Every week, vehicles arrive at our workshop that tell the same story. Somebody saved money buying a cheap used campervan. Then they spent far more putting it right — or worse, discovered they'd been driving something genuinely dangerous.
This isn't a scare article. It's a practical guide based on what we actually see, written to help buyers make better decisions and understand what lurks behind the plywood and the fresh coat of paint on too many campervans currently for sale.
Why the Used Campervan Market Has a Problem
The campervan boom of the early 2020s created an enormous surge in DIY conversions. Vans were bought, converted in driveways and lockups, and then sold on — sometimes within months. Some of these conversions are excellent. Many are not.
The problem is that campervans occupy a strange regulatory gap. Unlike a house, there's no building inspector. Unlike a car, the conversion itself isn't MOT'd. A campervan can be sold with wiring and gas systems that would fail every safety standard in existence, and the seller is under no legal obligation to disclose it — because in many cases they genuinely don't know themselves.
Add to this the explosion of YouTube tutorials, the availability of cheap components, and buyers who are understandably excited about the lifestyle rather than focused on what's under the floor, and you have a market where dangerous vehicles change hands every single day.
Real Things We've Found at the Workshop
We're not going to name vehicles or owners. But the following are all real faults found in vehicles that arrived at Keltie Campers for inspection, diagnosis or upgrade work. In our experience, the two most serious recurring issues are unvented lead acid batteries and gas leaks caused by incorrect installations with no drop vents. Both can be fatal. Both are entirely preventable.
Lead acid batteries with no venting
This is the one that most people don't know about — and it's the one that can kill you.
When a lead acid battery fails or is overcharged, it emits hydrogen sulphide gas. This is the same toxic gas used as a chemical weapon. In an enclosed, unvented space — like a sealed campervan battery box under a seat or in a locker — hydrogen sulphide can accumulate to lethal concentrations very quickly. People have died in campervans and boats from unvented lead acid battery failures. This is not a theoretical risk. It has happened.
Every lead acid battery installation in a campervan must have a dedicated vent to the outside of the vehicle, sized and positioned correctly to allow gases to escape safely. We regularly see installations with no vent whatsoever — battery boxes sealed tight, installed in enclosed lockers with no airflow, in vehicles that people sleep in overnight.
Gas leaks and missing drop vents
Alongside unvented batteries, this is the fault we find most concerning — and the one that causes us most alarm when a vehicle arrives at the workshop.
LPG — the gas used in campervan cookers, heaters and fridges — is heavier than air. Unlike natural gas, which rises and disperses, LPG sinks to the floor and collects in the lowest point of the vehicle. A small, slow leak from a poorly made joint or a failing hose connection won't announce itself. It will accumulate silently at floor level, building concentration overnight while people sleep.
Drop vents are low-level vents cut into the floor of the van, sized and positioned to allow any leaked gas to escape out of the vehicle rather than collect inside it. They are a fundamental requirement under BS EN 1949:2021 — the governing standard for LPG installations in leisure vehicles. We regularly inspect campervans with gas appliances fitted throughout and no drop vents anywhere. In some cases the floor has been fully sealed and covered, making remedial work significant. In every case, the vehicle is unsafe to use with gas until the venting is correct.
Gas pipework faults compound this risk. The most common errors we find are flexible rubber hose used for fixed internal runs — which is not permitted for permanent pipework — and incorrect jointing, in particular PTFE tape applied to compression fittings. A compression fitting is sealed by the olive, not the thread. Applying PTFE tape can prevent the olive from seating correctly and create a leak at the joint. We also find unsupported pipework vibrating against the vehicle structure, and joints made in locations that are completely inaccessible for inspection or testing.
Batteries not properly secured
A leisure battery can weigh 25–30kg. In normal driving that weight needs to be held firmly in place. In an accident, an unsecured battery becomes a projectile — and if the terminals contact anything conductive during that impact, the consequences extend well beyond the crash itself.
We see batteries sitting loose in lockers, held in place with bungee cords, balanced on makeshift shelves, or simply wedged between pieces of furniture. None of these are acceptable. Batteries must be secured in a properly built battery box or with dedicated battery clamps rated for the weight involved.
