I have a pair of tattu batteries and 1 of the cells have died on each.
Is there anyway of reviving these or is it a bin job??.
I was also wondering could you turn them into 2S by dismantling them??..
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Unless you REALLY know what you are doing I would discharge and bin them. Lipos can be seriously dangerous to mess with. For the sake of a couple of quid you don’t want your house burning down 
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If it’s puffy and below 3v that cell is dead, I have converted a 3 cell to a 2 but you have to be careful. There are loads of videos on YT
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Cheers buddy iv had a look and your right… Its not about the ££ more out of interest and would be doing it in my garage just to be on the safe side… 
Its not so much the damage to property if it goes wrong its you will get hurt…these things sometimes go off like an incediary bomb. Ditch it!!
I’ve brought dead cells back to life from 0.00V, you’ll need a charger capable of charging NiMH battery.
Set you charger to NiMH and make up a lead to plug into the balance connector i.e split say a servo lead. Connect your dead cell - /+ and set your charge rate to no more than NiMH / 100mA, charge, keep an eye on it.
Once it gets to say 3.2V stop the charge and connect the entire battery to lipo Balance Charge.
I have a couple of batteries brought back to life which I monitor and use carefully not to discharge below 35% if I fly them. They are handy for use setting up and powering on the bench.
As you’ve said it’s for your knowledge an experiment, it’s entirely you responsibility.
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Are they really bad cells or possibly a bad/broken connection to the balance plug?
If you are reading zero Volt for these cells, using a multimeter not a LiPo checker, I would suspect a break in the balance lead. As you didn’t say in what way they were bad or what voltage they were providing I’ll say the following:
If the cell is between the 2.5Volt and 3Volt mark it is possible to revive it but there are caveats, the primary one being if you have any hesitations don’t bother. The safest way to do this is to isolate the bad cell and try to bring it up, SLOWLY, to the same level as the two good cells. Most LiPo programs will not work below 3.2 Volt so you need to select an alternative program. In the past I have used the NiCad or NiMH program at a low current setting on my charger. Once the cell has the same voltage as the other two cells you can then charge as normal.
However this does not guarantee that the cell is now good. More than likely it will have been damaged, certainly if allowed to go below 2.5Volt in a no load situation. With that in mind I would test the pack under a moderate load such as a car headlight bulb. With the bulb connected watch the voltage drop of all three cells, if one of the cells is dropping significantly faster than the others discard the pack altogether.
Alternatively, and again I stress that you only do this if you are fully aware of the risks, you can always remove the bad cell altogether and use the remaining 2S pack to power your goggles or some other 2S device.
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Another method…
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I’ve used the same method but only when all the cells have discharged below the threshold of the charger’s LiPo program. Using this method to recover just one cell runs the risk of overcharging the remaining cells in the pack.
How? He put the charger into balance mode…
I see what you mean, in that if he allowed the voltage to go over say 10V while unbalanced then it’s possible. He’s quite clear though in how to do it that way.
Thanks for the feedback, I’d tried the Nicad method but no such luck,the + cell had blown on both of them and really puffy.
I viewed a number of YouTube videos on how to convert into 2S and applied the process to both but no such luck.
Once plugged in my charger read them both as 1S, not sure wot was going on their so I just scrapped the idea.
But it was a good learning experience and an insight into wots inside a lipo.
Is there a “legacy” feature on this site just in case a member were to blow themselves up ? I know Facebook has the feature 
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Yah mine was the same as the above diagram, I can only think I may of damaged the balancing plug, as getting the wires out to move it along is definitely not as straight forward as they demonstrate.
But like I said it was more of a curiosity than a cost thing…