Help me choose the right Batteries 🔋

B

b0lero

Member
Hi all, 👋 will get straight to my issue. I am trying to choose the correct type of batteries to power up Teensy 4.1 + GY91 + uBlox GPS + LoRa RF Module + 3x Micro Geared Servos + 2 Micro Geared Steppers (via DRV8833).

*Please ignore the Arduino Nano on the picture and replace this with Teensy 4.1 :D


Together this setup will be attached to a High Altitude Weather Balloon and hopefully reach up to 35km of high - TEMPERATURE is a huge factor here and with recent knowledge, I must rule OUT NiMh batteries (like the one I've got already)


By the shopping list, you can tell, I am a noob :D When I bought the NiMh batteries the model shop didn't have any chargers for it so I decided to go rough and get one online, even better Solar Panels with solar charger .... only if I knew it's NOT for NiMh batteries :D


However, the 6v NiMh batteries did a great job powering my 2 servos on the breadboard for prototyping and testing but when I reached the assembly I hit a stone :D and this is a big one... I was happy to use NiMh due to their weight ... perfect ballast...

So, is LiPoly an option for me? The expected flight time is around 2 to 4 hours where servos and stepper motors will work only 1/4 of the flight time. The main thing is the Arduino, GPS, Gyroscope, and the LoRa module, aw and we also have 5 solar cells (5.5V 60mA) that I love to use in this project :smiley:

Any suggestions are welcome. Thanks For Looking!
 
@b0lero:

Although we haven't executed a balloon launch for several years, the North Texas Balloon Project (NTBP) team previously launched at least one amateur radio experimental balloon per year. For all flight power, we extracted the 3VDC cells from a military surplus BA5590/U battery pack (see <this> URL for a typical listing - note that we have ordered BA5590/U pakcs from this source in the past). These cells consistently continued to operate well at the -80 degrees F external conditions that our packages typically reported at altitude with very little voltage sag due to the low temperatures. Most common (alkaline) batteries freeze at these temperatures, & frozen batteries tend to act more like a "brick" than a "battery" !! For safety (& greater assurance of package recovery), we only used cells for one flight, & in actuality, very little of their total capacity was used in-flight (the capacity allowed us roughly 24-hours of operational time worst-case for ascent, descent, & recovery . . . we typically recovered within an hour or two of landing . . . if somehow recovery was delayed past 24 hours, we would have much bigger problems !!). In addition, we continued to use the used cells post-flight for "bench testing" for quite a long time before they were actually depleted. Most of our electronics packages were designed to be fed with a 3-cell pack at 9VDC that was individually regulated down to 5VDC on the individual boards (e.g. TT4 for APRS, GPS unit, voice-beacon that speaks ID, internal & external package temperature, latitude, longitude, altitude, speed, and heading). The APRS & voice-beacon radios (Yaesu VX-3R HTs) were powered directly from a 2-cell pack for 6VDC direct. Since these battery packs are military surplus, they were very hard to get at times, & since it's been several years since we've made any purchases, I don't even know if they are actually even still available. We tended to buy a couple of packs at the same time & our experience was that we could power two launches from each pack.

I recognize that I didn't quite give you a "go here & get this" or a "use this" answer, but I hope that the insight into our past experiences over several balloon launches (particularly the extreme temperatures that our packages reported) might be helpful in your battery selection process.

Mark J Culross
KD5RXT
 
I also have another idea using PTC Heating Element - 5V up to 40°C and try to keep the thing within acceptable temperature range from the inside. Did any of you ever used one? 🤔 Thanks
 
kd5rxt-mark said:
Since these battery packs are military surplus, they were very hard to get at times, & since it's been several years since we've made any purchases, I don't even know if they are actually even still available.
Mark J Culross
KD5RXT
Click to expand...

