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Alternative Power Source Proof of Concept

Discussion in 'General Technical Questions and Answers' started by W4EGE, May 16, 2018.

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  1. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    The 18V Ryobi batteries are Lithium-Ion although I can't find if they're actually LiFePo or not; the new ones might be.
  2. W4EGE

    W4EGE Ham Member QRZ Page

    Like all good ideas...need to prove this is possible...or not.
    Is it practical...OH HEAVENS NO!!!
    I'm into the sport of trying and failing. If something works along the way...Great!!!
    W1TRY, KI7QVR and NH7RO like this.
  3. KD0CAC

    KD0CAC Ham Member QRZ Page

    I have similar plans , but a little more from scratch & cheaper [ hams are cheap - because they know how to do stuff ;)
    With electronics repair as part hobby / part side money , I get lots of stuff to recycle , and in this case laptop batteries with the 18650 cells in them .
    Been following lots of leads , links , Youtube videos on home-brew power walls - as in the Tesla Power Walls .
    And with that is learning how to test & classify the used 18650 cells , and weather to use BMS - Battery Management System , or just being aware of how to treat the batteries and use the brain to manage .
    One issue is how to combine the cell voltages to get close to 13.8v , then use voltage controller to reduce , 3.2 min. , 3.7 nominal , 4.2 max . So I will start with 4S , ?P , this is a standard on building battery banks [ combining sells in Series for voltage & Parallel as needed for amp hr rating ] .
    Have about 100 + or - so cells far .
    What I haven't settled on yet is the most efficient way to control the voltage within the working range of the cells to radio steady 13.8 .
    Moved recently , so another one of the projects waiting for more attention .
    If / when I get back to chasing laptop batteries again , would like to build a Power Wall for my RV & solar system , my Trojan L16's died after 12 + yrs. , and being mobile / RV , I like lighter smaller package .
    Replacing the 4 Trojan L16's was about $600 , now over $1,200 .
  4. K0OKS

    K0OKS Ham Member QRZ Page

    I have been using one of these DC to DC buck converters to power my 7100 from 2 High Rate 12V SLA batteries in series for 24V in. It provides about 12.8V out, and the 7100 is putting out full power on SSB at 100W. For $35 I couldn’t be happier with the setup. (Always use fuses in high current batttery circuits. I have seen what happens when you short circuit them... Fire is fun!)
  5. W4EGE

    W4EGE Ham Member QRZ Page

  6. KF5LJW

    KF5LJW Ham Member QRZ Page

    Not sir they are not LiPo which is a meaningless term today. They are INR = NMC = Lithium Manganese Nickel cells arranged in 5S2P configuration. Nominal cell voltage is 3.6 volts charged to 4.2 vpc using CC/CV algorithm terminating charge when current tapers to 100 ma. There were LiPo's years ago, but no market for them and no one makes them. A LiPo used a polymer (plastic) isolator between Anode and Cathode which resulted in high battery internal resistance making them low specific power. In other words they cannot deliver significant current or be charged in reasonable time. In the RC hobby world you see the Marketing Term LiPo for the batteries the RC Plane, Helicopters, Droids, and Cars/Trucks. But they are not LiPo, they are hybrid NCO cells with a gelled electrolyte which gives them very low internal resistance for extremely high discharge rates up to 50C or 1 minute. They are highly unstable operating at 3.7 vpc nominal making them prone to catching on fire you cannot extinguish. OK enough about LiPo

    For 12 volt applications designed for Pb batteries only LFP aka LiFeP04 cells are directly compatible with a nominal cell voltage of 3.2 to 3.3 volts arranged in 4s. Charge at 14.2 to 14.4 volts like a Pb battery with a nominal voltage of 13.8 volts. Using any other Lithium cells like LMO, NMC, NCA, LCO or NCO cell voltages are too high ranging from 3.6 to 3.7 vps. At 3S only yields you a range of 7.5 to 12.6 volts is way to low. At 4S the usable range is 10.0 to 16.8 volts which is to high. You can get away with 4S if you use a Buck Converter or Series regulator. However that brings the question is why would you do that when it is not necessary to make a compromise using a converter added expense and complexity when LFP is directly compatible Pb?

