*GI Equipment Batteries*
Powering up battery powered GI equipment There are times when you come across military surplus battery powered electronic equipment and, more often thannot, it uses some odd ball GI battery and not your basic BA-30( "D" cell).
This is a concept rather than a How To discussion
When this happens the good deal of the radio/NV/whatever fades and you pass by what probably was a real useful piece of equipment that would have enhanced the operational capability of your team/group. Rather than letting the gear go, you have to think differently about powering the equipment and use your noodle to work around the problem.
Usually with GI equipment there is a simplified schematic inside the battery compartment showing the hookup and voltage requirements along with the battery nomenclature which the equipment uses. With the voltage requirements known, you proceed to the next step.
First of all, you need to know some common battery stuff. Most common batteries are built around the 1.5 volt carbon zinc cell and variations. Nickel Cadmium rechargeable ones run about 1.2 volts and Nickel Metal Hydride rechargeables run about 1.4. These are good ball park figures. At full charge they run a little more and at full discharge a little less.The engineers take this into account when they build the gear so there is some "slop factor" to allow for battery condition.
For the basis of this discussion let's use regular old everready/duracells which are based on a 1.5 volt cell. If you look at the four most common type of batteries you have the; "AA", "C", "D" all of which are 1.5 volts. The 9 volt battery is 9 volts but if you cut the case off it you would find 6 internal cells each of which is a 1.5 volt cell. This is the key to the whole deal. The way you make different voltage batteries is by combining individual cell's. When you are looking at the power requirement for a battery powered piece ofgear usually the batteries are based on multiples of the 1.5 volt cell. Thereare exceptions to this basic rule, one example being a blasting cap continuitychecker. These are galvanometers which use silver nitrate batteries, a real oddball battery. But in the main , the engineers built your goodie to run offbatteries which you as Joe Team Member have access to even if they are in adifferent package/configuration.
The things you have to look at when powering up this stuff are:
1. What multiple of 1.5 volts is the battery I need?
2. Can I produce this battery by hooking known batteries together?
3. Once I produce the battery I need, can I place it into the battery compartmentof the equipment I need to power up?
If the answer is yes then hop on it and you're in business.
To get the battery voltage size where you need it might require you to build abattery bank of battery holders. You might have to solder batteries together.Youmight have to use smaller physical size batteries due to compartment sizerestrictions. You might have to remove the battery plug in connector on thesurplus equipment because in some instances the battery for the gear might be amultiple voltage battery. What they do there is to place 2 or more batteries in1 package for ease of use in a piece of equipment. Or the connector used on thebattery might be of a type you don't have access to. In that case you desolderthe original connector and replace it with the type you need for your battery.Save the original connector because, who knows, you might luck in some originalbatteries.
Now that you've got the concepts, let me give 2 examples of ex-GI equipmentwhich I acquired and powered up using the 1.5 volt rule and the 3 things you lookat.
Example 1. I came across an Air Force analog Voltmeter with the requirement for15 volts and a battery compartment which was about 2.5"X1"X12". So what type ofbattery did I need? First the electrical stuff. 15volts/1.5volt batteries= 10batteries. The width and depth of the battery compartment made me look at "C"cells. But I couldn't find a battery holder which would stack 10 batteries in 2rows of 5. What to do? I soldered the batteries together positive to negativeand they just fit in the battery compartment.
Example 2. Several years ago the Shotgun News had an ad for radiation detectors(radiacs) which were about $40.00 each. One of my friends bought one. After acouple years of looking for batteries for it he asked me if I wanted it becauseit was unuseable. I took it. When I looked into the battery compartment I foundit used 2 batteries. One was 3 volts and the other was 135 volts. 135 volts?Wow, that was a strange one. The 3 volt compartment was 2"X4"X3" and the 135volt compartment was 5"X4"X4". Ok, 3 volts is a no brainer, that's 2 batteries."D" cells for that one with a brass spacer to connect the positive and negative.Now the other one 135/1.5= 90? 90 batteries, man that's a bunch. Well thesolution is easier than it looks. Look back at the 9 volt battery. It's got 6cells in it. Guess what, if you take 90 cells/6 cells in a 9 volt you get 15batteries. And if you take 135/9 you still get 15.And they will plug intogether!. So I took the plug off and got a 9 volt plug from Radio Shack andsoldered it into the radiac. I then took 15 of the 9 volt batteries and pluggedthem together in series . I then taped them into a bundle which wouldn't shakeapart. It was still small for the battery compartment and I filled up the deadspace with foam.There you have it. Battery sizing in a nutshell.
It's important to know the why of what you're doing as much as the how. So, keepyour mouth shut, your eyes open, your head down and your feet moving. Keeplooking and you'll find useful gear which others pass up because they don't knowwhat you know.
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