How Long Will a Motorhome Leisure Battery Last? A Simple Way to Work It Out
If you're planning a van or motorhome electrical system, the question of how long the leisure battery will last comes up almost immediately. MotorhomeFun has a clear guide on it, and the honest answer is that it depends on three things: battery capacity, daily consumption and solar input.
On capacity, the type matters a lot. Lead-acid batteries shouldn't be discharged below roughly 50 percent, so a 100Ah battery gives you about 50Ah, or around 600Wh at 12V. A 100Ah LiFePO4 lithium battery can be used down to about 90 percent, which is nearly 1,080Wh, and it weighs far less.
Consumption is the other half. A compressor fridge draws about 45W but cycles on and off, averaging around 450Wh over 24 hours. Modest use with LED lights, phone charging, a water pump and the fridge typically lands at 200 to 400Wh a day, and laptops, TVs or CPAP machines push that up considerably. With 300Wh a day and no charging, lithium would last about 3.6 days and lead-acid about two.
Solar changes the picture. In the guide's UK example, a 200W panel getting about four good hours in summer makes roughly 800Wh, so the battery slowly tops up. In winter the same panel might only make 200 to 300Wh on a decent day, which is break-even at best, and grey days bring a deficit.
The article also points out that a hair dryer at 1,500 to 2,000W will drain a basic off-grid battery within minutes, so a 12V travel kettle or a gas hob is the smarter choice. I like how practical the numbers are for anyone sizing a build.
Source: MotorhomeFun
On capacity, the type matters a lot. Lead-acid batteries shouldn't be discharged below roughly 50 percent, so a 100Ah battery gives you about 50Ah, or around 600Wh at 12V. A 100Ah LiFePO4 lithium battery can be used down to about 90 percent, which is nearly 1,080Wh, and it weighs far less.
Consumption is the other half. A compressor fridge draws about 45W but cycles on and off, averaging around 450Wh over 24 hours. Modest use with LED lights, phone charging, a water pump and the fridge typically lands at 200 to 400Wh a day, and laptops, TVs or CPAP machines push that up considerably. With 300Wh a day and no charging, lithium would last about 3.6 days and lead-acid about two.
Solar changes the picture. In the guide's UK example, a 200W panel getting about four good hours in summer makes roughly 800Wh, so the battery slowly tops up. In winter the same panel might only make 200 to 300Wh on a decent day, which is break-even at best, and grey days bring a deficit.
The article also points out that a hair dryer at 1,500 to 2,000W will drain a basic off-grid battery within minutes, so a 12V travel kettle or a gas hob is the smarter choice. I like how practical the numbers are for anyone sizing a build.
Source: MotorhomeFun
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