# Question on Portable Power Sources??

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#### JStarStar

##### Well-Known Member
I have an Electron Beam controller I use for most of my schoolyard-level rockets, which of course run on four AA batteries and seem to be OK for normal duty.

The consensus seems to be that the Electron Beam will not reliably launch clusters, that you need more current to fire multiple igniters. I've got a couple cluster rockets I'm about ready to start launching, so I need to make sure my ignition system can do the job.

I also have an older Estes Launch Control System I kept from years and years ago - I soldered all the connections and it still works fine - and a newer control system I got with my Hobby Labs SR-71 kit, both of which use external power systems. I modified the Estes LCS to use an auto cigarette-lighter plug, so that's fine if I have a car handy, but not all launch areas allow you to drive the car right up to within 20 feet of the launch pad.

So I'm gonna need another portable power source (i.e. battery), in case I want to launch somewhere a little off the pavement where I can't drive my car.

I was looking for something rechargeable with plenty of power yet still lightweight enough that you can carry it a hundred yards or so without developing a hernia. (So that lets out a normal auto battery).

Would something like this work? This seems to be a good thing to have in the garage for other reasons, could I just hook up the battery leads of the LCS to this thing and let it rip? Has anybody else used these things as power sources? Any reasons it WOULDN'T work??

portable jump-starter

#### Micromeister

##### Micro Craftman/ClusterNut
TRF Supporter
Absolutely! Change the continuitybulb to 12v or a 12v buzzer you'll be good to go, I'd add a relay at, transfering the power supply for the controller side to the launcher base side. keeping 2 crank amps per igniter rule of thumb to determine your max motor cluster. You should do a search here in several of the section. this subject has been talked about a number of times.

#### DynaSoar

##### Well-Known Member
Originally posted by JStarStar
I have an Electron Beam controller I use for most of my schoolyard-level rockets, which of course run on four AA batteries and seem to be OK for normal duty.

The consensus seems to be that the Electron Beam will not reliably launch clusters, that you need more current to fire multiple igniters. I've got a couple cluster rockets I'm about ready to start launching, so I need to make sure my ignition system can do the job.

I also have an older Estes Launch Control System I kept from years and years ago - I soldered all the connections and it still works fine - and a newer control system I got with my Hobby Labs SR-71 kit, both of which use external power systems. I modified the Estes LCS to use an auto cigarette-lighter plug, so that's fine if I have a car handy, but not all launch areas allow you to drive the car right up to within 20 feet of the launch pad.

So I'm gonna need another portable power source (i.e. battery), in case I want to launch somewhere a little off the pavement where I can't drive my car.

I was looking for something rechargeable with plenty of power yet still lightweight enough that you can carry it a hundred yards or so without developing a hernia. (So that lets out a normal auto battery).

Would something like this work? This seems to be a good thing to have in the garage for other reasons, could I just hook up the battery leads of the LCS to this thing and let it rip? Has anybody else used these things as power sources? Any reasons it WOULDN'T work??

I'd be concerned that this thing would put out so much current that it'd burn up the wiring. Maybe not, I don't know. You'd need to look into the specs better.

The Electron Beam will launch anything given enough power. It is, after all, only a switch. See the 2004 NAR annual member's booklet for conversion plans for the EB to use higher power (essentially replacing the wiring with 18 or 16 guage and adding pad leads of 30' length for mid-power launching). I did the conversion on one and it was great. Until I stepped on it.

#### BlueNinja

##### Well-Known Member
I think that's what KCAR uses. Batteries Plus (don't know if there are any where you are?) has a nice little 12v battery that is maybe 4 inches tall and a foot long.

#### Stymye

##### Well-Known Member
those portable jump starters are ideal ( thats what I use) and it even has a handy light on it.. plus you can keep it in the car for those emergencys.

if you want something smaller, try R/C batteries. they also pack some punch.

