QRP UltraPack DIY 18650 Battery Pack for Field Comms

Project updated 13 August 2016

This is the main project page for the UltraPack DIY 18650 External Battery Pack in 4S1P, 4S2P, or 4S3P configuration.

YouTube Playlist

I’ve created a YouTube playlist for all the build videos. Take reduce stress for myself, I’ll make one video for each part of the build, and publish them sequentially.

What is the Ultrapack?


The UltraPack is an open source project using commercially available comoonents to build a light weight portable emergency power pack which fits in your pocket.

  • It’s a no bells or whistles pack in many ways like the Goal Zero Sherpa 50/100, or Hardened Power Systems QRP Ranger. Unlike those commercial products, the UltraPack has a utilitarian approach to portable emergency power. It can be repaired and maintained in the field, and is designed to promote learning and self-reliance.


13 August 2016

Lots of new updates since I last updated the webpage.

  • I setup a test jig to test all my connections, charging, functionality, …
  • I did a smoke test (check my YouTube videos)
  • I setup the DC/DC converter (Lithium charger) and tested that overnight charging the pack in 4S1P configuration.
  • Changed my prototype from 4S1P configuration to 4S2P cinfiguration
  • BMS Startup
  • Dumped the original enclosure!

Smoke Test

Quite simply, this was the most nervous I’ve been since the project started. Actually putting cells in the pack, and powering it up for the first time. Not to worry, everything was A-OK!

Test Jig for CV DC/DC charging board

I setup a test jig to test the DC/DC constat voltage regulator for an overnight test charging the pack. No heat, no problems no stress 😀 I set the CV DC/DC regulator for 16.45V and left is running overnight. The next morning the pack was charged to 16.45V respectively.

I am very happy this is working. It may be too early to say, but it appears to be a budget solution to charging protected lithium packs in the field. I suppose I’ll do a seperate build video for this, as some people may only be interested in the charging of lithium packs in the field and not the UltraPack itself. Fair enough!

BMS Startup Issue

For those of you who would like to configure the pack for removeable 18650 batteries, the BKS must be re initialized each time the batteries are replaced. Reinitialisation required applying DC voltage to the output (P+ and P-) for a short time. Thankfully, the board can be reinitialized, using its own voltage from thepack using a simple momentary, wired between P+ and B+.

Changed my Prototype to 4S2P


I decided to change my prototype from 4S1P to 4S2P. This doesnt in any way change the build for anyone else. When the detailed instruction for the build are written, i’ll include an optional step for wiring up the second battery tray for 4S2P. All connections other than adding atray are the same. Moreover, we can achieve this 4S2P configuration, still using a single BMS board 🙂


The enclosure I mentioned earlier is not a bad enclosure for the 4S1P version, but it is actually not needed! In my case, I will not be removcing my cells from the pack, and will heat shrink them in when the project nears completion. Fuel gage and controls could be placed inline along the wires for my version, so that the enclosure (if I use one) can be made relatively watertight. Furthr study on this as we get closer to that part of the project.

Next on the enclosure discussion was an offer to 3D print an enclosure, from a company in USA. I do like the idea of having a purpose built enclosure for this project, so lets come back to this as we move forward. If you have an opinion about a 3D printed enclosure offered commercially, let me know.

Weekend run test

I’ll be wiring up a temporary DC regulator for the FT-817ND to run a WSPR test using the UltraPack in 4S1P configuration. As usual, pictures on instagram, and short project updates on the UltraPack YouTube Playalist..

OH8STN UltraPack v0.5


Updated 23 July 2016
The UltraPack is a DIY 18650 battery pack you can build yourself at home. It can be a source of emergency portable power, or the external battery pack used with your emergency or bugout communications gear.

The UltraPack is designed to provide radio operators, emergency workers, or adventurers a low-cost, scalable, and customisable Portable and Emergency Power Solution for use in the field. Simply puy, it is an 18650 battery case, you build yourself. It’s also so much more.

Again I want to thank Jim K7JLJ for, and Greek Preparedness for continuously kicking me in the ass, and for challenging my belief on this project.

