My Hobbyking Zippy 4s1p-4200mAh just went puffy on cell #1. I saw it and and brought it to last weekends sota (FT-817 + 25W VHF PA). I had one of those beepers but when I saw one cell went to 2,5V (others were on 3,1V then) it was just seconds after it showed 0,7V. Pack was 22 months old. I recharged it later and discharged it the same day. I got around 3 Ah out of the pack. So one cell lost a bit more than 1 Ah. I will (of course) not trust this pack and will bin it shortly. I have also received a brand new puffy 3 Ah 3S LiPo from hobbyking. After an email I got a working one but this one is now also puffed. I am not a big fan of pouch cells, I prefer 18650s (3S for the 817) or 32650 for LiFePo4. I just ordered 4 of them: https://ebay.us/zbnu8l as the Hobbyking ones are out of stock.
Over 5 years I am now on my 3rd set of Hobby King 4200mAh LiPo 4 batteries. The spec sheet (small slip of paper with minuscule writing that nobody reads) says the temperature range is 4 - 40C. One battery ballooned at -8C and another at +50C (sunshine). The internal resistance also increased from 5 to over 20mOhms yet the capacity was only down to about 80%. The set I have now are described as Graphine. These were bought just before lockdown and only used a few times. I store my batteries at 11.1Volts and charge the evening before use. I charge at < 1C, 3Amp in my case. to 12.6V. On cold days I retain the batteries inside my clothing to keep the temperature up and in the shade on sunny days.
Compared to lead acid Slabs that I used to activate 330 Wainwrights, I am very satisfied with their life and performance.
Regards
David
G0EVV
Those values indivate a LiPo but not a LiFePo4.
They are both the same brand from Hobbyking but one was the 4200mAH and one was the 8400mAH which is a shame as that was quite expensive and only used a couple of times!
I tried to put it on the charger for a balanced charge but it comes back as failure due to I guess one or more of the cells being damaged. That is the only info it provides and I am unsure how to check anything further with this battery type!
Thanks for all the responses. Just to clarify it was a Hobbyking battery, Zippy I think. One was a 4200mAH and the most recent the 8400mAH.
I had my eyes on one of the Hobbyking Zippy 4S 4200mAH LiFePo4 for quite a while, but every time I made decision to buy they were out of stock and over time I kept finding more and complaints over life and cell’s falling in the pack.
I noticed they no longer carry that cell pack now as 4S1P but they do have the 4S2P (which for Sota is same capacity more weight on paper) but maybe that helps the pack survive more as they discontinued the 4S1P.
I was considering going LiPo with a circuit because the 18650 I have for some torches, XHDATA SW receiver and other stuff all seem very reliable, when used with the appropriate charger of course. Need to find the right circuit to use with a KX3 though, and always nervous of some eBay regulator on an expensive radio!
Right. But I ordered a new 4S2P 4,2Ah last night. Could not resist. 45 bucks is not so bad, even if it works only a year or two.
The old pack was available in 4S1P (which I had) and 4S2P which I did not order 2 years ago.
I am running 3S1P DIY 18650 packs since years. As 11,1V nominal voltage is perfect for the 817, with this rig no additional DC/DC converters are used.
I’m tempted. Looking at the rules for shipping etc. there is nothing suggesting their warehouse in The Netherlands cannot ship to the UK. Hell it’s only money!
Luc ON7DQ @ON7DQ made realise that for 817 owners, this is a brilliant solution. Easy to get on planes in a USB power pack (hahahahah remember when you could just fly somewhere for a SOTApedition 
), cheap as I have recovered them from laptop packs, simple to charge and more than man enough to power a couple of activations.
Hi Paul,
I needed to get the 4S 5Ah LIPO batteries I had down to 13.8v at up to 5 Amps to power my Xiegu X108G rig.
After trying several buck-boost converters - inverters that reduce the voltage efficiently - I got RF interference again and again. So that was not a good idea! I am told there are some of these units who don’t wipe out 20m or 40m with hash, I never managed to find one though.
My next option was to use high current diodes (6 of them if I remember correctly) in both the plus and minus leads of my 4S 16.4v charged LIPO battery. The diodes each drop a fraction of a volt. This solution actually worked fine, and I used it for several months however it did have one small problem. The diodes get VERY hot. So hot that on one activation the solder between two of the diodes actually melted! The diodes and battery were fine just this “automatic fuse” took me off the air. I didn’t give up though and rather than soldering the diodes together I then mounted them in high current terminal block. This solution then worked fine for several more months until I decided to change it.
