The Realist: Grid-Down Cell Phone Charging

Another guest post from the Realist:

(Source)

Disclaimer: All products mentioned in this article were purchased by myself. I did not receive samples, evaluation models, or other compensation from manufacturers or retailers. I have no formal relationship with any manufacturer or retailer mentioned in this review - I have only been an arms-length customer. Further, this review reflects my unique circumstances and subjective opinions with regard to performance and other characteristics of the products being described. Your mileage may vary.

After the recent hurricanes there has been a lot of discussion about the benefits of cell phones during the hurricane event and during the subsequent rescue operations, and the importance of keeping them charged after the power goes out. Hurricanes are only one of many reasons to have alternative means of charging your cell phone. There are many scenarios where having an alternative means of charging a cell phone could be beneficial.

Being able to keep a cell phone charged under a variety of circumstances has been a concern of mine since I first got a cell phone. When I finally got a smart phone, this concern became more pronounced as I started using my smart phone for a variety of non-telephonic tasks, including keeping abreast of local severe weather events in which I found myself.

This article is not intended to recommend any specific products or suppliers. Instead, by highlighting a few different evolving solutions I have put together for grid-down charging of my cell phone, I intend to give you an idea of what is available and give you a few data-points to aid your search for products to address your specific concerns and circumstances. I'm not going to show you the products I've purchased that have disappointed me, which were usually cheap or gimmicky.

 A typical cigarette lighter plug 12 volt USB car charger and cell phone charging cable.

Automotive

First off, you do have a 12-volt USB car charger and cable for your cell phone in your vehicle? While 12-volt USB car chargers are available for as little as a dollar, spend a few dollars more to get one with higher current capacity to facilitate quicker charging. For most practical circumstances, my vehicle is usually nearby wherever I happen to be, which is why I include it as a grid-down charging solution.

MintyBoost (top center), 2500 mAh flat lithium ion battery pack (center), 5200 mAh lithium ion battery pack (bottom center), multi-USB charging cables (far left), short Lightning cables (left), and micro-USB charging cables (right).

PowerFilm and MintyBoost

My previous grid-down cell phone charging solution, which also gave me the ability to charge AA and AAA batteries, incorporated a Powerfilm folding AA solar power charger and a MintyBoost AA battery powered USB charger. The Powerfilm solar power charger would charge AA nickle-metal hydride (NiMH) batteries, which would be used to power the MintyBoost charger, along other AA (or AAA) powered devices such as flashlights.

The PowerFilm AA folding solar power charger (https://www.amazon.com/dp/B001RMF7P8) weighs 4.4 ounces and folds up into a shirt-pocket sized package. It will charge two or four AA or AAA NiMH cells in pairs. Adapters are required to charge AAA cells (https://www.amazon.com/dp/B01EH5MJZW/). Unlike many solar battery chargers, this unit has a built-in charge controller and, via a pair of LEDs, provides a visual indication of operational state of the charger, including when the batteries are charged. In my experience, this solar charger would only charge NiMH AA cells to about 80-percent of capacity, but I was hanging it vertically in a window and not putting it in direct full sunlight.

The MintyBoost (https://www.adafruit.com/product/14) allows you to charge any device normally charged via USB, including cell phones, tablets, and other devices from alkaline or rechargable NiMH cells. The MintyBoost is only available in kit form, and requires modest soldering skills to assemble. You also need to be able to cut a slot in the side of the tin for the USB port. The MintyBoost was designed to fit in an Altoids gum tin. Although Altoids gum was discontinued several years ago, Adafruit sells a similar sized tin for two dollars.

You need to supply your own charging cable to plug into the MintyBoost. The MintyBoost will charge iPhones and Android cell phones.

Keep in mind that most cell phones and tablets have internal batteries whose capacity typically exceeds the capacity of a pair of AA batteries, so don't expect the MintyBoost to fully charge a completely dead cell phone battery. And, while operating, the AA batteries may get warm, and a small inductor on the MintyBoost circuit board will get hot.

The Goal Zero kit, which includes the Nomad 7 solar panel, battery pack, flashlight head, fan head, micro-USB charging cable, and a pair of small carabiners

Goal Zero

My latest grid-down cell phone charging solution is a Goal Zero solar panel that charges lithium ion battery packs that can subsequently be used to charge a cell phone. This is a less complicated - fewer "moving parts" - cell phone charging solution than the Powerfilm plus MintyBoost solution.

After Christmas, I ran across a Goal Zero "Switch 10 USB Multi-Tool Kit"
(https://www.amazon.com/dp/B00OLINB12/) substantially discounted on clearance at a local store. While I would have never paid full price for the kit, it was reasonably priced on clearance. It had two items worth mentioning - the Nomad 7 solar panel and an accompanying 3,000 mAh lithium ion battery pack. The Nomad 7 solar panel is primarily intended to charge USB devices. The lithium ion battery pack can be charged by the solar panel, and has a USB port for charging other devices.

The Nomad 7 solar panel itself weighs a little over 16.2 ounces, and has a small pouch sewn on the back to contain its attached cables and hold other accessories. The entire Switch 10 USB Multi-Tool Kit kit weighs 24.7 ounces.

There is nothing special about the Goal Zero battery pack beyond its ability to accept an LED flashlight head or a small fan. The battery pack also has small white LED on the side that is intended to be used as a flashlight. The battery pack can be unscrewed to replace the internal proprietary lithium ion battery should it fail.

