ELT Battery Expiration Date
 

OK, maybe a dumb question, but I can't find the ELT battery expiration date. I thought it was supposed to be on a label on the outside of the ELT but I can't find it. Here are all the external labels on my ELT. Am I missing it somehow? Could it be the "Manufacture Date"?

ELT battery expiration
 

Hi Tom,

you should find it etched (melted) into the battery case, which is the large section with the big "warning" label attached. There's no need to open the case to see it.

I've got an expired one in my hangar. I'll check it out today to confirm

And the new "warning label" about replacing the battery is new - it wasn't there when I bought mine several years ago, I guess that's a reaction to the thread here on VAF about where to find replacement batteries for that unit.

It needs to be replaced every two years regardless of the expiration date. The installation date should be in the log book. If not then you can not demonstrate that it is a current battery and must replace it anyway, even if it is only a few days old.

The ACK-04 batteries cost more, but at least they are good for 5 years, not the two years you state...:)

FWIW, after a little over two years, my AKC-04 started failing the 3-month self-test. The beep code indicated HIGH VSWR OR HIGH CURRENT, not LOW BATTERY. I removed the battery and it failed the "Load Test". I replaced it and that fixed the problem.

Could you have a bad co-ax causing the ELT to use more power than expected during the 3 month testing?

The "HIGH VSWR" warning is a possible hint.

But don't the FAR's require a 2 year replacement? If I am not mistaken the rule for certified ELT's also applies to experimental.

NO

From the FAR 91.207...

(c) Batteries used in the emergency locator transmitters required by paragraphs (a) and (b) of this section must be replaced (or recharged, if the batteries are rechargeable) -
(1) When the transmitter has been in use for more than 1 cumulative hour; or
(2) When 50 percent of their useful life (or, for rechargeable batteries, 50 percent of their useful life of charge) has expired, as established by the transmitter manufacturer under its approval.
The new expiration date for replacing (or recharging) the battery must be legibly marked on the outside of the transmitter and entered in the aircraft maintenance record. Paragraph (c)(2) of this section does not apply to batteries (such as water-activated batteries) that are essentially unaffected during probable storage intervals.

As usual, the manufacturer's approved instructions for a certified device take precedence.

91.207(c)(1) When the transmitter has been in use for more than one cumulative hour, or
(2) When 50 percent of their useful life...has expired, as established by the transmitter manufacturer under its approval.