I will help answer your charge question , before that respond to the lipo safe tpic .
( I used to be against Lipo's ) ...
Until I saw youtube videos of the , so called safer 18650 battery packs catching fire .
So
I take the following precautions
1) Build a Battery Bunker , with concrete retaining wall blocks and large paver blocks.
or
You can get a free old BBQ from someone who bought a new one.
or
Like DogmanDan , get a used free old oven that someone puts out on the sidewalk with free sign on it, same with a old BBQ
2) I charge outside, if inside I bring a few large paver blocks and a retaining wall block and set it right next to the back door. I also have some welder gloves near by.
3) When a charger charges up to 4.2 volts per cell I turn off the charger, the packs then settles down to about 4.15 volts per cell, and then go on a ride .
People too often just let the charger charge for longer than they need, it is good for balancing the pack to the higher 4.2 volts per cell, but by watching for a few times how long it takes for a battery charger start to lower its charge current ( Amps ) you can then tell about how long a charge to just get it to that 4.2 so that it settles down to about 4.15.
4) I use a timer ( alarm clock on your older cell phone works perfect )
That way I then charge battery # 2, and # 3 , and so on the same amount of time.
Now for a charger, you want the largest wattage and amperage charger you can get , especially for a large battery like a 20,000 mAh pack.
The new charger that is getting rave/good reviews is the iSDT series, for you with only 6 cells in series you can get the iSDT T6 , which is a little cheaper than the iSDT T8
You are also going to want a moderate to high wattage power supply , 500 watt or 750 watt or 1,000 watt . Mean Well or Surplus , Modified HP Server Power Supply.
When it comes to a item like a charger ( and the charge cords and/or connectors for making my own charge and input cords ) I trust the business I can call on the phone and get advice from people who really use RC products.
Here is a Short List
Aloft Hobbies
Progressive RC
Buddy RC
They also tend to sell the latest , newer software fixed versions of chargers .
Marv1337n said:
Hello
I'm currently thinking about replacing my 48V 13,6Ah 18650 battery with a 66,6V 20Ah LiPo battery.
I wanted to use 3 of these: https://hobbyking.com/de_de/multistar-high-capacity-20000mah-6s-10c-multi-rotor-lipo-pack-w-xt90.html
Now the question arises how to connect them in series and how to charge 3 of them?
Thanks for your help