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electrical:12v:intro

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 we start: there are two generally-separate electrical systems in your self-propelled camper1):

  • 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)

Most campervans use solar combined with another charging source, usually the van's alternator. This combination is cheap and highly effective if you pay attention to your usage.

what you can run in the van

Things that are run off the van's 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.

  • easy/cheap to run
    • phone and tablet charging
    • laptop charging/use if you do it when the sun is shining
    • ventilation
    • CPAP
    • 12v compressor fridges – they use little power and run intermittently
  • harder and a little more expensive to run
    • laptop charging/use if you do it at night
    • swamp coolers (due to high power fan motors)
    • gaming laptops
    • 120v refrigerators off inverter
    • charging e-bikes, etc during the day
  • hard and expensive to run
    • gaming laptops at night
    • heating or cooking with electricity, which is why we use propane
    • air conditioning, which is why we go where it is cooler
    • electric coffee makers, which is why we use propane3)
    • charging e-bikes, etc at night

sources of house power

Pro Con
shore power cheapest per watt
simple
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
silent
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 voltage4)
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+)
maintenance
needs to be stored when not in use
noisy
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.

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 capacity5)
Sealed lead-acid (SLA, AGM) able to charge/discharge more current than FLA
no maintenance required
more expensive per Ah6)
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.

1) trailers don't have chassis power
2) or doing something exotic like shallow cycling
3) see the pattern?
4) unless b2b
5) or longevity suffers
6) ~2x the price of FLA
electrical/12v/intro.txt · Last modified: 2019/12/06 20:26 by frater_secessus