Will this batter be too much

[rocketdoctor99]

I have a 5 pad launch control system with most of the wiring be 18 gauge. currently I power the launch with the 12volt lighter output of my Car Jump starter. I aquired an extra 12 Volt deep cycle battery that i want to start using instead. The question i have is will my wiring be able to handle it, Is there any difference in pulling voltage. Im assuming I should put an inline fuse from the battery to the launcher to protect the control wiring right?

I usually just launch one rocket at a time but if I were to launch multiple rockets at once how do i figure what the max amps that would pull?

 

[Woody's Workshop]

I wouldn't worry about it. The starters are much smaller wire, heat up fast and for only a split second on 12v high amp batter.
My old 5 pad system used really fine solid copper telephone wire. Never had anything heat up or burn.
Ran off 5 1/2" round door bell buttons.

 

[rharshberger]

The deep cycle will produce the same amperages and voltages as the jump starter pack, 12V and enough amps to start a car. The Cigarette Lighter plug is what typically is the restriction since they usually have a 5A or 10A fuse inline. The wiring should be fine for the near instant ignition of a rocket igniter, honestly I would wire directly to the jumper boxes alligator clips rather than the cigarette lighter plug, then you have no restrictions on what lighters you want to use. Deep Cycles are designed to be "deeply" discharged and then recharged repeatedly without suffering excessive degradation of the battery, if you do that to a normal car battery it doesn't take too many total discharge cycles to ruin one. I have been using the same two Deep Cycle Batteries (full size ones) for my personal launchers for years as well as for my boats trolling motors, my club has used them on occasion for back-ups to our jump packs (we use 4 of them to power our pads, one at HPR, one at MPR, and one a LPR, then one to power our PA system, and occasionally one at the competition pads), its rare to actually use my big batteries except on multi-day launches and then its usually the PA system than needs the backup.

 

[rocketdoctor99]

I wouldn't worry about it. The starters are much smaller wire, heat up fast and for only a split second on 12v high amp batter.
My old 5 pad system used really fine solid copper telephone wire. Never had anything heat up or burn.
Ran off 5 1/2" round door bell buttons.

I guess the igniter is litterly the fuse in the system

 

[423yjl]

what if the clips are shorting on each other

 

[Woody's Workshop]

Fuse the wire between the battery and the controller when: you are afraid of shorts in the controller.
Put a fuse between the controller and the micro clips if you worried they will touch (I have never heard of anyone doing this)
I'm sure is some sort of breaker you could install on the controller for shorted out micro clips as well.
But it's nothing to worry about, it's just Rocket Science. :eyeroll:

 

[bobkrech]

The resistance of 18 gauge copper wire is 0.64 ohms per 100'. Your wire run will be at least 50' so R wire => 0.32 ohms.

The resistance of the battery will be low assume 0.01 ohms.

The resistance of the clips (clean), switches, etc. would be about 0.1 ohm.

The resistance of an Estes igniter is 0.8 ohms.

Your current per leg is I = V/R = 12 /(0.01 +0.1 + 0.32 + 0.8) ~= 12/1.2 ~ 10 amps per igniter. Not a problem.

Even if you fire all 5 pads at once, not more than 50 amps from the battery. Again not a problem.

The only issue is that 18 gauge wire is only rated for 7.75 amps continuous. Should not be a big deal for a second or 2.

Bob

 

[sghioto]

Assuming 50' the total resistance would be 1.55 ohms using the values given, the cable has two conductors. Max current is limited to 7.75 amps per igniter so again should be fine.

Steve G