Backpacking with Nomad 14

sthusler
sthusler Member Posts: 7 ✭✭
in SOLAR PANELS

I need to charge Medistrom Pilot-24 battery (24 v 2.5A, discharging 3550mAh) battery in 4 hours or less while backpacking through the forest. Can I use the Nomad 14? What is the best choice?

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Answers

  • jg164
    jg164 Administrator, Moderator Posts: 337 admin

    The Nomad 20 is a newer version and should perform better.

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  • sthusler
    sthusler Member Posts: 7 ✭✭

    The answer provided was not helpfull. Will the Nomad 20 be able to charge the Medistrom Pilot-24 battery (24 v 2.5A, discharging 3550mAh) battery in approx. 4-6 hours while backpacking through the forest with indirect sunlight or overcast skies?

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  • sthusler
    sthusler Member Posts: 7 ✭✭

    I purchased a different brand due to the delay in understanding this product.

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  • sthusler
    sthusler Member Posts: 7 ✭✭

    Please take me off mailing list

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  • jg164
    jg164 Administrator, Moderator Posts: 337 admin

    @sthusler,

    Sorry I missed the other question!

    Here's the short answer, the Nomad 20(or14) can not recharge the Pilot-24. It would take more(at least 5-6 Nomad 20s chained in parallel)/different solar panels to compensate for spotty solar conditions, provide enough current to meet the charge demand and have enough solar time to full charge.


    Here is a longer explanation:

    If you want to charge that Pilot-24 pack fast, you would need to match its input max specs and account for the capacity in Watt Hours (98wH (as listed in section 9 of the manual pdf) and plan on part of the charge taking longer that the first part ( We can't push Max power into the battery all of the time, at the end it slows down )

    The specs of the Pilot-24 says it can take 90W max at 3.75A / 24V and charge in as little as 2-3 hours with this recommended AC charger provided by Medistrom http://medistrom.com/products-pilot24-lite-power-adapter.html

    To match that PSU output with solar and hope to get similar charge times of 2-3 hours (see section 2.7 of this pdf) you would need at least 100W of solar, probably more because conditions are usually not ideal. Solar power is reduced as the panels get hot and you would have to have the panels pointing directly at the sun the while charging adjusting them as the sun moves and shadows partially shade the panels. Hiking though trees on a cloudy day with a solar panel hanging from a backpack would probably reduce solar power to nearly nothing.

    If I was looking to run a CPAP I would look at a small foldable 100W solar panel (Something like this or larger) that provides more than enough current to meet the demand of the Pilot-24.

    Read more about Battery charging and Solar in this post: SOLAR + BATTERY EDUCATION – Goal Zero

    How CC and CV charging of Lithium batteries works: https://www.youtube.com/watch?v=FaEX_2Ubc7A


    Let me know if that helps!

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  • sthusler
    sthusler Member Posts: 7 ✭✭

    Thank you for the follow up. I contacted Medistrom and they recommended their 50W panel (Medistrom 50W Solar Charging Panel for Pilot-24 Lite Battery Pack (lofta.com)) with full charge in direct sunlight at 8 hr., so I purchased it. Based on your information I am assuming I'll get approximately one third to half charge in 6 hours indirect sunlight or overcast sky. Thanks again for your help and please let me know if I have unrealistic expectations.

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  • jg164
    jg164 Administrator, Moderator Posts: 337 admin
    edited May 2023

    @sthusler,

    Solar panels can be surprisingly easily impacted by conditions.

    Even a few blades of grass covering just a few inches of a small panel can completely stop it from putting out enough power to be accepted by a power bank's charge controller.

    Same goes for clouds, panel angle, air temperature, time of day, sun angle through the atmosphere, wire length/gauge, connector fit and corrosion, manufacturing issues, cracked silicon, moisture leaks into cell circuits and the list goes on.

    Before you set out on a trip, I would do some experiments at home to see what you really get when simulating conditions so you know about what you can expect on a trip.:

    • Test on a cloudy day
    • Point the panels away from the sun
    • Cover panels with your shadow and then uncover it to see if it can resume charging or gets stuck not charging

    If you are handy with soldering and know some electrical basics you could add/change connectors for a DC power meter that you can place in between different power sources and the Pilot-24 to see how Volts and Amps change as you experiment and see stats like accumulated watt hours over a duration.

    Ultimately what you need is to test if you can consistently recharge enough of the Pilot-24 to meet your daily needs in the conditions you will be expecting this setup to work.


    Thanks for checking us out! I hope you have a great trip!

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  • sthusler
    sthusler Member Posts: 7 ✭✭

    Thank you for your help. I am planning a 100 mi backpack trip around Mount Rainier in August.

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