What Battery Do I Need?
Your starter battery is not designed to be used to run a fridge or other auxiliary loads, so a second deep cycle battery is a must. What type of battery will depend on how often you go camping or whether you intend to run your fridge full time even when not camping (great for impromptu shopping trips, eating out for the day or keeping a few coldies on hand).
If you're an intermittent camper (and weight isn't a concern), then a single AGM of 100-120ah will do fine. We recommend going with a good quality AGM in the rear of vehicle or calcium battery for engine bay installations. This is sufficient for a 40-60L fridge and camp lights for overnighters or weekend trips.
If you're looking to install in the engine bay, we recommend the Delkor 100ah, it is a calcium battery and is warranted for engine bay use. It can handle the higher temps better than most AGM's.
Alternatively, the Full River 120ah AGM can sit comfortably in the canopy/rear of your fourbie, and will significantly outlast those eBay cheapies with 2-3 times the cycle life.
We recommend having battery storage for two days power consumption in case of really bad solar conditions ie. heavy cloud or very high temps or in the event of a component failure. Many campers use a lot more power than they plan to and expect solar to produce more than real world output so it's good to have a buffer. For larger power users or for longer trips (3+ days) having two batteries can be preferable for redundancy in your setup. If you want the option to put your feet up for a good 3 or more days or if you want to use an inverter for a coffee machine or kettle, then more storage and solar is required.
You'll be using your battery a lot, so investing in a lithium battery is your best option.
While the upfront cost is about double that of a good quality AGM, AllSpark Lithium Batteries have a cycle life 5-7 times that of an AGM, not to mention they are a quarter of the weight, have charging efficiency 20% better than AGM and are physically smaller in size. They can also be charged at higher current rates compared to AGM.
Given there is more safe usable power in lithium batteries (safely using 80% compared to 50% in AGM), a single 150ah AllSpark battery will be sufficient. This battery has an output current that will easily run a 2000W inverter (needed for most coffee machines/kettles/microwaves etc) from a single battery. Pretty much every other Lithium battery on the market has a 100A continuous output requiring two batteries in parallel or much large batteries to power a 2000w inverter. AllSpark Lithium can power a 2000w inverter from as small a size as our 100ah battery.
We recommend having battery storage for two days power consumption in case of really bad solar conditions ie. heavy cloud or very high temps or in the event of some sort of component failure - whilst unlikely sometimes it does happen. Many campers use a lot more power than they plan to and expect solar to produce more than real world output so it's good to have a buffer. For larger power users having two batteries (either 100ah or 150ah) can be preferable for redundancy in your setup. If you want the option to put your feet up for a good 3 or more days, or if you want to use an inverter for a coffee machine or kettle, then more storage and solar is required.
To set up a caravan, camper, motor-home or bus which will meet your high power usage, you will need multiple batteries, and if you're running a fridge in your tow vehicle as well, then you'll need a second battery and charging system in there also.
As a serious traveller, the only way to go with batteries is lithium. They are not only a quarter of the weight of AGMs, they last 5-7 times as longer and while the upfront cost is more than an AGM, the cost per amp hour/per cycle is significantly cheaper at about 1/3 cost compared to AGM.
They also have a higher charge efficiency*, meaning you'll need less hours of sunlight per day (or less overall solar) to charge your batteries when compared with AGM, plus they can also be charged at higher currents too.
The ideal set up for your van/camper/motorhome/bus has a minimum of 2 days storage in the batteries, which is a minimum of 250ah (or 300ah with 2 x 150ah) if you're running the TV for a few hours a day, making a few cups of coffee and/or boiling the kettle, using the microwave to re-heat a meal for 5 minutes or so, pumping water, charging mobile phones and laptops, running a large fridge (150L+) and maybe a second smaller fridge/freezer.
Your tow vehicle will need a separate battery, a 100ah lithium (the higher BMS model if mounting in the engine bay) with 25A DCDC charger will keep the fridge in here running all year 'round. You will also need solar if the vehicle isn't driven for at least an hour each day.
No two set ups are the same, but the information here can be used as a guide to get you started. There is nothing like real world use to discover what you do and don't need in a set up, so before heading off on any larger trips away from power, we recommend having a test run or two closer to home.
You can always add to a set up, but making sure you have the right components to begin with ensures you will only be adding, not replacing (which can be costly).
In addition, your batteries need to source their power from somewhere. This will come from either your vehicle (via a DCDC charger) and/or solar panels. Check out our other articles for information on sizing up solar for your needs, or choosing a DCDC charger.