Returning from Harlingen to Bulverde Airpark IFR today I was being vectored west of KSAT when everything went dead. I was in and out of the clouds and there was a good VFR ceiling fortunately. Also fortunately my KI 256 is vacuum powered and I had a Garmin 795 battery powered GPS. I stayed on my assigned heading until clear of Class C then headed to 1T8.  I lowered the gear manually but was not sure It was really down and locked. I was surprised there was no positive indication on the floor moun