recall, was noticeably more stable, "quieter" (radio noise) and enabled the generator to come on line slightly earlier than did the old points regulator. The Zeftronics equipment sure seems to be quality designed & built. That said, if it's anywhere near feasible for you to consider right now I'd suggest exploring an "upgrade" to an alternator as there are several good options out there. Mac

Generators generate their own field current. The "voltage" regulator (actually generator control unit) also has a current limiter function to prevent the generator from generating more than its rated capacity. Without this, if the load on the electrical system is greater then the generator's capacity the generator would try unsuccessfully to maintain the set voltage by increasing the current output until it melted. The GCU also prevents the battery from discharging through the generator when the generator's output is less than battery voltage. (Reverse current cutout.)

So, bottom line, the voltage regulator current setting should match the generator's capacity. That said, a very reputable repair facility once told me it was OK to use the 20 amp regulator with the 12 amp generator because the 12 amp generator simply cannot produce enough current to damage itself. As far as I know, there is no approved 12 amp mechanical regulator available, although I have been able to adjust the 20 amp version down to about 15 amps.

Thanks everyone for the input. Greatly appreciated.

Mike

I just replaced the regulator in my 140 with a Zeftronics. If you follow the instructions during installation it will result in a green light that tells you all is well. The light and the instructions are all you need to troubleshoot the system at a later date. They also make for clearer radio reception due to lack of relay contact s. A great product with great technical support behind it.