Undersized cable throughout
Cable sizing is one of the most common electrical errors in amateur campervan conversions. Cable that is too thin for the current it carries generates heat. Sustained heat causes insulation to break down. Broken-down insulation causes fires.
We've inspected vehicles where almost every cable run was undersized — including the main feed from the battery. These vehicles had been on the road, been slept in, been used for months. The owners had no idea.
No fusing — or wrong fusing
Fuses exist to protect cable, not appliances. If a fault occurs and draws more current than the cable can safely carry, the fuse blows before the cable overheats. Remove the fuses, or fit fuses rated far higher than the cable, and you remove that protection entirely.
We regularly see unfused connections, fuses fitted in the wrong location, and circuits protected by fuses rated three or four times higher than the cable they're supposed to protect. In one vehicle, the inverter circuit had no fusing at all — connected directly to the battery with nothing in the circuit to interrupt a fault.
Poor or missing earthing
Earthing is the foundation of a safe and reliable 12V electrical system. A poor earth connection causes voltage drop, intermittent faults, equipment that works sometimes and not others, and in worst cases heat buildup at the connection point.
We see earth connections made to painted surfaces rather than bare metal, undersized earth cables, shared earth points with too many connections, and in some cases equipment with no earth connection at all. Poor earthing is the root cause of more electrical problems in campervans than almost anything else — and it's almost always invisible until it becomes serious.
The Buyer Beware Section — What to Check Before You Buy
Ask where the battery is and how it's vented
Find the leisure battery. Is it in an enclosed locker or box? Ask the seller to show you the vent. There should be a dedicated vent tube or aperture running from the battery enclosure to the outside of the vehicle. If there's no vent, that's a serious problem. If the seller doesn't know what you're asking about, that's also telling.
Check the gas installation — specifically the drop vents
Look at floor level near gas appliances for drop vents — low-level openings that allow gas to escape downward out of the vehicle. If you can't find them, ask the seller where they are. If there aren't any, walk away or factor significant remedial work into your offer.
Ask who installed the gas system and whether it was pressure tested and signed off by a qualified technician holding STGW (Standards of Training in Gas Work) certification — the NCC-recognised qualification for caravan and leisure vehicle gas work. Check that pipework is copper, steel or stainless steel for all fixed runs, and that flexible hose is only used at the bottle-to-regulator connection or at appliance connections as the manufacturer specifies.
Check that the battery is secured
The battery should be in a proper battery box, secured with clamps or brackets rated for its weight. It should not move when you push it. It should not be held in place with bungee cords, foam, or friction alone.
Look at the cable quality and sizing
Open the battery area. Are cables labelled? Are they properly terminated with crimped lugs? Does the cable size look appropriate for the distance it runs and the equipment it feeds? Thin, unlabelled cable running long distances to high-draw appliances is a red flag.
Check fuse ratings against cable sizes
Check that fuse ratings make sense for the cable they protect. A 40A fuse on a cable that's clearly only 2.5mm² is a problem. Cable should be rated above the fuse, not the other way around.
Test everything under load
Run the inverter. Use the hob. Turn everything on at once and look for lights dimming, equipment cutting out, or anything getting warm that shouldn't be. Faults that only appear under load won't show up if you just flick switches.
Consider a professional inspection before you buy
A pre-purchase inspection from a qualified specialist will cost a fraction of the remedial work that follows buying a poorly converted vehicle — and will tell you clearly what condition the vehicle is in before you commit.
There's a Reason a Good Conversion Costs More
This is worth saying plainly, because it gets to the heart of why this problem exists.
A properly built campervan conversion costs more because the work takes longer, the components are specified correctly, and the person doing it knows what they're doing. Proper battery venting means buying the right enclosure and routing a vent tube to outside the vehicle. Correct cable sizing means calculating load, accounting for run length, and buying cable rated for the job. Gas work done properly means a technician qualified to STGW standard, correct materials, pressure testing, and documentation.
None of this is complicated. But all of it takes time, knowledge and care — and all of it costs more than ignoring it.
When you see a conversion priced well below what comparable vehicles sell for, the question isn't whether corners were cut. It's which ones, and where. Sometimes the answer is cosmetic — a cheaper worktop or budget upholstery. Sometimes it's the battery vent. Sometimes it's the drop vents. You won't know until someone checks.
