Can You Run a Heater Off a Car Battery

Battery Operated Heater - Can a Battery Power a Tent or RV Heater?

Space heaters are commonly used for heating tents, RVs, offices, rooms, cars, and even homes and apartments. They directly convert chemical or electrical energy into heat, warming up the desired area. Since space heaters directly convert chemical energy into heat, they are simple, reliable, and rather affordable, but also they are not as efficient as, for example, Air Conditioning units.

Battery operated heaters can be of great help when camping or being off-the-grid by keeping You warm during long, cold days and nights. Right? Well, things are not that simple ...

Types of Space Heaters

Space heaters differ in size, output power, construction, etc. but most importantly, they differ in the energy source they use, which they convert into the heat. Commonly, space heaters may be:

- electric space heaters,

- propane/natural gas space heaters,

- gas/diesel space heaters, etc.

Space heaters that burn fuel like propane, natural gas, gas (gasoline, petrol), diesel, and similar fuels convert chemical energy into heat and can easily heat up tents, RVs, log cabins, etc.

However, such heaters use oxygen from the area they heat up and can be very dangerous, even deadly - modern space heaters come with safety features like low oxygen sensors, carbon monoxide sensors, position sensors, and similar, but ...

IMHO, the author of this article would never recommend using a space heater that uses some kind of fuel and oxygen as an indoor heater. EOD.

If You have to warm up a tent, RV, car, or some similar indoor area, go for an electric heater or, if present, use an AC unit.

However, AC units and electric space heaters require plenty of electric energy, which can be a problem if You are off-the-grid.

Electric Space Heater vs AC Unit

When trying to heat up an area, one needs to convert some form of energy into heat.

Electric space heaters convert electric energy directly into heat - they are reliable and simple, but not very efficient.

Electric space heaters convert 1Wh of electric energy into 1Wh of thermal energy.

So, 1Wh of electric energy directly converted into heat equals ~3.412 BTU of heat.

Air Conditioning units feature heat pumps that 'pump the heat' (hence the name) from surrounding/outside air into the heated area, thus operating much more efficiently than common space electric heaters.

Most RVs come with AC units in 7000-15000 BTU range, requiring approximately 900-1900 Running Watts and 1700 - 2900 Starting Watts:

- RV Air Conditioner 7.000 BTU/h: 900 Running Watts, 1700 Starting Watts → ~7.8 BTU per 1 Wh,

- RV Air Conditioner 10.000 BTU/h: 1200 Running Watts, 2000 Starting Watts, → ~8.3 BTU per 1 Wh,

- RV Air Conditioner 13.500 BTU/h: 1600 Running Watts, 2500 Starting Watts, → ~8.4 BTU per 1 Wh,

- RV Air Conditioner 15.000 BTU/h: 1700 Running Watts, 2700 Starting Watts, → ~8.8 BTU per 1 Wh.

Over time, air conditioning units are improved and their efficiency can only increase.

So, if You are in RV and you can choose to power a space heater OR AC unit, go for the AC unit, since they will heat up the area much better while using the same energy/power.

For more about this topic, feel free to check our Will a 2000-Watt Generator Run an Air Conditioner? and Watts to BTU and BTU to Watts Conversions articles.

Battery Powered Electric Space Heaters

If the batteries can be used for powering even cars, they should be able to power space heaters as well, right? Yes, if the battery is large enough.

Car 12V Battery Heaters

One of the very interesting battery heater applications is car 12V battery heaters which are powered using car cigarette light adapters and are limited to ~120W when the engine is off and to ~140-150W when the engine is turned on.

Such battery heaters are used for quick defrosting of windows and for quick warming up of car cabins, while the engine is still cold.

Another application of car 12V battery heaters is that they can be used as fan-only during hot days.

However, as space heaters, car 12V battery heaters are rather limited.

For example, 12V 10Amps car 12V battery heater features 120 watts, which is equivalent to ~410 BTU/hr - and this is not much.

Also, car 12V battery heaters discharge the car's battery at a rate of ~10 Ah/h and after just a few hours they can discharge the battery almost completely.

So, in order to warm up your tent or RV, you need a stronger space heater, powered by either a larger battery or some other device.

120V AC Electric Heaters

120V AC electric heaters vary in size, power, construction, and other features, but generally, they are rated between 500 and 2000 watts, which is equivalent to ~1700 - 6800 BTU/hr.

This amount of heat is more than enough to warm up tents, RVs, log cabins, and similar areas.

The only problem is where one can get that amount of power over a longer period of time.

12V Battery + Power Inverter

Energy stored in batteries may be converted into 120V AC power using power inverters. However, energy in batteries is limited, even when larger batteries are used.

For example, Odyssey 31M-PC2150 AGM dual purpose 12V 100Ah lead-acid battery is able to provide 835 watts for 1 (one) hour.

If the power inverter with 85% efficiency is used, then that battery can power a ~700 W (~2400 BTU/hr) for one hour. And that is a premium 12V 100Ah battery that weighs 77.8 lbs (35.3 kg) - a little bit too much for 1 hour of heating.

For more about these batteries, feel free to check our How Long Will a 100 Amp Hour Battery Last? article.

In order to decrease the weight of the battery (or battery pack), one can go for deep cycle lithium batteries or to keep things simple, for lithium battery-powered portable power stations.

Portable Power Stations

Portable power stations are a convenient source of electric energy - they store energy in onboard lithium batteries and convert it to electricity via builtin power inverters.

During operation, power stations do not emit any fumes and can be used indoors.

