ok since noone is offering you much advice I will try
hopefully if i say anything wrong someone will correct me
first off
there are mech mods and regulated mods
you have a mech
now most mech mods have no saftey features at all. unlike regulated mods which have many built into the chipset
SO with your mod you need to know what you are doing so it dont go kablooey.
what do you need to know
1. you batteries are possibly the most important thing in the setup. You said you dont know if they are authentic. well guess what GO GET SOME AUTHENTIC ONES THEN. rtdvapors or liionwholesale are 2 HIGHLY TRUSTED VENDORS
why is this such a big deal
well they are your power source
and there are fakes out there and rewraps out there that out right LIE on the label. YOu think it can supply 20 amps and all it can do is supply 10 amps safely
so when you build your coils for something that may need 15 amps, you might blow you hand off using fake over rated batteries
25rs are great batteries but not the go to for mechs from what I have read
i dont own a mech but I do know I have read many experienced people using 25rs in a mech
the main brands of batteries to look for are samsung sony and lg
do not buy efest trustfire or anything with fire in its name - the are known to misrepresent the actual values of the batteries they sell.
NExt you need ohms law. Im no expert in it...but I am smart enough to know how to use an ohms law calculator like this one
http://www.steam-engine.org/ohm.asp
so assuming you use genuine 25rs tehy have a max amp of 20 for safe continuous discharge
so lets use that calculator
you punch in your resistance and lock it at .3 ohms
at that battery's max voltage when fully charged it puts out ABOUT 4.2 v so plug that value in
that means you will need 14 amps and it will fire at 58.8watts
so that is safe since 14 amps is below you 20amp discharge for the battery
but let keep playing
change the volts to 3.7 which is the nominal discharge for the battery
now you are only pully 12.33 amps still safe for a 25r
but only putting out 45.63 watts
now if you dont know
your voltage in a battery keeps dropping as you discharge it
so a half charged battery is going to give you less watts then a fully charged battery
lets look further
change the resistance to a .1 coil
and set the volts back to 4.2
well now you are going to push out 176.4 watts
and 42amps
ok warning sign
you battery can only safely handle 20 amps
so a .1 build can make it blow your hand off
starting to get the idea of what you need to learn to be safe?????????
oh and lets look at this again
lets say you bought some battery that says its 40amp
first off BULLSHIT their are no 40 amp batteries
those normally will be safely 15-20 amps
so lets say its only 15 amps
and you go thinking its a 40amp battery
and put a .15 ohm coil on that battery
well using .15 ohms and 4.2 v
you need 28 amps
and that gives you 117.6 watts
you think hey its a 40amp battery Im good
NOPE
cuz it says 40amps but is really 15 amps
and you can go boom
so getting genuine real batteries preferably samsung sony or lg for a trusted source like the ones i mentioned is CRITICAL
ok thats all i got hopefully you have somewhere to go and others may jump in