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Chippie
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The ideal way of charging singly would be to use either a dedicated lipo charger that has a single cell facility or you carefully use a variable bench power supply with current limiting, set to 4.2 volts and around 200mA…
Cells can be simultaneously charged individually by using separate, electrically floating charging circuits for each cell. There are a number of ways in which this can be achieved, depending on the features needed, cost, and size constraints, amongst other things.
yeah it will work but you should be using the "lipo balance" rather than "lipo charge" setting. if you watch the video below, the balance charge lead is the smaller 4 wire wire lead as this monitors the voltage of the individual cells, so make sure the cells dont get overcharged. With the Imax B6 chargers, there are more fakes about than genuine chargers and they do vary in quality. That version of the B6 charger you've got needs a separate power supply 11 to 18V DC, to work.
Chippie
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I have 2 of them for my model planes…
JOEPRO
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OK so I was naughty earlier
Only left it on for a few minutes and noticed the volts was sitting at 22v. (18v battery) so it must have a full charge.
I pressed the switch and it worked for the first time! And has been working just fine ever since I ran it until the battery was dead. Then when connecting the Stihl charger it lit up red which when checking the manual meant it was too hot.
So I let it cool for 20 mins and now it's showing its charging up so will see again later to be sure.
Only left it on for a few minutes and noticed the volts was sitting at 22v. (18v battery) so it must have a full charge.
I pressed the switch and it worked for the first time! And has been working just fine ever since I ran it until the battery was dead. Then when connecting the Stihl charger it lit up red which when checking the manual meant it was too hot.
So I let it cool for 20 mins and now it's showing its charging up so will see again later to be sure.
RWD3M
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How exactly?
JOEPRO
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Not sure what you mean. When I hooked them up to the power supply that's a no! It obviously just feeds a given voltage.
Re what Stihl have done when you use their factory charger I have absolutely no idea re individual cell monitoring. Doubt it though.
What I can tell you is I am charging it using the Stihl charger. So surely they produced a consumer product that is safe to use and charge?
During charging, if a Li-Ion cell's terminal voltage exceeds 4.2V, which would easily occur if there is a weak cell in an unmonitored string (i.e. cells connected in series in a battery), the cell is weakened further, CO2 is produced as a result, and raises the cell's internal pressure, with the eventual risk of venting with flame, and is the likely mechanism behind most of the battery scooter type fires, where the charger and associated circuitry are of poor design See e.g:
In @JOEPRO 's image, the power supply appears to be connected directly to the battery pack, which could be problematic if the cell monitoring circuitry cannot operate as intended to limit individual cell voltages.
JOEPRO
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Yep it charged up fully just fine and fully working. Not sure what was up with it as the power supply was only attached for 3 mins max so it couldn't have added much charge. But anyway very pleased it is charging and fully working. If it needed a new £100 battery pack it was scrap so good to save it. And it's actually very handy for clearing out my garage floor too 
Just been looking at some DeWalt battery packs, and the pin connections on all the packs are labelled: B+ TH ID C1 C2 C3 C4 B-Yep it charged up fully just fine and fully working. Not sure what was up with it as the power supply was only attached for 3 mins max so it couldn't have added much charge. But anyway very pleased it is charging and fully working. If it needed a new £100 battery pack it was scrap so good to save it. And it's actually very handy for clearing out my garage floor too
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Suggesting that the individual cells, or cell pairs, are available for monitoring, both by the charger, and by the tool.
Not sure how Stihl implement their built-in battery charging circuitry, but it ought to be safe for consumer use. The fact that the blower required a bit of charge from the Stihl charging supply, to make it work, suggests that some sort of "validation" is performed when the charger is used. It might just be an "enable" flag that is being set in the circuitry, if the pack voltage meets a certain criterion, or it could be more sophisticated, and store cell health information, too.
we used to use a 12 volt soldering iron to make up all our packs/cells when RC racing.Soldering directly to the ends of the cells can damage the seals…if you didn’t already know this…
Often when Li-ion cells drop below 2.5v they 'go to sleep' meaning that the normal charger will see them as damaged & refuse to charge them. They can usually be rescued by applying a small charge across the cell. I use an old phone charger, 3.2v, 200mA to do this.
Continually monitor the voltage until it gets to around 3.2 volts. Once it gets to 3.2 disconnect the charger & continue to monitor the voltage. If it drops down to below 2.5v within a minute or so the cell is probably knackered. If it stays above 3v I then hook it up via some fly leads to a proper li-ion charger. This is the one I have.
https://www.fogstar.co.uk/products/opus-bt-c3100
Once charged I let the battery sit for a few days to see if it holds charge. If all is good I use the test facility on the charger that discharges, charges & discharges the cell at a set rate to give you the battery capacity. Then I test the rest of the cells in the pack the same way to compare with the 'bad' cell.
I would not recommend anyone to try to charge the full pack at once with a power supply, even for a few minutes. You could be overcharging a good cell whilst trying to recue the one cell that's causing the problem.
The Imax B6 that @JOEPRO bought is a good charger, more functions than the Opus I use but just not as idiot proof. I still use one for some applications.
@JOEPRO if you are planning to use the Imax to charge the Stihl battery it will require a lot of extra wiring to hook it up directly to the battery plus an extra plug for the balance lead. You might find the original Stihl charger more convenient in the long run.
Continually monitor the voltage until it gets to around 3.2 volts. Once it gets to 3.2 disconnect the charger & continue to monitor the voltage. If it drops down to below 2.5v within a minute or so the cell is probably knackered. If it stays above 3v I then hook it up via some fly leads to a proper li-ion charger. This is the one I have.
https://www.fogstar.co.uk/products/opus-bt-c3100
Once charged I let the battery sit for a few days to see if it holds charge. If all is good I use the test facility on the charger that discharges, charges & discharges the cell at a set rate to give you the battery capacity. Then I test the rest of the cells in the pack the same way to compare with the 'bad' cell.
I would not recommend anyone to try to charge the full pack at once with a power supply, even for a few minutes. You could be overcharging a good cell whilst trying to recue the one cell that's causing the problem.
The Imax B6 that @JOEPRO bought is a good charger, more functions than the Opus I use but just not as idiot proof. I still use one for some applications.
@JOEPRO if you are planning to use the Imax to charge the Stihl battery it will require a lot of extra wiring to hook it up directly to the battery plus an extra plug for the balance lead. You might find the original Stihl charger more convenient in the long run.
