The Realist: Battery Adapters

I'm pleased to present another guest post from The Realist, who writes:

Adapters with batteries installed are on the top row, while empty adapters are on the bottom row. From left to right are AAA to AA, AA to C, AA to D (insert-from-bottom), AA to D (clamshell style), and 2AA to D.

Disclaimer: All products mentioned in this article were purchased by myself. I did not receive samples, evaluation models, or other compensation from any manufacturer or retailer. I have no formal relationship with any manufacturer or retailer mentioned in this article - I have only been an arms-length customer. All brand names and product names used in this review are the trade names, service marks, trademarks, or registered trademarks of their respective owners. This article reflects my unique circumstances and subjective opinions with regard to performance and other characteristics of the products being discussed. Your mileage may vary.

Battery Adapters

    While many of my battery powered devices (e.g. flashlights, radios, remote controls) use AA cells or AAA cells, I do have a few older/legacy/retro devices that use C or D cells. I have an ample supply of AAA and AA cells in my "prepper pantry", but very few C or D cells because I have only a few things that need them. (Don't forget to include rectangular 9 volt batteries in your supplies. Nine-volt batteries are regularly used in smoke detectors and digital multimeters.)

    Wouldn't it be convenient to be able to use AA cells to power your devices requiring C or D cells?

    In the past, I've seen adapters (also sometimes called spacers) for using AA cells to power devices requiring D cells, and I even bought a set. I also tracked down some AAA to AA adapters, which I purchased to enable charging AAA cells in a solar battery charger designed to charge AA cells. At the time, these adapters were difficult to find and were rather expensive.

    A couple of years ago, I needed a set of N to AA cell adapters so I could charge several NiMH N cells in a charger designed to only charge AAA and AA cells. Unfortunately, I could not find N to AA adapters for sale anywhere, so I was forced to make my own. While I was able to make my own adapters and they worked as intended, it was a tedious project.

    Recently, I was perusing TEMU and came across several listings for various battery adapters at very reasonable prices, and they had several configurations I had never seen before. I subsequently discovered those battery adapters are also available on Amazon for reasonable prices.

    I have seen the following adapters for sale:

•     AAA to AA
•     4AAA to C  (4 AAA in parallel to C)
•     AA to C
•     AA to D
•     2AA to D  (2 AA in parallel to D)
•     3AA to D  (3 AA in parallel to D)
•     4D to 6V Lantern Battery (4 D in series to output 6 volts)

Most of these adapters only work with a single cell, while a few gang two or more cells in parallel to increase capacity. Unless you are trying to power something that requires higher current output than a single AAA or AA cell, I don't see any reason to use an adapter that requires multiple AAA or AA cells.

    The 6 volt lantern battery adapter is a specialty adapter, which puts four D cells in series to provide 6 volts. There are still a few flashlights that use a 6 volt lantern battery, and curiously my local Walmart still sells such a flashlight. There may still be electric fence chargers that use a 6 volt lantern battery. If you have a device that uses 6 volt lantern batteries, such an adapter may be useful.

    For the single cell adapters, the negative end of the AA or AAA cell will remain exposed as the negative contact after being installed in the adapter. For the AA to C adapter, both ends of the AA cell remain exposed. For the AAA to AA, and AA to D adapters, the positive end of the AA cell will make contact with a metal stud that will then make contact with the positive terminal of device to be powered or the negative contact of the next cell in series. (For the insert-from-bottom AA to D cell adapter (the opaque white adapters in the photos), it has four fingers at the top of the AA cell cavity to help hold the AA cell in place. When pushing in an AA cell, it will feel like those fingers might break. Just keep pushing, the fingers will not break.)

    For the 2 AA to D cell adapter, there are metal contacts built into each end of the adapter. The AA cells are inserted into the adapter, with the negative ends being pressing against the springy contacts on the bottom when latched closed.

The battery compartment of a radio that requires 4 D-cells. Two different types of AA to D adapters are shown being used.

A Side Note About The Batteries I Store

    I primarily store AA, AAA, 9 volt, CR123A and CR2032 batteries. The CR123A and CR2032 batteries are lithium cells. The 9 volt batteries are alkaline. The AA and AAA cells are alkaline, Energizer Ultimate Lithium, and rechargeable low-self-discharge NiMH cells.

    I also maintain an inventory of other batteries, such as LR44 button cells and CR2 cells, either because they are difficult to find in local stores or are absurdly expensive in the local stores.

    For the alkaline batteries, I am giving up on the major name brands (Duracell, Energizer, and Rayovac) because they usually leak, sometimes leaking in their unopened packages long before their expiration date. When they leak in a device - not necessarily a forgotten device in a drawer, but in a device used daily like a TV remote control - they sometimes cause irreparable damage. I've even had name brand alkaline batteries leak just sitting on the surface of a desk.

    I have started using store-brand standard capacity alkaline batteries (e.g. Sam's Club, Harbor Freight) because, in my experience, they don't usually leak. (I have no experience with the Harbor Freight "Thunderbolt Edge" higher capacity alkaline batteries.)

    For the NiMH cells, I've had good success with the low-self-discharge (labeled "pre-charged" on their packaging) Duracell and Eneloop cells. I charge them using an intelligent charger designed specifically for NiMH cells - not the cheap charger frequently supplied with a package of NiMH cells.

Conclusion

    I purchased AAA to AA cell adapters mostly for the solar chargers that only charge AA sized batteries. I also purchased AA to C, AA to D, and 2 AA to D adapters for other devices (primarily for radios that use C or D cell batteries).

    Battery adapters are not exciting or sexy, but they can add flexibility to the supply of batteries you keep in your inventory of supplies. Battery adapters are readily available online for very reasonable prices. And, from personal experience, I can attest that buying adapters is far easier than making your own.