Wednesday, November 30, 2022


RVelectricity™ – Just Ask Mike (J.A.M.): Solar battery packs: The best way to use cell phone in emergency; Jackery update


Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) with the subject line – JAM. This week I dicuss solar battery packs, large and small, and the best way to use your cell phone in an emergency.


Dear Readers,
There were a lot of questions about the Jackery 1500 Solar Power Station and 400 watts of solar panels I recently received for review. I’m right in the middle of testing how long it can power a Vitrifrigo 12-volt DC compressor portable fridge/freezer set to -7 degrees F in a 70-degree room.

I should know more in a week or so and will then be able to publish preliminary data. But you can read about my first impressions HERE.

In the meantime, I’m also testing a rather small solar battery pack that would never be able to power your refrigerator. While it doesn’t have the power to chill your beer, it does have the power to save your life. Here’s why…

Don’t leave camp without a backup battery pack

I’ve been experimenting with small solar backup battery packs for cell phones and so far I’m really liking the Scorpion II from Etón. Not only is this a battery backup for your cell phone, which they claim has enough energy to recharge a cell phone several times on its own, it also includes a small solar panel (maybe 2 watts) and a hand-crank charger for when the sun don’t shine.

There’s also an AM/FM/Weather radio and a flashlight. A rugged carabiner lets you hang it on a belt loop or your backpack. And in case you need it, there’s a bottle opener (yippee). Just be sure to also take the proper USB-to-phone charging cable. It comes with a mini-USB charger cable, but you’ll need a separate USB charger cable for your Apple iPhone.

You can find the Scorpion II on Amazon HERE.

Why should you carry a backup battery for a hike?

I’ve seen a number of recent news stories about hikers who’ve gotten lost in the woods, and succumbed to their injuries from exposure. That prompted an ill-advised rescue method of leaving a voicemail message on your own cell phone service telling everyone that you’re lost and the approximate location. But if you have enough cell service to leave a voicemail, then you should have just called 9-1-1 directly.

Here’s a better way that works

Be aware that if your cell phone is out of range of a cell tower the battery will drain down quickly because your phone tries to keep pinging for a tower. And that uses up a lot of battery power.

A better method is to put your cell phone in airplane mode, which will shut down the RF transmitter in your phone. Then write a text message which you’ll set up to send to as many responsible people you know in your contact list. Be sure to note the date, time and location as best you can and ask them to call 9-1-1 immediately with this information.

And if you have a cell phone GPS app that doesn’t require a data connection to build a map, this would be a great time to copy and paste your exact location into the text message. Also detail if you’re injured, near your car, in a ravine or any other information the first responders can use to locate you.

Now take your phone out of airplane mode

That’s right, turn off airplane mode and your phone will try to grab a tower to send the text message. Try to get as high as safely possible (don’t climb a tall tree and get injured) and wave your phone around a bit. If it does grab a tower for even a few seconds that’s all it needs to send your message.

Shut off your cell phone to conserve the battery

This could be the hard part, but you should now shut off the phone to conserve battery power. Check in at the top of every hour by turning on your phone and seeing if you can get a text message back with any response. If not, try to send another text and shut off your phone again for another hour.

Follow first responder orders / and don’t wander off…

Once you do make contact with first responders, advise them of your situation as clearly as possible, then follow their directions. Don’t try to be a hero at this point – that’s their job. And unless there’s a really good reason to keep moving (like a forest fire or a flood) stay where you were when you made contact. Don’t make your rescuers go looking for you all over the wilderness after you’ve told them your location. So stay put!

And next time, be more careful not to get lost in the woods or fall down a ravine. Those brave men and women risk their own lives to save others, so let’s not make it harder than it needs to be….

OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.

Let’s play safe out there….

Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at For more info on Mike’s qualifications as an electrical expert, click here.

You don’t want to miss Mike’s webcasts on his YouTube channel.

For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign


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1 year ago

I actually have an older version of the Scorpion — all crank/battery operated flashlight/AM/FM/weather/charger, with a cute solar panel on top. Annoyingly, mine doesn’t have a way to plug-charge the 350mah 3.6V battery pack, so I modded that slightly. BUT, it’s a pretty good unit overall — I’m impressed how fast the crank actually does charge it’s internal battery enough for use from “dead”… I’ll have to meter it’s wattage for charging USB devices in a “last resort” case. Of course, I carry a half-dozen LiPO bricks for that purpose, so I’m skeptical I’d ever really use the crank in an emergency… but doesn’t hurt to have a last resort!

Jeff Craig
1 year ago

As a retired telecom worker, I’d also like to advise everyone to use text messaging in an emergency, like tornado or earthquake. Most companies use a 10-to-1 network architecture, so for every 10 customers, you have one ‘circuit’ available. This has changed A LOT with the advent of VoIP (aka ‘digital voice’ used by both mobile and landline carriers, but the routing switches that direct the calls locally can still busy out. Meanwhile, standard Juniper routers can handle 1,000 plus text or data messages (FaceTime, Messenger. WeChat, texts, etc…) in the same bandwidth as one old landline call.

kim paar
1 year ago

My concern with the idea of shutting your phone down would be the amount of power it takes for it to turn on again. Surely you would use your battery up quicker if you keep turning it off and on every hour.

1 year ago
Reply to  kim paar

This is a good thought, but “very unlikely” — simple test: Charge your phone and turn it on and off 5-10 times… observe the battery level. Now think about how long just sitting on, “connected” would burn the battery. I lose a couple percent per restart, or 30-some reboots worth… My battery dies almost daily (18hrs) but I could reboot-limp for 30. Now, if I turn on airplane and repeated both tests, those numbers might change. I’d say no matter what “experts” say, this is going to vary by your particular phone model and what apps auto-start every time. I’d still default to the reboot and check method.

Roger V
1 year ago

Great advice on the phone issue. That “change your message “ thing that went around the Internet drove me nuts!

Bob P
1 year ago

Again great info, keep up the good work!

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