How can I get 12V 1A charging voltage from USB?

[russ_watters]

Standard when charging LiPos is to use "1C" current - "C" meaning same current as the capacity of the battery (so if it is a 2200 mAh battery, you will charge it with 2.2 A),

So perhaps the way it is shown is a lazy way of saying 800ma to charge an 800mah battery.

 

[russ_watters]

12V batteries are available in all sorts of capacities. A Voltage converter from your existing USB Power block is, in my opinion, no more logical. How many times do you need to recharge your helicopter battery 'in the field' per day? A (cheap) 5000mAh 12 volt battery will give you around twice as many charges as your 5000mAh power bank.
Only if you are doing this on a shoestring would the DC voltage converter solution be worth doing.

I agree. I was thinking of something like this:
https://www.amazon.com/dp/B00935L44E/?tag=pfamazon01-20

 

[Borek]

So perhaps the way it is shown is a lazy way of saying 800ma to charge an 800mah battery.

Cheap chargers don't let you change the current so you have to use whatever they are capable of delivering. As far as I am aware it is not a problem for large batteries (other than it takes forever to charge 12 Ah monster), but using too large currents for charging shortens the life of the smaller ones.

To add to that most chargers let you balance the battery, which is another way of saying "charge each cell separately till they have the same final voltage". It is not like they really charge cells separately (cells are in series and most current goes through the main connector, one that is capable of surviving huge currents), but they do some tricks with charging them and discharging through additional balancing wires (standard in LiPo packets, often used also for powering some additional gadgets that need currents well below 1A).

Now that I think about it I have no idea whether they keep the current by changing the voltage throughout the process, or by keeping the voltage constant but switching the current on/off to keep the average as requested. My charger initially shows the current to be that I set up, but the closer it gets to the end the lower the current is - but at this stage it is typically balancing cells, not really charging them.

 

[donpacino]

To add to that most chargers let you balance the battery

To add to this, you SHOULD NOT charge LiPo batteries with a charger that cannot balance charge

 

[karabiner98k]

Problem solved!
I bought this DC-DC Step-Up Module today and tested it:

I increased the output voltage of my powerbank (5.0V) to 14.5V by connecting it to this little but handy device and connected the output poles of the device to my Lipo Charger:

I managed to charge my battery in about 45 - 50 mins (about 8.50V fully charged) and good news is that the module didn't get hot during the charging process (just a little warm).
I also flied with the charged battery and flight duration was excellent!

Thanks everyone for your help!

 

[jim hardy]

Good for you. We learn faster by doing than by reading about doing.