good day and thx for looking 
i have to run 18servos at ones from some kind og battery But it cant be too heavy ??
they are running 6v (and i cant find any 6v battery)
servo (http://www.servocity.com/html/s3003_servo_standard.html)
now it 8mA x 18servos so in theory it pulls 144mA, but i dont know in RL
BUT. i have two of them ni-Cd packes on 9,6v and 800mA but i can only use 6v
what is the best way to get that down to 6.. or is there a better way to handel it..
thx for any help i can get
" Current Drain (6.0V): 8mA/idle "
Small servo could drain 500 mA or even more under load, expect 18 x 0.5 = 9A if you switch on all of them simultaneously.
For power you better look for "step-down" DC/DC converters, for example auto +12V to USB +5V switching charger will be good, so not with 9A rather 1-2 A.
but can i get a battery for 12v and 9A at a low weight?? i have yet to find one
Depends on how long you plan battery to run, they express capacity in A / hours. For small weight Li-Po battery is the best:
http://www.all-battery.com/111vli-ionbatterypacksandmodules.aspx
sry am not good at this kind of things if i need it to run for 60min what battery will you pick??
60 min = 1 hour, capacity 9000 mA / hour. But with switching DC/DC from 12 V to 6 V you will need only half of 9000 mA/h or about 5000 mA/h incuding 10% losses in conversion.
This pack weight only 300 g. Tenergy Li-Ion 11.1V 5200mAh Rechargeable Battery 31199 - Tenergy
thx for the help
Check the battery setups for the below hexapods which usually have 18 servos. Also a power converter called a UBEC is often used to convert higher voltage battery outputs to either 5v or 6v.