How To Stay Warm In Your Truck Without Idling All Night (2026)

Affiliate disclosure: As an Amazon Associate, Trucker Gear HQ earns from qualifying purchases. This works the same whether you're a company driver, leased on, or running under your own authority — the cold doesn't check who holds the title.

The short version: You don't beat a cold bunk with one purchase. You beat it with four layers of the same idea — keep the heat you already make, add a little heat cheaply, store some power for the things that must run, and put a carbon monoxide detector where your head is before you do any of it.

1. Insulate first — window covers and a curtain, because it's free-ish and it multiplies everything else
2. Dress for it — a thermal base layer under your clothes does more than a heater does
3. Store power — a portable power station for the CPAP, the fridge, the electric blanket
4. Detect CO — non-negotiable the moment any combustion heater enters the picture

That order matters. Every dollar you spend on insulation and layers makes the power you're storing last longer. Do it backwards and you buy a bigger battery to heat the outdoors.

Why the engine-off night keeps happening

It isn't one thing. It's a stack of them, and most drivers hit at least one every winter:

• State and local anti-idling rules. Many states and quite a few cities restrict extended idling, with time limits and exemptions that vary by jurisdiction. Some carve out a specific exception for sleeper berths in cold weather, some don't. Check the rule for the state you're actually parked in — this is one of the few areas where "everybody does it" gets you a real ticket.
• Company policy. Plenty of fleets run idle-shutdown timers regardless of what the state allows.
• The APU is down. They fail, and they fail in January.
• Fuel math. A truck idling burns roughly a gallon an hour. Ten hours a night, a few nights a week, and that's a number worth doing something about — especially if you're the one buying the fuel.

None of those are solved by toughing it out. They're solved by a bunk that holds heat.

Step 1: Insulation, because it's the cheapest heat there is

A truck cab is a metal box with a lot of glass. Glass is where your heat goes.

• Windshield and side window covers. Reflective insulated covers are the single highest-return item here. They cut the radiant loss through the biggest openings you have, and they cost less than one night in a motel.
• A real bunk curtain that seals. Heating the sleeper is a much smaller job than heating the sleeper plus the whole cab and dash area. If your curtain has gaps at the top or the sides, closing them is free.
• Cover the floor. A cheap rug or foam mat over bare metal or vinyl stops a surprising amount of loss, and it makes getting up at 4 a.m. considerably less unpleasant.
• Vent covers. Roof vents leak heat. If yours doesn't seal, that's a five-dollar fix.

Do this part first. Everything below works better afterward, and this is the only step that costs you nothing to run.

Step 2: Layers beat heaters

The heat you're trying to keep is heat your own body is already producing. A base layer keeps it against you instead of letting it escape into the bunk, and unlike anything electric, it draws zero amps all night.

What actually works in a truck:

• A thermal base layer top and bottom. The point of a good set is that it's thin enough to wear under your jeans all day, so you're not changing clothes in a parking lot at 5 a.m. to fuel.
• A full-zip mid layer. A zip matters more than it sounds like it does. You're in and out of the truck a dozen times a day, and a zip fleece comes off without pulling it over your head — which is the difference between shedding a layer and staying overheated because it's a hassle.
• Wool or cushioned socks, and a spare pair for sleeping only. Sleeping in the socks you drove in is why your feet are cold. They're damp.
• A hat. Unglamorous, effective, costs nothing to run.
• A proper sleeping bag rated below what you expect. A rated bag on top of your normal bedding outperforms piling on more blankets, and it packs down.

Our picks for the base and mid layers are in the trucker workwear basics roundup.

Step 3: Store power for the things that have to run

Layers handle you. They don't handle a CPAP, a fridge, or an electric blanket. That's what a portable power station is for — a battery with outlets, charged while you drive, spent while you sleep.

The sizing question is the only one that matters, and it comes down to what you're actually running:

What you're running	Rough overnight need	Ballpark size
Phone, laptop, a fan	Small	~300Wh is plenty
CPAP (no humidifier/heated hose)	~30-60Wh per hour	500-1000Wh
CPAP + 12V fridge	Meaningful, all night	~1000Wh is the sweet spot
Above plus a heated blanket	Larger	1000Wh minimum, 2000Wh comfortable
A resistive space heater	Don't	See below

The honest note on electric heat: a 1500W electric space heater pulls 1500 watt-hours every single hour. Even a 2000Wh station runs one for a bit over an hour. Electric resistance heat is the one job portable power stations are genuinely bad at, and anyone telling you otherwise is selling something. What they are good at is a heated blanket or a 12V heated mattress pad, which pull a small fraction of that because they're heating you instead of the air around you. That's the trick: heat the person, not the box.

Two things to check before you buy:

1. Recharge speed matters as much as capacity. If you only drive six hours between rests, a station that takes eight hours to refill is the wrong station no matter how big it is.
2. Pure sine wave output if you're running a CPAP. Confirm it, and confirm your specific machine's requirements with its manufacturer.

