I’ve built electrical systems in four campervans. The first one had a battery that died after four months because I cheaped out and used the wrong charger. The second had a 2000W inverter that I used maybe three times in two years. The third had solar panels that never performed anywhere near the claimed output. The fourth? Finally got it right. Mostly.

Between those four builds, I’ve wasted £680 on batteries that failed prematurely, £240 on an inverter I didn’t need, and countless hours troubleshooting electrical issues that were my own fault. But I’ve also learned what actually works in the real world versus what the marketing claims.

After 30 years as a maintenance manager working with building electrical systems, you’d think I’d know better. And for mains voltage (230V) systems, I do. But 12V DC systems in vans have their own peculiarities, and I’ve learned them all the expensive way.

This guide is everything I wish I’d known before I bought my first leisure battery. Not the theory from textbooks. Not the perfect-world calculations. The actual reality of powering a campervan in the UK, what genuinely works, and how to avoid the expensive mistakes I made.

In this post, I will discuss the Best Campervan Batteries And Inverter Setup, sharing insights from my experiences and the essential components for a reliable electrical system.

Why Your Electrical System Matters More Than You Think

A bad electrical system doesn’t just mean no lights. It means:

• No fridge (food spoils, waste money)
• No heating controller (diesel heaters need 12V)
• No phone charging (can’t work remotely)
• No water pump (no water pressure)
• Sitting in darkness eating cold food like a cave dweller

Your electrical system is the most critical system after insulation. Get it wrong and your entire conversion is compromised.

What I’ve learned across four builds:

Van #1: Cheap 110Ah AGM battery (£95), basic split charge relay (£35), no solar. Battery died after 4 months because I was discharging it too deeply. Cost to replace: £150 for a better AGM. Total waste: £95 + time.

Van #2: Better 110Ah AGM (£180), DC-DC charger (£165), 100W solar (£180). Much better but still ran out of power in winter. AGM was too small for my actual usage.

Van #3: 200Ah AGM (£420), DC-DC charger, 200W solar (£280). Heavy (63kg), expensive, but worked reasonably well. Lasted 3.5 years before capacity dropped below 50%.

Van #4 (current): 105Ah lithium LiFePO4 (£449), Victron DC-DC charger (£157), 200W solar (£180), Victron MPPT controller (£85). Finally perfect. Indefinite power in summer, 2-3 days without charging in winter. Worth every penny.

Total money wasted learning: £680 on failed/inadequate batteries + £240 on wrong components = £920

But the knowledge gained: Priceless. Now I know exactly what works.

Understanding Your Actual Power Needs

Before you buy anything, you need to know how much power you actually use. Not what you think you’ll use. What you ACTUALLY use.

Everyone designs for massive power requirements they never need. I did this on van #2. Planned for laptop work all day, TV at night, electric kettle, hairdryer, the works. Reality? Used the laptop 2 hours max, never used the TV, used the gas kettle instead.

My Actual Daily Power Consumption (Van #4, Regular Use)

Let me show you real numbers from my current setup over a typical 3-day trip:

Lighting (LED):

• Interior lights: 15W total (3 lights x 5W)
• Average use: 4 hours per day
• Daily consumption: 15W x 4h = 60Wh = 5Ah @ 12V

12V Fridge (Alpicool C20, 20L compressor):

• Running: 45W
• Cycling: 50% duty cycle (on/off)
• Daily consumption: 45W x 12h = 540Wh = 45Ah @ 12V

Water Pump (Shurflo):

• Running: 40W
• Average use: 15 minutes per day
• Daily consumption: 40W x 0.25h = 10Wh = 0.8Ah @ 12V

Phone Charging (2 phones):

• Each phone: 15Wh
• Daily: 30Wh = 2.5Ah @ 12V

Laptop Charging:

• Laptop: 65W for 2 hours
• Daily: 130Wh = 11Ah @ 12V

Diesel Heater (Vevor 5kW):

• Running low: 15W
• Running high: 35W (startup: 100W for 2 minutes)
• Average winter use: 8 hours on low
• Daily consumption: 15W x 8h = 120Wh = 10Ah @ 12V

Misc (USB devices, speakers, etc.):

• Estimate: 20Wh = 1.7Ah @ 12V

Total Daily Summer Consumption: ~65Ah Total Daily Winter Consumption (with heating): ~75Ah

Reality check: I overestimated when planning. I thought I’d use 90-100Ah daily. Actual usage is 30% less.

How To Calculate YOUR Power Needs

Step 1: List every 12V device

Device	Watts	Hours/day	Wh/day	Ah/day
LED lights (total)	15W	4	60	5.0
Compressor fridge	45W	12 (cycling)	540	45.0
Water pump	40W	0.25	10	0.8
Phone charging	15W	2	30	2.5
…	…	…	…	…

Step 2: Add 20% contingency

You’ll always use more than planned. Things you forgot. Inefficiencies.

