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DIY LiFePO4 Battery Pack Headway 38120 50A/128wh

January 24, 2019 46 Comments

Hello Operators
Today’s topic, portable lithium power.
For the ham radio operator in the field, portable battery power needs to be light enough, small enough, modular, have enough capacity,  and above all it should be possible to charge with solar power, off grid, and in the field. For the high speed, low drag Amateur Radio Operatorr in the field, we need something a bit more special Thankfully, we can find the answer for this from the lithium battery family.
Most diy builders use 18650 batteries for diy builds. For this build we are going to step it up in performance and ease of build by using the Headway 38120 family of bLiFePO4 calles. These cells are safer to use, and easier to put together in a 12 volt battery pack.

here is the parts list:
You can find the original episode notes Here:

Background info:
Recently my channels supporters helped crowd fund a new Yaesu FT-891 for the solar powered field station. To activate that rig in the field, we needed to build a special power plant, one which would allow us to make use of the rig’s full potential if needed. Enter the 50A current draw, 128ah Headway 38120 based, 10ah LiFePO4 Day Pack for our Yaesu FT-891 Field Radio.

in this video, we build a 50A current draw capable, 128wh LiFePO4 battery pack for the solar powered field station. We augment the pack with our PowerF8lm FM16-7200 Solar Panel, for extended communications

video url:

Mentioned in the video
– PowerFilm FM16-7200
– Bestech 50A BMS
– DIY QRP LiFePO4 pack for ham radio
– Yaesu FT-891
– Solar Powered Field Station
– Powerpole distribution boards

Headway 10A 38120 cells
Max. continuous discharging current 10C(100A)
Recommended Constant Discharge 1C(10A)-5C(50A)

Bestech 50A 4S BMS for LiFe04
Max. continuous discharging current 50A:

Other interesting videos and playlists
– DIY LiFePO4 10ah battery pack for Ham Radio:

– PowerFilm FM16-7200:

– Ham Radio Off Grid with OH8STN

– Ham Radio with a Raspberry Pi:

– Better Power Distribution for Portable Ops

Better Power Distribution for Portable Ops.

Julian OH8STN

Video URL:

Support the channel.
Purchase this panel from PowerFilms Amazon shop here:

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46 Replies to “DIY LiFePO4 Battery Pack Headway 38120 50A/128wh”

  1. Paul Andrews says:

    Hey Julian I just noticed something…did you have any issues with the heat sinks not being able to shed heat with it wrapped in plastic? For this current its probably not noticeable but for the solar generator you may wish to keep the heat sinks open to the air by cutting a hole in the heat shrink wrap.

  2. Tim Carroll says:

    Do you have any idea what would cause a charger not to charge this pack,built it according to your specs,actually built two,good voltage all leads hooked up correctly but when I hook it up to charger no current wll flow to pack.When I disconnect the battery board from it,it will charge does this on both packs when I isolate the brd.Thank's

  3. Freddy Mack says:

    Julian, your work is great and inspiring. I rearely disagree with you, but on the cost/capacity comparison of LiFePO4 batteries with lead acid batteries, I have a different view. My remote shack (fixed site) runs at the moment on a single 70Ah lead acid battery. I agree it only has a real maximum capacity of 35Ah, and that for future use, I will have to add at least a couple more batteries. These lead acid ones cost roughly £1 per Ah stated capacity, so about £70 for a leisure battery of 70Ah. The closest LiFePO4 battery, at 100Ah, costs a staggering £859 ( That's nearly nine times the price per stated Ah, or 4.5 times per Ah when we allow for the 'deception' you correctly identify. Apart from the price, the ubiquitous availability of lead acid batteries is one major factor in choosing to use them, despite their weaknesses. I can pop down to the local garage and buy a leisure battery. I will have to get a (heavy) LiFePO4 battery delivered, adding yet more to the cost and time delay to those 'new ideas' we get.

  4. david carp says:

    Hi I suffer from dyslexia I have the batteries on order and all the other parts I just can’t find the BMS to go with it can you help me please 🇬🇧

  5. Thank you very much for a slow, step by step assembly tutorial. I am learning so I need to take time. I am building things as I watch so the pacing and level of detail you note, including the slow shrink wrap reason and the pack end cell coloring is helpful for me

  6. toobglued says:

    step1: throw those 'crimpers' in the garbage

  7. Harv W8HRV says:

    Hey first I would like to say I enjoy your videos keep them coming. But on your battery pack it's a 4S that setup only increase volt and not amps

  8. How would i put two of the 10 ah packs to make a 20 ah pack/

  9. Just a heads up, don't solder your crimps. It's bad practice and will leave you with a weaker joint in general. A good crimper is all you need.

  10. Shawn Dobson says:

    The videos are great! I am getting the components together to build my battery pack now. This channel is a great resource for emergency preparedness. Thank you for taking the time and effort to share your experiences with us. Stay safe.

  11. Hi bro you are doing a nice job contributing for the ham radio society I have enjoyed watching you and I made a 20 amp virgin like yours is 10 amp and then having a problem I don't know how to order the shrink wrap for it can you help me with that keep doing the good work thank you A61bn

  12. your pcb can't escape from moisture even when wrapped with plastic protection!!!

  13. I have four used red 8ah headways I broke off from my 44 pack project. I am trying to figure out why all the new charger balancers are so tiny compared to your bestech. The components couldn’t be that much better on the smaller ones and your model has the huge solder runs for big power. Thanks for the awesome video.

