By Santi — Head Van Engineer — December 9, 2025
Van Life Essentials — Why Power Planning Matters
If you’re planning a build, van life essentials start with a clear power plan. Your battery bank, charging strategy, and inverter define how far you can roam off‑grid and how reliably your systems run. A good design balances weight, cost, and independence while keeping safety front and center. This guide walks through battery chemistry, alternator limits, solar sizing, inverter selection, wiring basics, and a short troubleshooting flow so you can make confident choices for a weekend rig or a full‑time build. Expect practical examples and straightforward tradeoffs — no fluff.
Typical power needs on the road (lighting, fridge, charging devices, AC vs no AC)
Common loads in a 2‑person van: a 12V compressor fridge (30–60 Wh/hr while running), LED cabin lights (a few Wh/hr), water pump cycles, and phones/laptops (50–150 Wh/day). Add an inverter for 120V devices and daily consumption can climb fast. A simple method: estimate daily watt‑hours and convert to amp‑hours at 12V: Wh ÷ 12 = Ah. Example: 1,000 Wh/day ≈ 83 Ah/day — we use this worked conversion in the Batteries section below. In practice, keep a short log of your real usage for a week; the numbers almost always surprise new builders (in a good way — you learn what to optimize first).
Trade‑offs: weight, space, cost, and complexity
More battery capacity gives autonomy but costs weight and cash. Lithium (LiFePO4) offers much more usable capacity per pound than lead‑acid but has higher upfront cost. Solar reduces alternator dependency but needs roof area and careful placement. A DC‑DC charger adds cost and complexity yet often pays off in longevity and reliable charging—especially with LiFePO4 systems.
Batteries — Types, Pros/Cons, and Sizing
Battery chemistries explained: Lead‑acid (flooded/AGM/GEL) vs Lithium (LiFePO4)
Lead‑acid (flooded, AGM, GEL) is cheaper but heavier and typically limited to ~50% usable DoD for longevity. Flooded cells need ventilation. LiFePO4 is lighter, supports 80–90% usable DoD, and delivers thousands of cycles with a proper BMS. For full‑time or heavy use we recommend LiFePO4 for the usable capacity and lifecycle advantages — many folks end up saving money over several years despite the higher upfront cost.
Key specs: capacity (Ah), depth of discharge, C‑rate, cycle life, temperature limits
When choosing cells, check usable Ah at system voltage, continuous and peak discharge (C‑rate), rated cycle life at specified DoD, and operating temperature limits. LiFePO4 often requires temperature‑aware charging below freezing; some packs include heaters or the charger must limit charging when cold. A quick rule: document the extremes you expect (hot/cold) and confirm the battery vendor’s specs for those conditions.
How to size a battery bank — worked example for a 2‑person van
Worked example (moderate usage):
- Fridge: 40 Wh/hr × 24 hr = 960 Wh/day
- Lights & pump: 150 Wh/day
- Phones/laptop: 150 Wh/day
Battery management systems (BMS) and monitoring (SOC, voltage alarms)
A robust BMS is essential for lithium packs (cell balancing, over/under‑voltage, temperature cutoffs). Add monitoring (SOC, voltage, current logs)—this is the single most effective habit to extend battery life and avoid surprises. If you’re curious about upgrade paths, see our EKKO Lithionics battery upgrade case study for a real‑world example of improving on‑vehicle capacity and monitoring: EKKO Lithionics battery upgrade.
Charging Sources — Alternator, Shore Power, and Solar
Alternator charging basics — what the vehicle alternator can and can’t do
Alternators are convenient but rarely provide the multi‑stage, chemistry‑aware charging profiles batteries prefer. Bulk charging a large house bank directly from the alternator can overheat the alternator or leave LiFePO4 undercharged. For reliable alternator charging, use a DC‑DC charger or a smart isolator to manage voltage and protect both starter and house batteries. I've seen weekend rigs work fine with a simple isolator, but long‑term or heavy use nearly always benefits from a DC‑DC solution.