Step 3: Decide on days of autonomy

• Weekend warrior: 2 days (you’ll drive between trips)
• Regular user: 3 days (comfortable buffer)
• Off-grid living: 5-7 days (serious battery bank needed)

Step 4: Calculate required battery capacity

My example:

• Daily use: 75Ah (winter, worst case)
• Days autonomy: 3 days
• Total: 75Ah x 3 = 225Ah

BUT battery type matters here:

• AGM/Gel: Can only use 50% safely = Need 450Ah of AGM
• Lithium: Can use 100% safely = Need 225Ah of lithium (or 105Ah with solar)

This is why lithium is actually cheaper per usable Ah.

Battery Types: The Honest Comparison

I’ve used all three main types. Here’s what actually happens in real life.

AGM (Absorbed Glass Mat) Batteries

What they are: Lead-acid batteries with acid absorbed in glass mat. Sealed, no maintenance.

Costs:

• 110Ah: £150-£250 (Varta, Banner, Exide)
• 200Ah: £350-£500

Real-world specs:

• Usable capacity: 50% (discharge beyond this = damage)
• Weight: 30-32kg per 110Ah
• Lifespan: 300-500 cycles (2-4 years typical use)
• Charging: Need 14.4-14.7V (most alternators do 14.2V – barely adequate)
• Self-discharge: 3-5% per month

My experience:

Van #1: Budget 110Ah AGM (£95, no-name brand from eBay)

• Died after 4 months
• Why: Cheap, poor quality, I was discharging to 30% regularly (too deep)
• Lesson: Don’t buy cheap AGM

Van #2: Better 110Ah AGM (£180, Varta)

• Lasted 18 months
• Why it failed: 110Ah with only 55Ah usable wasn’t enough for my usage (60-70Ah daily)
• I was cycling it 80-100% depth daily
• That’s about 150 cycles – battery was done

Van #3: 200Ah AGM (£420, Banner)

• Lasted 3.5 years (about 400 cycles)
• Performed as expected
• But: Heavy (63kg), took up loads of space, slow to charge

Pros:

• Cheap upfront
• Available everywhere
• Work with simple charging systems
• Well understood technology

Cons:

• Heavy (63kg for 200Ah)
• Only 50% usable capacity
• Slow to charge (need 8-12 hours for full charge)
• Die quickly if discharged too deeply
• Limited cycle life (300-500 cycles)
• Need good ventilation (they off-gas hydrogen when charging)

Verdict: Adequate for budget builds or very light use. Not ideal for regular use or off-grid camping. I wouldn’t buy AGM again.

Best AGM if you must:

• Varta LFD90 (90Ah): £185
• Banner Energy Bull (110Ah): £215
• Exide Equipment Gel (80Ah): £195

Gel Batteries

What they are: Lead-acid with acid in gel form. Sealed, maintenance-free.

Costs:

• 80Ah: £180-£280
• 110Ah: £250-£380

Real-world specs:

• Usable capacity: 60% (slightly better than AGM)
• Weight: Similar to AGM (28-30kg per 110Ah)
• Lifespan: 400-600 cycles
• Charging: Need precise 14.1-14.4V (fussy about voltage)
• Self-discharge: 1-3% per month (better than AGM)

My experience:

Never used Gel in a van. I tested one in a mate’s van (Sonnenschein 80Ah, £240).

What I observed:

• Slightly better than AGM for deep discharge
• Very fussy about charging voltage (his DC-DC needed adjustment)
• Expensive for not much benefit over AGM
• Still heavy

Pros:

• Better deep discharge tolerance than AGM
• Lower self-discharge
• Longer lifespan than AGM
• Better for extreme temperatures

Cons:

• Expensive
• Still heavy
• Fussy about charging voltage
• Still only 60% usable capacity
• Hard to find in large sizes

Verdict: Marginal improvement over AGM for significant extra cost. Not worth it. If you’re spending this much, buy lithium.

Lithium LiFePO4 (Lithium Iron Phosphate)

What they are: Modern lithium battery chemistry. Completely different from lead-acid.

Costs:

• 100Ah: £380-£550 (Fogstar, Roamer, ECO-WORTHY)
• 100Ah: £550-£750 (Victron, Renogy, Battle Born – premium brands)
• 200Ah: £700-£1,200

Real-world specs:

• Usable capacity: 100% (can use full capacity safely)
• Weight: 11-13kg per 100Ah (about 1/3 of AGM)
• Lifespan: 2,000-5,000 cycles (8-12 years typical use)
• Charging: Need proper lithium charging profile (14.4-14.6V)
• Self-discharge: <3% per year (virtually none)

My experience:

Van #4: Fogstar Drift 105Ah (£449)

I resisted lithium for ages. “Too expensive,” I thought. £449 versus £180 for AGM? That’s 2.5x the cost.

