Off Grid Data Comms with a Raspberry Pi

Discussion in 'Amateur Radio News' started by OH8STN, Dec 11, 2019.

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  1. MW1CFN

    MW1CFN Ham Member QRZ Page

    Julian, a great post, as usual.

    One question: can you please tell us which model GPS module you plug into the Raspi's USB port?

    OH8STN likes this.
  2. OH8STN

    OH8STN Ham Member QRZ Page

    You are very welcome. It's a standard vk-172 ublox gps from Amazon, eBay, ... all the details and configuration instructions in this video.

    Julian oh8stn
    N0YG likes this.
  3. PA0MHS

    PA0MHS XML Subscriber QRZ Page

    Julian, I love watching your video's, especially the ones in forrests and snow. I just love Scandinavia and its rugged environment!
    I was wondering if you ever experimented with battery packs without BMS. And I mean the types of BMS that balance the cells. I am currently setting up a PV and battery system for my off grid summer cabin (in the Netherlands, unfortunately) and I am planning to use a 12.8V LiFePO4 battery pack without BMS system, only using the low cut-off protection in the inverter for 230V loads and a Battery Protector (all Victron stuff, by the way) for 12V loads. The idea is to bottom-balance the cells all in parallel (discharge them to 2.5V), then connecting them in series and "be done with it". I will let the solar charger cut off at 3.55VPC and, of course, regularly check each cell voltage. And when designing this system, I thought about doing the same with my Yaesu FT-897D: throw out the NiMH battery packs and fill that space with LiFePO4 cells without BMS but use bottom-balanced cells. Theoretically I should be able to keep the cells connected to the 12V power supply input, ensuring my shack's PSU outputs no more than the float voltage of the 4 cells in series (3.3VPC).

    Any ideas about this?

    73, Meindert PAøMHS
    KQ6XA likes this.
  4. OH8STN

    OH8STN Ham Member QRZ Page

    Another great quesiton.
    Yes I have, but won't ever show it on the channel. With the battery tutorials, I have found many operators can't won't follow instructions. Even worse, they don't do period checks to insure cells remain within spec and have an even discharge rate. The 20ah pack from my most recent video has no BMS. It was bottom balanced, but also has an active fail safe, which keeps the cells within ˜0.2v of each other. The active circuit transfer energy from higher voltage cells, to lower voltage at 1amp rate. Doesn't resitance bleed like traditional BMS. My shunt controls LVD through relays, while the Genason controller, mananges charge rate and prevents over-charge. It is very similar to your Victron system. These type of systems should not be ones first project imho. However, they can be very reliable and outlast/outperform any lead acid system. Initial cost is higher, but it will last forever. I left out the BMS from the 2+ah ld because of space restrictions. A good BMS (not the fake marked Chinese crap) can be a fail safe for your investment. You'll have to consider why you're leaving it out. Short circuit protection is a critical feature being left out of your system. Just saying
    Most Victron systems can be switched of for LiFePO4 chemistry. There is no need to run it on <lead Acid settings,. LiFePO4 don't need a float charge or any of the lead acid nonsense. So do your reading before you choose. I'm hoping to completely rebuilt the shack with Victron gear. It's nice to hear other are too.

    Julian oh8stn
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  5. PA0MHS

    PA0MHS XML Subscriber QRZ Page

    Julian, thanks for you exhaustive answer. I know the problem of users not following instructions. I run a small company and I design marine electronics (NMEA 0183 multiplexers and 0183/2000 gateways). I get indeed a lot of questions that could be found in my manuals. I always say: men don't read manuals. Yet those same men always complain that their wives don't come with a manual... ;-)
    This is indeed my first LiFePO4 setup but as I said, I'm an electronics engineer, know my sh*t and read about everything there is to find about BMS's and LiFePO4 batteries and their quirks. But I'm glad to hear some first hand experience from a "small battery" user. I had a lot of good tips from a ham on this forum who is very experienced in off-grid installations an EV's using those LiFePO4 batteries without any form of BMS. Just bottom balanced packs, decent LV and HV cutouts and regular checking of cell voltages, which I also intend to do.

    73, Meindert PAøMHS
    KQ6XA and OH8STN like this.
  6. KE0YEU

    KE0YEU Ham Member QRZ Page

    Mr OH8STN is a hard core dude... Wow.
    KQ6XA and OH8STN like this.
  7. OH8STN

    OH8STN Ham Member QRZ Page

    I'm not sure if that's true but it's appreciated. Although it's hard to know it from his YouTube channel, the Slowfood Survivalist is an excellent teacher. It was his cabin we visited as a staging point, on the first day. He's the guy who taught me how to Forest ski, build a snow shelter, basically how to be comfortable when everything around us is Frozen. I could do a whole series on the stupid mistakes he's helped me avoid over the years. Yeah it definitely takes teamwork.
    Anyway thanks for the nice comment.
    NC4AB and KQ6XA like this.
  8. AB9VJ

    AB9VJ Premium Subscriber QRZ Page

    Very nicely done video. I learned a lot. Thanks
    KQ6XA likes this.
  9. K3AFA

    K3AFA Ham Member QRZ Page

    Wow! Amazing.
    KQ6XA likes this.
  10. VE3ZTM

    VE3ZTM Ham Member QRZ Page

    great share. thks.

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