Over on QRPer.com, I just published a post on portable power that was The Spectrum Monitor magazine’s April 2021 cover article.
This article is essentially an overview of a few different types of rechargeable batteries including pros and cons of each chemistry.
While this article focuses on use in ham radio field applications, it also applies to anyone powering receivers–especially those without an internal power supply–in the field.
The MTR-3B 3 band transceiver is about the size of a pack of playing cards.
SWLing Post readers: I originally published the following post on QRPer.com. I thought I might share it here on the SWLing Post as well since we’ve so many readers who regularly use compact battery packs, earphones, and portable speakers. I’m looking for some advice as I build a super-compact SOTA/POTA field kit around the Mountain Topper MTR-3B. If interested in helping me sort this out, read on:
I received my Mountain Topper MTR-3B last week, and I’ve already taken it on a POTA activation.
Last weekend, I decided to break it in on a POTA “two-fer” site: Hampton Creek Cove State Natural Area (K-6246) and The Overmountain Victory Trail (K-4577) in Tennessee. Hampton Creek Cove was actually an ATNO (all time new one) so it was a trial by fire!
In short, the MTR-3B was marvelous. I’m so impressed.
As I mentioned in a previous post, I’m building a full SOTA/POTA activation kit for the MTR-3B. I already have a kit built around my KX2 and I don’t want to “borrow” any items from it (so I’m not surprised later in the field when an item is missing).
The TalentCell Rechargeable 12V 3000mAh Lithium Ion Battery Pack is the little black box.
For this activation, I powered the MTR-3B with this inexpensive 12V battery pack a friend recommended on Amazon.com (affiliate link). The battery pack is almost identical in size to the MTR-3B and works perfectly. The battery, charger and cable all set me back a whopping $25.
I also used my Whiterook paddle (which needs new paddle arms at this point) but that will soon be replaced with a set of N0SA portable paddles I recently ordered.
Since the MTR-3B has no volume control, I used a pair of 20 year old Sennheiser earphones I bought when I lived in Munich. These have been in a drawer for ages because I now prefer using in-ear earphones with silicon earpieces for better comfort and sound isolation. But the Sennheisers have one thing none of my other earphones sport: in-line volume control.
While the earphones worked well for this activation, I’d still prefer a set of in-ear earphones with in-line volume control. Any suggestions from MTR-3B owners? Also, I’d like a compact amplified speaker with volume control to carry as an option when needed. If you can recommend one, please comment!
I’m writing an article for The Spectrum Monitor magazine about portable power later this year. I noticed that a number of MTR-3B owners swear by 11V rechargeable Lipo cells that are used in the RC and drone markets. Many have a similar compact form-factor as the common 9V battery. I understand, however, some of these cells need special chargers and equipment to balance them.
I would appreciate any and all information about these batteries.
In the meantime, Rich (N8TGQ), recently shared a pic of his Mountain Topper portable pack. Check it out:
I think it’s brilliant how he’s mounted everything on a compact plastic cutting board inside the case. Rich says that what he loves about this set-up is that everything is there, ready to go–simply plug in the antenna!
Please comment or contact me if you have any suggestions as I build out a compact MTR-3B kit!
Many thanks to SWLing Post contributor, Adid, who writes:
I just ran across this adapter
https://www.aliexpress.com/item/4000202530136.html
I don’t know if D type is still available everywhere, but not here in Israel.
So this can be very handy if one needs to revive a D type device occasionally.
Thanks for the tip, Adid! This could be a very helpful product for radio enthusiasts who have some of the classic solid state receivers of the 1970s and 80s, like the Panny RF-2200.
It’s not difficult in the States to find D cells but rechargeables are not as commonplace and are quite pricey, often requiring their own dedicated D cell chargers. Since I almost exclusively use rechargeable batteries, I have two of these Eneloop “power packs” (affiliate link) that have AA to D cell adapters inside. Of course, your option is much less expensive and should yield better overall capacity when using standard alkaline cells.
I had a number of important plans and goals yesterday which I conveniently set aside to build kits instead. Have you ever had one of those days?
Building kits is a little like therapy for me. I find it relaxing, fun, and it gives me an opportunity to tune out everything else in the world while that soldering iron is hot.
The first kit I built was one I purchased this year at Hamvention: the Ham Radio Workbench 12 VDC Power Distribution Strip.