    I have another hobby and belong to a DIY electric vehicle working group and I/we build racing golf carts and EV conversions. In the early days we used LFP Chi-Com cells because they are affordable, large format, and the only large format available to the public which still holds true today. We do no tuse them much today because there are enough salvaged EV's around we buy the batteries from salvage yards and second hand suppliers. Leaf NMC packs are our favorite choice. Point I am trying to make here is a HAM can make his own LFP 12 volt battery very easily using one of the 4 Chi-Com manufactures and CALB is the best of the Chi-Coms They are prismatic cells and range from as small 40 AH up to 160 AH. No special charging equipment needed as they are drop in replacement for Pb batteries so you sue a standard Pb battery charger set to 14.2 to 14.4 volts. Chi-Com LFP cells are available at any of the custom EV suppliers, just Google EV Batteries batteries for sale EV West and EVTV Motor Verks are good sources in the USA. EVTV even makes assembled 12 volt and 48 volt modular battery blocks with built-in BMS. Do not try to use 18650 cells, way too expensive and requires a lot of skill to assemble.

    One word of caution using Power Tool battery packs. They do not play well in parallel or designed to be used in parallel with other modular battery packs. Just as little as .1 to .25 volts difference in SOC can likely start a fire you cannot extinguish. Do not learn that lesson the hard way. Really no reason to use them. There are less expensive and compatible options available to you.
    Last edited: May 17, 2018
    NH7RO and KB4QAA like this.
  7. W4EGE

    W4EGE Ham Member QRZ Page

    Whether or not this will be a tangible solution in the long run is not so much the goal at this phase. Im really just exploring the "what if" game now. I too have had your concern about the two batteries in parallel and have opted for using two anti-reverse diode modules inline with the batteries prior to the buck converter. Trust me...I appreciate EVERYONE's feedback here.

    Trust me...i know its simpler and likely cheaper to go with traditional AGMs and the like. However, I think what I'm really targeting is the rapid charge capacity offered from the ryobi batteries along with the weight.
  8. KB4QAA

    KB4QAA XML Subscriber QRZ Page

    Holy smokes. 100Ah battery that weighs 7.5 lbs for $155. That is stunning. I'm going to throw away my 32Ah, 25lb AGM hybrid deep cycle marine battery (U-1 class) when it dies. More than two and half times the usable power for the same price as West Marine, $159!!! AGM 300 discharge cycles vs. 2,000 discharge cycles at 80% Depth of Discharge with the EV battery; seven (7) times the working live!!!!!

    p.s. I can put three of these in the space of my portable battery box and still save weight!!!!!
    Last edited: May 18, 2018
    NH7RO and KD2ACO like this.
  9. NH7RO

    NH7RO Ham Member QRZ Page

    My thoughts exactly, too. One wrong move and one could end up in the morgue or in the hospital with huge regrets.

    I recently forked over about 400 bucks for a 30AH (360wh) Bioenno LiFePo4 system complete with a Gennasun MPPT solar charge controller (for my 20 year old big Solarex panel) and I am so glad I did so.

    I now have a set up that charges to full charge in a few hours and can run 100 watts portable 50/50 contest style operation all day long and well into the night (even without the solar panel).

    The great thing about these LiFePo4 batteries is that they can last for thousands of charge cycles---and they are featherweight and compact. I doubt I will ever need to replace it.

    It's like having my own personal power substation that I can carry around in a satchel, too.

    If you only operate QRP then even small LiFePo4 sytems are available well under $100. I also got a small 3AH (36wh) for a DIY 500 lumens 6.5 watt LED bicycle light that really lights up the street when I go for a night ride---but it could also power a 5-20 watt rig just as easily.

    Isn't battery technology wonderful?
    KB4QAA likes this.
  10. KI7CIL

    KI7CIL Ham Member QRZ Page

    Do you have the dimensions for the Bienno mentioned above? Solar I don't have, but rather a K-tor pedal generator.

    de KI7CIL, in the Southwest Cumberland

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