There are a lot of threads about batteries but most seem to be from the UK, and others are dated. I’d appreciate some recommendations from the North American ops on lightweight batteries currently obtainable on the west side of the pond.
For my activations I run QRP CW with an Elecraft KX1. The KX1 can hold 6 AA batteries but that only gets me to 9V supply voltage (7.2V if using NIMH) and the KX1 puts out more power with higher supply voltages up to about 12V. My experience has been that the seemingly small difference in dB makes a big difference in being heard.
I overbought on my first battery, a Bioenno Power 12V 4.5 Ah. I’ve had great success with it, and for a day trip I don’t mind humping the weight. However, the XYL is an avid backpacker and is now inviting me to do SOTA on her multi-day trips. If I am adding the SOTA system to everything else carried for multi-day backpacking, I need to reduce the weight of my system! The battery is an obvious place to start.
Any recommendations for reliable lightweight batteries, preferably LiFePO, that have enough capacity to get me through an activation or two? I’d welcome other ops’ thoughts and experiences. Likewise, current sources for appropriate chargers?
Thanks and 73,
Hi Scott, I echo Andy’s post I have used batteries from Hobbyking for sometime and am happy with them. They are most likely the cheapest option as well.
P.S. I don’t know if they still do it, but if you find the battery or charger or whatever that you want to buy on the HobbyKing website, leave your browser on that page for over 10 minutes without changing anything and there will be a pop-up come offering a 5% or 10% discount on the listed price, it’s their way to get a sale. Take advantage of it, if you can!
If you can characterise your power requirements (a watts-up meter may help) you will find how much power a 1 hour activation requires. I can say that my 4.2AH LiFePO4 has powered 4 activations of about 15 contacts each, on a mix of ssb and cw, using an IC703 which as a rx standing current of 300ma. If your kx1 requires more than half that, I’d be surprised. You may well find that a 3S (3 cell) 2500-3000 mAH LIPO starting at 12.3 and going down to 10v will power your kx1 quite adequately over 3 or 4 activations too. A 3 cell LIPO powers my FT817 happily for 3 or 4 hours of intermittent ssb/cw operation.
Two light (meaning lightweight) batteries, using one as a backup, could be useful too.
The manual for the Elecraft KX1 suggests the current consumption typically is 35-40 mA on receive, and 300-700 mA on transmit depending on supply voltage and power output. Since I am trying to keep power output up by providing ~12VDC ( the radio accepts 14 VDC max), I will use the higher figure. I’ll assume a 40% duty cycle for a busy SOTA operation, unless someone has a better figure, and do the math when I get a chance. That should give me what I need to know to choose battery capacity.
Used to run my KX1 on Eveready AA lithiums. They would last forever, like months. For a voltage that will get you in the 4-5 watt power out, just get an 8 slot AA holder and load it up. These lithiums have the highest watts to weight of any battery you can find either primary single use or rechargeable. They start at 1.7 volts when new, so choose whether you want 7 or 8 of them. John N0EVH
Or make a case change like I did. It worked for me and this ham also.
I also endorse the BioEnno batteries. I use a BioEnno BLF1206A I bought at Dayton a couple of years ago. It may not be the absolute lightest option, but it also by far and away isn’t the heaviest. Reasons I like BioEnno:
Good for several activations before it needs recharging. I can do 5-6 activations at 15W with my KX-3 before I need to recharge. I can do more activations if I’m OK reducing power to 10W. So if you’re doing multiple activations in a day, the one battery handles it all.
They seem to work the same regardless of the temp. I never think about battery performance during the winter, when I do a fair number of activations. The BioEnno perform the same regardless of temp.
The BioEnno batteries have the circuitry built in for balanced recharging. No need to buy a special charger or select specific recharge settings. BioEnno often supplies a charger for no extra charge (rim shot!).
I also have a larger BioEnno I use with my ICOM 706.
I got a 3 cell LiPo 5000mah for radio/amp. I just did 5 activations no charge needed. For straight kx2 I use a 4 cell LiPo 2600mah with voltage reducer which I get 4 activations from. Both from Amazon. No complaint from me.
