- The Battery Powered Heater – Mythical Heating System
- Safe Indoor Space Heaters
- Battery Powered Tent Heater
- Other Emergency Indoor Heating Options
- What about the risks?
- Questions and Answers About Batteries and Heaters
- More Winter Preparedness Posts
The Battery Powered Heater – Mythical Heating System
There are thousands of online searches each month for “battery operated heaters” and “battery powered heaters”. Small individual battery powered heaters for jackets, blankets, gloves, boots and 500BTU 12v car battery heaters do exist.The bad news? A large portable battery powered space heater does not exist.
Good News: There are some options available you might not know about. As an example you can buy safe indoor propane heaters.
It is possible a portable battery operated space heater might exist in the future. Newer batteries like the 18650, 21700 and 26650 can hold a lot more charge than older alkaline batteries. We will update this post as technology changes. Last Update: Jan 2020
Safe Indoor Space Heaters
There are a number of safe indoor propane heaters. Both of the units below are California compliant. If you stock a number of the propane tanks or have a larger external one you can provide relatively safe emergency backup heat.
- Mr. Heater F215100 MH4B 3800-BTU Indoor Safe Propane Heater, Medium (up to 3800 BTU)
- Mr. Heater MH18B Indoor Safe Propane Heater 18000-BTU + Propane One Pound Tank Refill Adapter (up to 18,000 BTU)
Both units have safety features including an auto shut off if they are tipped over or oxygen levels get too low.
How Much Heat do I need?
You need about 40 to 45 BTU per square foot. A 1000 square foot home needs 45,000 and a 2000 square foot home needs 90,000. And you will need more if the temperature is below zero. A 10×10 room is 100 square feet which needs 4000 to 4500 BTU.
Battery Powered Tent Heater
The best options for a cold weather camping trip tent heater are the Mr Buddy propane heaters. These propane tent heaters are safe. Depending on the size of the tent and amount of heat you need, the Mr. Heater F215100 MH4B 3800-BTU Indoor Safe Propane Heater is a good option.
For large tents, RVs or unheated camps, the Mr Heater F274830 MH18BRV Indoor-Safe Portable RV Propane Heater (4,000 , 9,000 and 18,000 BTU) is an option. Remember a 10×10 tent needs about 4000 to 4500 BTU per hour. You will need one or more propane cylinders, depending on the duration of your trip.
Other Emergency Indoor Heating Options
Consider a wood burning stove and install it with proper ventilation. Don't forget to add insulation and other weatherproofing improvements that reduce your heat loss. Related posts include: 25 Cheap Ways to Keep Your House Warm in Winter and Best Ways to Keep Your House Warm – New Construction and Remodeling Tips and if you have the time and skills a rocket stove is another option that requires construction.
If you have natural gas from a local utility as an option, you might consider a unit such as the Mr. Heater 30,000 BTU Natural Gas Blue Flame Vent Free Heater – but it requires natural gas feed installation. Remember in large storms and hurricanes natural gas may not be available.
For more information on general house heating, see “Types of Heating Systems“.
What about the risks?
Using a propane heater, even a safe one, still has risks. The risks are fire, carbon dioxide and carbon monoxide. The safer units have a risk you might not know about – water vapor. A propane heater that is burning correctly creates mostly water and carbon dioxide. The extra water vapor can be an issue if the heater is running for many hours or days.
The highly efficient indoor propane units are designed with shields, but there is still a risk of fire, similar to a plug-in electrical heater. Never place flammable objects near a heat source, especially a propane heater, unless your unit indicates otherwise. Some portable propane heaters do allow flammable materials on the back side of the unit, such as the Mr Heater Big Buddy shown below.
You need a fire extinguisher in your home or apartment and one in your utility area if you have a larger home. Even if you don't purchase a propane heater, or a wood stove, you need a fire extinguisher.
Carbon Dioxide (CO2)
The Mr Heater indoor propane heaters have oxygen sensors so they will automatically shut off if they detect too little oxygen. If your home is very tight, and the heater runs for a long time, you may need to crack a window to allow carbon dioxide and carbon monoxide to escape and oxygen to come in. You want to keep higher oxygen levels to be safe. This is especially true for small areas less than 20 x 20 feet. Get more information on the exhaust from an indoor propane heater.
Using a safe propane heater indoors can create a lot of water vapor. You may have issues with moisture on windows (condensation) if you use a propane heater in the winter. This can result in ice buildup, and slippery floors if they are much colder than the air.
If you do decide to get an indoor propane heater, consider a carbon monoxide detector just to be safe. If you want to be extra careful, you can instead purchase a combo carbon monoxide and smoke detector.
Questions and Answers About Batteries and Heaters
How does a 12 volt car heater work?
It actually isn't a heater. It is a fan that blows air past a coil with hot coolant from the running diesel or gas engine. The air blows past a coil. The air cools the coil, while it warms the air and then blows through vents into your car. So the heater is a combination of a fan and the gas or diesel cooling system.
Note: If you need info on a car battery heater for cold weather starts, see the post “Car Won’t Start in the Cold“.
Don't some cars have 12 volt heaters?
Yes, you can purchase 12 volt resistance heaters that create about 150 watts of heat and draw about 20 amps (so it needs a 20amp fuse). A 150 watt heater creates about 500 BTU per hour (a home system creates 40,000 to 200,000 BTU).