The Goal Zero solar panel will charge other lithium ion battery packs that are charged with a USB cable. So, you can even charge the inexpensive lithium ion battery packs intended for recharging cell phones. I have purchased additional lower capacity (2500 to 5000 mAh capacity) lithium ion battery packs to supplement the Goal Zero battery pack. They can be recharged in a reasonable period of time by the Nomad 7 solar panel.

Goal Zero sells a USB powered AA charger (https://www.amazon.com/dp/B00D2SQ6W8/). However, I believe it is overpriced and has some serious shortcomings.

Powerfilm (top) and Goal Zero (bottom) solar panels.

Experiment

As an experiment, I cobbled together a solar charging system for a parts cost of around ten dollars (twenty dollars if all parts were purchased new). This included a solar panel I'd purchased from a thrift store for $3.50 many months ago, a one-dollar 12-volt USB car charger from Dollar Tree, and a less-than six-dollar 2500 mAh lithium ion battery pack from Walmart (Walmart sells 2200 mAh battery packs for less than five dollars). (Not included in the cost of this experiment is the cable with a female cigarette lighter socket and alligator clips which I utilized simply for this experiment.)

The solar panel is very similar to a 1.5 watt unit sold by Harbor Freight for $14 (https://www.harborfreight.com/15-watt-solar-battery-charger-68692.html). It is inefficient and fragile compared to the previously discussed solar panels, but cheap.

The one-dollar USB car charger works, but is poorly made. Its internal construction quality actually makes me a bit nervous. Further, the side contacts intended to hold the charger in the cigarette lighter socket by friction are weak and the charger easily works its way out of the socket sufficiently to loose power.

In full sun, this cobbled-together solar charging system supplied about 75 mA per hour to the battery pack. It would take around 33 hours of full sun to charge a fully discharged 2500 mAh battery pack. And, since the typical smart phone has a battery capacity of around 2000 mAh, that means you would probably get enough power to fully charge you cell phone every three days if you had clear skies and diligently kept the solar panel aimed at the sun all day long.

Two or three similar solar panels could be ganged together in parallel to increase charging current and reduce charging time. With two of these solar panels in parallel, you could probably get a full charge ever other day. And, with three of these solar panels in parallel, you could probably get a full charge every day.

This experimental solar charging system is not very practical given its low charge current, but demonstrates that inexpensive or scavenged components could be utilized in a pinch to put together an off-grid cell phone charging system.

An experimental solar charging solution cobbled together with around ten dollars in parts.

Lithium Ion Battery Packs

While I consider lithium ion battery packs to be a component of a larger grid-down cell phone charging solution, others have suggested them as a primary solution for short-duration grid-down cell phone charging.

There are a wide variety of lithium ion battery packs being sold for recharging cell phones, tablets, and other devices. These battery packs usually come with a short USB (type-A) to micro-USB cable. The full-size USB end of the cable plugs into the USB port on a computer or a USB power supply, while the micro-USB end of the cable plugs into a charging port on the battery pack. The full-size USB jack on the battery pack is used to charge other devices.

Cables

Most Android phones are charged via a micro-USB port, so the charging cable supplied with the lithium ion battery pack can be used to charge an Android phone. For those who have an Apple iPhone or iPad, an additional Lightning cable is required for charging. Fortunately, there are a variety of Lightning cables on the market.

In the photo with the USB cables, I have shown two different short Lightning cables. The stubby fat cable was sold at Walmart for a while, but appears to have been discontinued - similar cables are available from other sources. The other short cable is a Belkin cable, which cost as much as a regular length cable.

Also in the photo with the cables are two "multi-USB" or "charge buddy" charging cables. These cables were being given away by exhibitors at a convention I recently attended, but similar models are sold on Amazon and eBay. These cables are only for charging and not for data transfer.

Not pictured is a cable I recently purchased at a gun show that has both micro-USB and Lightning built into a single plug to support both Android and Apple products - it looks like a micro-USB plug with lightning contacts on one side (http://www.cordsofsteel.com/). It supports charging and data transfer. I don't have a lot of experience with it yet. My only concern is that it fits a little too tight into the lightning port of my iPhone.

Final Thoughts

The PowerFilm and Goal Zero solar panels described above are marketed primarily for hiking and camping. Both solar panels have provisions for attaching the solar panel to a backpack, if hiking, or to something else to properly aim it at the sun. Lightweight cord or rope should be included with your solar panel kit for attachment to something else. In an emergency scenario, some care in placement should be exercised to minimize the risk of theft.

Don't go cheap on the USB charging cables. In my experience, most cables are somewhat fragile. I have tried to buy quality cables, and will keep the convention-give-away multi-USB charging cables for backup.

I am not going to suggest any particular type of alternative/emergency charging capability. The products mentioned above reflect my ongoing search for products that can charge and power my cell phone and other battery powered devices in an emergency.

Whatever capabilities you choose, be sure to test your equipment to make sure it performs as expected, paying particular attention to the charge state of your lithium ion battery packs (a battery pack that will not hold a charge will need to be replaced). Regularly retest those battery packs to make sure they continue to perform as expected. If you are a blended family with both Android and Apple cell phones, make sure you have cables for both types of devices.

Finally, in a grid-down situation, try to minimize the use of your cell phone to extend its battery life - don't watch movies or play video games with it.

Good luck!