But when you actually calculate cost per usable Ah over lifespan:

AGM (110Ah):

• Cost: £180
• Usable: 55Ah
• Lifespan: 400 cycles
• Cost per cycle: £0.45
• Cost per usable Ah per cycle: £0.0082

Lithium (105Ah):

• Cost: £449
• Usable: 105Ah
• Lifespan: 3,000 cycles (conservative)
• Cost per cycle: £0.15
• Cost per usable Ah per cycle: £0.0014

Lithium is actually 6x cheaper per usable Ah over its lifetime.

Real-world performance after 18 months:

• Can discharge to 0% without damage (I keep it above 20% anyway)
• Charges from 20% to 100% in 2.5 hours (versus 8 hours for AGM)
• Weighs 12kg versus 32kg for equivalent AGM
• Zero capacity loss (voltage still shows 13.3V after 18 months)
• Handles 100A loads without voltage sag (tried running 1200W inverter)
• Works perfectly in Scottish winter (-5°C) and Spanish summer (35°C)

Pros:

• 100% usable capacity
• Lightweight (1/3 of AGM)
• Fast charging (3-5 hours vs 8-12 hours)
• Long lifespan (2,000-5,000 cycles)
• Maintenance-free
• No voltage sag under load
• No off-gassing (no ventilation needed)
• Better for batteries in cold or hot weather

Cons:

• Expensive upfront
• Need proper lithium charger (DC-DC or MPPT with lithium profile)
• More complex BMS (Battery Management System)
• Can’t charge below 0°C (BMS prevents this)
• Fire risk if damaged (though LiFePO4 is safest lithium chemistry)

Common lithium myths I believed (all false):

Myth 1: “Lithium catches fire easily” Reality: LiFePO4 is incredibly stable. You’d have to really abuse it (short circuit, massive overcharge, puncture). AGM can off-gas hydrogen which is explosive. Both are safe if used correctly.

Myth 2: “Lithium dies in cold weather” Reality: Can’t charge below 0°C but works fine. I’ve used mine at -5°C. Just drive during the day (warms up from charging) or wait until above 0°C.

Myth 3: “Lithium needs expensive charging systems” Reality: You need a charger with lithium profile. A good DC-DC is £120-180. You needed a charger anyway.

Myth 4: “Lithium is dangerous to work with” Reality: Same precautions as any battery. Don’t short circuit. Fuse properly. Use correct cable sizes. I’m a maintenance manager – I know electrical safety. Lithium isn’t scary if you’re not an idiot.

Best lithium batteries I’d recommend:

Budget (£380-£450):

• Fogstar Drift 105Ah: £449 (what I use)
• Roamer 100Ah: £410
• ECO-WORTHY 100Ah: £385

These are Chinese-made with UK support. Work brilliantly. Fogstar has excellent UK customer service.

Premium (£550-£750):

• Victron 100Ah: £695
• Renogy 100Ah: £625
• Battle Born 100Ah: £750

Better warranty, premium components, slight performance edge. Worth it if you’re full-timing or want absolute best.

Verdict: Buy lithium. Seriously. The upfront cost hurts but it’s genuinely cheaper long-term and performs massively better. If I was building van #5 tomorrow, I’d buy Fogstar Drift 105Ah again without hesitation.

Charging Your Battery: What Actually Works

Battery is half the story. Charging is the other half. Get this wrong and even the best battery fails.

Method 1: Split Charge Relay (The Budget Option)

What it is: Simple relay that connects your leisure battery to your alternator when engine is running.

Cost: £30-£60

How it works:

1. Engine starts
2. Relay detects voltage rise (13.5V+)
3. Connects leisure battery to alternator
4. Both batteries charge
5. Engine stops
6. Relay disconnects (prevents leisure draining starter)

Pros:

• Cheap
• Simple
• Easy to install
• Works with any battery (AGM, Gel, Lithium with right voltage)

Cons:

• Inefficient charging (only charges when engine running at decent RPM)
• Can overcharge (alternator voltage varies)
• Can undercharge (many alternators only hit 14.2V – too low for proper AGM charging)
• Doesn’t isolate properly under all conditions
• Can drain starter battery if relay fails
• Slow charging (limited by alternator voltage)

My experience:

Van #1: Used a basic split charge relay (£35, Ring Automotive).

Worked. Technically. But:

• AGM never got fully charged (alternator was 14.2V, needed 14.7V)
• This contributed to battery dying after 4 months
• Slow charging (took 6+ hours driving to charge 110Ah from 50%)

Verdict: Only use this if:

• You’re on a very tight budget (under £500 total for electrics)
• You’re using AGM (not lithium – wrong charging profile)
• You drive a lot between stops (4+ hours)
• Your alternator is in good condition

Better option: Save another £100 and buy a DC-DC charger.

Method 2: DC-DC Battery Charger (The Right Way)

What it is: Intelligent charger that converts alternator voltage (12-14V) to optimal charging voltage for your battery (14.2-14.6V).