A 12 volt resistance heater is not going to heat a whole house, but it will still drain a 12 volt car battery dead very quickly. A 10×10 room needs 4000 to 4500 BTU per hour in a cold area.
Electric cars also use a 12 volt resistance heater. The electric car 12 volt resistance heaters use a LOT of electricity, and in electric cars, this quickly results in the backup gas engine being engaged or the car needing a charge quickly.
How Does a battery create heat?
Battery based heaters use electric resistance heating, which uses a lot of current (electricity) to create the heat. The battery goes through a high resistance coil (heating element) and it resists the electrical flow and heats up. This uses a lot of electrical power or current.
A home 1000 to 2500 square foot home normally needs 40,000 to 150,000 BTU. A small car battery heater creates 500 BTU at 12 volts 20amps. That means you would need 100 to 500 car batteries to heat a home with electricity for a short period and more for multiple days. It is not practical to use batteries to power resistance based heating systems.
Can't I get any heat from a battery?
Yes, there are small battery powered gloves, battery powered blankets and battery powered jackets. These type of gloves generally use expensive high wattage LIPO batteries and last from 1/2 hour to a few hours.
A better alternative for emergency use is chemical hand warmers, such as HotHands Hard Warmers. You can get 8 pair of HotHands Warmers for under 10 bucks, and each set of warmers provides up to ten hours of heat.
Readers commented that they've had them stay warm from around 3 hours to 12 hours, depending on conditions. The chemical hand warmers are far more effective, but they are one time use.
What battery heated clothing exists?
You can purchase battery heated clothing such as Lithium or Li-Po powered jackets, battery heated gloves, socks, and even battery powered blankets. Battery powered, heated clothing is available from Dewalt, Bosch, Makita & Milwaukee and many other providers.
The only thing we personally have experience with are the heated gloves and vest, that grandpa uses, as he appreciates the extra heat.
- Battery Heated Gloves:
- Savior Heated Gloves
- Milwaukee Electric Tools 561-21XL Gloves Red Lithium USB Heated – XL
- Motorcycle Heated Gloves (uses 12v motorcycle or car feed and requires special installation)
- Battery Heated Women's Jackets
- Battery Heated Jackets
- Cordless Heated Jacket
- Ororo Women's Heated Vest
- Milwaukee Electric Milwaukee M12 heated jacket
- DCHJ066C1-M 20V/12V MAX Women's Heated Jacket
- DCHJ060C1-XL 20V/12V MAX Black Heated Jacket Kit, X-Large
- Mens Black Quilted Polyfil Heated Jacket Kit with 20-Volt/2.0 AMP Battery and Charger (Large)
- Large – 20/12-Volt High Visibility MAX Unisex Heated Hoodie with 20-Volt Lithium-Ion MAX Battery and Charger – Yellow – DCHJ071C1
- DCHJ074D1-XL Realtree Xtra️ Camouflage Heated Hoodie, X-Large, Camouflage
- Hammacher Cordless Heated Stadium Blanket
Makita makes some heated clothing, but we don't recommend them based on other reviews (we have not tested them ourselves). Team up battery powered clothing with rechargeable batteries to keep from breaking the bank. (See battery and charge recommendations here.)
LIPO Batteries for Heating
LIPO based batteries are great, but you would need about $20,000 worth of them to heat a small home for a few hours. Then the batteries would need to be recharged. Also LIPO has higher risk of bursting and starting on fire, which makes them a poor selection for resistance heating.
Could I Heat my House using 12 Volt Resistance Heater?
A 12 volt resistance heater in a car uses the 12 volt alternator for power, not the car battery. The alternator is powered by a the gas or diesel engine. It creates about 100 amps of power while the engine is running (the 150 watt 20 amp heaters use up 1/5th of that power).
The alternator charges the battery and runs the electronics in the car, including the 12 volt resistance electric heater. A single automotive 12 volt battery can't power a 12 volt heater for very long without being drained completely. It can be drained so much that it will damage the battery. If you are not careful setting up the power for a heater that uses 12 volt car batteries, it can easily cause a fire. So you might be avoiding propane to avoid fire, but any resistance based heating can also cause a fire.
A safe 12 volt heating system would require multiple 12 volt car batteries. You would need to recharge all the batteries every day, which would be a challenge, as the batteries would drain faster than they charge. It would require overdraw protection and fuses or breakers to protect from excessive amperage draw. Further the amount of electricity needed to create space heating is significant. That is why whole house electric heaters or electric stoves are expensive to operate, they draw a lot of electricity.
Doing the Math
To heat a 1200 square foot home requires about 40,000BTU/hr. Using a 500BTU 150w 12volt resistance heater would require 80 to as many as 400 batteries to provide heat for just 1 day. Then the batteries would need to be recharged somehow. That is a LOT of 12 volt car batteries. So as we noted, there is is no such thing as a battery operated home space heater (yet). If you see one advertised, it is probably a scam or mislabeled product search result. Even if you used LIPO batteries, it would likely cost $20,000 or so to get a full day of heat for that same home. The MR Heater Big Buddy would cost less than $1000.
More Winter Preparedness Posts
Check out our other cold weather preparedness posts, including: