Choosing the right lithium battery size is essential to power your gear reliably while camping, touring, or going off-grid. Whether you're running a fridge, lights, inverter, or microwave, this guide will help you calculate the ideal battery capacity to suit your needs.
✅ Why Lithium Batteries?
Lithium iron phosphate (LiFePO₄) batteries offer major benefits over traditional AGM or lead-acid:
Longer lifespan (2000–5000 cycles)
Lighter weight
More usable capacity (you can use 90–100% of rated Ah)
Faster charging
Better performance with inverters and DC-DC chargers
? Step 1: List What You Want to Run
Start by writing down the power draw (in watts) and the average hours per day each appliance will run.
| Appliance | Power (W) | Hours/Day | Daily Energy Use (Wh) |
|---|---|---|---|
| 12V Fridge | 50W | 24 hrs | 600 Wh |
| LED Lights | 20W | 5 hrs | 100 Wh |
| Water Pump | 60W | 0.5 hrs | 30 Wh |
| Laptop Charger | 90W | 2 hrs | 180 Wh |
| Phone Charging | 10W | 3 hrs | 30 Wh |
| Total Daily Use | 940 Wh |
⚡ Step 2: Convert Watts to Amp-Hours (Ah)
If you’re using a 12V lithium battery, divide your total watt-hours by 12V:
940 Wh ÷ 12V = ~78Ah per day
✔ A 100Ah lithium battery can easily cover this daily usage — with room to spare.
? Step 3: Consider How Long You’ll Be Off-Grid
Multiply your daily Ah usage by how many days you want to run without charging.
Example:
Want 2 days of power without recharging?
78Ah × 2 = 156Ah battery bank recommended
(Or two 100Ah batteries in parallel)
? Step 4: Account for High-Draw Appliances
If you want to run high-draw gear (like kettles, microwaves, or induction cooktops), make sure your battery’s continuous discharge current is high enough:
| Appliance | Draw (W) | Current at 12V | Battery Recommendation |
|---|---|---|---|
| Microwave | 1500W | 125A | 200Ah lithium or 100Ah x 2 |
| Coffee Machine | 1000W | 83A | 150Ah lithium or better |
| Kettle | 2000W | 166A | 200–300Ah bank highly recommended |
? For these setups, inverter capacity and cable gauge are also critical.
? Recommended Battery Sizes (Quick Guide)
| Setup Type | Recommended Lithium Capacity |
|---|---|
| Lights + USB + Fridge Only | 100Ah |
| Fridge + Lights + Laptop | 100–150Ah |
| Add small inverter (300–600W) | 150Ah |
| Large inverter (1000–2000W) | 200–300Ah |
| Full off-grid (appliances + solar) | 300Ah or more |
? Bonus Tip: Pair with Solar Charging
To keep your battery topped up, add solar panels that can generate at least 30–50Ah/day per 100Ah battery used.
| Battery Bank | Recommended Daily Solar Input |
|---|---|
| 100Ah | 200W solar panel (min) |
| 200Ah | 400W solar panel (min) |
| 300Ah | 600W or more (fixed + portable) |
✅ Summary
List all your gear and calculate Wh/day
Convert to Ah/day using 12V system
Size your battery for your daily use × days of autonomy
Account for high-draw appliances (microwaves, kettles)
Add solar input for longer stays
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