As a follow-up for the benefit of anyone reading this thread sometime in the future, I did successfully place an order for the BA5590/U battery pack from the <link> given above & have successfully received the pack as ordered. So, as of the date of this post (August 2022), the BA5590/U packs are still available from that source. Hope that helps someone in the future looking for a power source which can survive/operate on a balloon lifted package at 100,000+ feet . . .

Mark J Culross
KD5RXT
 
Hi Mark, thank you so much for this info, although I aim for a TOTAL weight under 1kg / 2.20 lbs / for the whole project and this battery pack is slightly over the weight I can afford (7lbs or 3.2kg) I wonder what kind of weather balloon cargo do you send up there to use such battery?

I have recently purchased 40C PTC Heating element and Heating pad to run some tests in the freezer to figure out what I can and what I can't :D If I successfully can keep the temperature above 10C I will use LiPo

ptc-heating-element-5v-40-c.jpg electric-heating-pad-14cm-x-5cm.jpg insulation_tape.jpg
 
b0lero said:
I wonder what kind of weather balloon cargo do you send up there to use such battery?
Click to expand...

@b0lero:

We don't actually use the entire original pack. Rather, we dismantle the pack (if you acquire these BA5590/U packs, be VERY careful so that you don't accidentally active the "shorting tab" & kill the pack !!). We use just a few of the individual cells (connecting 2 or 3 in series, depending upon the desired source voltage) to power a variety of equipment (GPS, radios, small processors, voice talkers, repeaters, sensors, recorders, etc.) as described in P#3. The combined weight of three cells is 9oz / 255g.

We tinkered with using hand-warmer packs at one time, which worked great to keep the electronics warm at altitude. However, since we execute our launches in the state of Texas, we found that the electronics overheated during the time spent on the ground in the sealed styrofoam container after landing (opposite problem !!). If you have the ability to control the temperature using your heating element & pad, that sounds like a workable approach.

Good luck & have fun !!

Mark J Culross
KD5RXT
 
I've had a good experience with Energizer Ultimate Lithium AA batteries in temperatures down to -30C / -22F before (on Lake Baikal), maybe they could be worth a look.
 
Hi Chris, thank you for your reply. I have looked at Energizer Ultimate Lithium AA and they seem reliable on low temperatures, but they can only store 300mAh, in my case pack of 4 will get me 1200mAh, not like I know what the current draw will be at the end of my project as I keep adding and removing stuff. However, Energizer Ultimate Lithium gave me the label info of what chemical content they are made and I was able to look into different brands with more storage capacity with the same chemical structure as this one here: https://www.crazell.com/product/lfbaa/. With my little experience, I've learned 3 things... Test, Test, and then some more Test :) I will buy different types and test them out
 
b0lero said:
Hi Chris, thank you for your reply. I have looked at Energizer Ultimate Lithium AA and they seem reliable on low temperatures, but they can only store 300mAh, in my case pack of 4 will get me 1200mAh, not like I know what the current draw will be at the end of my project as I keep adding and removing stuff. However, Energizer Ultimate Lithium gave me the label info of what chemical content they are made and I was able to look into different brands with more storage capacity with the same chemical structure as this one here: https://www.crazell.com/product/lfbaa/. With my little experience, I've learned 3 things... Test, Test, and then some more Test :) I will buy different types and test them out
Click to expand...

Where did you get the 300mAh figure from? Their datasheet rates them at over 3000mAh which is in line with my experience of them. Do take notice though of the chart on the datasheet showing their drop in capacity at extremely low temperates. Also note that 4 of them will only give you 12,000mAh if wired in parallel at 1.5V, or 3,000mAh at 6.0V if wired in series.
 
chris.nz said:
Where did you get the 300mAh figure from? Their datasheet rates them at over 3000mAh which is in line with my experience of them. Do take notice though of the chart on the datasheet showing their drop in capacity at extremely low temperates. Also note that 4 of them will only give you 12,000mAh if wired in parallel at 1.5V, or 3,000mAh at 6.0V if wired in series.
Click to expand...

You are right, I have no idea where the 300 came from :confused: anyway thank You for the correction!
 
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