# Egg finder with 9v in next section

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#### ActingLikeAKid

##### Well-Known Member
Working on my L2 rocket and I had had a plan for the Eggfinder. Only ... the plan involved putting the Eggfinder and battery in the top section of body tube.

The top section is 29mm Blue Tube and things will be snug in there. The eggfinder should be fine, but ... I was re-reading the assembly instructions while I waited for it to arrive, and realized that this thing will run fine on a 9v. A tiny LiPo would fit easily in the top section, but the 9v is a lot bulkier. So I had an idea:

There's a sizable plastic transition from the top BT to the next BT (which is 38mm Blue Tube). Was thinking: If I drill a hole in the transition and feed the wires through ... I shouldn't have any problem with putting the 9v battery in the next section of the rocket, right?

Reasons I'm considering 9v over LiPo:
-It's one less point of failure - I have a LiPo charger (that's getting sent to me eventually, long story) and a battery (same deal) but I've not used them and I don't know about their reliability. I can go to Walgreens and get a 9v for like $5. -Putting it in this configuration moves more metal away from the antenna. Thoughts? #### Bat-mite ##### Rocketeer in MD First, let me say that I have not done what you are doing, and thus my opinion is virtually worthless. :wink: With that in mind, I don't see a problem, as long as the parts don't separate. With a GPS device, obviously, you want it to stay connected until the rocket is found. So if anything were to occur that caused the battery to separate from the unit, then, well .... But as long as the battery stays connected, you should be good to go. #### BDB ##### Absent Minded Professor Working on my L2 rocket and I had had a plan for the Eggfinder. Only ... the plan involved putting the Eggfinder and battery in the top section of body tube. The top section is 29mm Blue Tube and things will be snug in there. The eggfinder should be fine, but ... I was re-reading the assembly instructions while I waited for it to arrive, and realized that this thing will run fine on a 9v. A tiny LiPo would fit easily in the top section, but the 9v is a lot bulkier. So I had an idea: There's a sizable plastic transition from the top BT to the next BT (which is 38mm Blue Tube). Was thinking: If I drill a hole in the transition and feed the wires through ... I shouldn't have any problem with putting the 9v battery in the next section of the rocket, right? Reasons I'm considering 9v over LiPo: -It's one less point of failure - I have a LiPo charger (that's getting sent to me eventually, long story) and a battery (same deal) but I've not used them and I don't know about their reliability. I can go to Walgreens and get a 9v for like$5.
-Putting it in this configuration moves more metal away from the antenna.

Thoughts?
Cris discouraged me from using a 9V on my Eggfinder. I built a skinny sled for mine and used it in a Commanche 3 and used the LiPo that Chris suggested here.

That said, I don't see any problem mounting the battery separate from the EF, like you are suggesting.

#### ActingLikeAKid

##### Well-Known Member
Cris discouraged me from using a 9V on my Eggfinder. I built a skinny sled for mine and used it in a Commanche 3 and used the LiPo that Chris suggested here.

That said, I don't see any problem mounting the battery separate from the EF, like you are suggesting.
Ah, okay. So the long story about the LiPos is that my friend who helped me build the Quantum has my LiPos and my JST connectors and everything else.... so I may gently nudge him to send it along.

The cool thing about what I have planned is that I'm going to have a 3d-printed sled for the Eggfinder and battery that's part of the transition from the bigger tube. The top body tube and NC will slide over everything then get held in place either with a couple of screws or plastic rivets. It should have a kinda cool "arm the missile" look to it.

#### cerving

##### Owner, Eggtimer Rocketry
TRF Supporter
Don't use a 9V with the Eggfinder. They don't source enough sustained current. You can easily fit a 180 mAH 2S Lipo into a 29mm coupler, I have a Mongoose 29 that has both a Quantum in the AV bay and an Eggfinder in the (polycarbonate) nose, each running on a 180 mAH 2S LiPo.

#### dhbarr

##### Amateur Professional
Don't use a 9V with the Eggfinder. They don't source enough sustained current. You can easily fit a 180 mAH 2S Lipo into a 29mm coupler, I have a Mongoose 29 that has both a Quantum in the AV bay and an Eggfinder in the (polycarbonate) nose, each running on a 180 mAH 2S LiPo.
Have you checked out the new LiFeS2 9v's? They pack a pretty mean punch. I still intend to use the 180's, but a drugstore option is nice to have.

#### rharshberger

##### Well-Known Member
Have you checked out the new LiFeS2 9v's? They pack a pretty mean punch. I still intend to use the 180's, but a drugstore option is nice to have.
Can you post the Tech sheet for them, I know some batteries like Energizer Adv. Lithium include a PTC to limit them to 5A max output.

#### michigander

##### Well-Known Member
smallest battery I use is a 300 mah , its smaller than a 9 volt

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#### dhbarr

##### Amateur Professional
Can you post the Tech sheet for them, I know some batteries like Energizer Adv. Lithium include a PTC to limit them to 5A max output.
Hmm, I see the Ultimate also has a PTC, but I don't think they tell the rating?

In any case, I've fallen victim to branding as the AA/AAA Ultimates are LiFeS2, but the 9v "Ultimate" is apparently still LiMnO2.

https://data.energizer.com/PDFs/l522.pdf

#### rharshberger

##### Well-Known Member
Hmm, I see the Ultimate also has a PTC, but I don't think they tell the rating?

In any case, I've fallen victim to branding as the AA/AAA Ultimates are LiFeS2, but the 9v "Ultimate" is apparently still LiMnO2.

https://data.energizer.com/PDFs/l522.pdf
It has 1A max discharge rate (1000mah) so its a 1A PTC for the Ultimates.

#### scsager

##### Slightly burned-out old guy
smallest battery is use is a 300 mah , its smaller than a 9 volt
Thanks for that photo - I've been using a 500mah, which is a bit larger than a 9v.

What you have there is awesome!

#### ActingLikeAKid

##### Well-Known Member
Don't use a 9V with the Eggfinder. They don't source enough sustained current. You can easily fit a 180 mAH 2S Lipo into a 29mm coupler, I have a Mongoose 29 that has both a Quantum in the AV bay and an Eggfinder in the (polycarbonate) nose, each running on a 180 mAH 2S LiPo.
Duly noted, thanks. Looking forward to this...

#### Maxter

##### Well-Known Member
I use some of the batteries made for airsoft guns. They are long and skinny. You might try looking at those specs.