Reliable emergency backup power for disasters

Discussion in 'Amateur Radio News' started by OH8STN, Sep 14, 2019.

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  1. WA2LXB

    WA2LXB XML Subscriber QRZ Page

    Julian has a web page as well...very informative with lotsa videos and links to gear:
  2. WA2LXB

    WA2LXB XML Subscriber QRZ Page

    Julian's videos are like a ski lesson. If you get 5 good ideas and remember and productively integrate just one of them into your skiing, the lesson pays dividends every time afterwards. I'm a fan of Bioenno's stuff: Their charge controller is too bulky tho, go with the Genasun.
  3. W2JKT

    W2JKT Ham Member QRZ Page

    I didn't get to watch the entire video yet so I don't know if this is mentioned, but one thing that is critical for off-grid power backup, especially when you have a limited amount of energy on hand (i.e. no solar/wind), is to minimize the number of power conversions that are done in order to operate whatever it is you need to operate. Every time you go through a power conversion, you're going to lose at least 10% and up to 30% of your energy, depending on the conversion.

    Consider this setup:

    Solar -> Solar Battery Charger -> 120V Inverter -> 12V DC supply -> 12VDC Radio

    There are three power conversions between the power source (solar panel) and power consumer (the radio). Assuming you have spent a fortune on this setup and all of your power conversions are 90% efficient, you are still losing 37% of all of your energy on power conversions. That's a pretty staggering amount of loss. It gets even worse with cheaper equipment.

    Now consider this:

    Solar -> Solar Battery Charger -> Battery / Radio

    There is only one power conversion, so 90% of your harvested energy is available. I think some MPPT chargers are even better than 90% efficient.

    The lesson learned here is to choose your solar system voltage wisely so that you can go direct from battery to radio.

    Many solar chargers are set up for RV use, and these are the ones you want for ham radio power backup as well.
  4. KD8CIV

    KD8CIV Ham Member QRZ Page

    Be careful on brand of RV charge controllers. We have one in a travel trailer that when it's charge controller is active the HF radio is useless from the level of RF noise put out by the charge controller. If we are in a campground I have to unplug mains from the trailer to do anything with the radio. This is even when the radio is operated off an independent battery not connected to the trailer in any way. Genesun makes a really quiet charge controller.
  5. WL7PM

    WL7PM Ham Member QRZ Page

    Emergency power ? Easy:
    There are 250 MILLION automobiles in regular use in the USA.
    There is a functioning, nominally charged 70 + amp-hour 12 volt battery in every one of them.
    There are likely dozens, hundreds or THOUSANDS of charged, ready to operate emergency BATTERIES within a half mile of where you sit reading this thread.
  6. KA2IRQ

    KA2IRQ Ham Member QRZ Page

    Eh. Not the best idea. In a pinch, yes. But despite the thousands of nearby batteries, in a true emergency, no one is letting you use their car battery. The only car battery you can count on to use is yours. So you connect it up, start to use it (remember, these are not deep cycle batteries, so you really can't use it for long), and you don't want to waste gasoline to charge it (since you may have to evacuate at some point and you want all the fuel you can muster). After awhile, it isn't starting your car. Now you have to evacuate and there you are with a dead battery and a car that won't start.

    Now is the time to research and build yourself a dedicated backup power system to run your radios based on your needs, budget, and proper design.

    But I agree, in a pinch, you should be able to connect to your car's electrical system. But I would use that as a system of last resort. Also, you often can't get the car close enough to where you are operating, so now you're dealing with long cables and voltage drop, etc., or pulling the battery to move it - which is a problem that you don't want to have to deal with while you're trying to get radios up and running.
    W4NNF likes this.
  7. N3EG

    N3EG Ham Member QRZ Page

    I have a LiFePO4 RV 200 AH battery and two 100W solar panels. I also use a failsafe charger that keeps the batteries above low voltage dropout in cloudy conditions. There's a boost charger to bring the batteries up when anticipating a storm (or a contest!)

    My portable battery is a 25 Ah parallel/series lithium stack of analyzer matched cellphone batteries.
  8. W1QZ

    W1QZ Premium Subscriber QRZ Page

    Thank you.....The best one source dissertation on this subject I have seen.
    My own station is runs off a Grp 29 truck battery for an IC 7300, Hercules II amp to a OCF dipole. Charged from the grid with a 10A Xantrex Charger, with my limited operating time, of an hour per day, I don't charge very often.
  9. KM4FVI

    KM4FVI Platinum Subscriber Platinum Subscriber QRZ Page

    Rightfully so.... thermal runaway in an aircraft battery is intense!

  10. K7ART

    K7ART Premium Subscriber QRZ Page

    Well done Julian; one of the best and well organized video productions I've watched addressing the most important topic for Radio Amateurs'! Hopefully we will see a quality video from some of the commenters covering their ideas of same very soon, ; )

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