Smallest LiPo Battery?

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Bruce

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What is the smallest LiPo battery available?

This thread,

https://www.rocketryforum.com/threads/smallest-altimeter.139510/#post-1676966

shows pictures (courtesy of Gus and BEC) of the 20mAH Full River LiPo for the Adrel Altimeters.

Andrel Altimeters.jpg

With Dime.jpg


To me it looks like the battery is larger than the altimeter and thus would be the limiting factor size wise.

Are smaller rechargable LiPo (not lithium coin cell) batteries available?

If so, maybe an altimeter could be made small enough to fit in a minimum diameter MMX powered rocket?
 
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shockie

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What is the smallest LiPo battery available?

This thread,

https://www.rocketryforum.com/threads/smallest-altimeter.139510/#post-1676966

shows pictures (courtesy of Gus and BEC) of the 20mAH Full River LiPo for the Andrel Altimeters.

View attachment 443977
View attachment 443978

To me it looks like the battery is larger than the altimeter and thus would be the limiting factor size wise.

Are smaller rechargable LiPo (not lithium coin cell) batteries available?

If so, maybe an altimeter could be made small enough to fit in a minimum diameter MMX powered rocket?
The flitesketch mini and flitesketch comp will fit in a bt-20 as will the AltUno S. The fs comp can fit in a 10 to 13 mm bt
I'm sure a skilled person could make a mmx altimeter if they really wanted to.
 

OverTheTop

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I picked up some small LiPos a while back. Single cells around 1/2" x 1/2". If you are using these remember they can't deliver the high currents that the larger cells can deliver, so testing is important. Also the usual chargers put out way too much current for charging them. The chargers used for the little micro helicopters work well.

Just checked. The maximum "rated" discharge current is 2C (20mA). Keep in mind you can draw more from it under heavy loading conditions. It just means the battery life will not live up to the number of recharge cycles that they specify as minimum.
 
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BEC

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This is a prototype FS Comp next to a recent Adrel ALT-BMP (now marketed as Max-Alt by North Coast Rocketry). Russ says the cell (it's not really a battery, you know) is rated at 9mAh. It is much thinner than the 23 mAh cell shown with the Adrel as well as having a noticeably smaller footprint. The Comp and its cell together weigh ~1g.

It is still quite a bit bigger than something that could be put in a minimum diameter MMX tube.

IMG_2922.JPG
 

Bruce

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Wow, 9mAH is a small battery (cell) ! Who can beat that?

Will each of those 2 altimeters fit in a BT-5 coupler?

This 10mAH / 480mg battery might be a close second,

https://micronwings.com/Products/Battery10mahBareLipoCell/index.shtml

Note to altimeter makers: The gauntlet has been thrown down. The ne plus ultra of altimeters would fit in a Quest MicroMaxx 1/8A Engine Tube, 6mm (1/4") in diameter. An impossible goal?...
 
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dhbarr

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That looks like a Lithium Ion battery to me, not a LiPo...

But you could probably fit it in a minimum diameter MMX rocket!
Does LiPo vs LIon really matter all that much ? It's a half-gram rechargeable that could fit in an MMX coupler (3.5mm dia)...

Now I'm thinking about an alti wrapped around it with a tiny charge well at each end....
 

Bruce

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Does LiPo vs LIon really matter all that much ?
Yes, agreed. If the battery will work for an altimeter, it's fair game. And this appears to be a good one, 15mAH / 500mg and its 3.65mm diameter should fit in the coupler of an MMX engine tube.

What's the next step? What are the most bulky components on an altimeter circuit board?
 

BEC

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What's the next step? What are the most bulky components on an altimeter circuit board?
Well, I think in part you want to figure out how you want to get the data out of it. The biggest component, by far, on both FlightSketch units is the Bluetooth module. On the Comp the next biggest one is the connector for the cell that powers it. You can see that all the other components are quite tiny. There are none on the other side of the board.

