LiFePO4 battery 12 V — 314 Ah (4 kWh)

A 12.8 V lithium iron phosphate battery built from four 314 Ah cells in series, for roughly 4 kWh. Hand-assembled, compressed, balanced and tested before it ships.
What sets it apart isn't the chemistry, which everyone uses — it's what you can see of it. Its BMS talks over Bluetooth and RS485: Home Assistant reads each cell's voltage, the spread between them, the temperatures and the cycle count. You're not watching a four-bar gauge, you're seeing the real state of your battery.

How many days of autonomy

• 5 days with no recharging at all — and that isn't a calculation, it's a reading taken in a van
• The conditions: compressor fridge, four LED lights for three hours, roof fan for four hours, one hour of television, two phones charged, plus standby draw. About 640 Wh per day
• Autonomy is worked out on 80% of capacity, never 100%: claiming more would be selling you paper
• Run the numbers for YOUR equipment: the autonomy calculator is at heliolocal.fr/autonomie.php — fridge, lighting, fan, television, and it tells you the capacity you need

Depending on the capacity

• 105 Ah — about 1.3 kWh — nearly 2 days
• 150 Ah — about 1.9 kWh — nearly 2.5 days
• 200 Ah — about 2.6 kWh — about 3 days
• 280 Ah — about 3.6 kWh — about 4.5 days
• 314 Ah — about 4.0 kWh — 5 days (the model offered here)

What you see in Home Assistant

• The voltage of each of the four cells, and the spread between highest and lowest
• State of charge, current in both directions, temperatures
• Accumulated cycle count — the only real measure of a battery's wear
• All of it locally, over Bluetooth or RS485. No account, no server, nothing leaving the vehicle

What's inside — and why we tell you

• 314 Ah LiFePO4 cells from a recognised maker, EVE or CATL depending on supply, new and top grade. The exact brand and batch numbers appear on your invoice
• A JiKong BMS, better known as JK — a proven reference, with active balancing between cells
• A battery comes down to two parts: the cells and the BMS. The rest is a box
• Many keenly-priced batteries name neither. When a seller doesn't say what went inside, the question is worth asking

Build

• IP67 case, stated range -20 to +60 °C, built-in handles and protected terminals
• Cells held under compression, as prismatic cells require
• Full balancing plus a charge and discharge test before dispatch

How long it lasts

• The cell manufacturer states over 8,000 charge and discharge cycles, with 70% of capacity still available at that point
• To picture what that means: even fully emptying and refilling it every single day, that is over twenty years. In a van used a few weeks a year, it will outlast the conversion around it
• And that is exactly why we name the cells. Eight thousand cycles is the specification of new, top-grade cells. Downgraded cells will never reach it — and nobody could tell you, since nobody told you what was inside
• The figure and the name go together. Either one alone is worthless

Options and other capacities

• Remote BMS display, to check the state without a phone: 39 €
• Other capacities (105, 150, 200, 280 Ah) and a 24 V version: on request
• Pricing tracks the cell market, which moves several times a year. A quotation is valid for 30 days

Delivery

• Collection possible at Hirson (02), France
• Shipping: a 25 kg lithium battery falls under regulated transport and is quoted per address. That is why it isn't sold in one click — ask for the quote, the answer comes quickly

Before choosing a capacity: tell us what you run and how many days you want to last. Sometimes the right answer is a smaller battery and one more solar panel — we say so when that's the case.

Compared to alternatives