To find the powerplant go to data\equipment\goods.ini. Look at the package for your ship:
[Good
nickname = bwf_package <----dagger I think
category = ship
hull = bwf_hull
addon = ge_bwf_engine_01, internal, 1
addon = bw_fighter_power01, internal, 1 <-----powerplant

Then go to data\equipment\misc_equip.ini. Find the nickname that's in the package. In this case bw_fighter_power01:
[Power
nickname = bw_fighter_power01
ids_name = 263710
ids_info = 264710
volume = 0.000000
mass = 10
DA_archetype = equipment\models\hardware\li_fusion_reactor.3db
material_library = equipment\models\hardware.mat
capacity = 1800 <------Hello!
charge_rate = 183 <------and here
thrust_capacity = 1000
thrust_charge_rate = 100
lootable = false

Thanks, that fixed my problem.

Yep, that is the Dagger. If you edit these two lines, you can make it a better powerplant. And if you make the recharge rate pretty close to the capacity, you will experience very little powerdrain (even with a capacity of 1000 or 1800, if you have a recharge equal to that number, it will replenish all the energy as soon as it is used (duh), so your yellow energy indicator will remain nice and still - at 100% )

The trouble with doing it this way, that is modifying the file for all Daggers, is that all the Daggers in the game will have that. Perhaps it is not important in that the NPC's all seem to have the infinite power supplies attached to their ships anyway in the npc loadouts. Be careful about modifying engines though. The NPC's share those with you and they will crash into things as a result of too much speed. Best to make a modified engine unique for your ships only by renaming it and supplying it to only your ships. Thrusters ditto!

All NPCS use the infinite power supply, so don't worry about editing the power units due to the fact that only players mount them.