#### limd21

##### Well-Known Member
In normal operation, the amount of current drawn in all of these systems is almost totally determined by the resistive load in the ignition system (the reactive effects are negligible). An igniter is only capable of drawing a limited amount of current, no matter how big the battery. You could have a battery that's "capable" of delivering *mega*watts, but if the voltage is still only 12v, only a fraction of that capacity will actually be drawn. Lot's of clubs launch rockets with large car batteries that are capable of putting out several hundred amps (imagine the load of starting a car engine in cold temperatures...) Only the slightest fraction of this current is drawn when launching a single rocket, which is exactly why puny little AA batteries can work, too.

I'll qualify all of what I said above to exclude the situation where you tie the clips together in a dead short. There, the larger batteries are capable of using doing some damage, where a smaller batteries simply wouldn't have enough oomph to cause a problem. A suitable fuse NEAR THE BATTERY is the proper way to protect from such an accident.

Personally, I think these jumper packs are a really great solution for launching rockets, since they have such a nice "alternative" purpose, too. Similarly, I use the ni-cad packs from my cordless drill as my own power source. Perfect - high capacity, compact, and essentially "free" because I already own the drill.

#### bobkrech

##### Well-Known Member
That's a wonderful power unit at a great price. I keep a similar unit in my car for an emergencies, but I paid $40 for one and it didn't have the jump start or flashlight options. The only recommendation I would add is to use the 12 volt cigarette lighter output instead of the battery charging leads. This bypasses the charging electronics and provides straight 12 v dc out. My unit's DC power supply has a 20 amp fuse so there's plenty of current available for clusters. These units are a much better deal than buying a battery alone since you also get a battery charger to recharge the battery. AllElectronics.com sells an a 12 v 17 AH battery for$35, and a charger will run you at least $10. For$29, that multipurpose jumpstarter, air compressor, flashlight, DC power source presented here seems like a real bargin.

Technical Note: Ohm's law always applies. Current draw is always I=V/R. Power is P=IV. The battery may be able to source up to 900 amps into a dead short, however fuses take a few second to heat up and open under a typical overload. Your ignitor is basically a fast fuse witha reaction time of a few milleseconds. While the battery may supply 10's of amps to light a cluster, once lit, the circuit is open and no further current will flow so you shouldn't pop the fuse on the unit, nor will you burn up ythe wiring on the launcher.

Bob Krech

#### Daedalus

##### Well-Known Member
Yep, they work very well for Estes, Quest and Copperheads. I use mine with a relay controller hooked directly to the clips. If the ignitor can light it will - I have had Copperheads where there is a short between the two layers of foil and the entire copper section between the clip points (I use ordinary clips and tape - not a copperhead clip) has burnt away. When there are slight whisker shorts they just burn off miliseconds before the ignitor head lights.

Relay controllers and jump starter packs are excellent

##### Well-Known Member
I was in Lowes late last week, and I was thinking the same thing. Convenient, since it has a built-in charger for the battery, built-in cables to deliver the power, etc., and plenty of oomph.

At 18 pounds, it wonlt create a hernia, but it will get old carrying it 100-200 yards to a range head along with a range box, launch controller, rockets, water, etc. Might want to buy a kid's wagon to drag it all in.

Originally posted by DynaSoar
I'd be concerned that this thing would put out so much current that it'd burn up the wiring. Maybe not, I don't know. You'd need to look into the specs better.

The Electron Beam will launch anything given enough power. It is, after all, only a switch. See the 2004 NAR annual member's booklet for conversion plans for the EB to use higher power (essentially replacing the wiring with 18 or 16 guage and adding pad leads of 30' length for mid-power launching). I did the conversion on one and it was great. Until I stepped on it.
The current is determined by several factors, among them the internal resistance of the battery (an area where lead-acid excels), wiring size, capacity of the switching elements, resistance, number, and configuration of igniters, plugs, etc. A higher capacity battery is an advantage. The voltage is still 12v, so it won't "push" the current any harder. It will just hold it back less. Makes sense?