Cost: £100-£220

How it works:

1. Monitors both starter and leisure batteries
2. Only activates when starter is charged (13.5V+)
3. Draws power from alternator
4. Converts to optimal voltage for leisure battery type
5. Charges in proper 3-stage profile (bulk, absorption, float)
6. Protects both batteries

Pros:

• Proper charging profile (extends battery life)
• Works with AGM, Gel, and Lithium (selectable profiles)
• Fast charging (full current even at idle)
• Protects starter battery (won’t drain it)
• Protects leisure battery (won’t overcharge)
• Smart (adjusts to battery condition)

Cons:

• More expensive (£100-220)
• Slightly more complex to install
• Needs good alternator (old weak alternators struggle)

Popular models:

Budget (£100-£140):

• Renogy 20A DC-DC: £105
• CTEK D250SE: £125
• Sterling BB1230: £135

Mid-range (£150-£180):

• Victron Orion 12/12-18: £157 (what I use)
• Renogy 40A DC-DC: £165
• CTEK D250SA + Smartpass: £180

Premium (£190-£220):

• Victron Orion 12/12-30: £210
• Sterling BB1260: £215

Amperage matters:

• 18A charger = 18Ah per hour (5.8 hours for 105Ah battery from 0%)
• 30A charger = 30Ah per hour (3.5 hours for 105Ah battery from 0%)

But you need sufficient alternator capacity. My Transit has a 150A alternator. Using 30A for leisure charging is fine. Smaller vans might struggle.

My experience:

Van #2 & #3: Used a basic DC-DC (can’t remember brand, £120). Worked well. Better than split charge relay. AGM charged properly.

Van #4: Victron Orion 12/12-18 (£157). Perfect. Charges my lithium battery properly. Can monitor via Bluetooth app (shows charging voltage, current, state). Excellent bit of kit.

Installation tips:

Location: Close to leisure battery (within 1m). Shorter cable = less voltage drop.

Cable sizing:

• 18A charger needs 4mm² cable minimum
• 30A charger needs 6mm² cable minimum
• Use thicker if cable run is longer

Fusing: Must have fuse at both ends:

• Main fuse near starter battery (30A for 18A charger)
• Secondary fuse near leisure battery (25A)

Grounding: Negative cable direct to chassis near batteries. Not through van body.

Verdict: This is what you should buy. Victron Orion 12/12-18 (£157) for most people. Victron Orion 12/12-30 (£210) if you have a big battery and good alternator.

Method 3: Solar Panels (The Game-Changer)

What they are: Photovoltaic panels on your roof converting sunlight to electricity.

Cost: £180-£600 (panel + controller + mounting)

Typical setup:

• 100W panel: £90-£150
• 200W panel: £180-£280
• MPPT controller: £60-£150
• Mounting brackets: £25-£45
• Cable and connectors: £20-£40

What solar actually gives you (UK reality):

I have 200W solar (2 x 100W panels). Here’s real performance:

Summer (May-August):

• Perfect day: 80-90Ah
• Cloudy day: 40-50Ah
• Overcast: 20-30Ah
• Average: 60Ah/day

Spring/Autumn (March-April, September-October):

• Perfect day: 50-60Ah
• Cloudy day: 25-35Ah
• Overcast: 10-20Ah
• Average: 35Ah/day

Winter (November-February):

• Perfect day: 20-30Ah
• Cloudy day: 10-15Ah
• Overcast: 5-10Ah
• Average: 15Ah/day

Important: Marketing claims (100W = 500Wh/day) are based on California desert with perfect conditions. UK reality is 30-40% of that.

Solar controller types:

PWM (Pulse Width Modulation):

• Cost: £15-£40
• Efficiency: 70-80%
• Simple technology
• Don’t buy these. Waste of money.

MPPT (Maximum Power Point Tracking):

• Cost: £60-£150
• Efficiency: 93-97%
• Smart technology
• Extracts maximum power from panel
• Worth the extra cost

My solar journey:

Van #2: 100W panel (£90) + cheap PWM controller (£25)

• Performed poorly (maybe 30Ah on good summer day)
• Didn’t understand why at the time
• Controller was the bottleneck

Van #3: 200W panel (£180) + Better PWM controller (£45)

• Better but still disappointing
• Maybe 45Ah on good summer day
• Still using PWM (idiot)

Van #4: 200W panel (£180) + Victron MPPT 75/15 (£85)

• Night and day difference
• 60Ah on good summer day
• Even gets 15-20Ah on winter days

The MPPT controller made 30-40% difference in output. £85 well spent.

Best MPPT controllers:

Budget (£60-£90):

• Renogy Rover 20A: £65
• EPSolar 20A: £75

Mid-range (£85-£130):

• Victron MPPT 75/15: £85 (what I use)
• Renogy Rover Elite 40A: £120

Premium (£150-£200):

• Victron MPPT 100/30: £165
• Morningstar TriStar: £195

Solar panel recommendations:

Flexible panels (£90-£180):

• Easier to fit (curve with roof)
• Lighter
• More expensive
• Lower efficiency (15-17%)
• Shorter lifespan (5-8 years)

Rigid panels (£90-£200):

• Need proper mounting
• Heavier
• Cheaper
• Better efficiency (18-21%)
• Longer lifespan (20-25 years)

I use rigid panels (Renogy 100W x2, £180 total). Mounted with brackets and Sikaflex. Still going strong after 3 years.

