Recharge planning
Estimate how long it takes to move an RV battery bank from today's state of charge to your target using solar, DC-DC, shore power, or generator charging.
Quick recharge read
After daily loads, the array has about 550Wh/day left to refill the bank. That replaces the 2,000Wh state-of-charge gap in roughly 3.6 good-sun days.
Energy gap
35% to 90% state of charge
Charge rate
600W before conservative losses
Solar surplus
2.4 kWh harvest before daily loads
Use this as planning math, then verify charger output, battery charge limits, wire/fuse sizing, temperature limits, and manufacturer guidance.
Start over
This calculator stores inputs locally in this browser. Clear saved inputs when stale values are getting in the way.
Charging recovery calculator
Choose solar, DC-DC, shore power, or generator charging. The calculator estimates the energy gap, derates the charge source, and flags when running loads erase the recovery margin.
Recharge estimate
After daily loads, the array has about 550Wh/day left to refill the bank. That replaces the 2,000Wh state-of-charge gap in roughly 3.6 good-sun days.
Energy to replace
2.0 kWh
35% to 90% SOC
Effective charge rate
468W
600W before conservative losses
Daily solar harvest
2.4 kWh
550 Wh left after entered daily loads
Usable bank estimate
3.2 kWh
300Ah at 12V with lithium reserve
What this source assumes
Uses panel watts, peak sun hours, and daily loads to estimate net refill.
Solar recovery depends on real sun, shade, panel heat, roof angle, controller behavior, and daily loads running while charging.
Lithium can accept higher current, but the BMS, charger profile, wiring, and temperature limits still decide the safe charge rate.
Recommended next move
Compare the result against your normal stay length so you know whether the bank recovers before the next cloudy stretch.
Prefilled recharge scenarios
Each scenario opens with battery size, state-of-charge gap, solar watts, sun hours, and daily loads filled in so you can see whether recovery time is the weak part of the plan.
Short trip baseline
Weekend Couple Starter
Use this when the bank size looks fine but recovery time may decide the trip.
Load this profileWorkday-capable profile
Remote Work Desert Week
Use this when the bank size looks fine but recovery time may decide the trip.
Load this profileLower-sun profile
Shoulder-Season Forest Camp
Use this when the bank size looks fine but recovery time may decide the trip.
Load this profileMore people, faster tanks
Family Dry-Camping Long Weekend
Use this when the bank size looks fine but recovery time may decide the trip.
Load this profileLean system profile
Minimal Van or Small Trailer
Use this when the bank size looks fine but recovery time may decide the trip.
Load this profileWhy this exists
A big battery bank can still feel small if solar cannot replace the daily load, the DC-DC charger is undersized, or generator time is planned around hope. This tool connects state of charge, charge source, and daily use before you commit to another battery or another panel.
Use this with
Solar calculator
Use this when solar is not producing enough daily surplus to refill the bank.
Open next stepBattery sizing calculator
Use this when you need to confirm whether the bank itself is large enough for the loads.
Open next stepBattery charging guide
Use this when the real question is how shore power, solar, alternator, and generator charging fit together.
Open next stepTool notes
The important output is not just hours. It is whether your normal charging source can replace the state-of-charge gap before the next night, next workday, or next cloudy stretch.
The calculator converts the current-to-target state-of-charge gap into watt-hours using bank amp-hours, voltage, and battery chemistry.
Solar, DC-DC, shore, and generator sources each use conservative efficiency assumptions so the estimate is not based on perfect lab output.
For solar recovery, daily running loads are subtracted from the solar harvest before the tool estimates how much energy is left to refill the bank.
Avoid these traps
A 600W array is not a steady 600W charger for five straight hours. Heat, angle, controller losses, wiring, shade, and daily loads all reduce recovery.
A 2,000W generator does not refill the battery at 2,000W unless the charger can actually accept and deliver that much DC charging power.
AGM batteries slow heavily near full, and lithium systems can still taper because of BMS, temperature, or charger-profile limits.
Treat the calculator result as a planning range, then verify the relevant manufacturer guidance, safety limits, installation requirements, and local rules before changing the rig.See assumptions
Gear to compare after the math
These handoffs match the calculator family, not a one-click prescription. Verify fit, specs, clearances, and install limits before buying.
SOK SK12V100P 12V 100Ah LiFePO4 Battery
Best for
Budget lithium builds after a smaller bank result
A common 100Ah building block when the calculator result still fits a straightforward 12V lithium bank.
Current listing
SOK SK12V100P 12V 100Ah LiFePO4 Battery at SOK.
Victron SmartShunt 500A/50mV
Best for
Making battery runtime visible instead of guessed
A shunt-based monitor is the usual next buy when the calculator result depends on real state-of-charge tracking.
Current listing
Victron SmartShunt 500A/50mV at Victron.
Victron Orion XS 12/12-50A DC-DC Battery Charger
Best for
Improving recharge support for larger daily loads
Use this class of DC-DC charger when the battery answer only works if drive-day recovery is part of the plan.
Current listing
Victron Orion XS 12/12-50A DC-DC Battery Charger at Victron.
Frequently asked
No. It is a planning estimate for comparing recovery paths. Verify charger specs, battery charge limits, wire size, fusing, temperature limits, and manufacturer guidance before installation.
If the fridge, router, fans, and laptops are running during the day, part of the solar harvest is feeding loads instead of refilling the bank. The net-surplus number is usually more useful than the raw solar harvest.
Enter the DC charger output, not the generator rating. If a generator powers a 45A converter charger on a 12V bank, use 45A as the charge source.
Lithium can usually use more of its nameplate capacity and accept higher current deeper into the charge cycle. AGM can still work, but the final portion of charging often takes longer than straight-line math suggests.