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#### rklapp

##### NAR# 109557
TRF Supporter
Had many things going on this weekend.

More testing of my DIY launch controller on a windy day...

The continuity light appears to be working. I finally figured out I bought the wrong gauge of speaker wire so more on order. I have the parts to build a second controller. This will have three lights plus decided to go with 6v C batteries instead of AA.

My previous video from Wednesday. I realized that 15ft wasn't enough so added another 10ft.

After losing the Bull Pup 12D last week, I built an XL version. Here's the BP compilation video I made.

#### BABAR

##### Builds Rockets for NASA
TRF Supporter
Great rockets and nice video (your orange machine is probably the only video I have seen that showed a Mosquito size rocket flight from pad to landing!)

I am going to go out on a limb here and criticize your launch technique on the Dodging Hurricane Douglas video. It seems perfunctory, I.e., going through the motions, and maybe not even that. It may be that you were running the camera and you did all that before you had your friend push the button, just didn’t catch it on video, so I apologize in advance if my comments are out of place,

Before pressing that button, you should be actively looking at the sky overhead (no aircraft or low clouds) and checking out the launch area and probable landing site for unwary spectators or vehicles. Don’t just say the words. Also traditionally there is a countdown, main thing is what you are doing should be loud enough and clear enough that everyone in the launch area and (for low power in a park setting) the likely recovery area is aware a launch is imminent. Then if you have an incomplete deployment event like you had with the Spin Thing comment “the thing didn’t come out all the way” you want anyone in sight, on site to have eyes on the rocket so they can see and avoid.

I try to do this even when I have the field all to myself, simply to develop the habit so I always do it whether anyone is around or not. Again, I think the purpose of the loud countdown is to get the attention of people nearby so they know what is going on.

Congrats on all those great rockets and successful flights.

#### rklapp

##### NAR# 109557
TRF Supporter
@BABAR , I appreciate the comments. My son is not an enthusiastic rocketeer which is probably what you were picking up on. My other son is but was unavailable last Wednesday.

#### mo2872

##### Well-Known Member
Might want to stretch that cord out all the way, too.........but cool launches. Need to do a BullPup, always liked that one as a younger me.

#### Joshua F Thomas

##### Well-Known Member
C batteries are a good idea mainly because you’re looking for high amps, and the bigger batteries can deliver more.

If you really want to ensure powerful and reliable launches, try 18850 or 26650 sized LFP batteries. I use 4 in my launch controller. They’re rechargable.

#### rklapp

##### NAR# 109557
TRF Supporter
C batteries are a good idea mainly because you’re looking for high amps, and the bigger batteries can deliver more.

If you really want to ensure powerful and reliable launches, try 18850 or 26650 sized LFP batteries. I use 4 in my launch controller. They’re rechargable.
Good advice. Ironically, they can air ship A to E rocket motors but not lithium batteries. I'll have to check to see if they have it at Battery Bill's.

#### neil_w

##### Chuffed as ninepence
TRF Supporter
I would think 6xC alkalines would be more than sufficient for any any single motor and small BP clusters, although certainly nothing wrong with the lithiums if you want to go that way.

#### rklapp

##### NAR# 109557
TRF Supporter
I would think 6xC alkalines would be more than sufficient for any any single motor and small BP clusters, although certainly nothing wrong with the lithiums if you want to go that way.
The box can only fit a 4x case, I think. It'll be tight. Just doing LPR with it, so next one might be external.

#### Joshua F Thomas

##### Well-Known Member
The benefit of the lithiums are the recharge. It sucks to have to keep buying more batteries, and in theory is better for the environment.

i prefer the lithium iron phosphate (LFP) over lithium-ion for a few reasons. They have a base cell voltage of 3.2, making it easier to get close to 6 or 12 volts depending on your build. They handle high-drain better, which is what igniters are all about. Finally they have very stable voltages up until the end of their capacity.

#### rklapp

##### NAR# 109557
TRF Supporter
Might want to stretch that cord out all the way, too.........but cool launches. Need to do a BullPup, always liked that one as a younger me.
Did you see the first video? I added another 10ft. I found 16ga wire on Amazon so in the mail.

#### Old School Doug

##### Too energetic an ejection charge ??
The box can only fit a 4x case, I think. It'll be tight. Just doing LPR with it, so next one might be external.
Nice job on the controller. I took a different tack when designing mine (not as good looking as yours and most likely over thought/engineered). I set up a small waterproof Apache utility case with a 4 AA battery pack, safety lock key switch, green and red indicator LEDs and momentary contact launch switch. The output goes to a second Apache box I have located at the launch tripod. That box contains a N/O micro relay and two 6v lead acid rechargeable batteries that can be configured for either 6v or 12v operation. The launch controller energizes the relay in the battery case to trigger the launch. Since the relay will trigger all the way down to 1.5 volts, battery life of the AA pack is almost never an issue. On the downside, obviously an extra piece of gear to lug around.

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#### rklapp

##### NAR# 109557
TRF Supporter
So after reading the various posts here and seeing the nice job done on

Nice job on the controller. I took a different tack when designing mine (not as good looking as yours and most likely over thought/engineered). I set up a small waterproof Apache utility case with a 4 AA battery pack, safety lock key switch, green and red indicator LEDs and momentary contact launch switch. The output goes to a second Apache box I have located at the launch tripod. That box contains a N/O micro relay and two 6v lead acid rechargeable batteries that can be configured for either 6v or 12v operation. The launch controller energizes the relay in the battery case to trigger the launch. Since the relay will trigger all the way down to 1.5 volts, battery life of the AA pack is almost never an issue. On the downside, obviously an extra piece of gear to lug around.
My son suggested I install two keys that have to be turned simultaneously and a number pad to type in the launch codes which will be secured in a "football".

