the top diy campervan conversion essentials...

Hi, it's Reggie: You can either jump straight in by clicking the links above or scroll down for the lowdown on my top campervan essentials, including the technical info and why you need them.

1) Leisure Batteries

I'm beginning my self-build camper essentials guide with 12-volt power. Whether you add an electric hook-up or not, you'll definitely need a decent-quality leisure battery with enough amps to run all your chosen appliances for a reasonable time. Before you buy, check that the battery fits your space (dimensions), the seller's feedback, and the delivery time/options. For more info on how to choose the right size and type of leisure battery, plus my other recommended DIY camper essentials, scroll down the page.

Should I connect my 12-volt batteries in series or parallel?

12-volt or 24-volt camper van/leisure battery systems.

To connect 2 x 12-volt batteries in series, a link lead of a suitable grade must run from the positive (+) terminal of one battery to the negative (-) terminal of the other, creating a 24-volt battery system. To connect 2 x 12-volt batteries in parallel, run a link lead of a suitable grade between each battery's positive (+) terminal. You can either link the negative terminals the same way or earth both batteries to a suitable spot. Linking 2 batteries in parallel keeps the battery system/bank at 12 volts and doubles the Ah output; i.e., 2 x 110Ah leisure batteries linked in parallel = 220Ah.

Volts

Volts explained.

The electrical pressure between two points. The longer the distance between the two points (i.e. the cable/wire length), the greater the potential for voltage drop.

Amps

Amps explained.

The unit used to measure electrical current as it flows past a specified point.

Watts

Watts explained.

The rate at which electrical energy is used. Watts combine voltage and current (volts and amps).

Amp hours

12-volt battery amp-hours explained.

The amp-hour rating denotes the amount of energy that can be taken from a 12v battery before the terminal voltage falls below 10.8 volts. This test is usually carried out over 20 hours (20-hour rate). Thus, a 50 amp-hour car/leisure battery can be discharged at 2.5 amps for 20 hours before the voltage drops below 10.8 volts (i.e. 20 x 2.5 = 50). With leisure batteries, amp-hours are often abbreviated to amps (e.g. 85 amp leisure battery). How much 12 volt power (amp hours) do I need? The simplest way to calculate your leisure battery power consumption is: watts divided by volts = current in amps. Thus, on a 12-volt electrical system, a 120 W pump will take 10 amps (i.e., 120 watts/12 volts = 10 amps). In theory, using the above equation, you might think that an 80 amp leisure battery would be adequate to run the pump for 8 hours, but in practise by the pump will fail to run properly as the 12v leisure battery becomes completely discharged, so a safety margin of around 25% should be applied to the leisure battery amp hours required. See the equation below: i.e., a 10 amp pump running for 8 hours = 80 Ah + 25% safety margin (20 Ah) = a leisure battery of at least 100 Ah is required to run the pump efficiently. You can also do the equation the other way round by multiplying the leisure/car battery volts by the amps, e.g., 12 volts x 10 amps = 120 watts. Ok, let's show off. Here's another way: 120 watts divided by 10 amps = 12 volts.

Watt Hours

Watt Hours explained.

Leisure battery manufacturers often refer to the battery capacity in watt-hours. To calculate watt-hours, multiply the battery voltage (12V) by the amp-hours; i.e., 12 volts x 100 amps = 1,200 watt-hours. The number you calculate is the theoretical total capacity. In practice, how much of this energy you can actually use depends heavily on the battery chemistry. Lead-Acid / AGM / Gel: Should only be discharged to 50% to avoid damaging the battery. A 1,200Wh lead-acid battery only gives you about 600Wh of usable energy. Lithium (LiFePO4): Can safely be discharged up to 80%–90%. A 1,200Wh lithium battery gives you roughly 960Wh to 1,080Wh of usable energy.

Go back to camper conversion essentials.

Flooded, or Wet Cell, Lead-Acid Batteries - This type of battery is filled with liquid sulphuric acid (electrolyte) and may require periodic maintenance (topping up with de-ionised water), but most are virtually maintenance-free these days. Wet cell leisure batteries are the most commonly used and suitable for most leisure/auxiliary battery applications.
AGM (Absorbed Glass Mat) Leisure Batteries - The battery is filled with acid, but the liquid is fully absorbed, making AGM batteries spill-proof and suitable for any orientation, i.e., on their side or at an angle.
GEL Leisure Batteries - The battery is filled with an electrolyte gel, making it spill-proof, and GEL batteries can also be fitted in any orientation. GEL and AGM batteries may provide more cycles (battery discharging and recharging) than conventional wet cell batteries and, it is claimed, have deeper cycle parameters. Still, these advantages must be weighed up against the initial cost.
Lithium Leisure Batteries - These have become more popular and more readily available recently, but are still very costly. If you decide that money’s no object, then the fitting procedures and power calculations for lithium batteries are the same as for lead-acid batteries. Lithium leisure batteries have a longer lifespan and considerable weight advantages over lead-acid batteries.
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