However, power stations also suffer from the limited amount of energy stored in the battery - for example, one of the most popular models, Jackery Explorer 1000 stores ~1000 Wh of energy, and with 80% efficiency power inverter may power 800 W (~2700 BTU/hr) electric heater for up to one hour, which is not bad for ~22 pounds (~10 kg) device.

However, in order to use the 500-2000W electric heater for a longer period of time (overnight, for example), when being completely off-the-grid, is either using a large battery pack (for example, 25kVAh) or to use portable power generators.

Portable Inverter Power Generators

Portable power generators convert the chemical energy of the fuel into electric energy, which is then converted into heat by an electric heater.

Power generators require oxygen for operation and should be used only outdoors - never, but really never operate them indoors, regardless of 'how good' ventilation is, or 'how many' windows are open or similar. Power generators also produce carbon monoxide (CO) which is an odorless gas that easily kills humans and animals - if used indoors ...

One of the most popular classes of portable inverter generators are 2000W generators - they are well designed and balanced units, offering plenty of power, while still being relatively lightweight and compact.

The following comparison chart lists some of the best quietest portable generators suitable for camping, tailgating, in emergencies, and similar:

Model	Running Watts Starting Watts	Runtime	Noise	Receptacles
A-iPower SUA2300i	1800W 2300W	6.5h @50%	52 dB @25% 58 dB @50%	AC: 120V 20A 5-20R, 120V 30A L5-30R DC: 12V 8.3A, USB 5V
Champion 2000W Model #100692	1700W 2000W	11.5h @25%	53 dB @25%	AC: 20A 120V 5-20R Duplex DC: 12V
Generac iQ3500	3000W 3500W	8.9h @50% 14.1 @25%	45* dB	AC: 120V 20A Duplex 5-20R, 120V 30A L5-30R DC: two USB ports (5V/2.1A, 5V/1A)
Honda EU2000i	1600W 2000W	8h @25%	50 dB @25%	AC: 20A 120V Duplex DC: 12V
Honda EU2200i	1800W 2200W	3.2h @100% 8.1h @25%	48 dB @25% 57 dB @100%	AC: 20A 120V Duplex DC: 12V 100W (8.3 Amps)
Honda EU3000IS	2800W 3000W	20h @25%	50 dB @25%	AC: 120V 20A Duplex, 120V 30A L5-30R
WEN 56235i	1900W 2350W	10.5h @25%	51 dB @25%	AC: 15A 120V NEMA 5-20R Duplex DC: 12V, USB 5V (2.1A, 1A)
Westinghouse iGen2600	2200W 2600W	10h @25%	52 dB @25%	AC: 20A 120V Duplex DC: 12V, 2x USB 5V
Westinghouse iGen4500	3700W 4500W	18h @25%	52 dB @25%	AC: 120V 20A 5-20R Duplex, 120V 30A TT-30R 2x USB 5.0V (2.1, 1.0 A)
Yamaha EF2000iSv2	1600W 2000W	10.5h @25%	51.5 dB @25%	AC: 120V Duplex DC: 12V 8A
Yamaha EF2400iSHC	2000W 2400W	8.6h @25%	53 dB @25%	AC: 120V Duplex DC: 12V 8A

Note: Amazon affiliate links ('Model' Column) open in the new windows, feel free to check them for the most up-to-date offers and prices.

For more about these units, feel free to check our Best Portable Quietest Generator - For Camping, Tailgating, in Emergencies, etc. and What Can You Run on a 2000 Watt Generator? articles.

One of the quietest models is Honda EU2200i, although it comes with a very nice price tag.

Honda EU2200i features 1800 Running Watts and 2200 Starting Watts and can easily power electric heaters up to 1500-1800 watts. Also, it can operate on a single gas tank for up to 8.1 hours @25% load (450 watts), or 3.2 hours @100% load (1800W).

So, if You want to power a ~500W (~1700 BTU/hr) heater with Honda EU2200i, You may expect almost 8 hours of constant operation on a single fuel tank. Or if You want to power a 1700-1800W (5800-6140 BTU/hr) heater with Honda EU2200i, You may expect slightly more than 3 hours of operation.

If the combination of a battery pack and a power inverter with 80% efficiency are used for the same task, one would need a battery pack with an actual capacity of ~5000 Wh (12V 416 Ah, 24V 208 Ah, or similar) or ~6750 Wh (12V 560 Ah, 24V 280 Ah, or similar).

A 5000Wh capacity can be achieved using two Group 8D 12V 230-250Ah lead-acid (AGM or Gel-Cell) batteries or two 12V 210+Ah lithium batteries.

However, while Honda EU2200i with full tank weighs ~47 pounds (~21.3 kg), two large lithium batteries, for example, GreenLiFE GL260 (12V 260 Ah) weigh 160 pounds (72.48 kg) both, two Group 8D AGM batteries, for example, Mighty Max ML8D weigh 318 pounds (144 kg) both - and that is a lot of weight to carry around.

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Long Story Short: Battery operated space heaters for tents and RVs are still far away from commercial application - simply, current battery technology does not offer means of storing enough energy for any decent-size electric heater to operate for at least 5-10 hours continuously.

If You have the need to keep your RV or tent warm overnight, the best option is to use a quiet portable inverter generator to produce electric energy and an AC unit or electric space heater to produce heat.

Again - never, but really never operate internal combustion engines (power generators, for example) indoors...

Can You Run a Heater Off a Car Battery

Source: https://www.batteryequivalents.com/battery-operated-heater.html

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