When to use a DC‑DC charger vs direct alternator connection (voltage regulation, multi‑battery systems)
Choose a DC‑DC charger if you have a sizable house bank, LiFePO4 chemistry, or want optimal charging while driving. DC‑DC units handle alternator voltage fluctuations, provide correct charge profiles, and isolate the starter battery. For light weekend setups with a small lead‑acid tank, an isolator might work short‑term, but DC‑DC is the safer long‑term choice. We install and service DC‑DC systems as part of our electrical packages—book a consult if you want a systems review: Book a consult.
Shore power and converter/charger selection (smart chargers, multi‑stage charging)
When plugged in, use a multi‑stage charger with a profile that matches your battery chemistry (LiFePO4‑capable or selectable profiles). Match charger amperage to the battery bank size—30–60 A chargers are common for vans. If mixing shore, alternator, and solar, make sure each source is configured so they don’t fight each other. A short checklist: verify profiles, set appropriate float voltages, and stagger sources if needed.
Solar basics for vans — panels, charge controllers (PWM vs MPPT), realistic production estimates
MPPT charge controllers outperform PWM, particularly in non‑ideal light or cold conditions. A 400 W roof array under good conditions might yield 1,600–2,000 Wh/day, but production varies by season and location. For realistic solar planning and calculators see our sizing guide: How much solar do I need for van life? and our deeper system explainer at How to power your van: solar, batteries & electrical explained.
Inverters & AC Power — Choosing the Right Unit
Pure sine vs modified sine: which to use for sensitive electronics
Pure sine inverters are the recommended default. They run sensitive electronics, chargers, and motors cleanly. Modified sine inverters can work for simple resistive loads but may introduce noise or cause certain devices to behave poorly. For reliability and fewer headaches, pick a pure sine inverter sized for your expected continuous and surge loads.
Continuous vs surge rating; sizing for common appliances (kettle, microwave, hair dryer)
Match inverter continuous rating to your running loads and ensure the surge rating covers motor starts. Kettles and hair dryers are high draw (1,500–2,500 W) and typically require shore power or a very robust inverter plus a large battery/charging system. Many Vansmith builds use 300–1,000 W inverters depending on expected AC usage.
Installation considerations: placement, ventilation, remote panel, and safety interlocks
Mount inverters where airflow is adequate and keep DC runs short. Use a remote on/off panel and install a transfer switch or interlock if you’ll combine shore and inverter power. Always fuse the battery positive within a few inches of the terminal.
Wiring, Fusing & System Layout — How Components Connect
Block diagram: alternator -> DC‑DC/isolator -> house battery -> inverter/loads/charger/solar
System flow: alternator → DC‑DC charger/isolator → house battery. Solar → MPPT → house battery. Shore → AC charger → house battery. Inverter draws from house battery and feeds AC loads. This layered approach protects the starter system and keeps charging predictable.
Cable sizing basics, voltage drop, and choosing the right fuse/breaker
Use a voltage drop calculator and wiring charts for gauge selection. As a quick reference, 50 A short runs commonly use 6 AWG; longer runs need thicker cable. Fuse at the battery positive terminal with the fuse rated just above expected continuous current but below the cable’s max rating. Place fuses within inches of the battery for safety.
Grounding and common mistakes to avoid
Follow inverter and charger manufacturer grounding guidance. Avoid undersized cable, fuses placed far from the battery, poor crimping, and mixed charger profiles without isolation. Use proper lugs, heat‑shrink, and corrosion prevention on terminals.
Safety, Maintenance & Troubleshooting
Battery safety: ventilation, mounting, spill containment (for flooded), thermal protection
Secure batteries with straps and racks. Flooded cells require ventilation and spill containment. LiFePO4 needs a BMS and consideration for cold climates—either a heated enclosure or chargers that prevent charging below safe temperatures.