Our picks by size are in the portable power station roundup. If you'd rather hard-wire a proper auxiliary battery setup instead of using a portable unit, that's the 12V sleeper cab power guide.

Step 4: The one that isn't optional

Everything above is comfort. This part isn't.

The moment anything burning fuel is keeping you warm — a diesel bunk heater, an APU, an idling engine, a propane heater — carbon monoxide is on the table. So is a cracked manifold or an exhaust leak you haven't found yet.

And here's the part most drivers never think about: you can be completely shut down and still take on CO from the trucks idling on either side of you at a packed truck stop. Your engine being off is not the same as being safe.

Why this is worse for drivers specifically: early CO symptoms are headache, dizziness, nausea, confusion, and fatigue. Read that list again. Every one of them is something a driver at the end of a fourteen-hour day writes off as being tired. You feel foggy, you blame the miles, and you go to sleep. That's the trap.

Three rules:

1. Put it at breathing level — near where your head is when you sleep, not on the floor. Keep it clear of a heater's exhaust vent and out from behind curtains or gear.
2. Check the date. The sensor degrades whether it ever alarms or not, typically over five to ten years depending on the unit. An expired detector looks and beeps exactly like a working one. Go by what your manufacturer states.
3. If it goes off, get out first. Fresh air, then diagnose. Don't sit inside deciding whether it's a false alarm. A real exposure is a 911 call and a medical evaluation — we picked hardware, we're not safety inspectors.

The units we'd put in a sleeper are in the CO detector roundup.

The heater options, ranked by how much trouble they are

Diesel bunk heater (Espar / Webasto style)

The real answer if you're keeping the truck a while. It burns a fraction of what idling does — commonly cited around a tenth of a gallon an hour versus roughly a gallon idling — and it's designed for exactly this. It's also the most expensive to buy and install, and it's a combustion appliance, which puts the CO detector above squarely in play. Worth pricing out if you own the truck and run cold country.

12V electric blanket or heated mattress pad

The best cost-to-comfort ratio on this whole page. Small draw, heats you directly, works off a modest power station or a properly fused 12V circuit. If you buy one thing after the window covers, make it this.

Portable propane heater

Powerful and cheap to run — and the option that demands the most respect. Combustion inside a small sealed space means both CO and oxygen depletion, so ventilation is mandatory and a detector is mandatory. Check your company policy too; many prohibit them outright. If you carry propane, get a detector that covers propane as well as CO.

APU

The full solution if the truck is yours and the money is there. Nothing else does heat, cool, and hotel power off one unit. Still a combustion appliance — its exhaust can get pushed back at the cab by the wind, which is another reason the detector isn't optional.

Small things that punch above their weight

• Thermos of something hot before you shut down. Fill it at the counter while you're inside anyway.
• Eat before bed. Digestion generates heat. This is not folklore.
• Crack a window slightly. Counterintuitive, but sealing a cab completely traps the moisture from your breathing, and damp bedding is cold bedding. It also matters for air exchange if anything is burning.
• Warm the bunk before you shut down, not after. Run the heat hard for the last ten minutes of driving with the curtain closed. You're storing heat in the mattress and the walls.
• Low-draw LED lighting instead of the dome light, so you're not spending your stored power on light. The picks are in the truck interior lights roundup.

What this costs, in tiers

• Under a hundred dollars: window covers, a base layer set, good socks, a CO detector. This tier is most of the benefit and it's the one nobody regrets.
• A few hundred: add a mid-size power station and a 12V heated blanket. Now the CPAP and the fridge are handled and you're genuinely warm.
• Serious money: a bunk heater or an APU, professionally installed. Right call if you own the truck, run cold lanes, and plan to keep it.

Common questions

Is it illegal to idle overnight?

It depends entirely on where you're parked. Many states and cities limit extended idling, and the limits, penalties, and exemptions differ — some specifically exempt sleeper-berth heating below a certain temperature, some don't. Check the rule for that state rather than assuming.

Will a portable power station run a space heater all night?

No. A 1500W heater consumes 1500Wh per hour, so even a large station lasts about an hour. Use a heated blanket or mattress pad instead — same comfort, a small fraction of the draw.

How cold does a cab actually get overnight?

With the engine off and no heat, cab temperature tracks toward outside temperature within a few hours. Insulation slows how fast you get there; it doesn't stop it. That's why the layers matter more than any single device.

Do I need a CO detector if I'm not running any heater?

Yes. Exhaust from the trucks parked beside you finds vents, and it doesn't respect your property line. A detector is cheap; the failure mode is not.

Can I do this in a box truck or a day cab?

The layers, the window covers, and the power station all work anywhere. The bunk-specific items obviously assume a sleeper.

Bottom line

Window covers, a thermal base layer, a mid-size power station, a 12V heated blanket, and a carbon monoxide detector at head level. That stack keeps a bunk livable through a cold night with the key off, and four of the five fit in a duffel.

Start with the detector and the window covers this week. Everything else can wait for the next settlement.

More in-cab gear is in the in-cab gear category.