I was wondering what sources everyone uses for heat in colder climates and if anyone has any 12 volt DC heaters that run off of the house batteries? I know a person can buy
cheepy 12 volt heaters at truck stops ect.. that plug into cigarette lighters but i am interested in something larger scale that doesnt consist of a cheep plastic housing with a heating element inside.
12 VOLT DC Heating
Re: 12 VOLT DC Heating
Anything electrical to do with heat is typically a real power hog (heater, microwave, toaster, heat gun, etc.). That's not to say it can't be done (run generator, have a huge DC system, etc.). But.... that's why most RV-ers and boaters who leave the dock (or power post) heat with one of the other fuels (propane, diesel, kerosene, wood, etc.).
I have used a number of different options over the years (cabin/boat/RV): Wood stove, propane fired forced air furnace, propane "gravity" furnace (no fan), propane catalytic heater (no fan/unvented), propane "buddy" type heater, diesel heater, kerosene heater. To my mind they all have plusses and minuses. If one carries enough propane to get through from fill to fill, then I find it to be one of the cleaner/easier fuels to live with. As long as a fuel heater/furnace is vented, it won't put moisture into the room air.
Sorry to get off the topic of electrical heating, but on 12 volts that's a toughie. (And of course if you run a 110 heater via an inverter it's even a bit more consumption.) Would be clean and easy though if practical.
I have used a number of different options over the years (cabin/boat/RV): Wood stove, propane fired forced air furnace, propane "gravity" furnace (no fan), propane catalytic heater (no fan/unvented), propane "buddy" type heater, diesel heater, kerosene heater. To my mind they all have plusses and minuses. If one carries enough propane to get through from fill to fill, then I find it to be one of the cleaner/easier fuels to live with. As long as a fuel heater/furnace is vented, it won't put moisture into the room air.
Sorry to get off the topic of electrical heating, but on 12 volts that's a toughie. (And of course if you run a 110 heater via an inverter it's even a bit more consumption.) Would be clean and easy though if practical.
1999 Concourse
Re: 12 VOLT DC Heating
I am going to go along with Blue on this one,I followed those links and those heaters are rated at 30 and 20 amps respectively,and are connected directly to batteries.Power conservation is something that interests me,and the fans that are engaged in the chinook heating and cooling,can consume plenty of amps over time.I am more Spartan perhaps than most,and once managed well with electric lap blankets during several years in a trailer during home construction.Even today I like my Milwaukee electric jacket that uses the same lithium batteries as their tools,they also sell an extremely efficient and bright led lantern that runs off the same.In winter use I use the pink stuff to flush and carry water in jugs,so I am not obsessed with maintaining a high interior temperature,I use the furnace sporatically,but not continuously.If I was full timing and it got too cold,I would probably make like the rest of the retired folk and head to Arizona or Florida. Rooney
Re: 12 VOLT DC Heating
I took at look at the first link. The heaters look well made. Maybe they are aimed at something like truckers, who have large alternators and run engines a lot? For the typical RV while camping off the grid, "anything" can be done for either a very short time, or a long time with a monster-sized battery bank (or when running generator). But it may not be practical in real life. Here's why I say that. Specs from your link. I've bolded the text for the 12 volt options since most of us run a 12 volt system.
SD12-4000 12 Volt - 40 Amps - 480 Watts - Max BTU 8016
SD12-5000 12 Volt - 50 Amps - 600 Watts - Max BTU 10,020
SD24-3500 24 Volt - 35 Amps - 840 Watts - Max BTU 14,028
SD24-4500 24 Volt - 45 Amps - 1080 Watts - Max BTU 18,036
SD36-2000 36 Volt - 20 Amps - 720 Watts - Max BTU 11,664
SD36-2500 36 Volt - 25 Amps - 900 Watts - Max BTU 15,032
SD48-2000 48 Volt - 20 Amps - 960 Watts - Max BTU 16,032
SD48-2500 48 Volt - 25 Amps - 1200 Watts - Max BTU 20,040
Taking the first line, that puts out 480 watts. That's like one of the small 110 electric heaters on low, just for comparison. Most people would say that's not much heat in cold weather, but it's all subjective of course. I have run a 110 electric heater in my Chinook when plugged in, and with it on full (1500 watts, or over three times as many watts), it kept things tolerable, if not super comfortable, in 35-degree-ish weather (nighttime low). 480 watts would take the chill off in 50 degree or so weather, for me (although I find that blown air needs to be warmer, if that makes sense, as the "drafty" feel makes it seem less warm than radiant heat).
