Looking for battery to ignite F-I class motors

[RocketSquirrel]

Im building a launch controller and im looking for a small motorcycle battery or 12v 6+amp battery small enough to fit in the hobby box im looking to use (havent decided on dimensions yet). Im just looking at walmart for more questions i can look up later i guess, and i see this relatively cheap 12v jump starter kit with adjustable amp output. This seems perfect to hook up to a launch system, anything i should think about before trying it? Its about 40 bucks

 

[mh9162013]

Are you looking for a battery-based jump starter or a battery charger? I think the former can work to launch rockets; not sure about the latter. Assuming the charger could provide the needed amps, how would you power it at the launch pad? With a battery? Then why not use that battery to power the ignitor/starter?

 

[RocketSquirrel]

Are you looking for a battery-based jump starter or a battery charger? I think the former can work to launch rockets; not sure about the latter. Assuming the charger could provide the needed amps, how would you power it at the launch pad? With a battery? Then why not use that battery to power the ignitor/starter?

Well this is a portable battery charger, so it is a battery. I was thinkin i could just make a negative positive port on the wires going to the rocket with a switch in the middle.

 

[David Schwantz]

LiPo's. Small and powerful.

 

[waltr]

LiPo's. Small and powerful.

Yep. A 3S LiPo is nomially about 12V and the ones sold to power electric aircraft can output many, many tens of Amps and will fire any igniter.

Just remember that for H to I motors, safe distance is 100 feet. Be sure to take into account the Voltage drop of the wires or use a launch controller with a 'remote' relay.

 

[user 30299]

This is about as simple as it gets for a rechargeable battery for lighting up any and all motors.

Many of us have used these for years - and still use them.

The battery is 2.5" x 3.75" x 6". You can buy them cheap on Ebay. Power Sonic is just one of many brands.

There are clubs that use Lipos, and so you get a much more compact power source.

 

[PSLimo]

I use this with a dewalt battery I already have for a cheap way to test ground charges

Amazon.com

 

[David Schwantz]

waltr, I fly the EDF's. Some of my LiPo's will hold 120 amps.

 

[mh9162013]

Well this is a portable battery charger, so it is a battery. I was thinkin i could just make a negative positive port on the wires going to the rocket with a switch in the middle.

Chargers for car/motorcycle/boat batteries usually don't contain batteries themselves as a power source for charging the battery. However, there are portable jump starters that have a hefty battery inside. But this is to provide a lot of juice (amps) very quickly, not a little bit of juice over several hours or days (unless you're using it to charge a phone).

I think what you provided a picture of is a charger that plugs into a wall outlet (I see something on the box that talks about how you can store the AC cord). If not, do you have a link so I can get more information about what you posted a picture of? I'd be curious to see what kind of automotive battery charger is that small and contains a battery inside, but is designed to charge automotive batteries.

 

[David Schwantz]

A 3s 2200 mah Lipo is about the size of a granola bar. Will fire igniters all summer on a charge.

 

[David Schwantz]

Pic is of charger only. No on board battery.

I would not use it for igniters. First of all you will need 110 at the pad. To big for your box. Heavy.

 

[user 30299]

A 3s 2200 mah Lipo is about the size of a granola bar. Will fire igniters all summer on a charge.

I thought your comment needed some scale . . . . (lol)

 

[David Schwantz]

Me 2

 

[Steve Shannon]

This is about as simple as it gets for a rechargeable battery for lighting up any and all motors.

Many of us have used these for years - and still use them.

The battery is 2.5" x 3.75" x 6". You can buy them cheap on Ebay. Power Sonic is just one of many brands.

There are clubs that use Lipos, and so you get a much more compact power source.

View attachment 606343

This is what we use for our club.

 

[waltr]

waltr, I fly the EDF's. Some of my LiPo's will hold 120 amps.

I fly racing Quad copters and can pull well over 100 Amps at full throttle.

 

[David Schwantz]

Amazing how many amps a LiPo will pull.

 

[neil_w]

Well this is a portable battery charger, so it is a battery. I was thinkin i could just make a negative positive port on the wires going to the rocket with a switch in the middle.

These statements suggest that you should reconsider rigging up your own launch controller, at least until you have done more research and educated yourself (beyond this thread).

A launch controller, although relatively simple in the grand scheme of things, is quite a bit more than "wires going to the rocket with a switch in the middle". At minimum, according to NAR safety codes, the controller must have a safety interlock switch, and almost any worthwhile controller will have a continuity indicator circuit as well. There are many circuits that have been published here and elsewhere.

 

[cerving]

This is about as simple as it gets for a rechargeable battery for lighting up any and all motors.

Many of us have used these for years - and still use them.

The battery is 2.5" x 3.75" x 6". You can buy them cheap on Ebay. Power Sonic is just one of many brands.

There are clubs that use Lipos, and so you get a much more compact power source.