The UltraPack can be used to:

  • Portable power for field communications
  • Portable Emegency Power
  • Power personal medical devices
  • DC charge Smartphones or tablets or laptop computers
  • As a solar charged night-time battery reserve

For the radio operator using modern QRP rigs like the Yaesu FT-817, the Elecraft KX3, and the Elecraft KX2, the UltraPack is very much like a QRP Ranger, but smaller, and more configurable. The QRP UltraPack can be built at home as a 4S1P 3.4A (50watt hour), 4S2P 6.8A (100 Watt hour), or 4S3P 10.2A (150 Watt hour) power pack, by anyone with basic ham radio and ohms law skills.

The UltraPack can be used to power a variety of radios like:

  • Yaesu FT-817
  • Yaesu FT-897 @20watts
  • Yaesu FT-857 @ 20watts
  • Electraft KX3
  • Elecraft KX2
  • Yaesu FT-1D, VX-8R, FT-60, …
  • Baofeng UV-5R, UV-82, … (adding correct regulated voltage output,)

 The UltraPack can be setup in various configurations such as:

  • 11.1v 3S1P, 3S2P, 3S3P
  • 14.4v 4S1P, 4S2P, or 4S3P

These configuration options give the end-user the flexibility to choose between smaller size, and greater capacity, for radio comms or other DC equipment.

My prototype version is the 4S1P version, but if you’re following along with this project, you can easily build one of the other configurations.

The difference between the UltraPack and just using the WinCamp, OPP, or RC lithium-ion, LiFePO4, LiPO battery packs, is the ability to be simultaneously charged/discharged (e.g. through a solar panel like the Powerfilm solar panel) while powering your radio. THAT’S THE BIG POINT HERE GUYS! This increases your power independence, increasing your operating time in the field WITH LESS EQUIPMENT!

There are very few bells and whistles.In fact, the build only includes utilitarian functionality, and ignores any “Nice to have” features, which keeps costs down.

Parts started arriving


When you have the parts in front of you, it’s easier to see the vision behind the project. So far the batteries are here, the battery trays, the CV DC/DC converter, the Powerpoles, the voltage fuel meter the BMS Protection baord, and the enclosure.

This is enough to start prototyping, but I wish a had more components (and time) to just get on with it.

Began Prototyping (24 July 2016)

IMG_20160727_143711I seriously need a 3D printer.

I seriously need a 3D printer. I started putting everything together, but I may have put the cart before the horse. It’s very difficult to use standard parts and come up with an enclosure which allows us to safely get all the components inside, without it becoming a giant brick! So I have become a dremel ninja.

So far I can get all the main components inside this enclosure. In fact, this enclosure is strangely starting to look like a battery case for 18650 batteries 😀 Perhaps in the end, that is what this project is all about. A DIY battery case for 18650s.  Anyway, If I could 3D print the enclosure, the entire setup could be smaller, with a more efficient use of space.

I’ll come back to this soon.

Battery selection

4S version
In my version, I’m using the Olight 3.6V 3400mah 18650 batteries in 4S1P, or 4S2P  configuration to power the Yaesu FT-817ND. It’s possible to use other batteries! If you choose to do so, I would suggest the Panasonic NCR18650B Super Max for max quality and performance. Protected batteries are always a good thing, even when using a BMS. Don’t try to go cheapo on this project by using used laptop batteries.

3S Version
Some people are making a 3S version of this project. Wiring is the is the same for a 3S version of the project. We just need to change the BMS board, and remove one battery from the equation.

Using the 3S pack introduces a crap trade-off between output voltage for the radio, and loss of battery capacity (e.g. time in the field). I prefer the additional battery capacity, and added benefit of more amps for bigger radios. Still the requirements are your own, and you alone have to decide which is more important for your own build.

The following is my 4S version. I’ll add details and a BMS board to this project ASAP.

BMS battery management system – PCB protection circuit

The BMS is the heart of the entire system. It is the part of the system which gives us the charge/discharge functionality so important to off-grid communications. It’s also the component which saves us from damaging our batteries, as it makes handling lithium cells a “no-brainer”.

Here are the BMS specs.  PCM-L04S12-406-Specs

Updated 21 July 2016

UltraPack 4S lithium BMS Balance and protection board
UltraPack 4S lithium BMS Balance and protection board

The UltraPack BMS arrived today. The documentation is pretty poor, but I’ll make quality english language docs for this board during the project. I’ve also chosen a charge circuit based on a CV Boost converter. That will be the front-end for the BMS, allowing a PowerFilm (or other EU solar panels!? I need samples!) Solar panel to juice the battery pack off-grid.

