PIC of alternator restart battery's location
 

So I was under the pedestal working on my flap switch when I noticed some Duracell batteries. There are FOUR(4) "C" size batteries that will re-excite the alternator and make it produce power again after a total electrical system failure. With no aircraft battery power available, the alternators would be unable to begin making power after being taken offline without these batteries.

Mine were dated "BEST BY 2001" - LOL!!! They are fresh now. And be careful how they sit in the holder - its easy for them not to be in correct alignment, and therefore not have a complete circuit. If you look closely at the second pic, you'll see the batteries are slightly catawampus.

Photos were taken from the pilot's foot well, looking up. The plastic tubes are for the alternate static air source, which should help you locate the batteries.

To fix the mis-alignment of the batteries, see if you can get a zip tie to go around each of the lateral pairs to hold them down in position.

Hi there

Mine has a cover over the batteries, I should be at the plane over the weekend so I will take a few photos. This holds the batteries in place.

Dave

When items like this come up on the forum I suggest you use the SEARCH feature built into this forum. This particular item, D cell batteries, has been beat to death on the forum.

But I am never against another thread being started just trying to help those looking for info find it with the least amount of key strikes.

Hank, I know you have an older model 337 that is likely different, but the newer models don't use "D" batteries. Speaking for my 1978 P337H, there are 4 "C" batteries.

I did a search and found no good photos of the battery location, only some very dark, blurry attempts that I felt could be improved upon.

A site like this will often have several threads on one subject, but by reading them all, one can gain a unique perspective from each OP, resulting in a better overall understanding for the reader/member.

Cheers!

Do modern alternators still need standby 'batteries' to restart?
 

Inquiring minds would like to know...

Yes they do.

Hmmmm...
 

Haven’t seen anything like that in cars or boats.

Is it to recover from a situation of zero battery voltage available in flight?

Actually, cars and boats are exactly the same. Their alternators will not make power without "exciting the field" which requires electricity from their main batteries. If you lose your electrical system in one of those, its not a big deal, safety-wise at least. At little different in aircraft flying hard IFR, as these were built to do.

Zip ties go across the hooks, then the cover goes on

Dan

I haven't had time to get a picture of my replacement pack, I had a NOS Cessna Service Kit #337-46A that updated the system from D to C cells. I've attached a copy of the SK notice.

Here is a picture from a forum member that shows the location of where it should be (red circle).

Attachment 2707

My pack was hidden way up high against the firewall. My mechanic has moved it to where it is readily accessible.