View attachment 606343

Back in the day when I was doing R/C gas planes/helis, that was the battery for the starter motor. It worked great with the old Estes igniters, too... I had an old Centuri launch controller designed to be hooked to a 12v battery, it always lit them instantly. The nice thing about those gel cells is that they don't require the same level of maintenance as Lipo's... you can charge them up and leave them for awhile, and top them off any time you want. With Lipo's, you need to store them with a "storage charge"... typically 3.9V per cell, so you MUST have a balance charger to use them.

 

[waltr]

Very true Cris. If size and weight is not an issue then that 12V Gel Cell will work fine. This is also what my local club uses and many simple cheap chargers are available. We use a small Black & Decker changer, just plug in and wit until the LED stops blinking once a month..

 

[prfesser]

These statements suggest that you should reconsider rigging up your own launch controller, at least until you have done more research and educated yourself (beyond this thread).

A launch controller, although relatively simple in the grand scheme of things, is quite a bit more than "wires going to the rocket with a switch in the middle". At minimum, according to NAR safety codes, the controller must have a safety interlock switch, and almost any worthwhile controller will have a continuity indicator circuit as well. There are many circuits that have been published here and elsewhere.

I second this opinion. And third it. And fourth it.

The charger you are considering does NOT contain its own battery---if I'm looking at the correct owner's manual online. "Portable" in this context means that you can pick it up and take it to the car with the dead battery. But the charger still must be plugged into an AC outlet.

In addition to the safety considerations that Neil mentions, there's the practical issue of distance to the pad. A friend of mine attempted to make a simple launch system that used 50' of speaker wire. The voltage drop was high enough that it wouldn't ignite anything heftier than an Estes starter. (I don't recall what battery he was using, so there's that.) For anything over 30', a relay system is probably advisable. With the battery at the pad and not at the go-button, there is no significant voltage drop.

 

[SolarYellow]

There are threads where people talk about beefing up various launch controllers, but most usually the Estes "Pro" version. They are fairly consistent in having success with 50' or 100' of 16/2 extension cord and the rest of the wiring upgraded accordingly being effective with the (3S or so LiPo) battery at the controller. No relays needed.

 

[waltr]

My club also uses extension cords from the controller to the pads. At the pads is a short 'lamp cord' with plug. The other end has the igniter clips.

As I stated in my first post:

Just remember that for H to I motors, safe distance is 100 feet. Be sure to take into account the Voltage drop of the wires or use a launch controller with a 'remote' relay.

If not a remote relay then heavy gauge wire is needed if going 100'.

 

[Donnager]

Fairly sure there is protection circuitry in a jump starter for the strict purpose of jump starting a car. It can provide huge amps for a very short time, and some of these do not behave exactly the same as a battery.

I don't know that these will provide continuous reliable current without "triggering" of some sort to wake it up,.......

If you are going to spend the money, get a 12V lawnmower battery from Harbor Freight ($50) and a trickle/float charger ($30). You won't have to deal with any of those electronics and can concentrate on the safety/ignition portions that you want to work on.

 

[Titan II]

Fairly sure there is protection circuitry in a jump starter for the strict purpose of jump starting a car. It can provide huge amps for a very short time, and some of these do not behave exactly the same as a battery.

I don't know that these will provide continuous reliable current without "triggering" of some sort to wake it up,.......

I have been using a HT jump starter for the last 10 years. It works perfectly fine for the rockets. As a bonus, you have a jump starter for your car whan needed.

 

[Donnager]

I have been using a HT jump starter for the last 10 years. It works perfectly fine for the rockets. As a bonus, you have a jump starter for your car whan needed.

Some of them do.

I have a couple with electronic protection that require a series of actions to power, and they have to sense low voltage to turn on, and it's only for a few seconds. One I have has to be power cycled each time it provides cable power. That one would be a pain to use as a source for launches.

I was suggesting that it may or may not be able to provide continuous power at the amperage you like. Some have continuous power receptacles on the unit that make this concern a non-issue.

Read the instructions on the unit. It may do what you want, and it may not.

 

[Greg Furtman]

I built a launch controller a few years ago and used a 12v gel cell battery. It holds a charge for a long time. I put it in a plastic ammo box I got at HF. The system has safety interlocks. There is a separate hand controller that connects to the launch controller via 50' of Cat5e.

 

[RocketSquirrel]

I built a launch controller a few years ago and used a 12v gel cell battery. It holds a charge for a long time. I put it in a plastic ammo box I got at HF. The system has safety interlocks. There is a separate hand controller that connects to the launch controller via 50' of Cat5e.

Nice this is exactly what i was thinking about. Thank you!

 

[waltr]

I built a launch controller a few years ago and used a 12v gel cell battery. It holds a charge for a long time. I put it in a plastic ammo box I got at HF. The system has safety interlocks. There is a separate hand controller that connects to the launch controller via 50' of Cat5e.

Very nice design.
This easily allows getting to pad out as far as needed to meet NFPA regs without worrying about IR drop.

 

[Greg Furtman]

Nice this is exactly what i was thinking about. Thank you!

Glad to help. Might I recommend silicone jacketed fine multi-stranded wire? It is much more flexible than conventional wire and there is a lot of wire in that box. I had to rewire it with the silicone wire as I couldn't get conventional wire to twist into the areas I need it to go.