Verdict: Solar is brilliant in summer, mediocre in winter. If you camp April-October primarily, solar gives you indefinite power. If you camp year-round, solar helps but you’ll still need to drive to charge in winter.

Budget £250-£350 for 200W solar with MPPT controller.

Method 4: Mains Hook-Up Charging (Campsite Power)

What it is: Plug into 230V campsite supply and charge batteries via mains charger.

Cost: £60-£150 for charger

When you need this:

• You use campsites regularly
• You want occasional full charge
• You’re parked up long-term

Charger types:

Basic (£60-£90):

• CTEK MXS 5.0: £72 (what I have)
• Noco Genius 10: £85

Smart (£110-£150):

• Victron Blue Smart 12/15: £125
• CTEK MXS 10: £140

My setup:

CTEK MXS 5.0 (£72). Lives in the van. Use it maybe 10 times a year when on campsites with electric hook-up (EHU).

Charges my 105Ah lithium from 20% to 100% in about 5 hours. Works fine.

Verdict: Nice to have, not essential. Buy if you use campsites regularly. Skip if you’re wild camping only.

Inverters: What You Actually Need (Versus What Marketing Says)

An inverter converts 12V DC (battery) to 230V AC (normal plug sockets).

The marketing: “You need a 2000W pure sine wave inverter for £300!”

The reality: Most people need a 600W inverter or no inverter at all.

Do You Even Need An Inverter?

What inverters are actually useful for:

• Charging laptops (65-90W)
• Running mains phone/camera chargers (10-20W)
• Occasional power tool use (200-600W)
• Hairdryer (requires 1000W+ inverter)

What you DON’T need an inverter for:

• Charging phones (use 12V USB sockets – £8)
• Running lights (use 12V LED lights)
• Running fridge (use 12V compressor fridge)
• Boiling kettle (use gas kettle – electric kettles need 2000W+)
• Making toast (use gas stove or campfire)

My inverter journey:

Van #1: No inverter. Used 12V USB sockets. Worked fine.

Van #2: Bought a 2000W pure sine wave inverter (£285). Used it maybe 8 times in 2 years:

• Laptop charging: 3 times (could’ve used 12V car charger)
• Power drill: 2 times (could’ve borrowed mains on campsite)
• Electric razor: 3 times (should’ve bought a battery one)

Total waste: £285. Sold it for £140. Lost: £145.

Van #3: Bought a 600W inverter (£85). Much more sensible. Used it regularly for laptop charging.

Van #4: Kept the 600W inverter. Use it 3-4 times per week for laptop charging. Perfect size.

Inverter Types: Pure Sine vs Modified Sine

Modified Sine Wave:

• Cost: £30-£80
• Output: Stepped approximation of sine wave
• Works for: Basic electronics, resistive loads (lights, kettles)
• Doesn’t work for: Sensitive electronics, some laptop chargers, motors
• Makes buzzing sound
• Less efficient

Pure Sine Wave:

• Cost: £60-£250
• Output: Smooth sine wave (like mains power)
• Works for: Everything
• Silent
• More efficient
• This is what you should buy

Don’t buy modified sine wave inverters. The £30 saving isn’t worth the compatibility issues and noise.

Inverter Sizing: What You Actually Need

Small (300-600W): £60-£120

• Laptop charging (65-90W)
• Phone/camera chargers (10-30W)
• Small power tools (200-400W)
• This is what most people need

Medium (1000-1500W): £140-£220

• Hairdryer (1000-1200W)
• Coffee machine (800-1200W)
• Microwave (800-1000W)
• Only if you actually use these

Large (2000-3000W): £250-£450

• Electric kettle (2000-3000W)
• Toaster (900-1500W)
• Powerful power tools (1500W+)
• Rarely needed in van

My recommendation:

600W pure sine wave inverter (£80-£120). This covers laptop, phone charging, and light power tool use.

Good options:

• LVYUAN 600W: £75
• Giandel 600W: £95
• Renogy 700W: £110

I use a Giandel 600W (£95). Works perfectly. Charges my laptop (65W), partner’s laptop (45W), phones, camera batteries. That’s all we need.

Efficiency reality check:

Inverters aren’t 100% efficient. Typical efficiency: 85-92%.

Example: Charging a 65W laptop

• Laptop draws 65W from inverter
• Inverter draws 65W ÷ 0.9 efficiency = 72W from battery
• At 12V: 72W ÷ 12V = 6A from battery
• For 2 hours: 12Ah from battery

Compare to:

• Using 12V laptop charger: 65W ÷ 12V = 5.4A = 10.8Ah for 2 hours
• Slightly better but need specialist 12V charger (£25-£45)

Verdict: Buy a 600W pure sine wave inverter (£80-120) if you need laptop charging or occasional 230V power. Skip it entirely if you can use 12V alternatives for everything.

