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SOTA Batteries for QMX/QDX

 

What's a good battery to provide 12 V to a QMX or QDX for SOTA operation? I have a battery that I use for Field Day and other ops, but it weighs something like 30 lbs, and I don't think I want to carry it up a mountain on my back. It would have to power a QMX or QDX for a few hours to make it worth the trouble.
 

I have this one .? Very pleased since it won't overvoltage the QMX

Talentcell Rechargeable 12V 3000mAh Lithium ion Battery Pack.?

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Second vote for the Talentcells; I have 2 of them and rotate them. Very happy with them.
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Greg N1TR?
 

I have a DIY power bank made with 3 x 18650 cells I use on SOTA. ?I charge it to 12V and not more. ?After about an hour long session it only drops the voltage to 11.5V.
Next, I'm planning to move the cells inside the QMX+. ?Less to worry about missing the cable or the battery from the bag. I already have a dev board and it seem to fit easily.?
 

Yes, here the same 3x 18650 which I charge with a small foldable 20W solar panel. The charge voltage is kept to 12.2 Volt with a LM2596 step down voltage converter ( with display).

Have fun with QRP.?

72 Durk PA3BYW?

Op zo 11 aug 2024 06:06 schreef ggsubs via <ggsubs=[email protected]>:

I have a DIY power bank made with 3 x 18650 cells I use on SOTA.? I charge it to 12V and not more.? After about an hour long session it only drops the voltage to 11.5V.
Next, I'm planning to move the cells inside the QMX+.? Less to worry about missing the cable or the battery from the bag. I already have a dev board and it seem to fit easily.?
 

Another vote for 3 x 18650 cells. They're perfect for the job. I must admit to being a bit less cautious than the others regarding final charge voltage. When the cells are straight out of the charger, the pack sits at about 12.6V. The radio is safe to power up at that voltage in RX. After a few blasts of the QMX in SWR tuning mode, the voltage soon drops a little and is safe to operate. You can buy small plastic cases for 3 x 18650 cells from Scamazon or AliExpress etc. to which you can fit your connector of choice. I use XT-60 connectors on everything.
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I also have a couple of 3000mAh Lipo packs which work well with the radio. They're cheap and reliable but are a bit easier to damage than the 18650's.?
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Slightly off topic (because not 12 volt) but if anyone clicked this thread looking for ideas on how to power their 9 volt QMX, I use a small Anker USB-C power bank that supports USB-C PD. I combine this with a trigger module that requests 9 volts from the USB-C port. Works really well, and charging it is very convenient.
 

You can also get a 12v PD trigger board or cable for Power Distribution capable systems. I have one trigger board that can provide either 9v or 12v just by changing a switch. Make sure to plug the cable or trigger into the battery before plugging into the radio.
--
73, Dan - W2DLC
 

A PD powerbank with both 12V and 9V voltages is a very useful option for those running FT8 and don't want to risk burning out their BS170s...

I believe Talentcell also offers a battery with both 12V and 9V output.

72 de Russ, va3rr

On Sun, Aug 11, 2024 at 07:41 AM, Daniel Conklin wrote:

You can also get a 12v PD trigger board or cable for Power Distribution
capable systems. I have one trigger board that can provide either 9v or 12v
just by changing a switch. Make sure to plug the cable or trigger into the
battery before plugging into the radio.
 

Dr Ramsey
We have used this since 2022 for 12 volt QCXs and 9 volt QDXs.?
You may want to regulate the voltage for the QMX, as many have said, and Hans has suggested. Careful , Careful.....?
A week on the road (3 hours a night) of QSOs.
Hope that helps.
James and Dawn?
KB9NBL and KB9PIY?
?

TalentCell 12V LiFePO4 Battery Pack LF4100, 2000 Cycles Rechargeable 12.8V 6000mAh 76.8Wh Lithium Iron Phosphate Battery with DC 12/9 volt and 5V USB Output for LED Strip
 

On Sun, Aug 11, 2024 at 08:36 AM, va3rr wrote:
I believe Talentcell also offers a battery with both 12V and 9V output.
My Talentcell LF4100 has such an arrangement, the 9V output is regulated BUT the "12V" output is 4S LiFePO cells unregulated and can go over 14V.
I use a buck-boost module to tame this to 12.0V and have assembled my radios for 12V operation so I can reduce output power by merely re-plugging to the 9V output.
73, Don N2VGU
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Lots of good ideas here, thanks, everyone.
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The LF4100 looks like the cat's meow.
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The USB-C power bank with a module to get it to output 9 V on the line is a pretty good argument for building for 9 V instead of 12.
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I'm not too worried about 12.6 V vs. 12.? My current battery puts out 12.6 V and I haven't blown anything up yet. (Want to bet that inside it's a bunch of 18650s?) But if one was worried about it, it seems like a diode would solve that. If you really wanted to get fancy make it switchable. Or two cables, one with, one without.
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Or a resistor. During transmit it draws 1.2 A, so 0.6 V/1.2 A = 0.5 ohms would provide the right voltage drop. It would have to be able to handle 1.2^2*0.5 = 0.7 W.?
 

Supporting 12 volt doesn't seem to be part of the USB-C PD spec though, so before looking at this as an option for a 12 volt QMX, it would be good to check what a particular power bank supports.
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From usb.org:
?
Fixed voltage outputs:
? 5 V, 9 V, 15 V and 20 V depending on PDP
? Optional voltages may additionally be supported
?
Something I noticed by the way, is that leaving the trigger board plugged in (but not the radio) slowly drains the power bank's battery. Not sure if that is because of the power it consumes, or because it doesn't allow the power bank to turn off. Mine seems to drop about 10% per day when I forget to unplug the trigger board.
 

"Supporting 12 volt doesn't seem to be part of the USB-C PD spec"
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Apparently, the PD specs have changed over time and current specs exclude 12 volts. Any time I see PD power banks with support for 12 volts on sale, I snap one up under the assumption that eventually they will become unavailable.
 

(Want to bet that inside it's a bunch of 18650s?)
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It's amazing how many large battery banks use 18650's.? Early Tesla batteries used over 7,000 of these soldered together.? :)
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These things are everywhere!
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Mark
KD0QYN
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