The Electron Beam is limited by the wiring guage, which you upgraded (but not by a whole lot). 12 guage wire is used in wiring 20 amp circuits in houses. 10 guage is for 30 amp circuits. Outdoor wiring has a slightly different chart, as the heat disipation and safety considerations differ. 16 or 18 guage wire will have more resistance than you really want for high current cluster launches. It will disipate too much power along its length, warming the wire and decreasing the voltage at the igniters when current is flowing. Ditto the switch itself. It likely wasn't designed to carry 30+ amps or anything close to it. You could end up overheating it and possibly getting a burn or melting something. I'm not saying it won't fire clusters, but it won't do it as well as a built-for-the-current system will, and if you have to hold the button down a little longer than average, it could get hot. The voltage drop in the wire depends on the resistance of the wire (Thicker wire has lower resistance to electrical flow.), the resistance of the load (the igniters, their type, arranged singly, in parallel, etc.), the internal resistance of the battery (Big ones have lower resistance, generally.), the resistance of the switch or relay, etc., and the current flowing through those resistances. Light wires will rob the igniters of voltage, and therefore rob them of current as per Ohm's Law.

I like the idea of the moderately sized (and weight) gel-cell batteries. What do most people use to charge them with?

Originally posted by Micromeister
The man ask if it pictured jump starter would work; The answer is NO MATTER what the Specs and amp/hr output rating... Absolutely! It won't burn up whatever wiring it is attached to if an igniter is attached to the clips. The Igniter will pop first! Even the wimpy little 26gage wire on an electron beam will handle that much of a "monentary" power surge. I've used a jump starter like the one pictured and Much higher power output sources just for fun. like a huge 36 volt 1200amp/hr forklift battery with a converted electon beam controller with #8 stranded copper leading to the relay leads, and the same 26ga controller wire. NO Problem, the control wire didn't even get hot.

Good point on the EB conversion diagram in the last couple nar members handout.
I agree, as long as the igniters do pop quickly. If you have a short instead, things could get warm. If you have a relay-based system, better include a high-current diode (or even a pair in parallel for redundant safety and extra capacity) to shunt the surge, lest it breach the insulation on the wire and light up a rocketeer's life. Also, using higher voltages can cause some igniter wires to vaporize too quickly to allow motor ignition, actually defeating the purpose.

wwattles: The ideal method would be to use the battery box thingie to power a relay-based launch controller, rather than using it directly.

Fore Check: Wow! Bet ya can't do that again.

Ditto what limd21 says. To expand a bit on the small batteries, their chemical reaction and size combination can't supply that kind of current, but also, their internal resistance is high enough to become a significant current limiting factor.

bobkrech: Breakers vary in speed. Grount-Fault Circuit Interrupters are very fast. Slow-blow fuses are intentionally slow. Good points on the way current behaves. As long as the igniter is an effective and rapid fuse, all is well. Best to have a dedicated breaker adjacent to the power source, as limd21 points out, just in case you wind up with shorted clips. That way, the fuse heats up and burns, not the thinnest wires in the igniter circuit (typically the leads from launch controller to ingniters).

When you count in all the goodies in a system like this and figure you have a battery and a charger, it's all but a no brainer to use one of these. One disadvantage I can see in any external battery is that something like a tool or a spare launch rod could get dropped on the exposed battery leads. Hooking into a front panel power jack could avoid that, though it may be limited to a "mere" 20 amps or so. Also kids could kick the leads, etc. Still, it looks like the way to do it.

Sorry for the "book". Hey! Can I get credit for three posts?

#### bobkrech

##### Well-Known Member

My Coleman unit is simply an air compressor whose battery can be used as a DC power power supply. The 12 volt lighter socket is protected by a standard modern color coded plastic 20 amp automotive fuse. Cheap and reliable.

