Hey I`m currently using the LRP SXX TC SPEC V1 in my Associated 12R5.1
When I was using IB 5000mah 4.8v nimh batteries(cells)I had know trouble but since moving to LIPO 3.7v. I`ve had to add a 6.6volt LIFE reciever battery pack 200mah or the speedo would just shut down due to low voltage over a 8 minute run Mod it uses around 50mah from fully charged.
And when using a LIFE theres no need to use any voltage regulators
Hope this helps
Cheers Daniel