Fire prevention: fuses, breakers, correct wiring practices, and smoke/CO detector placement
Fuse on the positive side at the battery. Use appropriately rated breakers into inverters and keep wiring neat and supported. Install smoke and CO detectors in the living area and test them regularly.
Routine maintenance checklist (battery health, connections, charge profiles)
Inspect terminals and lugs for corrosion, torque per spec, verify SOC and charger logs, and ensure charger profiles match battery chemistry. Check alternator and DC‑DC operation under load periodically.
Quick troubleshooting flow: no charging from alternator, inverter tripping, rapid battery drain
No alternator charge: check DC‑DC/isolator fuse, alternator output, and wiring. Inverter trips: check surge loads and battery voltage under load. Rapid drain: log Wh usage, isolate loads, and look for parasitic draws like always‑on controllers or a fridge running due to thermostat faults. A small multimeter and a habit of logging symptoms will save hours and often point you to the easy fixes first.
Component & Parts Checklist (Campervan Supplies)
Recommended components by use‑case (weekend van, off‑grid full‑timer)
Weekend: 100–200 Ah house battery (AGM or small LiFePO4), 200–400 W solar, 300–500 W pure sine inverter, basic DC‑DC or isolator. Full‑timer: 200–600 Ah LiFePO4 bank, 400–800 W+ solar, 30–60 A MPPT, 30–60 A DC‑DC, 1,000 W pure sine inverter or larger depending on AC needs.
Example part specs: LiFePO4 100Ah, 300–1000W pure sine inverter, 30–60A DC‑DC charger, MPPT 30A
Typical parts: 100 Ah LiFePO4 modules, MPPT charge controllers in the 30–100 A range, 30–60 A DC‑DC chargers, 2–4 AWG battery‑to‑inverter cable for high current, and ANL/MCB fuses sized appropriately.
Tools and supplies for installation: test meter, crimper, heat‑shrink, ANL/MCB fuses, cable lugs
Bring a quality multimeter, ratcheting crimper, heat‑shrink, torque wrench, and spare fuses. If you plan to DIY, follow best practices or consult a professional for high‑current systems; The Vansmith offers installation and troubleshooting services.
Ready to scope your build?
Book a consultFrequently asked questions
How much battery capacity do I need for van life?
Estimate daily watt‑hours (Wh), convert to amp‑hours at 12V (Wh ÷ 12 = Ah), and add margin. Lead‑acid: avoid >50% DoD; LiFePO4: 80–90% usable DoD. Example: 1,000 Wh/day ≈ 83 Ah/day; a 100 Ah LiFePO4 covers about 1 day; a lead‑acid bank would need roughly 200 Ah to provide the same usable capacity.
Can I charge my house batteries from the alternator?
Yes, but alternator charging has limits. Many alternators lack multi‑stage charging and can overheat if bulk‑charging a large house bank. Use a DC‑DC charger or smart isolator to regulate voltage and protect batteries—especially LiFePO4.
Do I need a pure sine inverter for a campervan?
Pure sine is recommended for sensitive electronics and modern chargers. Modified sine can run simple resistive loads but may cause issues with motors, microwaves, or battery chargers.
How do I keep my battery safe and extend its life?
Use correct charging profiles, avoid extreme temps, securely mount and ventilate batteries (flooded types), use a proper BMS for lithium, fuse positive runs close to the battery, and monitor SOC regularly.
What fuse sizes and cable thickness should I use?
Sizes depend on current and run length. Use voltage‑drop calculators and wiring tables. As a quick guide, 50 A short runs often use 6 AWG; larger currents need thicker cable. Fuse near the battery and size to protect the cable and equipment.
Can solar replace alternator charging?
Solar can significantly reduce alternator reliance but depends on panel area, weather, and usage. A hybrid approach (solar + DC‑DC + adequate battery) is often the most reliable. For more on solar sizing and realistic production, see our guide linked earlier.
Further reading and tools: check our system explainer and solar sizing guide linked above. If you'd like a pro to review your proposed system or a quote for installation, book a consult with our team.