I'm sure the battery charger side of the freatured combo unit has all kinds of electronic safeguards such as reverse polarity protection and probably a minimum voltage detection circuit that most chargers incorporate to prevent the charging of a frozen or shorted battery. If it has a minimum voltage detection circuit, it won't supply DC power to the launcher because no voltage will be seen on hook up and the charger circuit will not turn on. The cigarette lighter socket DC supply doesn't have any electronics and is connected directly to the battery through the fuse so it will work all the time.

Bob Krech

#### JStarStar

##### Well-Known Member
Well, I hauled off and bought the portable battery booster, so I'll have that to use if I want to start launching clusters. Plus it does a few other useful things (air pump, flashlight, etc.) so I figured it was a good buy. I thought about just buying a separate tractor/cycle battery, but I figured there isn't all that much size/weight saving in doing that (to say nothing of  saving - plus then I'd have to buy a battery charger, which currently I do not have), so I might as well just buy something that actually DOES something rather than just sitting there.

Here's the wagon I have in my garage that I use to cart my rocket stuff over into the park adjoining my house when I want to go launch on the soccer fields over there. It's about a 200-300 yard trek, but no big deal. I can load a couple of plastic storage tubs full of rockets and launch equipment into the basket and there's still room for my niece and nephew to ride in the "Rocket Wagon."

It'd be a problem fitting this monster into the trunk of my car, though ... I gotta start thinking about an SUV. Maybe next spring ... I wanna nurse my old '95 Chevy through one more winter. That's the problem with these new consarned 90s-00s model cars - they last too long!! In my day (grouchy old man voice), cars rusted out and fell to pieces after 5 years - you never had to worry about driving around in a 10-year-old car!!!

##### Well-Known Member
bobkrech: Good points about the multi-purpose unit. One could get 20 amps (or whatever the plug on the front can supply) but no more. I'd want to be able to get at the whole amperage available from the battery. I guess I could take one apart inside and get it to do what I want, but that would be probably more work than it's worth, especially if it used small glued-in circuit boards and the like.

{McCoy voice on} I'm a EE, not a surgeon, Jim!

JStatStar: Nice wagon! That's just the thing. How about this. Get a trailer ball installed, and go find a small utility trailer to tow your stuff to launch sites that are far enough to have to drive to.

Be sure to report back here when you use the portable battery booster unit. Could you use the cable clamps? Did you have to use the front plug? How well did it work? How much of a pain/pleasure was it to lug around? Did the kids get into the electrical connection between the booster and the launch controller, etc.

#### Hospital_Rocket

##### Well-Known Member
For field launches I use two R/C Nicad packs. They deliver an awsome short punch and I have a trickle chargetr that attaches to my car battery to pump them up. Add to the fact that they are smallish (I mean they have to fly in an airplane) and do not weigh what a lead/acid monster can.

The portapack (for lack of a better noun) is a cool idea too.

My next experiment will be with polapulse batteries. These 1oz batteries can vaporize a paperclip!

A

#### Elapid

##### Well-Known Member
NiCd pack from my cordless drill.

##### Well-Known Member
What do you use to connect the drill power pack to the launch controller?

#### Cajunman06

##### Well-Known Member
I have built a similar system and use an 18v rechargable drill/tool battery. While it isn't real "purty", I built a prototype for a connector. Basically cut a hole through a block from a 2x4 that matched the shape of the "male" part of the battery. Then I made contacts from brass strips and secured them to the block with wood screws. At that point, you could simply solder your wires directly to the contacts but I chose to include a mounting screw/post so that I connect the battery to more than one pad at a time. My multipad controller is now about 95% complete.

Hoping to post pics of what did soon.

#### Micromeister

##### Micro Craftman/ClusterNut
TRF Supporter
I still prefer a good quality gel-cel here's a pic of the two types i'm most familiar with. The leather cases are home made, making transport and storage a breeze even the heavier 26 Ah type.