Eggtimer Quantum setup question

[HoldYourOwn]

Just finished building an Eggtimer Quantum and was wondering if people are adding a switch to turn it on? Just a little confused on powering the unit in the rocket. Any advice would be greatly appreciated!

 

[Andrew Brown]

I do add a switch. I’m not sure if the debate has settled regarding arming through software or powering up on the pad, and not something I want to risk. A switch is pretty trivial to add.

 

[waltr]

I use a 'screw switch' to completely disconnect power to the Quantum.
This allows ebay to be fully closed and ready to launch with no power.
Switch turned on when rocket is on the rail. Then ARM and install motor igniter.

 

[David Schwantz]

I also add a switch. I like the pull pins from LabRat rocketry.

 

[David Schwantz]

The debate is over. You do NOT need to add a switch to Alt's that use a WiFi switch.

 

[David Schwantz]

If you want a switch, of any kind, just put it between the battery and the Quantum in the red, positive, wire.

 

[HoldYourOwn]

The debate is over. You do NOT need to add a switch to Alt's that use a WiFi switch.

But isn't it drawing power the whole time? There is no on off switch in the WiFi settings that I have seen. Am I missing something?

 

[cerving]

The primary reason you would want to add a mechanical switch is so you can close up your AV bay ahead of your launch, although I personally open up my AV bays and check everything before every launch. This is an especially good idea if you use screw terminals... I have seen them come loose.

In terms of safety, the Eggtimer WiFi altimeters are some of the safest ones you can get... BOTH sides of the ematches are essentially "dead" until you remotely arm the rocket on the ground, the altimeter detects a launch (usually at 200' AGL), AND the first channel output event occurs. There is no "battery common" connection to the ematches, instead there is an electronic switch on the deployment power that doesn't turn on until the first output event.

And as Mr. Schwantz alluded to, this issue was resolved by TRA in 2020... electronic switches (whether wireless, magnetic, or whatever) are now considered equivalent to mechanical switches. They DO use a little bit of current, of course, which is why you don't want to connect them to the battery until you're ready to use them. If you forget about them they will eventually drain your battery.

 

[Kane]

I do not add a switch to mine. I do open the AV bay before every flight as a standard part of my pre-flight check: connect the power, connect to the Quantum wifi, confirm continuity to all deployments via the web interface (but do not arm), close the app, disconnect to the wifi, close up the AV bay. I've had a Quantum powered up this way for a couple hours between finishing up at the prep table and sitting on the pad before launch with no issues. I use 400 or 430 mah LiPo batteries. If you want even more piece of mind, go with the dual battery option.

 

[wonderboy]

I use 400 or 430 mah LiPo batteries.

This point is the key. I agree the safety aspect of this discussion is pretty settled. The concern is simply how much time elapses between the time you connect the battery until you fly. The unit will be drawing some power from the moment you connect the battery. It won't draw as much as when it is armed, but the draw is non-zero. You just need to make sure that you operate within the capacity limits of your battery. I don't have my numbers handy, but I checked the current draw with the altimeter off, and then again with the altimeter on. Then ask yourself how much time to you want to allow between closing up the av-bay until you want to fly. This will give you the Amp-hours (milliAmp hours) capacity you'll need.

For reference, similar to Kane, I use 450 mAh 2-cell Lipo batteries on my Quantum and Quasar.

 

[terryg]

I turn mine on when I reach the launch site. Be sure that the ebay is designed for easy access to turn on the power.

 

[cerving]

We recommend that you size your batteries for the Quantum based on an average current draw of 70 mA. That 430 mAH battery should last for six hours of "on time".... more than adequate for virtually any flight. I have an extended Polecat Thumper (7.5" dia., about 8' tall) with 4000 mAH Lipo batteries... it needed ballast, so I might as well make the added weight be something useful.

 

[atestani]

Just finished building an Eggtimer Quantum and was wondering if people are adding a switch to turn it on? Just a little confused on powering the unit in the rocket. Any advice would be greatly appreciated!

Keep in mind that on the Quantum, deployment power must be on before applying Quantum power for the Quantum to boot up properly. This is key if you are using separate Quantum and deployment power. You can turn off the deployment power once the Quantum powers up.