There's a new battery technology in town, and it promises to revolutionize portable ham radio operating. Lithium Nano Phosphate and Lithium Iron Phosphate batteries are lightweight and provide the right mix of power, voltage, and current for ham radio applications. The price point is now low enough that individuals can buy a pack and charger to try out for under $100 and be on the air with a field-operated SSB radio in 45 minutes!
Existing lithium batteries (Lithium Ion and Lithium Polymer) have excellent energy density (volts * amps * hours / weight), and great power delivery (instantaneous volts * amps). Lithium technology shares with lead-acid batteries and excellent self-discharge rate, so you can charge up a pack and know it's ready to go, without having run itself down the way Nickel Metal Hydride cells do.
In the weight and power delivery department, Lithium technology wins hands-down over lead acid, as the heavy SLA batteries are specified in discharge rates of 1/10th of their capacity: a 20 amp-hour SLA battery can deliver 20 amp hours only if used at a 2 amp rate!
These new-technology Lithium cells are exciting for two reasons: existing Lithium cells have safety problems, and are poorly matched to 12v radio equipment because the fully-charged voltage is often above 16v, making most of the energy unavailable to radios which have a maximum DC input of 14.4v.
The new technology Lithium Nano-Phosphate cells from A123 Systems and similar Lithium Iron Phosphate cells from other vendors break the mold for Lithium chemistry, and offer a maximum voltage of 14.4v, appear to have excellent safety features, and offer self-discharge and charge lifetime rates that are on par with existing Lithium batteries.
What's more, these new batteries (especially the A123) cells can source incredible amounts of current and still retain their energy amp-hour ratings. Let's taken example: the 20AH SLA mentioned may go down to 5 or so amp-hours when used at 20A, meaning you'd get only 15 minutes of 20-amp transmitter operation. Discharging an SLA 100% considerably weakens its cells and reduces it lifetime drastically, so a 30%-50% discharge is recommended for good lifetime. And the SLA weighs 15 pounds to boot!
By contrast, a 4.6 amp-hour A123 pack would provide the same service, and weighs only 2 pounds! And it can be discharged 100% and still retain its charge cycle lifetime.
We've had reports from one ham who used his A123 pack to run a 500W amplifier for half an hour SSB on field day, and then jump-started his truck with the same pack!
Tests by Ken WB6MLC and Oliver KB6BA presented at the Pacificon HFPack forum also showed that these battery packs are usable with today's 100W field radios, and provide excellent "talk time" and quick recharging.
For more information, including recommendations on what to do now, keep reading:
For now, If you want to power a 100W rig or a similar (or larger) amplifier, go for genuine A123 cells from one of the sources below. But be prepared to spend about $300 for batteries and charger. If you can limit yourself to 50W SSB or so, try one of the smaller A123 packs from K5OOR, or one of the Batteryspace packs, and get away with an under-$100 purchase.
These batteries truly raise the bar for 12v applications: they feature max voltage 14.4v, flat discharge curve for excellent use of available energy, safety from over/under charge and impact fires (especially as compared to traditional Lithium packs, low self-discharge, high energy density, and high power density.
Not to be outdone by MIT's spinoff A123, Stanford now has its own technology using nano-silicon cell, though they will have a hard time catching up to A123's manufacturing base and reported $350 million capitalization. A123 has some major marketing coups under its belt already, including DeWalt and Black and Decker tools now, and the Chevy Volt hybrid vehicle planned.
The recently released "one laptop per child"> uses Lithium Iron Phosphate cells as well.
The financial interest in this area is considerable, and either this (or another breakthrough spurred by it) will likely obsolete SLA and NiMH the way that NiCD and Carbon batteries are now limited to special applications.
Virgil K5OOR offers two 12v packs with these new technology batteries.
These packs are unfused and are are usable up to almost 70 amps continuous, 138A peak, and can power an amplifier or a 100W SSB/CW radio.
These packs are usable up to 14A continuous, and can run a 50W SSB/CW radio or a similar-sized amplifier. They are less expensive than the genuine A123 cells but can source less current.