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):
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 for most people.
|shore power|| cheapest per watt |
| 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 voltage5)
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
Note: So-called solar generators do not generate power: they are battery banks, usually AGM or lithium. See below.
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.
|Flooded lead-acid (FLA)|| cheapest per Ah |
most tolerant of abuse
| lowest current throughput
maintenance (“watering”) required
can only use 50% of rated capacity6)
|Sealed lead-acid (SLA, AGM)|| able to charge/discharge more current than FLA|
no maintenance required
| more expensive per Ah7)
cannot check or replace electrolyte
|LiFePO4 (LFP) lithium|| very close to normal 12v ranges |
available as “drop-in” replacements for lead-acid
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 |
| 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 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.