The workshop consumables checklist: what to keep on the shelf
Batteries
Lithium battery replacement for caravans: 100Ah vs 200Ah
When it comes to powering a caravan or camper, lithium batteries are a significant upgrade over traditional lead-acid. They store more energy in a smaller, lighter package, so you can run more for longer with less weight on the drawbar. They also last: a well-treated lithium battery can give ten years or more, against the three to five years typical of lead-acid. The question is how big a bank you need.
Why LiFePO4
The lithium batteries sold for caravans use lithium iron phosphate (LiFePO4) chemistry. It is the stable, safe member of the lithium family: high discharge rates, resistance to thermal runaway, and a built-in battery management system that protects the cells from over-discharge, overcharge and short circuit. You can use 80 to 100% of the rated capacity, where a lead-acid battery should only be taken to about half, so a 100Ah lithium gives roughly the usable energy of a 200Ah lead-acid bank.
Choosing the size: 100Ah, 150Ah or 200Ah
Add up what you run. Typical daily consumption in a van:
- A 12V fridge: anywhere from 40 to 100Ah a day depending on size, ambient temperature and how often the door opens. It is usually the biggest load
- LED lights: about 5W each, so a few lights for several hours adds a few amp-hours
- Fans: around 2 to 5A an hour while running
- Phones, tablets and a small TV: modest, but they add up over a week
- Heating: electric heaters draw up to 1,500W and will flatten any 12V bank quickly; diesel or gas heating with a small fan is the realistic off-grid option
Matching the bank to the trip
Three things decide it: how often you camp off-grid rather than on mains power, how many people are drawing on the system, and how much high-draw gear you run. A couple running lights and a small fridge on short trips will often find 100Ah is enough. A family of four on a week away with a bigger fridge, lights, fans and a lot of devices to charge will be more comfortable on 200Ah, without the worry of running flat before the solar catches up. Cold or cloudy weather tips the balance towards the bigger bank too, because the fridge works harder and the panels give less.
Short version: 100Ah for short trips and light loads; 200Ah for long stays, bigger fridges, more people or any heating. If you are in between, 150Ah exists for a reason.
Cold weather and lithium
Lithium batteries lose some capacity and charge more slowly in the cold, and most LiFePO4 battery management systems will not accept a charge at all below freezing to protect the cells. Keep the bank fully charged going into winter, mount the battery inside the van or in an insulated box rather than on an exposed chassis rail, and if you camp in sub-zero conditions look at a battery with built-in heating or a heating pad. The battery will still deliver power in the cold; it is the charging that needs looking after.
Upgrade the charger as well
Lithium needs a charger that knows it is lithium. The old lead-acid charger in the van, and the vehicle charging circuit, will either undercharge the new battery or hold it at the wrong voltage. Fit a mains charger and a DC-DC charger with a lithium profile, sized for the bank: a 200Ah bank wants a higher-current charger than a 100Ah one if it is going to refill in a day. Check the solar regulator has a lithium setting too. Follow the battery and charger manufacturers' guidance on compatibility, disconnect all power before you start, use quality connectors and secure every connection, and give the charger ventilation. If you are not confident with 12V wiring, have it fitted professionally.
Making the right choice
The best choice comes down to your typical consumption, the gear you run and how often you are off-grid. Either way, a quality lithium replacement brings the weight down, the usable capacity up and the lifespan out, and makes the van a more comfortable place to be. The RedPoint team can run the numbers with you and match the battery and the chargers to the setup.
