Question 1

Is Swags & Volts free?

Accepted Answer

Yes. Every calculator works without an account. Signing in is only needed if you want to save a rig and come back to it later.

Question 2

Where do the numbers come from?

Accepted Answer

Every result shows its working underneath, so you can check it. The maths uses a nominal 12V system. Appliance draws are typical figures for common gear, so swap in the numbers from your own labels or manuals. Sun hours come from Bureau of Meteorology mean daily solar exposure (1990 to 2026) at a major airport station in each region, averaged by season. Real sun at your campsite will differ, especially inland of the coastal stations.

Question 3

Why is my fridge number different from the sticker?

Accepted Answer

The sticker shows what the compressor draws while it runs. It switches on and off, so the daily total depends on how often it runs. That is the duty %. A 40L fridge might run a third of the time on a mild day and much more in a hot car with the lid opening often. If your fridge or battery monitor shows real daily use, enter that instead.

Question 4

Lithium or AGM?

Accepted Answer

Lithium (LiFePO4) lets you use about 90% of its rated capacity. AGM gives about 50% if you want it to last. So a 100 Ah lithium does roughly the work of a 180 to 200 Ah AGM, at about half the weight. Lithium costs more up front but usually lasts many more cycles. AGM is cheaper and simpler if you only camp a few weekends a year.

Question 5

Do I need a DC-DC charger?

Accepted Answer

If your vehicle was built after about 2015 it probably has a smart alternator, and a plain relay (VSR) will not charge a second battery properly. A DC-DC charger fixes that, and lithium batteries need one in any vehicle.

Question 6

Why does the solar result take off 25%?

Accepted Answer

A panel rarely delivers its label rating. Heat, dust, a flat or poorly angled panel, cable losses and the controller all eat into it. Allowing 25% for those losses gives a number that holds up in the real world. If you park in shade or travel in winter down south, allow more.

Question 7

How many days with no charging should I plan for?

Accepted Answer

Two days suits most weekend and touring trips. Go for three or more if you camp in one spot for long stretches, travel in winter, or rely on a fridge for medication or food you cannot replace.

Question 8

My cable is called 6mm. Why does the calculator say it is 4.6 mm2?

Accepted Answer

Auto cable is often named by its outside diameter, including the insulation. What matters for voltage drop is the copper area in mm2, which is much smaller. Check the copper area on the spec sheet or packaging. B&S sizes are a more reliable guide.

Question 9

Can I install it myself?

Accepted Answer

Plenty of people wire their own 12V gear. Use the right cable and fuses, and get fixed wiring checked by a qualified auto electrician before you head off. Any 240V wiring in a vehicle, camper or caravan must be done by a licensed electrician.

Question 10

Does Swags & Volts work with no signal?

Accepted Answer

Mostly. Open the site once while you have signal and the calculators keep working out bush with no signal. Saving a rig, the Ask helper and loading new guides need signal again.

Question 11

Are you paid by any brands?

Accepted Answer

No. The calculators recommend sizes, not brands, and nobody pays for a result. If we ever add sponsored or featured listings, they will be clearly labelled.

Question 12

Who can see my saved rigs?

Accepted Answer

Only you. Saved rigs and their gear lists are tied to your account and are not shown to other users.

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