The lifestyle is genuinely brilliant — you can park up in places simply not accessible any other way, from Glencoe to the NC500 to the Jurassic Coast. But a campervan is a vehicle you sleep in, cook in, and run electrical equipment in overnight. It deserves to be built properly.
Frequently Asked Questions
Are DIY campervans legal to sell in the UK?
Yes — there is no specific law preventing the sale of a DIY campervan conversion in the UK. The conversion itself is not independently inspected or certified in most cases. This means the responsibility for checking safety falls largely on the buyer. Some professional conversions carry NCC certification, which provides a degree of assurance, but most private DIY conversions carry none.
Can a lead acid battery really be dangerous in a campervan?
Yes — seriously so. When a lead acid battery fails or is overcharged it emits hydrogen sulphide gas. In an unvented enclosed space the concentration can reach lethal levels. This has caused fatalities in campervans and boats. Every lead acid battery installation must have a dedicated vent to the outside of the vehicle. This is non-negotiable.
What is a drop vent and why does a campervan need one?
A drop vent is a low-level vent in the floor of a campervan that allows LPG gas to escape downward out of the vehicle if there is a leak. LPG is heavier than air — it sinks to floor level and collects rather than dispersing upward. Without a drop vent, leaked gas accumulates inside the vehicle. Drop vents are a requirement under BS EN 1949:2021 for any leisure vehicle with LPG gas appliances.
What gas pipework is correct for a campervan?
Under BS EN 1949:2021, fixed internal pipework must be copper, steel or stainless steel. Copper pipe with compression fittings is the most commonly used and entirely correct choice. The most frequent fault is incorrect jointing — specifically PTFE tape applied to compression fittings, which can prevent the olive seating correctly and cause a leak. Flexible hose is only permitted at the bottle-to-regulator connection or directly at an appliance where the manufacturer specifies it, and must be under 750mm in length. It must never be used for fixed internal runs.
Do you need to be Gas Safe registered to work on a campervan?
No — and this is widely misunderstood. Gas Safe registration is required for work on domestic premises and vehicles used for hire or business purposes. For privately owned touring caravans, motorhomes and campervans, the correct qualification is STGW (Standards of Training in Gas Work) — the NCC-recognised certification for caravan industry technicians. At Keltie Campers Ltd, our gas work is carried out to STGW standard, which is the qualification required by the NCC for approved workshop status.
What is the most dangerous fault in a badly converted campervan?
In our experience, unvented lead acid batteries and gas leaks from incorrect installations with missing drop vents are the two most serious recurring faults — both have been responsible for fatalities. Electrical faults including undersized cable and missing fusing represent a significant fire risk. Any of these alone warrants serious concern. Finding multiple faults in the same vehicle, which is common, compounds the risk considerably.
Why do good campervan conversions cost more?
Because doing the job correctly takes longer, requires better components, and demands the knowledge to specify everything properly. Battery venting, correct cable sizing, proper fusing, solid earthing and qualified gas work all add time and cost. That cost is the difference between a van that's safe to sleep in and one that isn't. When a conversion is priced significantly below market rate, it's worth asking what was left out.
How much does it cost to get a campervan inspected?
At Keltie Campers Ltd, a workshop inspection is carried out at our standard labour rate of £40 + VAT per hour. Most inspections take between two and four hours depending on the complexity of the vehicle. This is significantly less than the cost of remedial work on a poorly converted vehicle — and considerably less than the alternative.
Do you carry out pre-purchase campervan inspections?
Yes. Keltie Campers Ltd carries out electrical and habitation inspections from our workshop in Callander, Perthshire. We're 45 minutes from Edinburgh and Glasgow and regularly work on campervans, motorhomes and caravans from across the UK. Contact us to arrange an inspection before or after purchase.
Keltie Campers Ltd is based in Callander, Perthshire. We specialise in campervan and motorhome electrical systems, off-grid power installations and electrical diagnostics. We are Scotland's Victron Approved Installer for leisure vehicles and hold STGW gas certification as required by the NCC. If you have concerns about your vehicle's electrical system or gas installation, get in touch.
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