I’ve been on a search for two types of fused Anderson Powerpole distribution panels: a portable one for the field with at least 4 ports, and a large one for the shack with 12-16 ports and at least two USB 5VDC ports.
Sadly, there is no large one on the market that I would like right now. I checked every vendor at Hamvention and the Huntsville Hamfest this year and while there are large panels available, none of them have USB ports. That and the price for a 12-16 position DC distribution panel can easily exceed $120.
As for the small panels for field use, many of them are a bit too bulky and pricey. The inexpensive ones lack individually fused ports.
My buddy Dave (K4SV) knew I was on the hunt, so at Hamvention he directed me to the Ham Radio Workbench podcast table. There, I found the ideal portable solution in kit form. And the price? A whopping $25.
Take my money!
Yesterday, I built the kit in near record time. It went together so fast, I forgot to take progress photos.
What I love about this DC distribution kit is it actually has more features than other products on the market:
I also love the size and configuration.
The kit does not come with an enclosure or base of any sort, so I had planned to simply attach it to a dielectric plate to prevent the bottom of the board from shorting on a conductive surface.
This morning, however, I discovered a 3D-printed enclosure from Rocket City 3D:
This enclosure protects the entire panel on all sides so I’ll be able to throw it in my backpack and not worry about the connectors snagging on other items. The price is a reasonable $12 shipped. Done!
This little DC panel pairs well with the 4.5 aH Bioenno Lithium Iron Phosphate battery I purchased on sale at the Huntsville Hamfest. Together, they’ll power the portable SDR system I’m putting together. More on that in a future post! Stay tuned!
Click here to check out this kit at HamRadio Workbech. It’s currently out-of-stock, but you might contact HRW and see if a future run is in the works. Click here to check out the custom enclosure from Rocket City 3D.
UPDATE: I understand Ham Radio Workbench may eventually print the circuit boards for this project. In the meantime, another affordable option I’ve used is this pre-built panel from Electro Sales on eBay: https://ebay.us/UyJPkh
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Many thanks to SWLing Post contributor, Steven Crawford, who writes with the following inquiry:
[I’m searching for] good quality USB powered battery chargers for AA and D size rechargeable batteries.
Wall outlet chargers are common but quality USB powered battery chargers appear much less common…less common than the packable solar panels with USB ports such as Anker’s, that could be used to power them. Ideally the charger should handle Nicad’s, NIMH and Ii-on but have standardized on AA, AA + D adapter sleeves, and D batteries for my storm supplies.
If I understand correctly, you’re searching for a good qualityUSB-powered battery charger that supports multiple battery chemistries (nickel-cadmium, NIMH and lithium ion) so you can recharge AA, AAA and D batteries with a portable solar panel.
I’m hoping SWLing Post readers can offer some suggestions.
I’ve also looked into this type of charger for both Ears To Our World and my own personal use when off-grid in the summer. I’ve never found one that truly supports all of the battery chemistries you mentioned. The one I’ve used (an EBL) works quite well, but only supports NiMH AA and AAA batteries. As you mentioned, you can use D cell sleeves with the AAs.
EBL makes a number of USB chargers that can be found by searching Amazon. This one–an EBL Quick Charger (affiliate link)–can recharge NiMH batteries within 40 minutes and I’ve personally used one. I’ve been pleased with EBL batteries as well.
I never use nickel cadmium rechargeable batteries at this point, so really don’t know what’s available on the market.
I have found that there are a number of USB-powered lithium battery chargers, but typically for specific lithium cell configurations like 18650, 16340, 14500, 26650, etc. Some of these inexpensive chargers have magnetic contacts that can fit almost any battery type and on Amazon and eBay they claim to recharge multiple battery chemistries, but frankly I’m quite skeptical. These $9 devices don’t seem to have a way of detecting battery chemistry, thus I’m not sure how they would adjust the charging cycle accordingly. Perhaps I’m incorrect in this assumption?
Other than using Powerfilm solar NiMH battery chargers (I can recommend these) which are incorporated in their folding panels, I’ve never charged batteries directly from a solar panel. Typically I have a 9ah or larger 12V battery floating between the PV panel and the charger.
I’ve found that using a 12VDC charger–like this–that’s pulling power from a 12V battery is simply a little more efficient, faster and reliable than charging directly from a small PV panel. Since I always have 12V batteries on hand when off grid, it’s a simple solution for for my system.
