The manufacturer of my medical device has provided a Lithium-ion battery with these characteristics:

  • 97 Wh
  • Output 3.75 A
  • Input 100-240 V, 50-60 Hz, 1.0-1.5 A
  • Protection: overcharge, overdischarge, excess current, short circuit, high temperature

The manufacturer is unable to provide any assistance for charging the battery from any source except a wall outlet.

I would like to take a high mountain trek and use PV panels to charge this battery. What components will I need to charge this battery? What rating for the portable solar panel? What components to connect the PV panel to the battery?

Many who depend on electrical medical equipment will be very grateful for your answer.

Please let me clarify: This battery powers a CPAP machine which I need but is not life-supporting. I will not die and nobody will sue you if this charging system doesn't work.

I intend to include a photo below (if I can figure out how to do it). Here is the info printed on the battery:

  • input 24 V 1.64 A
  • output 24 V 3.75 A
  • "Charge using power supply R360-760, 369102, or 370001 only"

I can get a 100 W flexible solar panel. I would like it to charge this battery in 4-5 hours.

You guys are great! Thank you for your interest!

  • 3
    \$\begingroup\$ Is this life supporting equipment? I am not sure I would want to offer any advice for fear that something might go wrong and someone down the line might elect to sue me. Still, in order to have a chance at a decent answer, what is the voltage of the battery pack? The voltage you have given as an input is the AC input voltage for the charger. Not the battery output voltage. 97Wh sounds like maybe 11 or 12 18650 cells. Maybe. Also, please post a picture of the battery pack. Any text on the pack should be legible in the picture. \$\endgroup\$
    – user57037
    Commented Apr 17, 2017 at 3:15
  • \$\begingroup\$ Also, how fast do you want to charge it? To a first approximation, you can calculate the required panel using 97 Wh / charge time *1.5 de-rating factor. So for 1 hour charging, you would need around 150W panel (big). \$\endgroup\$
    – user57037
    Commented Apr 17, 2017 at 3:16
  • 1
    \$\begingroup\$ If you are willing to viod the warranty, there are endlessly posibilities. If not, a huge solar panel and in inverter would be just about the only way. \$\endgroup\$
    – winny
    Commented Apr 17, 2017 at 6:55
  • 1
    \$\begingroup\$ Pack an EPIRB in-case anything goes wrong. \$\endgroup\$ Commented Apr 17, 2017 at 7:04
  • \$\begingroup\$ Their battery product is for at-home for overnight power outages, not camping. Honestly I would tell them which dark hole they can shove their CPAP, since their whole thing there is a scam to lock you into their hardware and force you to pay more. I would get with CPAP communities and have them help you find a CPAP that has lower power requirements to begin with, and then has a tolerant "12 volt" input on the unit proper. You can spot this because it'll offer a car cigarette lighter cord that is only made of wires, with no embedded silicon. When you have that, this problem becomes easy. \$\endgroup\$ Commented Jan 26, 2023 at 20:24

1 Answer 1


You have at least two options. The power from the panel can go 1) through a "charger" that produces 24V DC @ 2A, or 2) through an "inverter" that produces 120V AC @ 2A.
The advantage of option 2) is that you can plug your device just like you normally do (wall plug), but is less power efficient.
The advantage of option 1) is that it is more power efficient, but you have to "pull out" the battery and connect it to the charger.
The equipment for either method is readily available on eBay (less than $100).
Your 100W panel should be able to charge your battery in 2 to 3 hours.

Just remember that Li batteries can burst into flames. Make sure the charger is current and voltage limited!

  • \$\begingroup\$ If bursting into flames is an issue, maybe not buy that stuff on eBay lol. \$\endgroup\$ Commented Jan 26, 2023 at 20:25

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