I got that, but what I was talking about was treat the recharge rate to power the same way heat-sinks is applied to heat. The recharge rate is 10 for the fuel cell. But, this could be modified or fine-tuned by upping the unit's power generator. Not quite the same as adding extra heatsinks adds to the cool-down rate, but you get the idea. Of course, the power generator should probably lose charging capacity when it takes light damage.
The recharge rate is being applied almost exactly like Heat Sinks are (recharge is applied at the beginning rather than at the end of the turn). The 30-point heat chart is exactly matching the Protomech's reserve power. The batteries just represent an amount of energy that is drained before the Protomech's power reserve is used.
In that case it was a 120-capacity battery and a 10-rated Fuel Cell. Another Protomech might be designed for more up-front combat and have 60-capacity Battery and a 20-rated Fuel Cell. A third might be designed for ambush with less support and might have a 75-rated battery with a 5-rated Fuel cell, but include a much larger fuel supply for the Fuel Cell. So you would have a variety of Fuel Cell options when building the Protomech, but during combat you would just keep track of the Fuel Cell's recharge rate, and how many turns of fuel the Fuel Cell had (likely more than a single battle).
There could even be a case where what would be a 10-rated Fuel Cell for a 2-ton Protomech would be listed as a 2-rated Fuel Cell for a 10-ton Protomech. These details would be only dealt with during construction, while in combat the player only has to worry about how many points of power the Fuel Cell recharges per turn (and how many turns of fuel the Fuel Cell has, plus the number of turns of endurance per critical slot of fuel).
A Protomech using a mixed power system would have XX amount of battery capacity, YY amount of recharge rate, and 30 pts of suit reserve.
The Protomech would first use power from the battery capacity, and if exceeding the amount of power in the battery capacity, would start to consume power from the 30-pt suit reserve. At either the start or end of the turn, the recharge rate provides additional energy, either lowering the 'heat' level, raising the energy amount stored in the battery capacity, or a mix of both. The battery + power plant combo is designed to operate almost exactly like the current Mech heat scale (just with more capacity at the bottom).
Losing charging capacity would be treated like any other critical hit. Hit one of the fuel storage critical slots, you lose some turns of endurance, based on how much is present in that critical. Hit the batteries, you lose that much capacity. Hit the Fuel Cell (or Fusion plant) directly, yep, it is gone, and all you have is what is in the batteries and the suit reserve. Not sure if allowing multiple Fuel Cells could be a good idea (maybe make it where two 5-rated Fuel Cells take up more mass than a single 10-rated Fuel Cell).
The other odd thing about power generation is that there should be choices when you get low. One of the things I appreciated about the first edition CAV rules. When you're at full power, you don't have to worry about moving and shooting having penalties. But, when you're low, you should be able to, say, ignore the modifier to movement or gunnery if you don't use the other. So, you want to fire with accuracy, you ain't moving that turn. You want to book, you ain't shooting that turn.
For Battletech, since the Mech is the key unit, I want to make it where smaller units are easier to work with. So instead of making a new chart for ProtoMechs, I wanted to use the existing Heat scale and relabel it as reserve power.
To me, ProtoMechs on a field with Battlemechs would be a secondary focus, so they should have fewer rules to work with. The more I can imitate from Mechs, the better. Now on a smaller scale, this option for focusing power could be done
Quick question about reserve power. If the unit shuts down due to ultimate power drain, does that turn off the cell/reactor, too? So, if you manage to burn all your power, are you ultimately stuck?
If you burn all your Fuel Cell fuel and battery power, I figure the only things you can still run are passive sensors, local radio, and onboard small computer. The suit itself is stuck. Time to find an extension cord. The nice part is that as long as you still have at least 1 pt of power, you can move within the hex (but that movement will likely drain the last point of power). Hope a buddy with a vehicle comes along to let you recharge off them. Omni-units include charging ports automatically, while non-omnis will need to allocate tonnage to a recharging port. These recharging ports allow for in-battle recharging.
Out of battle recharging is done by having someone hook up jumper cables from the vehicle to the Protomech.
A Fuel Cell would be fluffed as having enough power onboard to be able to restart if there is any fuel left. The Fuel Cell would use a small amount of Fuel to trickle charge and keep itself going. This amount would not be significant tactically, but could be addressed for strategic purposes (i.e. a Protomech standing guard for several hours might burn a little fuel just running its sensors, radios, computer, aso).
A Fusion plant will obviously have plenty of power and the fuel it consumes is a teaspoon per mission, if that. Protomechs with a Fusion plant would tend to the heavier end, be 'leader' units, and have recharge attachments so the Protomechs they are with can recharge off the leader. They might even just use large power cords and the other Protomechs have an auto-jettison in case of combat, while the leader presses the emergency retract. Another option would be backpack fuel supplies for ProtoMechs, where they use backpack fuel first then internal fuel.
For the same mass a Protomech fusion plant would be less productive than a Battlemech fusion plant, since it has to fit inside the same torso where the pilot is stationed. Installing a Mech reactor in a ProtoMech means either the pilot is getting shoved out of the torso or the plant is sticking out of the torso. The first means massive penalties to G/P skills if you keep the head the same size, or expanding the head size so the pilot has enough room resulting in thinner armor protecting the pilot. The second is known as a weak point.