Please do your research!  there are two different versions of the board I’ve chosen.  One for lithium-ion. and the other for lithium iron phosphate. For this prototype I’m using the Lithium-ion version with lithium-ion batteries.

I’ve purchased this one from www.lipopower.de (corrected the url). You can see the specs below. I’ve chosen this board because it balances, and protects the cells. It also allows us the freedom to update from 4S1P 3.4A, to 4S2P 6.8A or 4S3P for 10.2A capacity (with my cells), using a single board for all three versions.

This board also allows us a max current drain of 10 Amps, which would actually power QRO radios like the Yaesu FT-897, 857 for a limited time, or a QRP radio like the FT-817, KX2, KX3, TJ2B for a very long time 🙂

  • Number of Cells: 4
  • Cell type: Lipo, Li-ION,
  • suitable for LiFePo as load and under-voltage protection
  • Balancer: about 70mA
  • Max. Continuous load current: 10 A
  • Max. short-term peak load current: about 12 A
  • Discharge protection: about 2.4 volts per cell
  • Surge Protection: about 4.35 volts per cell
  • Power consumption: 50 uA
  • Internal resistance: about 50 milliOhms
  • Dimensions (LWH): 70 x 40 x 3 mm
  • Weight: 9.4g
OffGrid Lithium 4S charging made simple
Constant voltage DC DC voiltage regulator.
Constant voltage DC DC voiltage regulator.

Although it is possible to partially charge these batteries and power the BMS with less voltage, we are doing this right. I’ve decided to use a DROK CV Voltage Regulator (Constant Voltage) Boost converter to supply the required 16.8v DC from my solar panel to the BMS for off-grid charging of the battery pack. Essentially we have made a solar charge controller. The various voltages coming from our external DC input need to be stabilized to keep the BMS happy, and a positive charge on our cells. As I’ve mentioned, the marriage between the BMS and CV regulator make the simultaneous charge/discharge possible on this project.

Noise from the CV Regulator
Updated 23 July 2016
I suspected I would need to make some modifications to this board to reduce noise on HF. Slowfood Survivalist sent me an idea. He suggested a toroid wrap for the power wires (good cheap idea!). So I’ve decided to put this board inline with the wires coming from my DC supply (PowerFilm panel) in its own case. The Power+ and – wires with be wrapped through a toroid before exiting the case through Anderson powerpoles. This should help reduce any noise generated from the CV regulator. I’ll update this when I’ve built and tested the mod. If you’re following along and have a modification in mind, please let me know.


Another option for this is simply using a Genesun GV-5 Solar charge controller for lithium cells The GV-5 already puts out the required 16.8 volts needed for our 4S pack, and is also completely radio quiet! This is easier to implement, but adds to the project cost. When I am building the BasePack version of this project, I will certainly use the Genasun GV-5 for 4S lithiums in 3P or 4P configuration (which will make the GoalZero Sherpa series obsolete).

Battery Tray
18650 battery tray
18650 battery tray

I’ve decided on the 18650 Battery Holder which can be configured for series or parallel, depending on how they are wired. Again this gives us some configuration freedom, makes it easier to build the project for those worried about heat damage to their cells, and allows us to remove the batteries from the pack if we want to replace them, or use them in another project. Most importantly, it allows us an easy way to configure the parallel batteries for 4S2P, which is certainly more than enough for our QRP field rigs.

Be careful on getting the cheap china made trays. Some are good, some not so good. It is best to spend the extra bucks to get a solid design since heat will distort the plastic which could lead to arching (which is a bad thing with 18650s)

Fuel Gauge


I’ve decided on a simple DROK Voltage Display Panel on the 4S battery +/battery – terminals, so I know the voltage of the cells AAT (At All Times). I’ll use a momentary switch to trigger the voltage reading (and saving power rather than having them on constantly). I know this is rather redundant since the BMS will shut down the batteries before damage occurs, but as a simple troubleshooting tool, the voltage reading is more of a benefit than the trouble of not inlcuding it.

