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Lithium batteries in a launch controller?

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dragon_rider10

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Would using lithium AA batteries in an Estes launch controller provide any benefit? Other than longer performance in a camera, I don't really know what the difference is vs. typical alkaline AAs. Figured one of the electrical wizards here might know.
 

bobkrech

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The cheapest and best change you can do to the Estes Launcher is to replace the 250 ma light bulb with a 10 ma LED. (To limit the current to ~10 ma at 6 volts, you want a red led in series with an ~500 ohm resistor.)

That continuity light bulb really kills your batteries. Your igniter will draw several amps for a <1/10 of a second or so until the bridgewire breaks: 6 volts x 3 amps x 0.1 seconds = 1.8 Joules. If you hold the continuity button for 12 seconds per launch: 6 volts x 0.25 amps x 12 seconds = 18 Joules; you used 10 times more energy than the igniter usesin a launch! An LED would consume only 6 volts * 0.010 amps * 12 seconds = 0.72 Joules or about 1/3 of what the igniter uses.

You'll get 10 times as many launches out of a set of plain old alkaline batteries if you simply get change out the light bulb with an LED.

If you go to AA lithiums you will get probably twice the number of launches compared with alkalines, but if you go to rechargable NiMH batteries instead of Lithiums, you'll get more current out at a lower voltage, and you can recharge the batteries so you'll win all around, and you'll never have to buy batteries again.

Bob
 

dragon_rider10

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The cheapest and best change you can do to the Estes Launcher is to replace the 250 ma light bulb with a 10 ma LED. (To limit the current to ~10 ma at 6 volts, you want a red led in series with an ~500 ohm resistor.)

That continuity light bulb really kills your batteries. Your igniter will draw several amps for a <1/10 of a second or so until the bridgewire breaks: 6 volts x 3 amps x 0.1 seconds = 1.8 Joules. If you hold the continuity button for 12 seconds per launch: 6 volts x 0.25 amps x 12 seconds = 18 Joules; you used 10 times more energy than the igniter usesin a launch! An LED would consume only 6 volts * 0.010 amps * 12 seconds = 0.72 Joules or about 1/3 of what the igniter uses.

You'll get 10 times as many launches out of a set of plain old alkaline batteries if you simply get change out the light bulb with an LED.

If you go to AA lithiums you will get probably twice the number of launches compared with alkalines, but if you go to rechargable NiMH batteries instead of Lithiums, you'll get more current out at a lower voltage, and you can recharge the batteries so you'll win all around, and you'll never have to buy batteries again.

Bob
I knew I'd get some good ideas! That sounds like an excellent modification.

Do you have any feeling which is the better LPR launch controller? Estes or Quest, as far as efficiency goes? Quest uses a 9v and has an audible alarm and a flashing light. Estes has the light but no alarm and uses the AAs.
 

bobkrech

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I knew I'd get some good ideas! That sounds like an excellent modification.

Do you have any feeling which is the better LPR launch controller? Estes or Quest, as far as efficiency goes? Quest uses a 9v and has an audible alarm and a flashing light. Estes has the light but no alarm and uses the AAs.
They are both very simple inexpensive basic launchers.

The Quest launcher is designed to work with Quest igniters which needs only 120 ma. It has a low continuity current of less than 10 ma that will not fire the Quest igniters. It is not well suited for Estes igniters since 9 volt transistor batteries are not great for higher current igniters like the Estes.

The Estes launchers are designed for Estes igniters. They have a high 250 ma continuity current that will fire a Quest igniter on a continuity check, so you can not use it with Quest igniters. Estes igniters require at least 2 amps so the use of AA batteries is ok.

Neither one is suitable for use with APCP igniters from AT or other sources, however the Quest igniters will ignite APCP motors.

It's pretty easy to make a better launch controller out of parts you can get from an electronics store for not much more money.

