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Powering your vanlife

Making, storing, and using power wisely is important for happy vandwelling. Power issues can seem overwhelming and confusing; this article intends to lay out the basics.

Before you spend money on making/storing power in your vehicle, be sure to leverage other sources:

  • plugs at your work, church, or anywhere else you visit regularly
  • plugs at cafes and restaurants – ask for a table near an outlet
  • look for outlets at bus stops, park pavilions, etc.

It may be useful to carry a gym bag with a power strip, extension cord, and any items that need to be charged. The power strips allows you to charge many things at once, and the extension cord helps you reach faraway outlets or outlets in inconvenient places (on a wall, behind furniture).

the Big Picture

There are two generally-separate electrical systems in your vehicle1):

  • House power (coach power, leisure power) is the (usually 12v) electrical system in the living area. It runs fans, lights, etc. It's what we are discussing here.
  • chassis power is the electrical system in the vehicle itself. Starter, alternator, headlights, etc. The two are usually separate systems, except when actively charging from the alternator.2)

what you can run in the vehicle

Things that are run off house power are called loads. Unlike a wall socket where you can run pretty much anything you want, using power you make yourself is a series of choices and compromises. Some things are easy to run off off-grid; some things are harder and require more infrastructure, planning, and money. Some things are impractical in vans. Cardwelling presents additional power challenges.

Here are some very general ideas to get you thinking:

  • trivial to run off the cigarette lighter port while driving
  • easy to run off a portable power pack3)
    • fan
    • CPAP - especially with humidification turned off
  • average loads - small ($) house power system: Example: 200w of solar and 100Ah of battery.
    • 12v compressor fridges – they use little power and run intermittently
    • laptop charging/use during the day
    • swamp coolers (due to high power fan motors)
    • gaming laptops run off solar during the day
    • 120v refrigerators off inverter
    • charging e-bikes, etc during the day
  • harder and more expensive to run - substantial ($$$) house power system - 400w+ of solar, 200Ah+ of battery
    • charging/ussing laptops at night
    • gaming consoles|laptops|PCs
    • charging e-bikes, etc at night
  • difficult and very expensive to run - $thousands in solar, battery, and alternator charging.

Note: devices that have "wall wart adapters" typically will not necessarily require an inverter.

sources of house power

Most campervans use solar combined with another charging source, usually the van's alternator. This combination can be both cheap and highly effective5)

Pro Con
shore power (outlet) cheapest per watt
abundant power
often not available
if available you are tied to the outlet by your cord/adapter
campgrounds with outlets are more expensive
solar automatically makes power when the sun shines
makes high voltages needed to fully charge lead-acid batteries
lasts for decades
most expensive per watt
can be complex
panels are large
output drops dramatically when shaded
alternator automatically makes power when driving
about 1/10th the cost of solar for the same current output
relatively low charging voltage6)
can result in chronic undercharging
should not idle to charge
most people don't drive enough to fully charge lead-acid
generator can make 1000w+ of 120v
can run for days
inverter models are quieter
can be expensive ($1000+)
needs to be stored when not in use
not allowed in some areas/times

Alternator & solar charging enhance each other when used together. Adding alternator charging to solar can significantly reduce the amount of solar required to meet your needs.

Note: So-called solar generators do not generate power: they are battery banks, usually AGM or lithium. See below.

use patterns

  • People who can camp in driveways can cheaply run shore power to the van with an extension cord.
  • people who weekend camp can charge the batteries from shore power on their return, augmenting with alternator, solar, or generator if needed
  • people who drive hours each day (delivery, trucking, etc) may be fine with DC-DC charging alone. This also applies to lithium chemistry batteries
  • people who spend long periods off-grid will probably want a robust solar install
  • people who want to run big loads off-grid can do it cheapest with a generator.

storing power

Power production tends to be heaviest during the day while power use tends to be heaviest overnight. This means power needs to be stored when power is abundant so it can be used later. The most common storage for power is in a deep cycle battery bank.

Pro Con
Flooded lead-acid (FLA) cheapest per Ah
most tolerant of abuse
lowest current throughput
maintenance (“watering”) required
can only use 50% of rated capacity7)
Sealed lead-acid (SLA, AGM) able to charge/discharge more current than FLA
no maintenance required
more expensive per Ah8)
cannot check or replace electrolyte
LiFePO4 (LFP) lithium very close to normal 12v ranges
available as “drop-in” replacements for lead-acid
current throughput
can be more deeply discharged than lead-acid
most expensive upfront per Ah
cannot be charged in freezing temperatures
Non-LFP lithium cheaper than LFP per Ah
current throughput
thermal runaway
voltage not well-suited for 12v systems

The battery bank is sized to meet your daily power needs and as well as any extra margin you might like.

using power

Using power is the simplest part. It's so simple the newbie may find themselves overdrawing from the available power. A low voltage disconnect (LVD) is one way to keep from overdischarging the bank.

trailers don't have chassis power
or doing something exotic like shallow cycling
which you will have to recharge somehow
see the pattern?
Isolators are inexpensive, and the combination allows one to run much smaller solar configurations than if one were charging by solar alone
unless b2b
or longevity suffers
~2x the price of FLA
electrical/12v/intro.txt · Last modified: 2021/07/08 11:30 by frater_secessus