Thanks for the additional comments. I, too, can endorse the Bioenno Power LiFePO batteries - I have one charging right now for a planned activation tomorrow. Mine is the BLF 12045W, 12V 4.5 Ah, and I have been using it for 16 months since purchasing it at the Orlando Hamfest in 2018. With the low power demands of the KX1, I have been able to use it several days back-to-back without recharging. Like Paula K9IR, I have used mine in winter activations with temperatures at or just below freezing with no problems. For a rig with higher power demands, like a KX3, it would be perfect. For the KX1, it is overkill for a one or two day trip.
As mentioned in the original post, the quest now is for something lighter for multi-day backpacking trips. When I was in my early 20s, a 6 day backpacking trip with a pack that started out weighing 23 kg (50 lbs) was considered typical. With knees that are now forty years older, and with major advances in outdoor gear, the goal is to stay below 30 lbs - preferably well below. I’d like to get my SOTA kit as much below 2 lb as possible.
The suggestion from John N0EVH to use lithium AAs is worth serious consideration. I have used those in handheld GPS when going on 2 week trips where food resupply is available but batteries may not be - even alkaline AA batteries add significant weight when you must carry multiple spares. The lithium AAs are incredibly lightweight and their power density is just short of fantastic. The two strikes against them, IMHO, are that they are quite pricey and, not being rechargeable, they add to the waste stream when exhausted. I am willing to compromise a bit on weight to in hopes of being more on the “green” side.
As you contemplate extended trips, i wonder if using a small rechargeable lithium battery and charging it using one of the film type solar chargers would appeal to your wish for a more sustainable power source.
I have been experimenting with a small phone power pack that has the same size as a snartphone and a solar panel on one face, about 6” x 3”. Its charging rate in sunshine is only 160ma. Something with 4 or 8 times the area, like the film type solar cells may be enough to keep a lithium battery charged enough for your radio needs. I’d envisage a solar collector spread over your backpack and the battery under charge somewhere inside the pack.
The phone version is a nominal 5v but internally is no doubt a single lithium cell with an inverter to produce 5v from the 3.6v cell.
I see some film solar collectors on Ali Express. Will try one of those too.
Scott: you have a very energy efficient transceiver there that only uses 40mA RX and 700mA (max) on TX. You could easily use 3 18650 lithium cells in series that would get you 12.6V fully charged and last you a good 12 hours or more. They are very lightweight - nominal 3.7V but fully charged they provide 4.2V each.
I have a YouKits HB-1B with similar (slightly more) power draw to your KX1. I use a 3pack 18650 2600mAH pack. They are very small and lightweight and fit inside my HB-1B. I calculate I can get 12 hours of use from them. Unless you are going overnight I don’t think you need more than that. You can also get 18650 cells at up to 3400mAH capacity, but they tend to get expensive ($20-$30 each) for that capacity.
They are the same cells used in Tesla cars, so they can’t be too bad…
I bought TENERGY-30001-0-14500-800 : Tenergy 30001 14500 800mAh 3.7V Unprotected Lithium Ion (Li-ion) Flat Top Battery - With or Without Tabs - Bulk - 3 pcs for ~ $15.75 total for YouKits HB-1B. It last me for 2-3 activations.
The internal batteries in a KX2 are really light and has about 12V at full charge. (Right now it reads 11.6V inside my KX2 but there is a 0.5 V internal voltage drop). It is rated for 2600 milliamp-hrs. For a minimalist set-up - probably the way to go. Your KX1 probably draws only 55 mils on RX and about 1 amp on TX like my K1. The 2600 mAh should last you a long time, at 1 QSO a minute and 30% duty cycle for CW. If my math is correct - the math works out to about 360 QSO’s depleting the Li-ion battery to 20% capacity. That is - 0.8 x 2600 x 60/(38 mils RX + 300mils TX) = 369. The weight is claimed to be 4.8 ounces. It should work as an external supply for a KX1.
Hardened Power Systems make some very nice self contained battery packs. Built in solar and standard power charge regulating systems, USB charge ports, Anderson power-poles built right in. We bought one their units for our KX3 and we are very pleased with the results. I highly recommend checking them out.