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HobbyKing: LiFEPO batteries not showing

Similar, but that has an Australian mains plug. Mine has a UK plug but the IMAX-B6 is the same.


SKU: 9052000068-2 but it is showing as out of stock.

How do you distinguish between swelling of the cells and swelling of the cell packaging due to gas? A spongy feel when you squeeze them? Electrical performance?

Hi Andy,
Just ordered the above it is in stock, thanks.

Yes, that’s exactly what you get, the battery looks and feels as if it’s blowing up with gas. When the cells themselves are swelling they feel hard over their whole area and often swell more at one end than the other.

My battery fits the “spongy” description.
One issue is that one of the cells reaches 3.6V a lot quicker than others and then it takes a long time to balance the whole thing.

Hi Angel,

If the battery is otherwise behaving itself - delivering the expected amount of charge, voltage not sagging under load, no cells swelling etc. - I wouldn’t worry about it too much. LiFePO4 cells seem to show very considerable variability when getting close to full charge.

73 Paul G4MD

Ok, my very enlarged battery was not spongy. So by your analysis that indicates faults that should not be ignored.

I think I originally made the mistake of setting the charger to LiFePO4 “charge” instead of “balance”. But I really don’t know whether that caused the battery to deteriorate. It lasted about 4 years and for 2 of those years it gradually expanded.

I believe there is a lot of hype written about these batteries, but most of that seems to be from a group of users whose main interest is charging them at maximum rate. Their definition of “safe” seems to be “it didn’t explode”.

I have now just had to recharge this 4200mAHr LiFePO for the 2nd time.

It lasted for 4 activations using an 817 at 5W nominal. Only 179 QSOs but the times for each activation from first QSO to last were 1hr28, 1hr29,1hr22, 2hr00. That’s just the QSO times, there’ll be some time the 817 is powered before the 1st and after the last QSO. That looks like the cell pack was in use for 6hr30. I noticed my 817 voltage readout showing 10.0 V on TX peaks. This 817 under reads by about 0.5V which means the cell was showing about 10.5V on TX peak. Certainly time to stop and switch to another cell pack. The charger said the cell was charged to 40% when I connected it up, yet the cells were probably giving 2.625V-ish on load. I left it charging at 1A as there’s no point beating the thing to death charging it up fast if I won’t be out for a week!

I’m very impressed so far and well worth the money to me. YMMV

You and I are alike Andrew, I would squeeze every last erg out if that thing before retiring it. Come to think of it, that battery looks good for another few activations…

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Normally recharge my 4200mAh LiFePO4 at the end of the day to maintain full output on the KX3. Typically lasts for 8 hours of full tilt operating at 15W and in the last hour or two power out may reduce to 12W or 10W on the rig due to voltage sag. Always carry a spare anyway but prefer to run one for as long as possible. Certainly an excellent power source.

  • Gerard VK2IO
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Indeed. It only got recycled because I was in the battery shop buying a bigger battery and they offered to recycle it.

They did look askance at the size of it. I don’t know of a puffed up battery that caused a serious problem but as I carry the battery in my pack, sometimes for long periods at a time I decided to terminate it.

The lifepo4 4.2 usually survives for 4 activations using the ic703 at 10w output, on a mix of SSB and cw.

73 Andrew VK1DA/VK2UH

I cant believe in the charger. A voltage of 10.5 V under some load means the battery is empty or very short before empty.
I’ve calculated a little bit. When you make one QSO after an other, not or no much calling CQ, you need about 0.95 Ah each hour. This calculation was made for CW or SSB with speech processor. For SSB without processor it may be 0.85 Ah or so. Working for 6hr30 would take about 5 … 6 Ah. Ok, if you had sent less 4.2 Ah would be possible. But absolutely not 2.5 Ah (60% from 4.2 Ah). Only receiving would take 2.6 Ah.
Which type of charger do you use? How many Energy the charger stored in the battery after these activations?

Interesting… Have I recharged it partly at some point and forgotten? That’s a possibility Ludwig, I’m getting older and find my memory less resilient than it was. But we now have this record when it was charged and I should be able to use this and the DB logs to figure out how well it does.

You know you can recalibrate the voltmeter in the 817, using a software setting in the deep menu. Wind around to that setting and change its value until the voltmeter agrees with your dvm.

I’m lacking a “round tuit” and I’ll sort it when I do get a “round tuit” :slight_smile:

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Someone did publish one in the club magazine about 30 years ago, I could scan it for you and send by email, then you’ll have no excuse!

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The 4200mAh LiFePos are currently on sale, both 4S1P and 4S2P versions:

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Good batteries, I’ve not had any issues with the two I bought so far, and it makes life so much easier compared to using LiPos and buck converters and the like. Runs the FT-857 full power 100w with no issues.