Amperage meter.
One of the things I found strange about the QRP Ranger was its amperage meter. I understand why to have one, but I think its in unnecessary luxury. It also consumes power. Any ham radio operator can calculate in his/her head how many amps are being pulled from the battery by knowing ohms law. It’s nice to have, but if it’s there, how about a momentary or timed switch to activate it. That’s where I am at, and that’s how we will suggest the UltraPack be built.

Power to the gear & radio

My pack design has a regulated DC output to keep the FT-817ND and YouKits TJ2B happy. P+ and P- from the BMS are split for simultaneous charge/discharge. One set of leads is regulated for the rig, while the other is unregulated for charge input. Both input and output will terminate through fused 30A Powerpoles mounted to the enclosure.



Hammond 1597 enclosure

I’ve decided on a Hammond enclosure .  This enclosure can handle a 4S2P build, with BMS, voltage regulator, fuel gauge, and input/outputs. The snap-top design allows me to easily remove or replace the batteries if desired. It’s also lower profile, and has a smaller footprint than the FT-817. So mounting it underneath the 817 won’t add any inconvenience like the Tracer 4A, Tracer 8A, or QRP Ranger.

I’ve included the Specs, AutoCAD, and 3D files for you to do your own layout. 

There is a version from Amazon which has nearly identical dimensions. It’s also easier to find  than the Hammond version. Check the Amazon version of the UltraPack Enclosure.

Customisable elements
  • 4S1P, 4S2P, 4S3P
    The UltraPack can be configured in 4S1P, 4S2P, or 4S3P. If configuring for 4S2P, a single BMS boards is used with its batteries wired in parallel. Please see the image for details.
  • more to come.
Parts list

These are the parts I am using in my prototype build. I seriously recommend that you always use “Protected” batteries in your builds. There is no benefit in trying to save cash, using cheap rebadged Chinese cells, which have already proven to be under-capacity and/or counterfeit at best.

  • Low Amp prototype 3.4A
    I decided to build the first prototype as a single 4S protected cell, to keep costs down, and show feasibility every step o the way. I also think a pocket-sized external battery pack for our QRP radios is more desirable than the QRP Ranger for example, with all its bells and whistles, pushing the cost up.
  • Why did I use the Olight Lithium-Ion
    I chose the Olight lithium-ion only because I am using them in other projects and headlamps already. There are less expensive or better quality  18650 batteries (like the Panasonic NCR18650B ) one could use to reduce the cost or increase the quality of the project.
  • Tracer battery packs
    Tracer has introduced a line of external Battery packs which work perfectly for radio communications. Their price is also quite reasonable. The only issue I have with them is the limited recharge cycle/lifetime. 300 cycles is very costly if one can’t replace the internal cells on his own. Low entry cost, low lifetime. With my operating style, these packs would last about 1.5 years. Sorry Tracer.
  • QRP Ranger by Hardened Power
    The QRP Ranger is a great power pack. Its features and functionality are magnificent! Unfortunately, there are a couple of things which might make users pass on it.
  • It’s cost prohibitive!
    At the end of the day, the QRP Ranger is rather costly. I would very much like to see a trimmed down version which is smaller/lighter, with fewer extras.
  •  It’s unnecessarily massive!
    There are lots of bells and whistles on the QRP Ranger which make it more expensive than it has to be. It’s also larger and heavier than it has to be. At its core, I like it, but if I am on a size, weight, or cash budget, the QRP Ranger might not be my first choice. So I owe it to myself to see how difficult it is to build a pack like the QRP Ranger at home, using parts I specify, while having its main features, with none of its one size fits all extras.. Please don’t misunderstand this. I like the QRP Ranger, but I would like it more if it was smaller, and more portable.
  • OPP-817 and Wincamp
    These battery packs were a huge update to the FT-817. Unfortunately, they added one undesirable “feature” to the battery capability.
  • The battery door for the 817 must be modified or changed.
  • An external charger must be used
  • Neither of these packs allow the operator to use the FT-817 while charging these battery packs.

So in this regard, these battery packs are kind ofa  fail for the portable operator who wants to spend extended lengths of times off grid, with his/her FT-817.

I’ll update this page, when the other components arrive. When everything is here, I’ll do a build video.

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