Battery Relay

JMACFLY · Post by **JMACFLY** » Wed Sep 28, 2005 6:21 pm

Battery Relay, seems to be in-op. Multi-tester shows continuity for wires to Master, battery new and fully charged. In-line Fuse blown in thin wire lead from relay to Master. Fuse # Buss AGC 1/16 ??? What kind of fuse is this?

Battery Relay seems corroded and burnt.
Friend's C170B's battery relay seems to be an "automotive style" and does not look like mine. My part # CR2792D.

What model battery relay do you guys use, and where do you get it?
Thanks, recently back stateside and all my parts manuals are still in boxes. John MacKay

By the way, my Wells 35 amp voltage regulator from AutoZone looks just like the one we took off the firewall.

blueldr · Post by **blueldr** » Thu Sep 29, 2005 3:00 am

You can get the proper relay at any NAPA parts store. Ask for a 12 volt, continuous duty relay. It should have electrical continuity between the "Batt" terminal and the small control terminal. This control terminal connects to the master switch which makes to ground to close the relay. I do not believe the master switch circuit in my airplane is fused, but it could be fused to provide protection for the wire size used on that circuit.

Post by **GAHorn** » Thu Sep 29, 2005 4:43 pm

blueldr wrote:You can get the proper relay at any NAPA parts store. Ask for a 12 volt, continuous duty relay. It should have electrical continuity between the "Batt" terminal and the small control terminal. This control terminal connects to the master switch which makes to ground to close the relay. I do not believe the master switch circuit in my airplane is fused, but it could be fused to provide protection for the wire size used on that circuit.

You COULD get such a unit from the autoparts store...(last time I priced one for my truck it was $25) ....but it's CHEAPER to get the genuine part from Aircraft Spruce, (877-477-7823) their PN 111-226 for only $17.30.

The battery relay style did indeed change from the original box-shape to a can-shape. The small terminal connects to your cockpit Master switch...which grounds the terminal to close the relay. It is normally not fused. (Therefore, the small terminal is a "hot" terminal in that it has battery power always supplied to it. Since the small terminal is hot, the small fused item is probably a "keep alive" circuit for your avionics memory circuit.)

JMACFLY · Post by **JMACFLY** » Fri Sep 30, 2005 12:44 am

Thanks George, and Dick
I posted my note last night. Messed around with the existing relay this morning after installing a 1 amp fuse. Got no results. Your reply was waiting when I checked the forum at lunch time. I called Spruce, and tomorrow before noon the new relay will be here. We have a ferry permit for Saturday. The information given by you, the IC170A, is timely, factual and absolutly critical to help us make the decissions necessary to keep and maintain our classic airplanes. We have a good thing going here. Thanks,
JMac

blueldr · Post by **blueldr** » Fri Sep 30, 2005 3:32 am

NAPA store price $25.00, two blocks away, delivery time 15 minutes.

Spruce price $17.90, shipping and handling $7.70, total $25.60, delivery time 3 days(maybe more).

Your Call!

P.S. Last time I got one at NAPA it was the same manufacturer, White-Rodgers, same manufacterers part number and "Made in Mexico".

Post by **GAHorn** » Fri Sep 30, 2005 1:50 pm

blueldr wrote:NAPA store price $25.00, two blocks away, delivery time 15 minutes.

Spruce price $17.90, shipping and handling $7.70, total $25.60, delivery time 3 days(maybe more).

Your Call!

P.S. Last time I got one at NAPA it was the same manufacturer, White-Rodgers, same manufacterers part number and "Made in Mexico".

But Dick, these days the gasoline to run down to Napa costs 70 cents, and in the Houston area the line for gasoline is three blocks long. The Spruce part will save about 10-cents!

(On a more serious note, it's a pity the Fellows Against Aviating cannot come up with a more reasonable attitude about some aircraft parts. An example of an automotive part I would have absolutely no heartburn over installing in an airplane would be a very similar part....a starter relay. After all, if it doesn't start, you're not likely to get into trouble with flying it.
As for a battery master-relay such as being discussed in this thread...I'd consider the risk that if it failed in flight, it would cause a total electrical failure. The new-in-the-Spruce-bag example I have holding in my hand at the moment (well, not exactly in my hand...as I'm typing right now, but it is sitting on my desk) certainly looks exactly like the one at Napa...but it is stamped "USA" on it.)

PS- The Mexico thing may not be that big of a deal, tho'. I seem to recall my replacement cockpit rocker-switch for the nav lites on my C-206 came directly from Cessna complete with a Cessna picking-tag, but the switch had stamped on it "Mexico".

spiro · Post by **spiro** » Sat Oct 01, 2005 8:02 pm

or I could saunter over to the local Cessna dealer and get the correct OEM, FAA-PMA part with paperwork for under $30. I know more than one IA who won't sign off an annual if he sees auto-style solenoids or voltage regulator. I believe the Spruce part is "for homebuilt use only".

Post by **GAHorn** » Sun Oct 02, 2005 12:23 am

That's good advice, Spiro, and your mechanic is absolutely correct to recommend traceable, aircraft parts for use on aircraft. (But I don't think it would be correct to "eyeball" installed parts to condemn an aircraft, providing the documentation is correct for the installation. Many parts are stamped "FAA-PMA" with ink, or with stick-on labels which can be worn off or lost.)
Spruce's catalog states "used on production aircraft". The one I purchased from them as a spare 5 years ago ...(of course, if you have the part in-stock it will never fail...)

... has a sticker on it "FAA-PMA". But their catalog also states it is "applicable to all homebuilts" (just as any FAA-PMA part would be.)
Whenever in doubt, it is best to require suppliers to provide documentation. Your suggestion that the price difference is worthwhile is good advice IMHO.

JMACFLY · Post by **JMACFLY** » Tue Oct 04, 2005 12:25 am

Well guys, I went with Spruce because I wanted certificated airplane paperwork. I needed to get a part in two days or less and chose the $26 overnight option added to my $17.90 part. When the part got here in it's little FedEx box, I find that there was no documentation, and no visible stamp on the part to comfort my IA or the Friendly Aviators Assn.

Napa is just North East of the airport boundary..................

JMac