Bob
 

dragon_rider10

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I'd like to explore building my own controller but have no clue about electronics. Any threads on such a topic for the electronics ignorant?
 

luke strawwalker

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Use the search box above-- I've posted quite a few times on launcher mods over the past few months, along with pictures and a wiring and component diagram of the guts of the Estes controller and how to modify it to 'be the best it can be' for what it is...

There's also a lot of other good information in those threads by other folks on how to make a homemade launch controller. Once you get the basic circuit down and get a line on components (Radio Shack is your friend, among others) it's not very hard at all to whip up a really nice basic controller, and not particularly expensive, either. The circuits are pretty simple for the basic controllers, even when you start replacing bulbs with LED's. Relays kick it up slightly in complexity if you want a mondo-cluster launcher, and if you want to go high-tech and install semiconductor microelectronics such as timers or stuff, then you're above my pay grade...

Best thing you can do is read, learn, and experiment... :) Have fun! OL JR :)
 

Zack Lau

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Lithium AA cells will operate at a significantly lower temperature than alkalines, if you are trying to set a record for launching at the lowest temperature. We have an outdoor temperature sensor that specifies lithiums for lower temperarature use. Energizer says its Ultimate Lithiums can work to -40 degrees, though I couldn't find a data sheet that explains how well it works down there.
 
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dragon_rider10

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Well, I try not to have anything happen in the lowest possible temperature. I'm quite fine with things happening at our record cold of 19 degrees in Florida. Even then, anything much lower than 30 and I'm staying inside. -40 is unfathomable and is certainly no place for me or my rockets.
 

stickershock23

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I hope I didnt miss someone saying this already. LI poly batteries are designed to put out a steady power for a long period of time. If you are igniting simple estes igniters, maybe a few copper heads that is perfect. BUT they do not hit as hard under a big load, meaning they wont work as well for Clusters etc.

For situations were you need HIGH amperage you are better off with Ni cads. but then they wont last quite as long. one more thing to think about is temp. I hear Lipolys really do bad in really cold temps.

just my .02
 

bobkrech

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I hope I didnt miss someone saying this already. LI poly batteries are designed to put out a steady power for a long period of time. If you are igniting simple estes igniters, maybe a few copper heads that is perfect. BUT they do not hit as hard under a big load, meaning they wont work as well for Clusters etc.

For situations were you need HIGH amperage you are better off with Ni cads. but then they wont last quite as long. one more thing to think about is temp. I hear Lipolys really do bad in really cold temps.

just my .02
Would that it be so simple. Ir isn't!

The best bang for the buck for a launcher comes from a lead acid gel cell. You can get a 12 V, 7 AH lead acid gell cell for $21 and it will deliver over 100 amps on a relay system if your wiring resistance is low enough. http://www.batteryspace.com/sealedleadacidbattery12v75ah20hrsforupsseascooterande-bikes.aspx

You can get good information on all rechargeable batteries here. http://batteryuniversity.com/index.htm It will take you several hours to read all of it, but if you want to get fairly well educated on battery technology, this is a good place to start. (And only to start as much of the data is 5 years old data and the NiMH and Li battery technology has got a lot better since this was written.)

The temperature ranges of the most common rechargeable batteries are listed here, but read the fine print. http://batteryuniversity.com/partone-3.htm While NiCads have the lowest rated operating temperatures, the rest of the pack is not far behind. The rest are rated down to -20 C, and if you insulate a big battery well, it will stay warm for a long time.

Also Li-ion Mn and Li-ion-FePO4 batteries source more current unit capacity C (capacity), and last longer for a given current drain on a per unit C rating, than NiCads, but Pb-acid gell cells are so inexpensive relative to all other chemistries, that they win hands down for high pulsed current delivery (several seconds long).

If weight is not an issue, Pb-Acid gell cells always wins in a practical, low cost launcher, and if you're really cheap, you don't even need to buy a charger. Just get a cigarette lighter plug and charge it from your car on your way to and from the launch field. Your car's charging system already had the protective circuit built-in to prevent overcharging.