  14. How many volts is this?

  15. george bendt says:

    Really like all your videos, And I'm currently building this battery Pack for myself. One question I have is on the 2 layers of heat shrinking you have over the BMS. On the Bestech 50A BMS, there are cooling fins for the components, and by covering them with heat shrink you are blocking in that heat. I would think this could cause a failure if you are really drawing some power for the radios and other equipment. Have you had any issues with the heat build up?

    Thanks – N0WTR

  16. Tom B says:

    Very professional review

  17. Toney N says:

    With me living in South Carolina, would the f16-1200 panel be the right solar panel for this build?

  18. ac2fv says:

    Jukian, my components are arriving to build this battery. I noticed on the BMS that the black metal on top of the board is a heat sink to cool the transistors, etc. Wrapping the BMS in a couple generations of heat shrink cuts off any airflow, and will eventually cause a failure. Just an FYI…

  19. Ben says:

    Question on those balanced cell leads. On the BMS there's the JST wired for four pins. There's four wires that we put ring terminals on. But during the final assembly, you say there are five leads and the video shows five leads. Where did that fifth lead come from?

  20. ac2fv says:

    Hi Julian, one more question. I have the cells ordered and the BMS. You show in the video the Genesun -5V, yet your parts list shows the 10-V model. I'm assuming the 10-V unit is an upgrade for better performance?

  21. ac2fv says:

    Julian, do the screws and washers come with the battery cells, or do you have to order them separately? I'm purchasing from evComponents. Thanks. 73 from NY

  22. Croaker says:

    I'm using a 55 Ah SLAB and just came across your channel. This sure looks like a nice upgrade. Will be building one soon! Thanks and +1 sub from me.

  23. Rollyman375 says:

    Yes I agree, great build.

  24. Check those crimp jobs. At 9min you are soldering a ring connector that had been crimped but the wire is moving by your soldering iron. A good crimp will not allow any movement like that. 73 de KK6QMS

  25. Kevin Roose says:

    Julian, Thanks for the video. I'm planning on building one of these myself. Having operated portable with agm battery and seeing its very limited ability to sustain power with a 100 watt receiver, I will use your solution for maintaining operations for Parks on the Air and Summits on the Air activations. Being new to the hobby and new to these types of batteries in general I understand the purpose of the BMS to ensure equal use of cells and also to avoid overcharging. How do I charge at home on regular power? Is there a smart battery controller for charging? If so where would it be connected to the pack? Does in connect into the BMS? Once I find this information out I will be building the pack. I know the bioenno batteries you reference in the video come with their own connectors and include the bms within the battery. But am unsure how to do it without having the solar as the charging source. I do have a "smart charger" for lithium batteries but unsure if it was compatible with these type. Thanks so much for your time. 73's W8BRY

  26. Lyfan Deth says:

    Pack looks like a great bargain. I had been coveting a Tracer 24 A battery for portable use. How does your 10A pack compare for overall size?

  27. Jay Land says:

    Great how to. Can you share the math on the pack? I got my hands on 12 cells and 2 BMS, I would like to run the math to decide what configuration will work best for my rig set ups.

  28. I have a question regarding the shrink wrap. Does that impact the heat sink ability to dissipate heat on the board when it is operating at higher temperatures? Great Videos and thank you.

  29. YankeeRoad says:

    Great write-up and video. I have a question. The charge controller appears to only have an input for the panel? What if I have a 12v source or what about a 100V wall outlet source that can charge the battery during storage or even during use?

  30. just a question, are the batts ok being charged in the cold like that? i dint know,, lol thats why im askn 🙂

  31. LilBlighter says:

    Julian, your comment at 4:06 is so true and related to so many other things in life. Try, give it a go you’ll get better every time. It’s as much about making the effort to try as achieving the result itself.

  32. Paul Andrews says:

    Julian: Have you done any testing of true Amp hour capacity before the BMS cuts off? Obviously 15AH isn't 15AH when the voltage cuts off prior to critical voltage.

  33. I'm confused about the powerpole distribution board; what is it for, and which kit is in on the k9jeb site? Do you have a video where you talk about it, and I missed it? Thanks.

  34. OH8STN says:

    Check that link for the entire parts listing.
    Julian oh8stn

  35. Thank you so much! You have a new fan😎

  36. Mill Berd says:

    thank you Julian for a well done informative video

  37. Reid Lanham says:

    Awesome video! I am beginning to source these parts so I can build my own as I just acquired an FT-891 myself!! My question is: Do I need a solar charge controller if I don't plan to charge by solar just yet? In other words, I want to charge the batteries at home, then operate portable for as long as I can, then re-charge again once I get back home. Thanks!

  38. Aastan says:

    Do you think you should slot the heat shrink where the BMS heatsink is located? I don't think you should cover them up.

  39. Paul Andrews says:

    Those crimpers make all the difference in the world. I suggest getting ratcheting crimpers for your ring terminals as well. They provide an even crimp, and are much easier on your hands 🙂

  40. Doc XOXO says:

    You are such an inspiration!! Now there's a way to play HF radio off grid without those heavy SLA batteries. This will benefit those who are recovering from physical ailments like me. TY DE KF7DMY.

  41. VideosByDPF says:

    Outstanding video! This is the power I have been looking for, to run either my FT-891 or IC-7200, yet weighs less than my Goal Zero! I suck at soldering, but might have to give this a try! Keep up the great work!

  42. Curious… Is it not good to charge Li Batteries at temps below 0C?…. BTY Like the build….

  43. Artur K. says:

    Hello, Julian. Great video. I ordered components but I have a problem with the charging controller. I can not find LiFePo4 4S. The link on your site leads to Genasun GV-10, lead acid. Can you help me find the right controller?

Comments are closed.