Sunday, September 11, 2016

3rd party internal battery for KX2

KX2 and $36 Li-Ion battery
Someone on the YahooGroup for KX2/KX3 radios recently mentioned a lower priced alternative to Elecraft's internal battery for the KX2. I ordered this battery from China via eBay and will be the first to confess to being leery of Chinese products. Their quality seems to be hit and miss - my DJI Phantoms have been fantastic in every way; a lawn sprinkler turned out to be junk.

So I took a $36 gamble to see if this battery offered a level of quality to allow it to serve as a viable alternative to Elecraft's $60 battery and their required dedicated $25 charger. The battery arrived from a warehouse in Arizona, well packed and with a connector that I cut off and will replace with a suitable barrel connector.

Like the Elecraft battery, this one is a 3-cell lithium-ion pack rated at 2600 mAH, fits easily into the KX2 and has protective circuitry built in. Unlike the Elecraft battery, this one doesn't require a dedicated charger and can be charged by any charger suitable for lithium-ion batteries.

A perfect fit

I couldn't help but buy one and test its rated capacity at an average discharge rate that I believe is comparable to a KX2 in heavy use. My KX2 draws 185mA on receive and about 2 amps key down with ten watts out. This means that a string of dits would draw a bit over an amp. Assuming we listen more than we transmit, I settled on 400mA as a discharge rate for this battery.

Protection circuit is beneath the battery's heat-shrink material

Top of protection circuit

The capacity of this $36 battery after 3 charge/discharge cycles is about 2400mAH at a 400mA discharge rate. I have no doubt thatif discharged at a lower rate, the capacity would meet the 2600mAH specification.



  1. Sounds like a great deal. My only concern is how the circuitry is designed and the protective circuitry. While the batteries look like those in a computer battery supply, I still have need to know more about the construction and cell matching. I assume that Elecraft has done all the engineering before they offered their packs under their store front. The Chinese battery, IMHO, I do not trust. Too many knock offs and short cuts. I have been burned by trying to save money for the last time and will by through a trusted vendor. Just sayin'.

    1. I understand your concerns having bought products from China myself that turned out to be less than advertised and lacking in quality. However, all of my RC (planes & copters) batteries are of Chinese origin and I have never once been disappointed in them in any way. These batteries are driven hard with outputs in the 25-40 amp range for my particular models. No fires, no swelling, no explosions despite crashes of the models from time to time :-(

      I monitor and test them regularly with the battery analyzer that made the discharge curve shown in this posting - I could accurately be called a battery geek! Due to my own experience with such batteries, I have no qualms whatsoever about putting one of these batteries in my KX2.

      One thing I don't like is having to buy a charger dedicated to a specific battery - not a battery chemistry type - a specific battery, as with that from Elecraft.

  2. Agreed. I would have preferred a balancing lead so I can do it on my RC Charger. But I wanted to go the correct route with a charger that shuts down. When reading the specs on the charger itself, it is intended for the config for the Elecraft pack.

  3. Here's another even cheaper option and I'll soon be a Guinea pig for this one too:

    I like that it has a JST connector (that's the red one) for charging.