Solar panel to battery charger

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Solar panel to battery charger

As I was camping last week, I found that having all the family out with me for more than 2 days, devices start to die. Usually, we’re at a spot with power, but this time we were not.

I have 5 flashlights using 18650, cell phones and kindles and flashlights that charge off USB, and a few headlamps with AAA eneloops (we’ll leave those for now).

I would like to dip my toe in to solar, and I’m not clear what goes between the panel and any of those things,

I did a search here, but came up with 2018 and before threads, so assume recommended gear has changed.

I have an Xtar WP2H. It charges 2 18650s to my satisfaction. It has a USB out. It wants 12v in. Can I just put the correct barrel on any dumb solar panel, and start charging 18650s and my USB powerbank? If not, is there a cheap (under $15) thing I would wire between the two? I understand some panels and some chargers basically shut down if the voltage drops too low.

For all the USB stuff I see a thing called a wide voltage usb regulator, for $10 ish, which appears to convert 12v to 5v with a USB port. So I could wire that to the solar panel. If that’s the way I go, then I would have to buy a new charger for the 18650s (xtar x4 seems to accept usb in, feed usb out, and looks like it would charge the AAAs as well). WP2H would stay home.

ChrisGarrett's picture
Last seen: 44 min ago
Joined: 02/12/2014 - 22:03
Posts: 765
Location: Miami, Florida

If your stuff is 5vdc USB, then stay in that format and get a good power bank that allows you to interchange cells, like my older Tomo V8, or my newer Xtar PB2S (21700, 20700, or 18650 only.)

Charge that during the day with your solar panel and than charge your stuff during the night. Carry a few pair of 21700s and charge them when needed.

12vdc systems need a digital charge controller if the panels are 20w or greater, so while they’ll provide more power, they’re also more cumbersome to employ in the field.

I just got a 28w USD Blue Sky USB panel for just under $100 and it gets very good marks on the survival/camping sites.


Last seen: 6 hours 33 min ago
Joined: 06/14/2012 - 13:48
Posts: 585
Location: Virginia

Welcome to the forum.

One thing I would recommend (which doesn’t answer your question) is to test out whatever you buy in partly cloudy and overcast conditions. Thats when thing get interesting.

You probably want to put your solar panel (whatever you get) and some kind of battery (probably a usb power bank) in the sun to charge all day, then you can use the power bank to charge your devices at night.

TimMc's picture
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Joined: 06/26/2020 - 02:22
Posts: 444
Location: Melbourne, Australia

I got an XTAR ANT MC1 Plus charger with the hope that it’ll be more resilient to dips in power coming from a portable solar panel and not suddenly stop working. There are a few YouTube videos… I need to get around to buying some solar panels. Silly

Interested to see some recommendations.

Last seen: 1 week 5 hours ago
Joined: 10/26/2020 - 20:34
Posts: 57
Location: upstate NY

I think it would be cheaper to buy a USB-powered charger than to buy the solar charge controller that would be necessary to use to get the proper output for your 12V charger.  My charge controller cost half as much as the solar panel.


I use a Bioenno 28W foldable panel, a 12V 9ah LiFePO4 battery and their solar charge controller suitable for LiFePO4 batteries.

Last seen: 2 weeks 17 hours ago
Joined: 12/17/2017 - 21:16
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Location: United States

Thanks for the replies

Last seen: 15 hours 57 min ago
Joined: 12/05/2012 - 13:35
Posts: 25
Location: Hudson Valley, NY

“5 flashlights using 18650, cell phones and kindles and flashlights that charge off USB, and a few headlamps”

That’s a lot of stuff to charge, even if only half of them a day.

You can’t connect a solar panel directly. There has to be a controller in between, either separate or internal to the solar panel.
When I camp off grid, I use a deep cycle battery, power inverter, phone and 18650 chargers and charge the battery with solar panel.
The solar panel charges the battery during the day while we’re out and about.

I upgraded to this panel the other day because it was 50% off. I haven’t used it yet, but it appears to have every thing you need.
There’s probably something similar around for Black Friday or other holiday sale.

I just ordered this too to eliminate all the clutter and have it in one package.

Good Luck