Keeping it Fresh — Upgrades for the SDU-5/E


Submitted by Eric Daniel

Many of you have commented on the availability of upgrade and adapter parts, as well as a few in-house modifications you have done to keep your AN/SDU-5/E distress strobes working and I figured it was time to create a separate entry for that venerable, but definitely still functional, pocket strobe light.

For the uninitiated, the AN/SDU-5/E is a personal distress strobe light originally carried by aviators as a piece of their survival kit.  The strobe light was originally designed to run off of one BA-1574/U mercury battery (NSN 6230-00-067-5209.)  These batteries have been rendered obsolete and have since been replaced by a number of alternatives, including the BA-5374/U lithium manganese dioxide battery (NSN 6135-01-455-9846) as well as the Kodak 123 lithium camera battery (in the case of the 123 battery two are required, as is an adapter for the battery well.)

The SDU-5/E can also be equipped with a flash guard/Blue Filter FG1C NSN 6230-00-401-2285.  The purpose of this filter is to change the color of the strobe flash from white to blue.  The filter also channels the strobe, making the beam steer-able, rather than omni-directional.  When not in use, the blue filter can be stowed over the body of the SDU-5/E.

The second filter the SDU-5/E uses is an IR cap.  The IR cap completely covers the strobe light, rendering the pulse invisible to the naked eye.  Night vision devices, however, can readily see the pulse.  Both filters cannot be used simultaneously.  When not in use, the IR cap is stored over the SDU-5/E light.

AN/SDU-5/E Strobe light

  • chuck

    Good overview but where is a source for finding the 123 adapter?

    • Dan

      On eBay PRC68

  • Steve DeCeuster

    Is there anyplace where replacement, batteries can be purchased/website?

  • There is a 12/24 volt adaptor available so you can hook it to a 12 or 24 volt source (great for boats and cars).

  • mikethebikemodel

    the mod kit is easily available on just search for the sdu and you can buy the brass nut replacement with oring easy, alternativly got to a plumbing store and you will find that there are parts that can be modded to fit and worth the effort. then buy a supply of cr123 batteries off ebay for very little money 10 for a dollar + post.
    and your SDU will last a few more decades, just dont drop it.
    then again it’s replacement strobe is freely available on ebay for silly money..
    have fun all keep safe…

  • Great article! I’ve got a handful of these strobes and, of course, none of them work (old batteries).

  • BattleKat383

    all of these mode (especially the battery adapter are available on ebay. for the non ebayer, you can google sdu-5 and you should also be able to find a vendor. i took one to kosovo with all the mods and it worked great.

  • Rick Connors

    Where can I buy one,or two?

  • Tim South

    Streamlight has developed a new light that will not only be able to replace the SDU-5 but also the old L-shaped light. It will be released in April and it will work off of 2 AA’s.

  • SeaWolf

    If you still have the old battery with the brass cap, you can remove the old battery cell and salvage the cap. Then reuse it with the camera batteries.

  • MARK
  • kevin campbell

    what a coincidence i just was going through my old duffle and found my an/sdu and the bat still worked .probably 10 years old.but now i know i can keep it working .good job guys. nuff said ..out.

  • Greg Raynard

    when I carried one of those, the only thing we could do was smack it against the bulkhead to get it to work. I really enjoy seeing the new features and technology available to all of you now.

  • benito

    Get a MS-2000 stobe light and use AA batterys. These are used in most survival kits as well. (USAF)

  • javier

    its great on the freeway when you get a ready to slow traffic down though , they thing its a cop

  • L.J.

    I was wondering where I could purchase the strobe light since I spend a lot of time in the mountains and desert hiking and camping. If you could send me the info I’d be happy . Thanks L.J.

  • Randy Schumann

    The SDU/5-E will run on a standard 9 volt bettery if you create an adapter from the cap of an old BA-1574/U. a piece of dowel (to emulate the battery), some wire and a soldering gun. Run the hot wire through a SMALL hole drilled through the dowel and old battery cap, and solder the cold wire to the old battery cap. Connect the wires to the 9v battery.

  • Tony DeFazio

    I have several of the “SDU-30 Lightmarker Distress” marker lights that take the old BA-1328/U mercury batteries ($30.00 each, if you can find them) I’ve modified some AA batteries to work (the BA-1328/U has the +/- in the same end) but this is not always reliable. Anybody know of a replacement for those batteries?

  • Thomas J Hunter

    go to or and you will find the 5BA adapter, machined part for $15.00.

  • James

    Great review, I use this light at work (wildland firefighting) and need a new switch boot. Does anyone know where I can find a replacement? Thanks


  • Andez

    The SDU-5 will run just fine on one CR-123 battery with a little ball of aluminum foil placed inside the bottom of the battery cap, and then the cap will screw on tight against the o-ring for wet work. I’ve got SDU-5’s set up that way and tethered to my offshore type 3 PFD’s for my sailboat kit and ditch bag.

  • jon huffman

    where can i get a ir cover for my sdu-5??? anyone know???

  • PLEASE: If you are in the military, let go of the SDU-5/E and get a Firefly Two (NSN 6230-01-448-8340 w/pouch; 6230-01-411-8535 w/o). Keeping the SDU-5/E going is creating a problem in acquiring the replacement BA-5374/U battery, which has no other use. The cost to DoD for acquiring this specialty battery is very high and will continue to rise.

  • Another Country

    PLEASE: If you like your SDU-5/E, don’t listen to the above plea.

    Some poor pencil pushing, paper folding sap wants to lighten his work load.

    If only the IR filters were more readily available. Anyone have an NSN for them?

  • Jeff
  • Robert Stokes

    Just found you. You have GREAT info. on the SDU-5/E. I bought a HELECOPTER crew survival vest with th SDU-5/E. BUT, after replacing the batteries, still wont work. Any ideas here?? Have not seen a vest like this since NAM. Date og MFG? 1970. Came with whistle and survival knife. Anyway, thanx for your info and hope to hear from you soon.


    • robert

      using super fine (oooo) steel wool clean brass threads inside and also top of brass port, once all the brass is hiny it will work, promise

  • Tom K

    Does anyone know where I can get the flash tube / bulb replaced? I got a cap and replacement battery for mine, but now it’s not working with a black spot at the end of one end of the flash tube. – Thanks!