Electrical problem SOLVED!

DrDave · #1 01-23-20, 01:29 AM

Quote:

Originally Posted by cessnadriver

Dr. Dave. Thanks for the reply. The newer C337s have a charging voltage of the mentioned 28.7. But mine C337 is a 1965 the maint. manual calls for 27.7 voltage. So when I contacted Zeftronics they said that was the ACU approved in their STC list? So I went with that one. DO I HAVE TO CHANGE TO THE HIGH VOLTAGE ACU? What about the STC approval?? I'll change the field wiring when I replace the switches. I do have another parts C337 that I could swap the circuit breaker panel, I didn't think of that! Although I did try to remove a couple of old C/Bs once and the screws attaching wires are REALLY tight and the screws are NOT very good quality. But you're right I should do the swap. QUESTION: The odd 8 AMP size in the panel are hard to find any chance I could replace them with the modern 7 1/2 AMP?? MANY THANKS. BILLS

BILLS:

A more complete answer would be that the battery installed in your plane in 1965 was a flooded lead-acid battery. In comparison to a Concorde sealed battery of today the charge voltage was about 0.6v lower than the specified charge voltages of the newer batteries. Running the older, lower voltage regulator will maintain the battery in an undercharged state. For best longevity the higher charge voltage of 28.5-29.0v is ideal in the 32-59 degree temperature range. Those numbers come from the Concorde manual. Since the manual is copyrighted I couldn't simply copy it.

Dave

rmorris · #2 09-22-20, 04:35 PM

Dr Dave/ Bills,

Read through your posts on electrical issues and solutions. Thinking i might run a 8ga ground wire back to front like you.
On related issue: there is a pkg deal offered in the parts for sale area of this site talking about upgrading vr to 400 series and placing in parallel. Any thoughts on that option v your zeftronucs acu option?

DrDave · #3 09-22-20, 05:06 PM

Are we talking about a G model here? Those run two separate regulators with a common battery and parallel the regulators. The Zeftronics or the Plane Power regulators would be a good upgrade.

Dave

rmorris · #4 09-22-20, 06:18 PM

no, talking about a T337C model... if you look at the parts for sale area of 337skymaster.com, you'll see an offer to upgrade, via field approval, to the 400 series regulators in parralel... looks interesting, like your opinion

DrDave · #5 09-22-20, 06:59 PM

I believe the C system is the same as the A and B and D. There is no paralleling function of those regulators. Please refer to the charging system diagram. There are two separate regulators that operate one at a time. You can easily confirm this by identifying the regulator 1,2 switch. Just because they screwed two regulators to the firewall doesn't mean it uses both of them at the same time.

In this system it has two alternators charging one battery. The two alternators are controlled by one regulator. As an aside, there are two-and-a-half ways to run this system; regulator 1, regulator 2, run/standby switch with each regulator. I give half-credit for that since in the standby mode it bypasses the contactor, alt field breaker, and master switch. The standby circuit goes to the battery terminal of the OVR. Cool system. I see no reason to change the architecture of the system.

Now back to your original question, I would put in one Zeftronics R25102A. This will charge the system around 28.4V with a healthy field circuit. This model is approved for your airplane. You don't have to live with that low 27.4V system. Your battery will thank you.

Report your results. As always I would be glad to help.

Dave