Working out what size Victron lithium battery you need is easier once you stop thinking in amp-hours and start thinking in watt-hours. A 100Ah battery at 12.8V and a 100Ah battery at 25.6V store very different amounts of energy. This guide converts Ah to kWh using Victron’s own datasheet figures, then sizes a bank from your daily use.
Ah vs kWh: What Size Victron Lithium Battery Stores What
Energy (Wh) = amp-hours × nominal voltage. Victron’s 12.8V Smart range:
| Model | Capacity at 25°C | Energy | At 0°C | Recommended max discharge |
|---|---|---|---|---|
| 12.8/50 | 50Ah | 640Wh | 40Ah | ≤50A |
| 12.8/100 | 100Ah | 1,280Wh | 80Ah | ≤100A |
| 12.8/160 | 160Ah | 2,048Wh | 130Ah | ≤160A |
| 12.8/200 | 200Ah | 2,560Wh | 160Ah | ≤200A |
| 12.8/330 | 330Ah | 4,220Wh | 260Ah | ≤300A |
Source: Victron Lithium Battery 12.8V & 25.6V Smart datasheet.
Step 1: Add Up Your Daily Watt-Hours
List each load, multiply watts by hours used per day, and add 10–15% for inverter losses on AC loads. Example van day (estimate):
- 12V fridge averaging 45W × 24h = 1,080Wh
- Starlink Mini at 40W × 6h = 240Wh
- Laptop 60W × 4h = 240Wh
- Lights, fan and phones = 200Wh
- Total ≈ 1,760Wh per day
Step 2: Choose How Deep You’ll Cycle
Victron’s datasheet rates 2,500 cycles at 80% depth of discharge and 5,000 cycles at 50%. Dividing daily use by 0.8 gives a bank that lasts one day at 80% DoD: 1,760 ÷ 0.8 = 2,200Wh, so a 12.8/200 (2,560Wh) covers it. For two days without sun, double the daily figure: 3,520 ÷ 0.8 = 4,400Wh, which means a 12.8/330 plus a 12.8/100, or two 12.8/200s.
Step 3: Check Cold-Weather Capacity
Capacity drops in the cold: a 12.8/200 delivers 160Ah at 0°C and 100Ah at −20°C. Charging is only allowed from +5°C. If you camp in winter, size up or keep the battery inside the heated space.
Step 4: Check the Inverter’s Minimum Bank Size
Big inverters need a big bank. Victron’s MultiPlus-II 120V manual lists 400–1,200Ah for the 12/3000/120 and 200–700Ah for the 24/3000/70. A 200Ah 12V bank is too small for a 3kVA 12V inverter-charger by that table, even if your daily energy use is low.
When to Go to 24V
Above about 400Ah at 12V, cables and fuses get very large. Victron’s 25.6V Smart batteries store the same energy at half the current. Victron’s Lithium Battery Smart page lists the full range.
Worked Example: A Weekend Camper
A small trailer used on weekends with daily loads of about 600Wh (lights, water pump, phone charging and a fan, estimate). At 80% depth of discharge, that’s 750Wh per day. A 12.8/100 (1,280Wh) covers a day and a half without charging, and a 12.8/160 (2,048Wh) covers about two and a half days. With a little solar, a 12.8/100 or 12.8/160 suits most weekend trips.
Worked Example: A Home Backup Bank on 24V
A home backup system for an outage, covering a fridge, freezer, lights, internet and some phone and laptop charging, at roughly 3,500Wh per day (estimate). For two days of autonomy at 80% DoD: 7,000 ÷ 0.8 = 8,750Wh. Victron’s 25.6V Smart batteries store twice the energy per Ah of the 12.8V range, so a 25.6V 200Ah battery holds 5,120Wh. Two of them give 10,240Wh, which covers the target with some margin.
Energy Conversion Table
| Battery | Ah | Voltage | Energy |
|---|---|---|---|
| 12.8V 100Ah | 100 | 12.8V | 1,280Wh |
| 12.8V 200Ah | 200 | 12.8V | 2,560Wh |
| 25.6V 100Ah | 100 | 25.6V | 2,560Wh |
| 25.6V 200Ah | 200 | 25.6V | 5,120Wh |
The same Ah figure means twice the energy at 25.6V, which is why comparing in Wh or kWh is the clearer way to size a bank.
Recharge Planning
Size the charging sources to match the bank:
- Solar: a 2,560Wh battery needs roughly 600–800W of panels to refill from 20% in one good summer day (estimate).
- Alternator: an Orion XS at 50A adds about 640Wh per hour of driving on 12.8V (estimate).
- Shore or generator: a MultiPlus-II 12/3000’s 120A charger refills a 200Ah bank from 20% in under 2 hours of bulk (estimate).
Checking Charge and Discharge Current
Each Victron Smart battery lists a recommended maximum discharge current, such as 200A or less for the 12.8/200. Divide your inverter’s peak DC draw by that figure to see how many batteries you need for current, not just energy. For a 12V 3,000VA inverter drawing up to about 270A at full load (estimate), two 12.8/200 batteries in parallel share the current comfortably.
Planning for Growth
If you think you’ll add loads later, it’s easier to start with a battery voltage that leaves room to grow. Victron’s Smart batteries connect in parallel and series under one BMS, so a bank can expand within the BMS’s limits as long as the batteries are the same model.
Victron Smart vs NG Batteries
Victron also offers the Lithium NG range, which works with the VE.Bus BMS NG, Lynx Smart BMS NG or smallBMS NG. The sizing method is identical: convert Ah to Wh, add up daily use, divide by depth of discharge and check cold-weather capacity. The main thing to get right is pairing each battery range with a compatible Victron BMS.
FAQ
Is a 100Ah Victron the same as any 100Ah LiFePO4?
In stored energy, roughly, since both are about 1.28kWh. The Victron Smart range needs an external Victron BMS, which most drop-in batteries don’t.
Can I mix sizes in parallel?
Victron allows up to 20 Smart batteries per BMS. Use identical models in a bank.
How long will it take to recharge?
Divide the Ah used by the charge current, then add time for absorption.
Should I size for summer or winter?
Size for the season you use most. If you camp in winter, allow for the lower cold-weather capacity and longer runtimes for lights and heating fans.
Does a bigger battery charge slower?
With the same charger, yes, in hours. The charge current is the same, so a larger bank takes longer to fill from the same state of charge.
Sources: Victron Lithium Battery 12.8V & 25.6V Smart datasheet; MultiPlus-II 120V manual, battery cable table (victronenergy.com, accessed Oct 2026).
Related: LiTime 12V 50Ah LiFePO4 Battery Review, EcoFlow Delta 3 Max Van Life Leisure Battery, EcoFlow Delta 3 Max Refrigerator Runtime, plus the Victron Energy Guide