Inverter Installation Tips

Location:

• Close to battery (within 2m)
• Well-ventilated (they get hot under load)
• Accessible (you’ll turn it on/off)
• NOT in a sealed cupboard (fire risk)

Cable sizing (critical):

Undersized cables = voltage drop, power loss, fire risk.

For 600W inverter:

• Maximum current: 600W ÷ 12V = 50A
• Cable needed: 10mm² minimum (I use 16mm²)
• Length: Keep under 2m if possible

For 1500W inverter:

• Maximum current: 1500W ÷ 12V = 125A
• Cable needed: 25mm² minimum
• Length: Keep under 1.5m

Fusing (absolutely essential):

Main fuse between battery and inverter:

• 600W inverter: 60A fuse
• 1500W inverter: 150A fuse

Use ANL fuses or MEGA fuses. Not automotive blade fuses (too small).

My setup:

Giandel 600W inverter connected with 16mm² cable (1.2m length). 60A ANL fuse at battery end. Inline switch to turn inverter on/off (saves standby drain).

Complete System Design: Three Levels

Let me show you three complete electrical systems at different budget levels.

Budget System (£580-£780)

For: Weekend warriors, tight budget, minimal power needs

Battery:

• 110Ah AGM (Varta LFD90): £185

Charging:

• Split charge relay: £35
• 100W solar panel: £120
• PWM controller: £35
• Shore power charger (CTEK MXS 5.0): £72

Distribution:

• 6-way fuse box: £35
• Cable (various): £40
• Fuses and connectors: £25

Outputs:

• 4x LED lights: £40
• 2x 12V sockets: £12
• 2x twin USB sockets: £20

No inverter (use 12V for everything)

Total: £619

Performance:

• 55Ah usable capacity (50% of 110Ah)
• 1-2 days autonomy (light use only)
• Slow charging (8+ hours from alternator)
• Summer solar: 20-30Ah/day
• Winter solar: 5-10Ah/day

Verdict: Bare minimum. Works for occasional weekend use with minimal electronics. Not adequate for regular use or working remotely.

Standard System (£1,180-£1,450) – RECOMMENDED

For: Regular users, comfortable power, year-round camping

Battery:

• 105Ah Lithium (Fogstar Drift): £449

Charging:

• Victron Orion 12/12-18 DC-DC: £157
• 200W solar panel (2x100W): £180
• Victron MPPT 75/15: £85
• Shore power charger (CTEK MXS 5.0): £72

Distribution:

• 12-way fuse box: £60
• Cable (various sizes): £85
• Fuses, terminals, connectors: £45

Outputs:

• 4x LED lights: £45
• 2x 12V sockets: £12
• 2x twin USB sockets: £20
• 600W pure sine inverter: £95

Optional:

• Battery monitor (Victron BMV-712): £185

Total: £1,305 (or £1,490 with battery monitor)

Performance:

• 105Ah usable capacity (100% of 105Ah)
• 2-3 days autonomy (normal use)
• Fast charging (3-4 hours from alternator)
• Summer solar: 50-70Ah/day (indefinite autonomy)
• Winter solar: 15-25Ah/day (extends autonomy significantly)

This is what I have. Works brilliantly. Perfect for 80-100 nights/year use. Can go off-grid for a week in summer. 3-4 days in winter.

Verdict: Sweet spot. Adequate power for real use. Fast charging. Solar makes huge difference. This is what I’d recommend for most people.

Premium System (£2,100-£2,600)

For: Full-time or near-full-time living, maximum power, redundancy

Battery:

• 200Ah Lithium (2x100Ah in parallel): £900 OR
• Victron 200Ah Lithium: £1,280

Charging:

• Victron Orion 12/12-30 DC-DC: £210
• 400W solar (4x100W or 2x200W): £380
• Victron MPPT 100/30: £165
• Victron Blue Smart mains charger 12/25: £185

Distribution:

• Premium fuse box with monitoring: £120
• Cable (various, larger sizes): £140
• Fuses, terminals, connectors: £70

Outputs:

• 6x LED lights: £65
• 3x 12V sockets: £18
• 3x twin USB sockets: £30
• 1500W pure sine inverter: £220
• Battery monitor (Victron BMV-712): £185

Total: £2,688 (with 2x100Ah Fogstar) Total: £3,068 (with Victron 200Ah)

Performance:

• 200Ah usable capacity
• 4-6 days autonomy (normal use)
• Very fast charging (2-3 hours from alternator)
• Summer solar: 100-140Ah/day (more than you’ll use)
• Winter solar: 30-50Ah/day (near-indefinite autonomy)

Verdict: This is full-time living spec. Massive battery, loads of solar, fast charging, 1500W inverter for hairdryer/coffee machine. Overkill for weekend use but perfect for 200+ nights/year.

My Actual System (Van #4) Detailed

Since this is what actually works in real life, let me break down every component and cost.

