Ultimate Portable Power for the Elecraft KX3

[Moleculo]

In my opinion, one of the best features of the Elecraft KX3 is the very flexible power capability - the rig is rated to operate between 8 and 15 volts and will typically only draw 1 -2 amps during transmit and as low as 150 mA during receive.

While the transceiver can accept 8 AA size batteries and will soon have an internal NiMH batter charger, serious portable operators will quickly desire the capacity that only larger battery packs can supply. Fortunately, the market desiring light weight, quick charging, powerful baterry packs is not limited to ham radio operators; the Radio Controlled hobbies have been driving the demand for these products for some time.

I recently purchased a battery pack and charger that has completely transformed my KX3 capabilities.

The battery pack I purchased is a 4200mAh 4S2P (4 batteries in series, and 2 banks in parallel) LifePO4 pack intended for RC planes and cars: HobbyKing R/C Hobby Store : ZIPPY Flightmax 4200mAh 4S2P 30C LiFePo4 Pack

The charged voltage of this pack is 13.2 volts, well within the specs of the KX3. At approximately $40, this battery pack is half the price of the equivalent pack that Buddipole sells! Weighing only 558 grams (19 ounces), this battery pack will barely be felt when added to your backpack. As you can see from the picture, the battery pack is even much smaller than the KX3.

You need a special charger for these batteries: It needs to charge at the correct rate (or risk explosion!) and the chargers also balance the individual cells using the smaller supplied connector. I purchased this Turnigy charger for $23: HobbyKing R/C Hobby Store : Turnigy Accucel-6 50W 6A Balancer/Charger w/ accessories

These chargers are DC powered, which means that you can charge them from an existing power supply or even your car power while driving to your operating destination. Keep in mind that these chargers and batteries are equipped with connectors common to the RC industry, so you will probably want to fit all of the wires with Anderson Power Poles. The charger / battery combination recharges a battery quite fast: it's not uncommon to charge a dead battery pack in under an hour!

In this picture, you can see that I've rigged up multiple power options for the KX3, everything containing power poles for ultimate flexibility:

This setup allows me to power the Turnigy charger directly from a power supply, a cigaratte adapter, or clipped directly to a car batery. Likewise, I can power the KX3 from the battery, a cigarette lighter, a direct 12v source like a power supply, or also clipped directly to a car battery.

I've yet to find the total discharge time of this 4S2P battery pack, although I will report back when I do. So far I have more than 6 hours of RX time mixed in with about 1 hour of total talk time. The voltage is holding steady at 13 volts. I love this little battery pack and will probably buy another soon!

 

[Moleculo]

can this battery pack be charged while in use safely without risk of damage to the appliance?

I assume the rig is used qrp with this battery pack.

I don't think you should charge the pack while trying to use it at the same time.

The rig is a 10 watt rig, so a battery pack like this is perfect for it.

 

[Happy_Hamer]

I was at the Sturgis Bike Rally and I found a vendor selling lithium batteries in a sealed container with a built in circuit so you can use a regular battery charger. It is just a weight saving option for bikes.

Of course my wife tossed the business card I had set aside for the vendor :sad:

 

[Qrpisbest]

I have purchased a number of Zippy LiFePO4 cells from Hobbyking, including the 4200 mAh 4s2p. Unfortunately at least half, including this big one, had at least one bad cell. My 4200 mAh Zippy had a cell that would not charge to peak voltage with my CellPro Multi4, and when I did finally take it off the charger and do a discharge test, that cell died and began to reverse charge and puff before 1600 mAh had been pulled from it.

Just a warning about these batteries. I don't know why their QC is so bad, though at their prices you can buy two and discard one and still come out ahead of the Buddipole batteries.

 

[Wade Holguin]

In my opinion, one of the best features of the Elecraft KX3 is the very flexible power capability - the rig is rated to operate between 8 and 15 volts and will typically only draw 1 -2 amps during transmit and as low as 150 mA during receive.

While the transceiver can accept 8 AA size batteries and will soon have an internal NiMH batter charger, serious portable operators will quickly desire the capacity that only larger battery packs can supply. Fortunately, the market desiring light weight, quick charging, powerful baterry packs is not limited to ham radio operators; the Radio Controlled hobbies have been driving the demand for these products for some time.

I recently purchased a battery pack and charger that has completely transformed my KX3 capabilities.

The battery pack I purchased is a 4200mAh 4S2P (4 batteries in series, and 2 banks in parallel) LifePO4 pack intended for RC planes and cars: HobbyKing R/C Hobby Store : ZIPPY Flightmax 4200mAh 4S2P 30C LiFePo4 Pack

The charged voltage of this pack is 13.2 volts, well within the specs of the KX3. At approximately $40, this battery pack is half the price of the equivalent pack that Buddipole sells! Weighing only 558 grams (19 ounces), this battery pack will barely be felt when added to your backpack. As you can see from the picture, the battery pack is even much smaller than the KX3.

You need a special charger for these batteries: It needs to charge at the correct rate (or risk explosion!) and the chargers also balance the individual cells using the smaller supplied connector. I purchased this Turnigy charger for $23: HobbyKing R/C Hobby Store : Turnigy Accucel-6 50W 6A Balancer/Charger w/ accessories

These chargers are DC powered, which means that you can charge them from an existing power supply or even your car power while driving to your operating destination. Keep in mind that these chargers and batteries are equipped with connectors common to the RC industry, so you will probably want to fit all of the wires with Anderson Power Poles. The charger / battery combination recharges a battery quite fast: it's not uncommon to charge a dead battery pack in under an hour!

