An awesome power source for the launch field


Wizard Pretender
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Jul 3, 2021
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Las Cruces, NM
Some years back I was yet again faced with replacing a worn out 12v battery for club launches. This time when I searched for automotive jump starters, I saw something new. At least it was new to me. It was a small Lipo battery with jumper clamps that was advertised to supply 500 amps to jump start a car or small truck. I decided to order one and test it out.

It first I was disappointed because it would not light up my launch controller. I quickly figured out what the issue was and set it right. I have been using these ever since and have never been disappointed. They are lightweight, easy to charge, hold an excellent charge all day, and last for several years. They have the added benefit of a USB port so you can charge your altimeter on the way to the launch, or your phone before you head down range to find that rocket that is trying to escape.

Screenshot 2021-07-21 8.16.48 PM.png This one is my favorite. Now let me explain the problem. You see that big housing just above the EC5 plug? That is a safety feature that will prevent the battery from connecting if you hook it up backwards. There is a polarized power relay in there. If you hook up the alligator clips backwards (or for that matter, if the battery is so dead that it cannot supply ~50 mA of current) then the relay does not trip and you get nothing. SO, as delivered, this is not a useful power supply. Which is a shame because it is a big-ass lipo battery wired to supply 12 vDC.

At the time, my solution was to tear apart the module and desolder the interlock unit. I then re-soldered the jumper wires to the RC5 plug elements and Bob's yer uncle. The only issue I EVER had with one of these was on a long, cold February morning when one stopped supplying sufficient current. On a whim I decided to put it in my pocket for ten minutes to warm it up. Then it worked fine.

Ok, so what do you do if you don't happen to have a blow-torch soldering iron, or are not inclined to make a modification like I just described?

Screenshot 2021-07-21 8.17.43 PM.png

You search Amazon or eBay for an "EC5 Jump Starter Cable" and you will be in business. I do so adore these battery units that our Launch Controllers are designed to work with them out of the box. We don't use the alligator clips. Our controllers have an EC5 socket and 6 inch EC5 jumper to plug right into the battery. We offer an attractive Power Pack option for $50 so you can go straight from unboxing your new controller to launching rockets.


Well-Known Member
Dec 7, 2009
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I spent a couple hours today figuring out how to use one of these power sources for an electric bear fence..I used some large "bullet crimp" connectors and dome shrink tubing.



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