Battery:

• Fogstar Drift 105Ah LiFePO4: £449
• Rated 3000+ cycles
• 18 months old, zero capacity loss

Charging:

• Victron Orion 12/12-18 DC-DC: £157
• Charges from alternator while driving
• Victron MPPT 75/15 controller: £85
• 2x Renogy 100W rigid solar panels: £180
• CTEK MXS 5.0 shore power charger: £72

Distribution:

• 12-way bus bar fuse box: £62
• Main isolator switch: £18
• 100A ANL fuse (main): £12
• Various fuses and holders: £28

Wiring:

• 16mm² battery to fuse box (2m): £18
• 10mm² fuse box to inverter (1.5m): £12
• 6mm² solar to MPPT (8m): £22
• 4mm² DC-DC to battery (2m): £8
• 2.5mm² lighting circuits (15m): £14
• 2.5mm² 12V sockets (10m): £9
• Various connectors and terminals: £35

Outputs:

• 4x LED strip lights (5W each): £45
• 2x 12V cigarette sockets: £12
• 2x twin USB sockets (2.4A each): £20
• Giandel 600W pure sine inverter: £95

Monitoring:

• Victron BMV-712 battery monitor: £185
• Monitors voltage, current, Ah consumed, time remaining
• Bluetooth to phone app

Total system cost: £1,538

Performance over 18 months:

Summer (June-August):

• Daily use: 60-70Ah
• Solar generation: 50-80Ah/day
• Result: Never needed to drive to charge
• Battery stays 80-100% constantly

Winter (December-February):

• Daily use: 70-80Ah (heating + lights longer)
• Solar generation: 10-25Ah/day
• Result: Drive every 2-3 days (1-2 hours) to recharge
• Battery cycles 80% → 30% → 80%

Spring/Autumn:

• Daily use: 60-70Ah
• Solar generation: 30-50Ah/day
• Result: Drive every 3-4 days to top up
• Very comfortable

Actual cycle count after 18 months: ~180 cycles (monitoring shows this)

Estimated lifespan: 3000 cycles = 16+ years at current usage

Problems: None. Zero issues. System has worked flawlessly.

What I’d change: Nothing. This setup is perfect for my use (80-100 nights/year, mix of camping and working remotely).

Common Electrical Mistakes (That I Made)

Mistake 1: Undersized Battery (Van #1)

What I did: 110Ah AGM, using 60-70Ah daily

Math: 60Ah used ÷ 55Ah usable = 109% of capacity daily

Result: Deep cycling to 30% remaining every day. Battery died after 4 months (120 cycles).

Cost: £95 wasted + £150 replacement

Lesson: Size battery for actual usage plus 30% buffer. Don’t deep cycle AGM daily.

Mistake 2: Oversized Inverter (Van #2)

What I did: Bought 2000W inverter thinking I needed it

Reality: Maximum load ever used was 90W (laptop)

Cost: £285 for inverter, sold for £140 = £145 loss

Lesson: Calculate actual maximum load. Most people need 300-600W, not 2000W.

Mistake 3: Cheap PWM Controller (Van #2 & #3)

What I did: Used PWM controllers (£25-45) instead of MPPT

Result: Got 60-70% of possible solar output

Lost generation: 15-25Ah per day in summer

Cost over 2 years: Equivalent to £100-150 in campsite fees or fuel for charging

Lesson: MPPT controller (£85) pays for itself in 1-2 years. Don’t cheap out.

Mistake 4: Cable Too Small (Van #1)

What I did: Used 6mm² cable from battery to fuse box (3m length)

Load: 40A occasionally

Voltage drop: 40A x 3m x 0.0044 (resistance) = 0.53V drop

Result: Voltage at fuse box was 12.2V instead of 12.7V. Inefficient.

Cost: Not huge but wasted power

Lesson: Use proper cable sizing calculators. Don’t guess.

Mistake 5: No Battery Monitoring (Van #1-3)

What I did: Relied on voltage readings to estimate battery state

Problem: Voltage is a terrible indicator of lithium battery state

Result: Never knew actual state of charge. Overestimated or underestimated constantly.

Fix: Bought Victron BMV-712 (£185) for van #4

Lesson: Battery monitor is worth it. Know exactly what’s happening with your power.

Mistake 6: Fuse Box Too Small (Van #1)

What I did: 6-way fuse box

Reality: Needed 10 circuits (lights x4, 12V sockets x2, fridge, water pump, diesel heater, inverter)

Result: Had to add inline fuse holders (messy, not ideal)

Cost: £15 for inline fuses, plus time to redo

Lesson: Buy 12-way fuse box (£60) even if you only need 8 circuits initially. You’ll add more.

Mistake 7: Battery Location Wrong (Van #2)

What I did: Put 63kg AGM battery in back corner (1.5m from fuse box)

Result: Needed 2.5m cable run. Voltage drop. Also weight distribution was off (tail heavy).

Cost: Extra cable (£28), handling issues

Lesson: Battery should be central and low for weight distribution, close to fuse box for efficiency.