Of course all that heat was energy from the battery being wasted and not an ideal solution as I had to be careful not to leave something on top of the diodes in the battery box.
My current solution is to go back to how one would approach this in a normal radio circuit using a LM338 5A adjustable voltage regulator semiconductor mounted on a small heatsink and with resistors to give the required output voltage. This circuit does not get hot at all and creates no RF interference.
I basically went with this circuit but substituted a fixed resistor for the variable.
73 Ed.
I’ve had a few batteries from hobby king @M0WTL and use the fleabay alarms @G4IPB mentioned, but the ones with the single loudenscreecher (which a bit of hot melt glue down the hole - it makes them a bit calmer).
The hobby king batteries I had felt swollen but it is a plastic covering round the cells that makes them feel swollen, I had exactly the same concern as you.
Thanks. mine is definitely swollen and even though I have power out of the two main cables if I plug into the charger it says there is a cell failure. I’m guessing it is dead (or dying) and don’t know how I might save it if at all - expecially without creating any fire risk!
I have the screecher alarm but I didn’t use it on this occasion as the noise is so annoying and loud even one first plug in. Your glue tip could be the way to go to protect future batteries!
Sounds dead then
Fill the aperture at the top with a generous amount of glue, blu tac, mud, whatever takes your fancy. It makes them much less annoying.
These are the ones I use. Interestingly they regularly give 3 reds when you plug them in first, then alarm even when its a freshly charged battery. Unplug them then plug them back in and they’re fine. The bigger ones never do that
I have just ordered one of the Zippy Compact 4200mAh 4S2P LiFePo4 packs from Hobby King.
They have been out of stock for months, so thanks to whoever mentioned they are back in stock.
73’s
David
So where do the electrons you don’t want go if they don’t heat the LM 338 up?
16.4 in 13.8 out = 2.6V lost. 5A load = 2.6 x 5 = 13W. 13 Watts of heat is going somewhere.
OK, better put the heat is dissapated over the heatsink. Compared to the extremely hot diode solution, this is way better!.
Ed.
Wire ended diodes ( 1N4001 etc) use the wire to dissipate the heat, you are meant to stand them vertical (skyscraper style) so there is a longer length of wire available. Likewise some very small transistor like the (probably long obsolete) ZTX651 which could have 2A of Ic in a tiny package because the PCB pad/track had to be a minimum size to dissipate the heat. A bridge rectifier on a heatsink with a pair of switches and two diodes in series would be my way.
As for boost and buck converters, I have been lucky. I bought a bag of 3 from the Middle Kingdom for use with the 13cms transverters (get the 11.1LiPo upto 13.8). Mine is silent, can’t hear any noise on HF when it sits under the HF antennas on an activation. I gave on to Jack GM4COX and he said his screaches away across the bands.
You might want to test the integrity of the balance charger connections. I had a LiPo that the charger told me had failed on one cell, but it was an intermittent fault in the balance line.
Ian
If you delete the Global and Netherlands warehouse on the webpage it should show that the UK warehouse has them in stock, so no problems with shipping. The Netherlands warehouse will ship to the UK anyway. Buy 2 and it should be free post and packing.
Now do I buy 2 ready for the next Trans-Atlantic S2S Event in early November?
Edit - I didn’t see the little orange note confirming that it would be the EU warehouse that has them in stock.
Thanks Ed for the detailed circuit info.
All these sort of challenges were why I was looking at the LifePo4 because I like to keep it simple where possible - enough challenges getting out a good signal without adding more challenges.
Lots of things in short supply at the moment so took the plunge and ordered the 4S2P, problem is that they had no chargers in stock - had forgotten how frustrating the website is, you select in stock EU it offers a range of stuff then the turnigy one that is reasonably priced is only in the global warehouse and it’s out of stock!
Have to go order a charger somewhere now, probably Far East and take the wait.
Hi Paul,
LiFePo4 batteries used to be expensive but once you add in the extra components to get the voltage down safely to 13.8v with a 4S 5Ah LIPO, a 4Ah LifePo for $45 as John DK9JC has found, doesn’t sound that much more! I remember when they were €65-80 !
When the LIPO batteries that I currently have finally give up, I think I’ll most likely switch to LifePo4 at least for the rig (the portable amplifier needs to run straight off the 16.4v from the 4S LIPO).
73 Ed.