Having aquired a tidy KX2 with the builtin ATU I now need to power the radio in the field as there is no internal battery.
I already have Zippy compact battery 4S2P @ 13.2v 4200mAh.
I could use this. Or maybe go for a slimmer battery pack.?
I did also pick up two sets of battery packs that are made up of 10 x 1.2v 2900mAh AA batteries
Charging 4 AA batteries at a time will be time consuming.
Cheers
I use a 4200mAH LiFePO4 with my KX3. With this capacity the rig runs for hours. Then again it is a proverbial anvil of a battery when you consider the low weight of a KX2.
You might want to try to acquire a lower capacity battery, but I fear rocking horse droppings might be easier to find. There are numerous options for building up a pack from individual cells, but that approach has never floated my boat.
I got a hape of packs recently from a site @MM0EFI pointed me to at the end of last year. Called Grandad I think. The order took a while to arrive, but arrive they did. Very pleased with the packs and the prices.
I did have to splice in new connectors over the existing ones, but that was easy enough to do. I used those heat shrink tubey things with solder already in them. Worked a treat and waterproof too apparently.
Here, try this:
Switch region to UK etc as the URL is for EI. I bought a couple of 3S, 6S and 8S. All are great so far, no issues. Works fine with my KX2 as well.
Cheers. I think Fraser sent me a link to those battery packs but I had it in my head the battery packs where for the internal battery. But appears external is an option.
The battery is heavier than the radio 
but it does save my buying more batteries/chargers. But there is a weight advantage of buying a lighter spec battery pack
You can make the 3S one internal if you want, just crop the cable right down so it doesnāt bunch. I made that mistake so I just use the 3S I spliced already as an external battery and leave my original Elecraft 3S internal (til it needs to be retired).
Canāt fault the packs though. Very pleased with them. Just the Grandad order updates are quite lengthy so I did wonder was it a sketchy website. It isnāt, I just think they ground ship from China via the Kazakhstan train line loophole possibly.
Cheers. After having another look inside the KX2 I did spot the power connector on the board.
I had (wrongly) assumed that the optional KX2 battery required addtional hardware/connectors - but looks like the connector is actually there already.
Yep. Have a look at a post I made before Christmas. I forget where it is now, but I took a photo of my KX2 hooked up to one of these batteries external. The barrel connector does fit both the internal and external ports so youāll be all set.
I charge my batteries with an iMax B6AC charger. If Iām just running the KX3 at 2.5 watts to drive a linear (separate HF and 2m) I use a 3S LiPO to power the KX3 and a LiFePO4 to power the linear.
I used to have a couple of Zippy 2200mAH 3S LiPOs, but they died and Iām currently using my 2009 vintage 4000mAH 3S LiPOs which can still supply 2800mAH. I need to get a bit more value for money out of themā¦ 
Ah so many options. I have a 4s2p 4200mAh LiFePo I use. Itās quite big and heavy but outlasts the energiser bunny. I did a 65min, 80min and 52min HF CW&SSB set of activations and charged mine, the charger said 1925mAh recharge. Iād already guestimated my KX2 uses about 11mAh/min of SOTA activation and so that fits. That was for 197mins of activation. Iād expect to be able to do a total of 400mins or 6hrs 40mins before it was discharged.
Yes itās big and heavy (relatively) but not big/heavy like NiMH D-cells or SLABs. Itās a brute in that you can operate without concern for so long. Iām lucky enough to have a 4200mAh 4s1p LiFePo as well.
However, I was looking about and Hobbyking, who were the āgotoā supplier of RC packs no longer have LiFePo cells listed never mind just out of stock. They have plenty of LiPo packs and they are cheap. But TBH, I really want to avoid investing in more LiPo as it is poor compared to LiFePo. (Not as safe, large voltage during discharge, some radios are snooty about the voltage).
For LiFePo, there were some 6000mAh packs that looked a bit like the old SLABs available on Amazon. Seemingly with OK reviews. But it looks like the manufacturers are now pumping out rigid cells in a huge number of sizes including 18650, 26650, 26700 etc.
I have an Eremit 4000mAh pack made from 8x 18650 sized cells with a BMS. Itās excellent but Eremit wont sell outside of Germany. You wont get one shipped from Germany either. If you want one, you need someone who lives in Germany to buy one and then you need to meet up with them and bring the pack back to the UK yourself.
