In ham radio, we pay a lot of attention these days to lithium iron phosphate - known as LiFePo or LiFePo2 - batteries. They are all the rage, and they really are good - great performance, lightweight (compared to lead acid batteries), lots of neat features like Bluetooth integration for battery monitoring, and thanks to the Chinese, remarkably low cost for the larger capacity units.
Before moving on from this brief LiFePo battery discussion, I have to pause to sing the praises of a little company out of California called Bioenno. My observation is that Bioenno, with their very high quality, small capacity batteries (3 Ah up to 20 Ah 12 volt units) is almost singularly responsible for introducing the benefits of the LiFePo battery to the American ham radio community. Bioenno also bends over backwards to support the ham radio community not just with excellent products, but with excellent customer support and expert advice. Whatever success the Chinese LiFePo battery manufacturers have today in the American ham radio market (and it's a lot), they owe credit to Bioenno and its early efforts with ham radio. Now, on to today's real topic.
On this blog I've discussed a lot of battery chemistry types. LiFePo, but also regular lithium ion (ya' know, the ones that catch fire, explode, and can't be extinguished), regular lithium, lead acid (for over 100 years, the ham radio power standard), NiCad (as late as 4 years ago, Yaesu was still selling new production radios with NiCad battery packs), and good, old, leaky alkaline. But one battery chemistry flew under my radar until fairly recently, and now I'm giving it a serious look: nickel-metal hydride, or NiMH.
Actually, I've known about NiMH batteries for a long time, but not by their chemical name. Instead, I've known them by a major commercial brand name - Panasonic's Eneloop brand. While NiMH batteries don't have the capacity or run time of lithium or even alkaline batteries, they come close, plus they are rechargeable and don't leak or burst into flames.
I got re-introduced to NiMH when I purchased my Elecraft KX3. The KX3 comes with an internal battery tray and charger that can take AA size NiMH batteries. It's an awkward charging setup, and it's slow, but it works and it allows you to power the rig at low output levels without an external battery. Plus, there's little danger of leaking cells damaging the radio if they are stored in the radio.
My foray into the world of NiMH batteries has revealed an odd little sub-culture of battery geeks who love testing different chemistries in different devices. It seems that there's a lot of respect out there for the NiMH chemistry, and a lot of respect for the Eneloop brand. So much so that on many forums the terms NiMH and Eneloop are interchangeable. Within the limiting physical envelopes of the AAA, AA, C & D-cell form factors, it seems NiMH offers the best power delivery chemistry that is rechargeable, doesn't leak, and is non-hazardous.
The undisputed champ of AA-sized power cells are the lithium batteries made by companies like Energizer (Energizer Ultimate Lithium). These things are not just good, they are very good. I've had some installed in my wi-fi enabled smoke detectors that have lasted years, and still put out plenty of voltage. But they are pricey - about $1.75 per cell if bought in bulk through Amazon. If you grab a supermarket 4-pack, expect to pay almost three bucks per cell. And, they are not rechargeable. This makes them uneconomical to use in a high drain device like a transceiver.
Alkaline batteries still rule when it comes to a 'penny per watt' calculation. I go through a lot of them, and buy them in bulk from Amazon (the Amazon Basics brand). They are a great power source for high drain devices like an HT - good power output for their size, and reasonable run time. Very economical. But the damned things leak. I'll only use alkaline batteries in cheap electronics, or use them in important electronics like HTs for specific events (camping trips, local ham radio event support, etc.), then toss 'em. I throw away a lot of alkaline AA batteries each year, and I feel better for it.
NiMH batteries are not inexpensive, but the are rechargeable and safe, so the total cost of ownership is actually on-par with alkaline cells |
Back to NiMH batteries. Panasonic isn't the only manufacturer. As you can imagine, a lot of companies make them. Some are quite good (like Tenergy), and some 'off' brands that have interesting back-stories. The most famous one is the rumor that the Ikea LADDA brand of rechargeable batteries are actually re-branded Eneloops. But most of the NiMH batteries sold through on-line retailers like Amazon are, in my experience, poorly made garbage. I just stick with Eneloops, and buy them on special.
Right now NiMH batteries power my KX3, I'm testing them in an HT, and I have them installed in two of my larger table-top receivers that I want to have ready to go at all times without worrying about leaking alkaline cells. These table-top radios use D-cells, and I'm running a NiMH battery brand called EBL in them.
Here's my current battery management philosophy. Critical low use devices that I want to have always ready to go without worrying about batteries get NiMH cells installed in them. I don't really expect the NiMH cells to power these devices for very long - a few hours perhaps. But when they do die, I have alkaline cells ready to replace them for the remaining emergency period (power outage bad weather, etc.). When the emergency is past, the alkaline cells get tossed, and recharged NiMH batteries get put back in. This way I know the radios, flashlights, lanterns, etc. are ready to go, but don't have to worry about alkaline batteries leaking and ruining the devices. I've had to throw away far too many expensive electronic devices due to leaky alkaline batteries. I use them, but I no longer trust them.
W8BYH out