Somehow this Li-ion set made it through the filter. Should I order or just use the C batteries for the new controller?

#### Joshua F Thomas

##### Well-Known Member
. That box contains a N/O micro relay and two 6v lead acid rechargeable batteries that can be configured for either 6v or 12v operation.
Just out of curiosity, when do you need only 6v and not 12v?

#### Joshua F Thomas

##### Well-Known Member
My son suggested I install two keys that have to be turned simultaneously and a number pad to type in the launch codes which will be secured in a "football".

Somehow this Li-ion set made it through the filter. Should I order or just use the C batteries for the new controller?
I would not use those in a launch controller! If you see *any* lithium ion battery that is not 3.7 volts or a multiple of that, it is using other circuitry to regulate the voltage - and you very much don’t want this on something that needs to draw as much power as possible as quickly as possible.

#### rklapp

##### NAR# 109557
TRF Supporter
I would not use those in a launch controller! If you see *any* lithium ion battery that is not 3.7 volts or a multiple of that, it is using other circuitry to regulate the voltage - and you very much don’t want this on something that needs to draw as much power as possible as quickly as possible.
So 4 x 3.7 = 14.8v?

How about these? They'll ship. Is this preferred over 4 C batteries? I have the room for the larger battery case so could go with either.

What's awesome about Amazon is that they'll tell me the shipping costs for non-Prime items without me having to enter my credit card every frickin time.

#### Joshua F Thomas

##### Well-Known Member
For reference, here’s what I did:

1) Bought two 26650 cell holders: https://www.ebay.com/itm/26650-Dual...-2-pcs-Brass-SMD-clip-US-Seller-/132490043800

2) Bought four 26650 LFP cells. Many many sellers of these, they’re very common in DIY power banks. Check ebay. Don’t pay more than $10/battery. 3) Wire as you would normally for other batteries. Make sure to use heavy gauge wire on the battery terminals ( I used 14g ). 4) Buy an LFP battery charger. You *must* find one that says “3.2 volt” compatible - lithium-ion or “3.7 volt” is not compatible! Dual chargers are available. Make sure it fits 26650 size cells. #### Joshua F Thomas ##### Well-Known Member 1) Cell size directly relates to instant current delivery. If you insist on sticking with AA size, just don’t bother with the lithium, and use rechargable NiMH or regular alkaline. It doesn’t help to have 15v if you can’t get high current out of it. This is why you don’t see anyone using 9v batteries. 2) Or use 5-6 C NiMH batteries. The voltage is lower, you get 1.2 v/cell, but the current is higher. 3) Amazon, which I use a lot, is absolutely the wrong source for lithium battery projects. Availability and price is miles better on ebay and battery specialist vendors. #### rklapp ##### NAR# 109557 TRF Supporter Looks like I'm visiting Battery Bills tomorrow. Shipping: Does not ship to Alaska/Hawaii | See details Item location: Ontario, California, United States Ships to: United States See exclusions #### rklapp ##### NAR# 109557 TRF Supporter My next project. Turns out the button I ordered is latching and not momentary. I’m thinking of using it anyways. #### Joshua F Thomas ##### Well-Known Member It’s not the launch button, is it? Using a non-momentary launch button violates the NAR safety code. #### OverTheTop ##### Well-Known Member There is usually a small spring-loaded catch in the mechanism to make them latching. Might be easy to extract... #### Joshua F Thomas ##### Well-Known Member There is usually a small spring-loaded catch in the mechanism to make them latching. Might be easy to extract... I tried this with a Radioshack latching button and was never able to get it working correctly, but if you can... #### rklapp ##### NAR# 109557 TRF Supporter I tell you guys my ideas and you talk me out of them. That’s how it works. #### Joshua F Thomas ##### Well-Known Member Hey, it beats building a thing and then having to tear it apart. Been there, done that. #### Old School Doug ##### Too energetic an ejection charge ?? Just out of curiosity, when do you need only 6v and not 12v? If I'm only launching black powder motors on a given day I go with 6v. If doing both black powder and composite I up it to 12v. #### Joshua F Thomas ##### Well-Known Member If I'm only launching black powder motors on a given day I go with 6v. If doing both black powder and composite I up it to 12v. Why not just use 12v all the time? #### dhbarr ##### Amateur Professional 1) Cell size directly relates to instant current delivery. If you insist on sticking with AA size, just don’t bother with the lithium, and use rechargable NiMH or regular alkaline. It doesn’t help to have 15v if you can’t get high current out of it. This is why you don’t see anyone using 9v batteries. If you're going to use AA's, use Energizer Ultimate LiFeS2 , they are quite beefy relative to other things that size If you're going to use 14500's, make sure they are 2C max discharge I've used both configurations with a standard Estes "E" Launch Controller to start up clusters of D composites or single G's #### Joshua F Thomas ##### Well-Known Member I meant the rechargable lithiums, but the primary lithium cells are a good choice if you’re not using rechargable #### rklapp ##### NAR# 109557 TRF Supporter I went to Battery Bill’s today. They have 3.7v 3500mah for$11 each and 5000mah for $16 each. They also have a recharger for$17. No case but can get from Amazon. I could solder them together but how would I recharge them?

I admit that I’m in decision paralysis now with the options laid out before me. Maybe I’ll stick with the C batteries for now and work my way up from there which is more than adequate for the A to D I launch.

LHS had no resisters so will order the pack JFT recommended.