SDU-5/E Battery Adapter   5BA

© Brooke Clarke, N6GCE 2000 - 2018

Engraved Top		Stands on Cap

General Information

This is a cap designed to fit the SDU-5/E Distress Marker Light and allows the use of readily available type 123 commercial photo batteries.  Photo installed on SDU-5/E Strobe

It turns out that the adapter allows the SDU-5E to stand on it's end without any batteries, the BA-1574/U is shorter and the SDU-5/E falls over.  When batteries are installed it will stand on just the cap.

Positive end of Lithium battery goes to the cap.    Tested with either Duracell or Radio Shack 123 batteries. 2 each Duracell DL123A or CR123.  You can use a pair of any of the 123 photo batteries, but do not use the new rechargeable type because their shelf life is very short.  The rechargeable batteries should be OK for use in a disco situation where you're not concerned about shelf life.

Threads Notice

23 May 2007 -About 1 in 1,000 SDU-5s have threads that are undersized.  This happens when the tap used to make the strobe gets worn out.  To check the threads in the strobe I now have a certified Go-NoGo plug gauge (shown at left laying on it's Calibration Certificate) and in case the threads need to be chased I also have the needed bottom tap.  If you buy my adapter and find that your strobe has defective threads I will clean them up for the current cost of postage.  This applies to all past customers just send me the strobe and the cap.  If you have tight threads contact me.

O-Ring Notice

BA-1574 Gap	5BA Gap

Less than 1% of the time an SDU-5/E is made with a defective female battery thread that will cause the battery to make contact before the O-ring.  If you install the BA-1574/U or BA-5374/U in these units the O-ring will not seat properly.   If this happens to you let me know and I will send you a part to fix it (no charge).

Not Tested

I have not tried to certify this adapter to any specifications or get any approvals for it.  I know of no problems but, if you use it for life saving applications you do so at your own risk.

Battery Life

The LiMnO₂ DL123A is rated at 1.4 AH with a 100 Ohm load.,  The SDU-5/E pulls about 100 mA (12V/100 mA = 120 Ohms) so might last 14 hours.  The BA-1574/U is rated for only 9 Hours at 80 deg F, so this adapter may offer over 50% more capacity.

The booklet in the bottom of the BT-2B battery tester shows the effect of cold on Mercury batteries.  At 80 deg F and a meter reading of 1.0 there are 9 hours operation in the battery, but at 32 deg F there is only 30 minutes of operation.  The LiMnO₂ battery looses only about 10% capacity at 32 deg F.  Note the BT-2B tester is obsolete since all the batteries it was made for are Mercury types and the replacements are different chemistry and can not be easily tested.

Some Sources for Batteries

The 123 type of photo battery is sold in camera and drug stores and most supermarkets as well as on the internet.  They typically are blister packed in either singles or doubles (two are required for this application).  Shop them as the price varies a lot.  Last I heard Streamlite had a good deal on a box of 12.  If you have access to military supplies your local PX  probably stocks the BA-5123 batteries for the Streamlite flashlights.

As of 12 April 2004 Engraved  adapters are the only ones available.