I have two LiFePo4 Zippy 4200, I don’t use them often but do stick them on the balance/charger often. Unfortunately I noticed mid September that one of them has swollen slightly since the end of July and it is a tad over 4 years old. One of the cells is reading a bit higher than the rest.
A quick read of the customer feedback at the HobbyKing web site reveals some unhappy customers with a common complaint on new LiFEPO battery quality.
As I haven’t seen anything untoward written here about quality, is it safe to assume our community is happy with the 4Sxx products?
Paul
I bought a 4S1P Zippy LifePO battery from HobbyKing about 3 years ago. I have looked after it carefully, and it is still apparently in good condition. I’m probably not the heaviest user, though…
The reviews I have read recently on their website imply problems with the batteries on delivery, which almost rules out user error…
Adrian
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I’d seen the review comments so I checked the one I bought last week as soon as it arrived… each cell was 3.25V. Not had a chance to charge/discharge it yet…
Have decided to retain the stock 5.5mm bullet connectors rather than chop them off and fit Powerpoles though, just in case…
73 de Paul G4MD
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I must say, I found my 4200 mAh was dropping off peak voltage before I even connected a radio. If you have any doubts, send it straight back. I think someone here mentioned that the Imax B6 clones are junk and not properly calibrated. I’m happy with my original.
de OE6FEG / M0FEU
Mattt
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Regarding the chargers.
I have the SKYRC IMAX; B6AC Version 2, and the B6.
I have used both for 2-3 years and been very pleased with them.
The B6AC is my preference, and it has more features, and also enables you to measure cell impedance, which is a good indication of battery condition, and trends towards possible failures.
The B6 is smaller, and a bit more basic so I take it with me when I travel, particularly abroad, where weight and space is an issue.
Regards,
David
I have just ordered one of these (certified genuine) to go with the new LifePo batteries also just ordered. I will take care to test the cells before doing anything else after unpacking them.
The old LiPos have swollen and the cells no longer balance nicely. They don’t seem to have lasted very long. I suppose they have done a couple of hundred activations between four of them so that is only 50 each 
73,
Rod
Thanks for helpful comments above.
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It’s not yet Advent but an order to Santa for a LiFePO cell and genuine IMAX B6 has been placed.
Well my swag arrived sooner than expected and everything seems to work. I do feel a little overwhelmed having gone from a simple fixed balance charger that no options (connect it, light flashes till battery is charged) to an IMAX B6 which has lots and lots.
My question is simple: for a 4200mAh LiFePO cell, what charging current should I use?
I have an iMAX B6AC and 4S2P LiFePo4 batteries and I set charge voltage at 13.2V and current at 1.0A
Never had an issue with that.
Good luck!
73,
Guru
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I always use 2A. I can’t remember exactly why I chose that value when my battery and charger arrived from HobbyKing, but a couple of years on and the battery seems to be happy with it…
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My packs have occasionally suffered from stuck cells on both charge and discharge cycles at higher charging current. I sorted it out by letting them rest and reducing the charge current. Just something to bear in mind.
73 de OE6FEG M0FEU
Matt
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Hi Andy,
Most manufacturer’s data sheets recommend 0.5C (ie about 2A for your 4200mAh battery) for the constant current part of the charge, with a maximum of 1C .
HTH 
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I always do a balanced charge for the LiFePO4 batteries, but occasionally one cell will not reach full charge at the same time as the others. What I do then is discharge them down to 3.3v each and then charge them again. This seems to occur when the battery has not been used for a while, but I find this usually cures the problem.
Although my charge current is set at 2.0A initially it drops as the cells reach their end voltage, sometimes to as low as 0.1A. When the charge current is as low as this it takes a long time to bring up any cells that are lagging.
73’s
David
Hi to all,
While viewing this thread, I checked out the Hobbyking UK site.
I bought the ZIPPY Flightmax 4200mAh 4S1P 30C LiFePo4 Pack a couple of years ago.
There are 2 versions of the ZIPPY Flightmax 4200mAh battery, the 4S1P 30C (1 Piece) and the 4200mAh 4S2P (2 Piece). I bought the 4S1P 30C as it weighed slightly less at 512g versus 558g of the 4200mAh 4S2P.
However, the 4200mAh 4S2P version is on offer at the minute with a discount of £13.98, may be of interest to anybody making a purchase.
Here are the links :
Regards,
Martin
I spotted the reduction in price on that pack the day my box of new swag arrived 
I consoled myself over the £14 saving by thinking that a 4S2P has twice as many cells as a 4S1P so is twice as likely to fail
And its 46g heavier!
The 2p versions have parallel cells. Thats fine while they track well but once a cell deteriorates, it seems to me the good cell will always be charging the bad one and that surely signals the early end of the pack.
For this reason I have avoided the 2p format.
Andrew VK1DA/VK2UH
I read somewhere that the charge current should be less than or equal to 1C. I usually use between 0.5C and 1C.
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I have now used this very cell on 2 activations using only an FT817 on a mix of SSB and CW.
I charged the cell to full using a balance charge at 2A max.
Dec 9th, 1hr30m operation (60m SSB, 40m CW, 30m CW, 20 CW)
Dec 28th, 1hr40m operation (60m SSB, 2m SSB, 30m CW)
When I connected the charger it told me 61% charged. So if I read that right, 3hrs of typical full power 817 operation has used 40% of the cell’s capacity suggesting it will easily last for 4hrs30 of typical FMF operation.
I charged up my old LiPos on the charger I have been using for years, a simple Mystery charger then connect them to the new IMAX B6 charger. It looks like the Mystery charger only charged the cells to about 85-90% of their capacity. I’ll try and old one next time I’m out as it may be less worn than I think.
So far, this new charger and cell seem to be money well spent.
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