CER (Camp Establishment Reserve)

[turbopilot]

@josephpRV coined an important term that will be the subject of many discussions by future LightShip owners - CER (Camp Establishment Reserve). This term captures the tension of having an RV with 77 kWh of power in the chassis that can be used for two purposes: camping and locomotion. Balancing the demand on the battery packs to enhance travel efficiency and yet still have enough power to camp at unimproved locations will require lots of planning. The choice of tow vehicle, EV, EV with power sharing, EREV's with power sharing, HEV, HEV with power sharing and ICE vehicles will make calculating a CER a unique experience for each owner. The ability to symmetrically power share between a EV/EREV/HEV tow vehicle and the LightShip offers more options to "tanker" electricity to the LightShip and use the LightShip as a source of electricity for an EV, PHEV and EREV. And finally the ability to convert gasoline into electricity at the campsite by EREV's and HEV's adds yet another variable to calculate the optimal CER for each use case.

All of these variables apply to the LightShip in an unimproved camping location. If your destination is a KOA with a 50 amp pedestal, none of this applies. I suspect the typical customer for a LightShip is not looking for that camping experience.

So I thought I would break out this topic into a new thread first started in the "Florida Update" thread to continue the discussion. For reference here is @josephpRV first post introducing the subject with his thought about applying the concept with a Rivian tow vehicle:

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I've taken the liberty of token-blitzing my AI tool of choice. After quite a few rounds I'm comfortable with the hypothesis below based on my R1T and the Lightship. As @Rory (Lightship Team) and the team travel around FL and back up to CO and CA, I'm going to enjoy watching their energy based decision making to update my model.

Lightship + R1T Battery Strategy - A Three Axis Model

When towing the Lightship, energy strategy isn’t just about efficiency, it’s about managing three key axes that determine your options mid-drive and at camp:

1. Energy liquidity, prioritize R1T over Lightship (mobility, escape, and ability to fetch energy)
2. Camp viability, prioritize CER* (Camp Establishment Reserve)
3. Charging friction, in-transit decoupling, stall geometry, stop count, and fatigue on long tow days

On short/moderate trips, axes 1 & 2 dominate, on long-haul trips (e.g., 500+ miles), axis 3 may temporarily override energy logic mid-route to reduce stops or hassle. Axes 1 & 2 always dominate when you reach camp.

*The CER is the minimum Lightship SOC required to establish and operate camp (unhitching, leveling, systems bring-up, HVAC, comms). CER is not a fixed number. In boondocking scenarios, it’s a function of daily energy usage, and expected daily solar refill. In practice, CER must float upwards if daily usage exceeds solar recovery.

Core Strategy Principles

1. Spend Lightship energy first, but never below the CER, and
2. Protect R1T energy unless downstream charging is guaranteed and abundant

Why This Works

• Axis 1: Energy that can go get energy is more valuable than energy that can’t.
• Axis 2: A powerless trailer isn’t a campsite, Lightship CER is sacrosanct.
• Axis 3: Charging friction affects mid-drive decisions on long days, but arrival priorities still govern..

The Three Real Scenarios

1. Abundant, concurrent charging at destination, i.e., multiple pedestals / EVSEs, no load constraints

Play: Bias to travel speed. Use TrekDrive aggressively. Spend Lightship energy freely (respecting CER).
Why: Energy is liquid, speed/time can safely dominate.

2. Limited charging at destination, i.e., one pedestal or shared power

Play: Use TrekDrive. Arrive with R1T SOC higher than Lightship SOC, while respecting CER.
Why: A charged truck keeps options open, a charged trailer doesn’t.

3. No charging at destination (boondocking)

Play: Use TrekDrive until Lightship approaches CER. Preserve CER and as much R1T SOC as possible.
Why: Lightship can slowly recharge via solar, the truck is irreplaceable.

One-Line Rule

Spend Lightship energy down to the CER (which floats with usage vs. solar) and protect the R1T unless charging is guaranteed and abundant.

 

[turbopilot]

When I first placed an order for a LightShip I began running different scenarios trying to figure out the best tow vehicle for the LightShip. My goal was to get the LightShip to a remote destination with the highest CER. A year ago I did not have all the variables to plug into a spreadsheet but over the last year many of those variables have been determined. I just refined my spreadsheet simulation I started a year ago for my F-150 PowerBoost with a gasoline to electricity inverter system. There are still some variables that are best guesses. As soon as I get my LightShip I am going to get some better numbers. The one number that I still don't have a good estimate for is the in motion rolling efficiency of the PowerBoost inverter to convert gasoline to electricity. That number is around 1 gallon of gasoline for 7.2 kW generated of electricity when the F-150 PowerBoost is sitting still at idle. But the in motion rolling efficiency of that generator is much better because the PowerBoost traction motor is capturing regenerative energy from both the PowerBoost and the LightShip (if TrekDrive is off). My current estimate based on experience towing my Airstream is that 1/2 gallon of gasoline can make about 7.2 kW of electricity in motion with regenerative energy adding to the output. In the spread sheet below that is the conversion number I applied.

So below is my "first mistake" running the simulation for a 651 mile trip pulling the LightShip with a PowerBoost at 62 MPH. This simulation suggests I can arrive at a destination 651 miles away with the total capability of consuming ond/or generating 137 kW of electricity with only one fuel stop en route averaging a "door to door" speed of 59 MPH. So my CER would be 137 kW minus whatever fuel would be required to get the PowerBoost and LightShip to a gas station after camping.

However, given the current firmware In the LightShip Ben advised me the power distribution module currently will not allow the LightShip to accept a charge via the NACS port whenever TrekDrive is active. So for now this is a dream.

I am now going to redo the simulation to arrive at a CER alternating turning on TrekDrive and the PowerBoost inverter generator to see what that does over the same 651 mile trip. Last time I talked to Ben about this he thought there may be a way to charge the battery and run TrekDrive simultaneously but that is not something they are currently working on. That capability is only important for HEV's with generators and soon EREV's with an engine driven generators.