I have played with 26650 LiFePo cells. I bought a number second hand to experiment with. These were 2500mAH cells were the capacity was down to ~2300mAh. They were ex-Ebike and so you could pull huge currents from them. I bought some BMS boards, 26650 holders and assorted cables to make my own packs. A few SOTA people bought them from me. I know Andy MM7MOX (@mm7mox) has a pack he uses on his FT818. He has enough to make a 4s2p pack so it will allow QRO operation with his 857. Thereās another GM with a set locally. I canāt remember who else took a set. As they were older cells they were very cheap, around Ā£2.50 each or Ā£10 for a set. Only 2300mAh but that will run a KX2 for well over 3 hours.
There are plenty of 26650 cells new on AliExpressā¦ the worry is how good they are. Some will be usual Chinesium quality.
A selection of LiPo packs: top left green cells, 21700 4000mAh acquired new but I canāt remember where from, top right purple cells, 18650 2200mAh ex-HP laptop, bottom centre yellow, black, red cells 1000mAhr 3s2p KX2 backup pack ex-Vape ādoggingā cells. Centre is an AA cell for scale.
LiFePo packs: left 4200mAh Zippy 4s1p, centre bottom Eremit 18650 4000mAh 4s2p, right 26650 2500mAh 4s1p ex-Ebike, centre AA cell for scale.
The emergency pack is to satisfy my OCD. I donāt want to do a big walk/ascent only to find the main battery is at home still, or discharged. So the emergency pack is big enough to run a KX2 for about 1 hour or so and weighs 75g including wires. Not quite 2 KitKats, so is an acceptable weight. The production one is in a nice 3d printed case.
Like Gerald I use a Imax B6 for all LiPo, LiFePo charging.
My Zippy Flightmax has powered my KX3 for 550 plus Activations over 13 years. Itās not really that heavy just adds to the few kgās you need in your equipment to do SOTA. You have to carry something on a hike and 380 grams of reliable battery is fair I think. One trip up north I used the same battery for 6 activations over 3 days on the same charge, thatās pretty reliable I think.
Regards Ian vk5cz ..
Plenty of options to consider. But if I stick with Zippy it does mean, I donāt need any more chargers (at least right now) or need to make up/buy additional battery packs.
So far its taken me two days to charge 8 x AA batteries and still have 2 left to do,
I did a quick weigh of the batteries I have right now
Zippy 600g
10 x AA 400g
Not a huge amount in it really.
A great question to ask @M0VAZ John, if you want 1000 answers back that will make you struggle for choice, hi!
Hereās my two pence: I was lucky enough to purchase my KX2 a few years back with the Elecraft battery that came with it. Because I sometimes do long days, and activate both on SSB & CW, the 10.8v battery didnāt last for me on a long day. So, I purchased from the ever so reliable RS, two 11.1v Li-ion 2600mah batteries, and after 3 years, they are still charging and going strong. There extremely light, and do the job 
link below:
Hope this piece of information confuses you even more on what to get, hahaa. They really are a good purchase though.
Good luck and I hope you enjoy the best portable SOTA radio out there!
73, Ben
GW4BML
Actually itās very valid. I forgot about the internal option because I seldom use it. I have a genuine Elecraft KX2 LiPo pack that came in my package but no chargerā¦ so I rolled my own out of junk box parts. However, the genuine pack and charger are a bit pricey. Or you can buy the genuine Elecraft inboard charger and fit it yourself or soon the much cheaper HB9DQM version. Fraser and others have rolled their own internal LiPo packs as well for not too much money.
So you can have an internal pack and it makes the KX2 very neat. Itās just that I have enough of the ānot so safeā LiPo/LiIon cells and would always advise people to go LiFePo where possible. YMMV!
A simple question with many answers!
Thanks Ben - what charger do you use with the 11.1v Li-Ion batteries?
I am looking forward to getting out on the hills with the new toy.
A quick look on the HobbyKing site and they have a few 11.1v - 11.4v batteries available
11.1v
https://hobbyking.com/en_us/turnigy-2200mah-3s-40c-lipo-pack-w-xt60.html
https://hobbyking.com/en_us/turnigy-3300mah-3s-11-1v-30c-shorty.html
11.4v
its like going out for a meal and menu is 5 pages long with options!
I use the following charger for all my SOTA batteries:
Looking forward to working you on your new toy 
73, Ben
GW4BML
Thanks Ben. I have the HobbyKing equivalent - Turnigy charger
Hi John @M0VAZ,
Here some interesting thing about KX2
73, Ćric F5JKK