Post readers: do you have any USB-powered battery charging suggestions for Steven? Please comment!
Many thanks to SWLing Post contributor, Mario Filippi (N2HUN), who shares the following guest post:
by Mario Filippi, N2HUN
(All photos by author)
Ever consider what life today would be like without the humble dry cell battery? Old timers know the term “dry cell” as opposed to “wet cell.” The dry cell is your garden variety battery for sale composed of a semi-dry composite or paste of chemicals designed to make electrons flow when the circuit is complete, such as in flashlights, radios, remotes, watches, etc. “Wet cells” on the other hand have fluids, such as sulfuric acid that work in conjunction with lead plates. But let’s stay with dry cells for now. Walk into any house and you’ll find some form of battery powering a plethora of devices that contribute to the quality of daily life. In short, life without the humble battery would be unfathomable.
Electronic Menagerie: Radios, Timepieces, Flashlights, Remotes, Test equipment, Mouse.
Batteries, like humans, unfortunately expire due to age or use. True, they toil tirelessly while out of sight and mind, hidden behind plastic compartment panels somewhere in the bowels of a device and for the most part are ignored or taken for granted. That is until the device they are powering ceases to function. We’ve all been there and done that countless times in our lives with an array of consumer products. Most instances of battery failure tend to occur at the most inconvenient times, that is when the device they are powering is needed most (a corollary of Murphy’s Law hi hi). A good example is the toolbox flashlight. It can sit amongst the tools quietly and ready to go (at least in our minds) until we switch it on while working in some dark, cramped location. Or late at night when under the covers and the bedside shortwave radio starts spewing out distorted audio. To boot, the radio’s convenient dial light is too weak to determine where you are in the shortwave spectrum.
Motley Crew of Cells in Author’s Armamentarium Awaiting Call to Duty.
Well, all is not lost my fellow hobbyists; it is time to do some cell (dry cell that is) soul searching and plan for future failures. I propose a useful acquisition for the home, shack, Go-Bag (or what have you) that won’t break the bank; a simple battery tester that’ll be the end to your power problems.
At this QTH an AMPROBE BAT-200 was purchased a few years back from Amazon and has proved its worth and utility many times over. This simple tool, which ironically needs no batteries, will test many of the common batteries around the shack and home such as AAA, AA, C, D, 9V, and button batteries.
Pocket-size BAT-200. A Snap to Use.
Since purchasing the BAT-200, life in the battery cosmos has become a lot less complicated. Armed with one of these, you can immediately rule out battery failure when troubleshooting myriad devices. You can also test outdated batteries to determine their status.
Flashlight, Magnifying Light, and Head Lamp…
…Test meter…
…And Various Remotes Use A, AA or Button Batteries.
AA Battery from Remote Tests “Good.”
An item such as the BAT-200 can be found for less than five dollars if you shop around, and will pay for itself by taking the guesswork out of the bad battery scenarios. You’ll wonder how you ever did without one!
Thank you very much for sharing this post, Mario!
At the SWLing Post HQ, we keep all of our loose batteries in a “battery box.” All new cells stay in the packaging where we mark the date purchased (although many alkaline cells now have a “best by” date). We recently pulled all of the loose/orphan batteries out of the box–there must have been 40+–and tested the voltage of each one. I used the test meter from my toolbox to do this, but I’ve just ordered one of the BAT-200 chargers from Amazon and will now keep this in the battery box permanently.
Thanks for enabling me, Mario! Ha ha!
Click here to check out the BAT-200 in Amazon.com (affiliate link).
Many thanks to SWLing Post contributor, Anil Raj, who writes:
I wanted to share a small but useful hack with your readers.
I use a common garden variety smartphone “Powerbank” 10,000 mAH Li Ion pack to power my Sony 7600GR which is perfectly happy with the 5V which the pack supplies. [See photo above.] I see no reason why this won’t work with other radios which require a 6V supply.
As you can imagine, the setup typically lasts for many weeks of extended daily listening and recharges in a jiffy. However, one needs to sacrifice a USB cable by soldering a DC plug at the other end. Haven’t bought AA batteries in a long time…
Thank you, Anil! What a simple but useful hack. The best part is, battery packs/banks are very inexpensive these days and, I for one, have a number of USB cables I could sacrifice for the job!