If it's for rentals:
Sky RC Quattro, Runs at about £120-150 will do 4 batteries without much fuckery, Will do more with balance boards. Trouble is if it goes kaput then you have £150 replacement costs.
The knock off Imax B6AC, on the other hand, runs at £15. 4 of them is £60. You can almost afford 10 for the price of a single Quattro.
The difference between the 2 is the end-user. For me, the Quattro is the better charger as I charge many batteries that are all dissimilar. And space is a premium in my house.
If you have space to set up a charging station and have those 10 chargers running then the B6AC takes over as the better charger. You don't have the same cost for replacements. And replacements can be held on the shelf for sale and for spare. Added into that you get more than double the charging ability and no drawbacks from capping out ampages over balance boards. The only drawback is you are really going to be wanting to run the charging station on it's own ring-main and RCD. With perhaps beefed up cable as well to cover all bases.
10 chargers charging at 4 amps is a 40 amp load on a ring-main, Most domestic socket ring mains are not rated for that. Most domestic ring-mains are 32amps.
The number of sockets also becomes a factor to consider. There is a hard cap on the number of sockets allowed on a 32amp ring main. So you may want to speak to a qualified electrician and have them design a station that is both safe and capable of delivering what you need. That is hardwired into the fabric of your building.
It would also be prudent to do this on a steel desk so if any batteries do set on fire you have a surface that can cope with the heat and is not flammable.
As for batteries, I would look at giant power or turnigy. They have a range of 11.1's that charge at up to 5C.
https://www.componentshop.co.uk/11-1v-1300mah-15c-continuous-discharge-lipo-airsoft-battery-185mm-long.html
The advantage to those is charge time. You say you want 100 batteries. Well that's 100 hours at 1C. With 10 chargers thats 10 hours and 10 charge cycles.
The giant power ones even at 2C will halve that to 5 hours. At 5C they will reduce it 2 hours with a 12 minute charge per battery.
The disadvantage of 5C charging is the Amp load. Each charger is going to be charging at 6.5 amps. That's 65 amps not including power loss over the chargers. So getting the charging station right becomes very important. The Imax B6AC will cap out at 6.0amps so in real terms it'll be closer to a 60 amp total drawn on the mains, And the total charge time will be closer to about 15 minutes so 2.5 hours to get them all charged.
A 63 amp garage breaker box running 2 Ring mains for charging sockets might provide enough overheads to make this work. You would have to speak to an electrician about the legalities of this and how it works in practice.