In this picture, you can see that I've rigged up multiple power options for the KX3, everything containing power poles for ultimate flexibility:

This setup allows me to power the Turnigy charger directly from a power supply, a cigaratte adapter, or clipped directly to a car batery. Likewise, I can power the KX3 from the battery, a cigarette lighter, a direct 12v source like a power supply, or also clipped directly to a car battery.

I've yet to find the total discharge time of this 4S2P battery pack, although I will report back when I do. So far I have more than 6 hours of RX time mixed in with about 1 hour of total talk time. The voltage is holding steady at 13 volts. I love this little battery pack and will probably buy another soon!

Would you mind sharing your charge settings and how to monitor when charge is complete as I just purchased this setup and want to be sure I have everyhing right on the charger per online instructions I found which are somewhat vague. Does the charge automatically stop when the battery is fully charged? Do you use the balance mode and does you unit have a callibraton menu? Thanks.

 

[Moleculo]

Sorry, just saw this post.

First you need to tell the charger you're using a LIFE battery. When it comes on, it will say "USER SET PROGRAM". Hit "Start" and it will display a default battery type. Hit "Start" again and then use the arrow buttons to select the LIFE, 3.3v battery.

Now hit the Type/Stop button to scroll back through the menus and find the menu called "Program Select LIFE Batt". Hit "Start" and the next screen should and select your battery type. If you bought the same battery, it should display LIFE Charge 6.0A 13.2V(4S). If it doesn't, hit "Start", use the arrows and select the correct settings. When you're done, HOLD "Start" and follow the prompts to start the charge cycle. The charger will beep when it's done. After it's done, you might want to repeat the process, but select "Balance" in the last menu before starting the cycle.

Hope that helps.

 

[Wade Holguin]

Sorry, just saw this post.

First you need to tell the charger you're using a LIFE battery. When it comes on, it will say "USER SET PROGRAM". Hit "Start" and it will display a default battery type. Hit "Start" again and then use the arrow buttons to select the LIFE, 3.3v battery.

Now hit the Type/Stop button to scroll back through the menus and find the menu called "Program Select LIFE Batt". Hit "Start" and the next screen should and select your battery type. If you bought the same battery, it should display LIFE Charge 6.0A 13.2V(4S). If it doesn't, hit "Start", use the arrows and select the correct settings. When you're done, HOLD "Start" and follow the prompts to start the charge cycle. The charger will beep when it's done. After it's done, you might want to repeat the process, but select "Balance" in the last menu before starting the cycle.

Hope that helps.

Thanks for responding. I get the 3.3v setting x 4 = 13.2V which is spec for this battery. Would it be better to use a 1C charge rate @ 4.2A even though the max is 2C?

 

[Moleculo]

Thanks for responding. I get the 3.3v setting x 4 = 13.2V which is spec for this battery. Would it be better to use a 1C charge rate @ 4.2A even though the max is 2C?

Honestly I don't know. I can't think of any reasons why that would be better, but I'm not a battery expert, either!

 

[antivirus]

liFePo4 battery

I use my Kx3 and my Ft 817Nd with a 12.8Volt- 6.6 Ah LiFePo4 battery with Buildin Balancer/ BMS (2*4 / 3.3 Ah A123 LiFePo4 Cells - 30 Amp Max Output, 740 gramms )

Small Price and i can charge it with a simply Power Supply or some of my foltable 30, 62 and a Spezial 74 Watt Triple Junction Solar Modules..

regards

 

[antivirus]

KXBC3

Today my KXBC3 incoming
Build in 5 min...

Now my Kx3 run with 8 Pieces "Ansbach" 1.2 Volt / 2850 mAh AA batterys..

here some Pics..


73

 

[ka5y]

KX3 w/ Zippy LiFe 4200 mah

I bought the battery from Hobbyking and it charged kind of funny the first time. I thought one cell a little low....long story short it went down to around 11v then just died and would not recharge. I had to send the battery back at my expense and pay shipping on another. Still much cheaper than anyone else. The problem with Hobbyking is they hide behind email and you can never talk to anyone. I use the Thunder AC6 (balance) charger which performs well. The battery does a great job and last a long time. I made a stand that the battery sits in and the KX3 sits on top and puts the bottom of the key about 1" off your table. Pictures are posted on Yahoo group.
73 Tex

 

[rfkid]

I do exactly the same thing and fuse my positive and negative leads for the KX3 with a 2.5A fast act glass fuse.

The real advantage to the Buddipole batteries seems to be the internal thermistor internal polyswitch but I think the fusing I described should provide protection as well.

Any comments?

 

[buickid]

I use these products for RC, just a few comments. The lithium batteries are pretty safe as long as you follow a few guidelines. Don't exceed their recommended charge/discharge rate (indicated in units of "C", where C is the capacity, ie 4200mAh, 4.2 = 1C). Do not discharge them below their recommended cutoff voltage. I'm not sure about LiFePO batteries, since we use the 4.2V LiPo (or whatever it is), but for the 4.2V batteries, its recommended that you don't let them reach below 3.7V resting voltage (which is around 3.3V under heavy load, say 30-40A). You'll find that the discharge curve of lithium batteries tends to stay pretty flat for roughly 85% of its rated capacity, then voltage will drop sharply. When you see that voltage drop, I would advise recharging so you don't exceed the low-voltage threshold.

On that Turnigy charger (which I have and use), you want to be using the BALANCE function, not the CHARGE. BALANCE will charge and balance it at the same time, CHARGE will not equalize the voltage in the cells. Make sure you're using the balance plug, and always balance charge. Doesn't take mcuh to do, but adds a huge margin of safety and longevity to your battery.

-Trevor