Eggtimer RevD Battery Options: which is better?

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Viperfixr

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I am at the point in assembling my first Eggtimer where I need to solder in the Voltage Regulator...or not. I've never used an altimeter that requires multiple batteries before, although I have a few of the 3.7v LiPo batteries from my Ravens. I would prefer as few battery connections as possible, just from a simplicity and ease of setup standpoint. I've soldered switches, tinned wires and other small soldering needs. But, this was my first soldering project, really. So, I am not an electronics guru by any stretch.

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After reading every Eggtimer posting I could find, reading the User Manual and Assembly Manual, I am still unclear on how each of the power options eventually works out. The options appear to be:
A. Take the 3V option, requiring three 3.7V LiPos (main power & channels A and B)--need some kind of connector to solder in
B. Install the voltage regulator and use one or more batteries? Not sure how this will work.

For those of you that took B, how well did it work and how did you wire it all up? Any pictures of either or both options built on a sled and wired up? Suggestions welcomed.

Thanks!
 
I added the voltage regulator and use two 9v batteries. Since almost all of my avbays use them, I opted for consistency. Remember that your pyro circuit will drain a battery if you leave it connected, even if the Eggtimer is off. I set up an Eggtimer to fly five days before the launch, when I checked it at the launch, the primary battery for the altimeter was still at 9.3v but the pyro battery was at 2.8v.
 
Ok if you go with A you can only use 3.7V. Any higher and you will fry the board. With choice B yo can use 4.5V(I think) to 30V(I think). Because you have the locking headers you will only need to use 2 batteries. Depending on what way you decide to go you will have one battery for the power that is either 3.7V or 4.5V+. The other battery is for the deployment channels. what i do is attach 1 battery to power channel A and B. to do this you have to make extension off of your Jst connector so that you have leads going to channel A and leads going to channel B.



If you have any more questions feel free to email me at [email protected]
 
My single-battery recommendation (with the voltage regulator installed) is that your battery must be able to put out 10x the all-fire current of your ematch. Unless you're using Q2G2's, a 9V battery won't cut it if you factor in the safely margin. A 2S (7.4V) 350 mah LiPo will be more than adequate for J-Teks.
 
I am mounting the Eggtimer as the other altimeter in a 4" rocket--redundancy. The other altimeter (Marsa54L) will use a 2S/7.4v LiPo. Sounds like I could get three of these batteries, one for the Marsa54L and two for the Eggtimer (one for power and the other for deployments), or perhaps just a single 2S for the Eggtimer as Chris points out (not sure how the wiring would go on that). Is there an amperage discharge maximum for LiPo batteries connected to an Eggtimer, in either 3v or the higher option?

I do not have a multi-cell LiPo charger, but was going to need one anyway for the Marsa54L battery. Any suggestions on 2S/7.4v batteries that would work for all three purposes and a 2S charger?

Wayco, I missed the pyro output battery drain issue until you pointed this out. That's too bad, as I prefer to prep the av-bay at home a few nights prior. Do you just make the deployment connections at the field?
 
I dont have a problem with the small batts , used 3.7v 1s with my last eGGtimer flights. I DO have a problem with my little MicroJST lipo connectors bought from hobby king.. had one break as I was installing and another broke after the flight where it connects to the eGGtimer.

So am going to retro to 9v on the next go around ..not the eGGtimer or the batts fault - just too fragile of a connector whip .

Kenny
 
I added the voltage regulator and use two 9v batteries. Since almost all of my avbays use them, I opted for consistency. Remember that your pyro circuit will drain a battery if you leave it connected, even if the Eggtimer is off. I set up an Eggtimer to fly five days before the launch, when I checked it at the launch, the primary battery for the altimeter was still at 9.3v but the pyro battery was at 2.8v.

That is the problem with some dual battery systems. If you want to pre-prep in advance in order to fly more rockets (important if one resides in an area with fickle weather) you'll either have to put the pyro battery on its own switch, use a double pole single throw switch of some kind (Keyswitch) or open the bay up and attach the pyro battery on the field. (Which with some ebays can be a hassle and takes away from flying time.)

I have the C revision board and found this out by testing at the bench. The EggTimer is a unit it really helps to sit at the bench with the computer and the instructions to get a handle on the features.

Personally, I like to throw one switch to activate everything so Perfect Flite MAWD's and Stratologgers are appreciated in that regard.

On the other hand, I like the concept of a separate battery just for the matches. Somehow it's psychologically pleasing.:wink:

With the opto-isolation of the electronics on the EggTimer it should technically be resistant to the vagaries of high Rf fields. Anyone try one with a Garmin Dog Tracker? The dog trackers do 2 watts on the MURS frequency (Multi Use Radio Service) at 151 and 154 Mhz. If a device can work without shielding around one of these babies it's pretty darned good.

That is also likely why the altimeter can fly sitting on the board with the 100mW EggFinder GPS with no problem in the TRS. The TRS I believe has the issue with a separate pyro battery so a switch would be needed there too.
Kurt
 
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I am mounting the Eggtimer as the other altimeter in a 4" rocket--redundancy. The other altimeter (Marsa54L) will use a 2S/7.4v LiPo. Sounds like I could get three of these batteries, one for the Marsa54L and two for the Eggtimer (one for power and the other for deployments), or perhaps just a single 2S for the Eggtimer as Chris points out (not sure how the wiring would go on that). Is there an amperage discharge maximum for LiPo batteries connected to an Eggtimer, in either 3v or the higher option?

I do not have a multi-cell LiPo charger, but was going to need one anyway for the Marsa54L battery. Any suggestions on 2S/7.4v batteries that would work for all three purposes and a 2S charger?

Wayco, I missed the pyro output battery drain issue until you pointed this out. That's too bad, as I prefer to prep the av-bay at home a few nights prior. Do you just make the deployment connections at the field?

The Lil' Rascal that I'm flying my Eggfinder in has the alt. in the N/C with a cable cutter for dual deploy. I'm just not comfortable setting it all up in the field, so I did it the day before the launch at home. Chris can tell you how much drain there is for the pyro circuit, and you can probably figure out a Lipo battery that would still let you prep it a couple of days prior to a launch, but Lipo's go bad if you drain them below a certain level, and are more expensive than my trusty Duracell 9v. Never had a problem firing e-matches with them, and I fly a bunch of dual deploy rockets.
 
The Eggtimer's continuity circuitry will draw about 1 mA from a 2S 7.4V LiPo. That's about 2 weeks, continuous. NAR/TRA rules require that you disconnect the deployment power until you're on the pad, so it's a moot point anyway.
 
The Eggtimer's continuity circuitry will draw about 1 mA from a 2S 7.4V LiPo. That's about 2 weeks, continuous. NAR/TRA rules require that you disconnect the deployment power until you're on the pad, so it's a moot point anyway.

Soooooo. One would have to go to the RSO with no pyro battery installed, get cleared and then install the battery. Or do a switch of some kind. As long as low current ematches are used a small switch would be reasonable. Kurt
 
Yes, the deployment battery either needs to be disconnected or switched off. That's no different than having a single-battery altimeter switched off at the RSO.
 
I ended up buying the 460mAh Lipo, 7.4v 2S, 25C, for the deployment channels to share and the 180mAh 7.4V 2S version for the computer itself. Also got an iMax B6 charger since I am formally getting into Lipo batteries--I am sure it will get a lot of use.
 
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