On coin-cell-powered units (FS Mini, FireFly, MicroPeak) the cell holder clearly sizes the board. With a separate power supply they can be smaller.

For your amusement, here is the same FS Comp prototype posed with a MicroMaxx motor. And then a closer (apparently a bit too close) view. The grid on that cutting pad is 10mm squares.

IMG_3791.jpg
IMG_3792.jpg
 

gtg738w

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Diameter is really only half the battle. Sure, if you really are flying min diameter MMX then yes, that is obviously important but for most competition types it’s a balance between total mass and actually being able to use it with adult sized fingers. There are skinny batteries being mass produced (AirPods, etc...) but they usually weigh more because of the form factor. So it’s absolutely possible to package the Comp in a 6mm package but it gets more difficult to use and might actually weigh more too. It might be fun to try as a stunt but not really a practical product. Not that everything we do is always practical anyway...
 

BEC

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Sure, if you really are flying min diameter MMX then yes, that is obviously important but for most competition types it’s a balance between total mass and actually being able to use it with adult sized fingers.
Thanks for popping into this discussion, Russ.

Agreed. The Comp prototype in the pictures is just about as small a device as I'd want to be manipulating with any regularity at all, especially at the flying field rather than under a magnifier lamp at my workbench at home. ☺
 

BEC

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Will each of those 2 altimeters fit in a BT-5 coupler?
I neglected to answer this the other day. I suspect you can tell from the subsequent pics that the FS Comp in its current form certainly can. I believe the Adrel ALT-BMP (AKA "Max-Alt") will also - but I need to check that 23 mAh cell in a JT-5C to be sure. The altimeter itself certainly will.
 

shockie

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This is a prototype FS Comp next to a recent Adrel ALT-BMP (now marketed as Max-Alt by North Coast Rocketry). Russ says the cell (it's not really a battery, you know) is rated at 9mAh. It is much thinner than the 23 mAh cell shown with the Adrel as well as having a noticeably smaller footprint. The Comp and its cell together weigh ~1g.

It is still quite a bit bigger than something that could be put in a minimum diameter MMX tube.

View attachment 444006
Who makes that 9 Mah battery?
 

cerving

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If it was something like the Adrel that has a minimal power draw (no RF, no buzzer) you can probably power it with a supercap. Charge it from your USB and you're good to go.
 

shockie

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BEC: I found this source....https://cardreaderpro.com/en/9-mah-3-7V-ultra-thin-battery-BAT091518.p2956. They even have a 5 mAh one! Alibaba in China has all kinds of small mAh batteries......if you want to buy a 100 of them at a time .
are you allowed to say anything about how well that Flightsketch Comp works? I assume you are a beta tester?
 

BEC

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Terry,

Right capacity, wrong dimensions. That cell would be kind of useless in the context we're talking about (MMX) being 15mm x 18mm by 0.9mm thick. The cell Russ sent me to use with the FS Comp prototype is roughly 15 x 8 x 2mm.

The Comp is functionally identical to the FS Mini and the only operational difference I have found is that the Bluetooth range is shorter. In use that doesn't matter since you arm (start the recording) with your phone next to the rocket anyway. Likewise with the download of data after a flight.
 

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Who makes that 9 Mah battery?
We had to import our cells direct. I’m not aware of any sources over here yet. And yes, the Comp is identical to the Mini except for the power system and smaller packages. Same sensors, same processor, same firmware except for two pin assignments.

If it was something like the Adrel that has a minimal power draw (no RF, no buzzer) you can probably power it with a supercap. Charge it from your USB and you're good to go.
I briefly looked at this and they are surprisingly big for the capacity needed. The LiPo ended up being the smallest option.
 

Bruce

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I wonder if the battery in the AirPods wireless earphones is in the cylindrical part on the bottom? If so, it looks like it would fit in a minimum diameter MMX coupler. For that matter, it would probably fit in an 1/8" launch lug...

AirPods.jpg
 

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