25C should work perfectly fine for 99.9% of Eboards unless you are adding big brushless motors on the side, with propellers, and planning on making it fly. Then your gonna need a larger discharge capacity such as 65C. The C rating is related to internal resistance, which basically prevents a battery from outputting too much power at once. In an ideal world, there would be no ISR (internal series resistance) and a battery could output as much current as it needed to at once, but the internal resistance can prevent that. (Don’t quote me on that one though.) A 65C battery basically can deliver more current when its needed than a 25C battery.
First, before I get to that… HOLY S***, you are going for graphene batteries?? If you are going to spend that much, you should just get a 18650 battery pack made. You can get a 4S 3000mah battery for alot less then that, you don’t need the C rating that the graphene batteries output to get a nice ride. The graphene batteries are made almost exclusively for high powered planes and multirotors which pull a lot of power, I mean this is a 4S 5000mah battery for almost half the price: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9179
Ok onto your question, if you are going to wire them in series you have to use the same capacity. This is very important. The same thing is true for parallel. What happens (when wired in parallel) is when the the battery with a smaller capacity gets fully drained, the other batteries try to refill it… and boom.
Basically, yeah, you are all good with either of those batteries, just use the same exact ones when connecting them together.
Yep naming convention is weird, it looks like you get it now though…
I believe that you can connect it directly to the VESC because it’s a lipo, a BMS is for 18650 batteries and similar li-ion cells.
Terminology? Well most people diy it by soldering them directly together or something. Hobbyking does sell a series wiring thing though, so all you do is plug your batteries into it and then there is a connector which is the output, it does the wiring for you and you can also unplug it and use/charge the batteries individually. They also have one for parallel.
(two options for parallel, one is smaller format)
The best way to charge it? Well you could charge them all individually, or you could wire them together if you feel confident…
This link may be helpful, http://www.electric-skateboard.builders/t/charging-2-x-3s-lipos-in-series-please-look-over-my-schematic/734/6
Along with this hobbyking part: http://www.hobbyking.com/hobbyking/store/_27078__JST_XH_Parallel_Balance_Lead_4S_250mm_2xJST_XH.html
Hobbyking only sells the balance leads for packs in parallel, not in series.
Honestly I would personally either charge them individually or just get one massive 8S lipo, because I don’t want to mess around with the balance port.
Charger for 2-6S batteries: http://www.hobbyking.com/hobbyking/store/_5548__IMAX_B6_50W_5A_Charger_Discharger_1_6_Cells_GENUINE.html
Charger for 1-8S batteries: http://www.hobbyking.com/hobbyking/store/__7523__Turnigy_Accucel_8_150W_7A_Balancer_Charger.html
Keep in mind that working with lipo batteries is dangerous and you have to be careful!