Bob
 

Zack Lau

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AA cells work just fine in my modified Estes launcher for launching low power rockets--it uses a buzzer so I don't have to look at the controller when launching rockets. Not only are the AA cells smaller and lighter, but they don't destroy the igniters--it is quite possible for the igniter to survive the launch for reuse. I just happen to have rechargeable AA cells for other electronics, so cost isn't really an issue. A spare set of alkalines is also a good idea, if it takes a while to get to the launch site.

Of course, if I were using copperheads or some other igniter that used a lot of current, sealed lead acid batteries would then be my first choice--a dry variety that won't leak.
 

Samuron

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Granted that igniters usually fire pretty quickly, doesn't any one else see an explosion risk in deliberately shorting lithium batteries?
 

bobkrech

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Folks need to adopt the KISS principle when it comes to batteries. Use the least expensive ones that work for your application.

AA cells work just fine in my modified Estes launcher for launching low power rockets--it uses a buzzer so I don't have to look at the controller when launching rockets. Not only are the AA cells smaller and lighter, but they don't destroy the igniters--it is quite possible for the igniter to survive the launch for reuse. I just happen to have rechargeable AA cells for other electronics, so cost isn't really an issue. A spare set of alkalines is also a good idea, if it takes a while to get to the launch site.

Of course, if I were using copperheads or some other igniter that used a lot of current, sealed lead acid batteries would then be my first choice--a dry variety that won't leak.
Zack

For a 6 volt Estes launcher, AA alkaline batteries are fine, as are 1.2 volt recharhable NiMH or 1.5 volts Lithium batteries. As you mentioned, replacing the continuity bulb with a piezo buzzer, or as I have said, a LED, is the most important change you can make to your Estes launcher.

If you want or need a launcher that will activate high power rocket motor igniters then 12 V Pb-acid gell cells are the way to go.

Granted that igniters usually fire pretty quickly, doesn't any one else see an explosion risk in deliberately shorting lithium batteries?
Samuron

Using Lithium batteries to activate igniters is not shorting the batteries. Igniters typically have a resistance between 0.5 to 2 ohms (2 to 0.5 amps per volt). Pulling 10-20 amps out of a Lithium battery for a second or so does not hurt or heat the battery.

Typicall wire shorts have a resistance below 0.01 ohms (>100 amps per volt). What shorting the batteries means is putting a very low resistance wire across the battery and walking away, or driving a nail through one. In fact, in order to be transported (and sold), all commercial Lithium batteries must pass a UN standard shorting test. If they explode, they fail, and can not be shipped.

Bob
 

Samuron

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Samuron

Using Lithium batteries to activate igniters is not shorting the batteries. Igniters typically have a resistance between 0.5 to 2 ohms (2 to 0.5 amps per volt). Pulling 10-20 amps out of a Lithium battery for a second or so does not hurt or heat the battery.

Typicall wire shorts have a resistance below 0.01 ohms (>100 amps per volt). What shorting the batteries means is putting a very low resistance wire across the battery and walking away, or driving a nail through one. In fact, in order to be transported (and sold), all commercial Lithium batteries must pass a UN standard shorting test. If they explode, they fail, and can not be shipped.

Bob
True, but every type I could find, including the Eveready Li-Fe types, carry a warning of possible explosion, even though they incorporate shorting protection.

Even acknowledging the low current draw of igniters, it is hardly uncommon for igniter clips to come in contact with each other.
 

bobkrech

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True, but every type I could find, including the Eveready Li-Fe types, carry a warning of possible explosion, even though they incorporate shorting protection.

Even acknowledging the low current draw of igniters, it is hardly uncommon for igniter clips to come in contact with each other.
Lawyers, not reality, drive the warning labels.

We develop several types of Li batteries and we can't get them to explode even when we try.

Bob
 

Samuron

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We develop several types of Li batteries and we can't get them to explode even when we try.
Since your experience would appear to far exceed mine, I will concede the argument.
 

Zack Lau

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Don't forget the inexpensive construction of Estes Launch controllers--the resistance in the battery contacts, switches, and wires add up, so shorting the clips isn't really shorting out the batteries.
 
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