Best battery for GTR 200, no alternator

Rebuilding a PA-11 with no alternator and want to install a Garmin GTR 200 and power it with an Aerovoltz battery.

GTR 200 draws 3 A during transmission, 600 mA during receiving and requires minimum of 9.5 V

Aerovoltz battery specs as follows:

4-cell: 1 lbs 2.5" (L) x 2.5" (W) x 4.25" (H) 8 Ah
8-cell: 1.7 lbs 4.5" (L) x 2.5" (W) x 4.25" (H) 15 Ah
12-cell: 2.5 lbs 4.5" (L) x 3.5" (W) x 4.25" (H) 20 Ah
16-cell 3.5 lbs 4.5" (L) x 4.5" (W) x 4.25" (H) 28 Ah

In comparison, a popular handheld transceiver draws roughly half the amps (1.5A T, 300 mA R and 70 mA standby) and the best Li battery pack provides 1.8 Ah. This battery Ah to current draw ratio is roughly less than 25% of the ratio we would have with the 4-cell Aerovoltz battery

We anticipate typical flights of 1 h or less with transceiver use for position reports while in pattern of uncontrolled airport, but would like to have enough battery power to use the radio for an 8-hour cross country. I do not find any data showing what the draw is when using the intercom.


  1. Which battery would prove best in this application? Looking for adequate but not overkill. The smaller the better if it will be enough.
  2. Do we need to consider a special charger? (currently have a 500 mA battery maintainer
  3. Do we need to install a BMS to prevent my partner from ruining the battery when he leaves the radio on and forgets to plug in the charger?