Critical Safety Stuff (Don’t Skip This)

I’m a maintenance manager. I’ve seen electrical fires. Don’t be an idiot with your van electrics.

Essential safety components:

1. Main fuse/breaker (100-150A):

• Between battery positive and everything else
• ANL fuse or MEGA fuse
• Close to battery (within 30cm)
• This prevents cable fires if there’s a short
• Cost: £12-25

2. Circuit fuses:

• Every circuit must be fused
• Size fuse to cable rating, not device rating
• Use automotive blade fuses (10A, 15A, 20A, 30A)
• Cost: £2-5 per circuit

3. Isolator switch:

• Main switch to disconnect battery
• Use when working on system
• Use when van stored long-term
• Cost: £18-35

4. Proper cable sizing:

• Use cable sizing calculators
• Account for length and current
• Bigger is always safer
• Cost: Variable but worth it

Cable size guide (12V, 3m max length):

• 0-10A: 1.5mm²
• 10-20A: 2.5mm²
• 20-40A: 4mm²
• 40-60A: 6mm²
• 60-100A: 10mm²
• 100-150A: 16mm²
• 150-200A: 25mm²

5. Quality terminals:

• Crimp properly (ratchet crimpers)
• Heat shrink over connections
• No twisted wire connections
• Cost: £30-50 for assortment

6. Ventilation:

• AGM/Gel batteries off-gas hydrogen when charging
• Lithium doesn’t but still needs ventilation for heat
• Battery compartment must vent to outside
• Cost: £15-25 for vent

7. Fire extinguisher:

• Keep one near battery area
• ABC or CO2 type
• Check annually
• Cost: £25-40

Electrical safety checklist before first use:

• [ ] Main fuse installed and correct rating
• [ ] All circuits fused correctly
• [ ] All cables correct size for current
• [ ] All terminals crimped properly
• [ ] No exposed connections
• [ ] Battery secured (can’t move in crash)
• [ ] Isolator switch installed and accessible
• [ ] Ventilation adequate
• [ ] Fire extinguisher accessible
• [ ] Tested all circuits with multimeter
• [ ] No shorts or voltage drops
• [ ] System works under load

Don’t:

• Wire directly to battery without fusing (fire risk)
• Use automotive wire for high current (too thin)
• Twist wires together (connections fail)
• Over-fuse circuits (cables overheat)
• Put battery in sealed box (gas buildup)
• Work on live circuits (get shocked)
• Assume anything is safe without testing

Tools Needed for Electrical Work

Essential:

• Multimeter (£15-45)
• Wire strippers (£15-25)
• Ratchet crimpers (£25-40)
• Cable cutters (£12-18)
• Screwdrivers (£15-25)
• Hole saw set for cable entry (£25-35)

Useful:

• Heat gun (£20-40)
• Cable tie gun (£12)
• Label maker (£25)
• Electrical tape (£5)

Total: £145-250

My Final Recommendations

After four van builds and £920 wasted on wrong choices, here’s what I’d buy today:

For most people (£1,200-£1,500):

Battery: Fogstar Drift 105Ah (£449) DC-DC Charger: Victron Orion 12/12-18 (£157) Solar: 200W panels (£180) + Victron MPPT 75/15 (£85) Mains Charger: CTEK MXS 5.0 (£72) Inverter: 600W pure sine (Giandel, £95) Distribution: 12-way fuse box (£60), cable (£85), fuses/terminals (£45) Outputs: Lights, sockets, USB (£80) Battery Monitor: Victron BMV-712 (£185)

Total: £1,493

This gives you:

• 105Ah usable (2-3 days autonomy)
• Fast charging from alternator
• Solar for summer independence
• Mains charging for campsites
• Inverter for laptop/phone charging
• Monitoring to know exactly what’s happening

Perfect for 50-150 nights/year use. Comfortable power for working remotely. Indefinite off-grid in summer, 2-3 days in winter.

This is exactly what I have. Zero regrets.

Final Thoughts

Your electrical system is the heart of your conversion. Everything else depends on it working properly.

I’ve wasted £920 learning what works. Don’t repeat my mistakes:

• Don’t buy cheap AGM that’ll die in months
• Don’t buy oversized inverters you’ll never use
• Don’t use PWM controllers when MPPT is available
• Don’t undersize cables or skip fusing
• Don’t guess at battery sizing – calculate properly

Lithium costs more upfront but it’s genuinely cheaper long-term and performs massively better. DC-DC charging is worth every penny over split charge relays. MPPT solar controllers extract 30-40% more power than PWM. Battery monitors tell you what’s actually happening.

The system I have now – £1,493 total – has been flawless for 18 months. Powers everything I need. Charges fast. Lasts for days. Works in Scottish winter and Spanish summer.

If I built van #5 tomorrow, I’d buy exactly the same components. That’s how I know I finally got it right.

Now stop reading, calculate your actual power needs, and build a system that’ll actually work. Your future self will thank you when you’re sitting in a cozy lit van with a charged laptop while everyone else is running out of power.

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