So 480 watts, which is fairly minimal, heat-wise. But it's taking 40 amps from your batteries! And due to Peukert's law, using 40 amps for an hour is a lot "worse" than using one amp over 40 hours, so you have that "hammering the batteries" effect that Peukert gives you. The typical Chinook battery bank is around 200 amp hours. For longest life, you typically want to draw down to only 50%*, so that means you have 100 amp hours to work with. That's 2.5 hours of using the heater if you are not using ANY other power. And it might be less than that due to Peukert's law. Say 2 hours or less. Everyone is different, but I wouldn't want to give all my usable battery power to heat for two hours with a weak heat.
Now, there are a few caveats: You may have a much larger battery bank (I have 375 amp hours, but still wouldn't choose to heat with electricity while parked). You may have a lithium bank. With lithium you are still needing to supply the amp hours, but can go below 50% and there isn't a big Peukert effect. I still don't think I'd find it very practical, but you may. And of course if driving, or running the generator its a different story.
Just to compare, let's take the Wave 6 propane-fired radiant heater, because that's 6,000 BTU's and a reasonably close comparison to heater number 1 on the list. Since the above example uses the entire battery bank capacity for heating, let's see how long the entire propane tank would run the Wave 6 on full blast. With the 80% fill rule, we have around 14.4 gallons of propane to work with in our 21-footers with the 18.x gallon tank. Doing BTU conversion math, our installed propane tanks would run the 6,000 BTU Wave 6 heater for 219.6 hours. Of course that's the whole tank without leaving any propane for other appliances, but then we were using the whole battery bank too, for the previous example. This is also not a direct comparison of how much power is stored in a battery vs. a propane tank, but rather takes into account what most of us DO carry in our Chinooks.
So, even for my "largish" 375 amp hour battery bank, I have at most around 200 amp hours to burn (which I then have to put back!). That would run the first (electric) heater for five hours. OTOH, my propane tank would run the similarly sized Wave 6 for just about 220 hours. And even though 6,000 BTU's is a bit less than 8,000, I find the radiant factor to make it feel "warmer" vs blown heat, so I'd rate them around the same.
The numbers could change slightly with a larger lithium bank, a smaller propane tank or etc., but this example shows why I don't think too many people heat with 12 volts in an RV while off the grid. The other fuels (kerosene, diesel) are closer to propane for how much you can "get" with what you can store.
In my case, I've tipped things even more in favor of propane for heat. Reason is, with my larger battery bank and solar to re-charge it, I've gone to a compressor (DC/AC electric) refrigerator. So I use my battery bank for that, and now I have the entire propane tank (minus the tiny amount used for cooking) to use for heat. Our tanks in the Chinook are relatively "huge." I can easily run my refrigerator 24/7, on 200 watts of solar and 375 amp hours of battery bank (or more solar and smaller bank would actually be a better balance, but I'm set up for adding more solar, hence out of proportion battery bank for now). So for me, it's much more efficient to run refrigerator on DC electric, and heat on propane, than the other way around (and there are some other advantages to compressor refrigerators too, such as no problem with slants, quick temp recovery or start up, somewhat safer design, etc.). In other words, I think it's more efficient to run refrigeration on 12 volts, and heat on fuel (propane in my case), than the other way around.
That does look like a nicely made heater though. I can see it being really nice for some situations. It wouldn't work for me off grid, but it might for some people. What I carry, for when I'm plugged in, is a couple of $15 110 electric heaters from Wal-Mart. Yeah, they are cheapish, but they do the job and store small. What I used in a previous trailer, when plugged in more of the time, was an electric "oil filled radiator" heater. Takes up more space, but a MUCH more pleasant and "warm feeling" heat, plus no noise. Each one lasted about two years under full time use, and they are under $50. I'd buy one again if I were going to be plugged in for any length of time.
BG
*Another battery bank strategy is to have a smaller bank, run it down much lower than 50%, and just replace more often. This could be effective if, say, you only had room for one battery and had to make it do as much work as possible. OTOH, you can get 375 amp hours from three Group 31 batteries (but these are not the type you'd want to run as "disposables").
PS: Rooney posted while I was typing, but as usual, he makes lots of good points in a simple paragraph or two
SD12-4000 12 Volt - 40 Amps - 480 Watts - Max BTU 8016
SD12-5000 12 Volt - 50 Amps - 600 Watts - Max BTU 10,020
SD24-3500 24 Volt - 35 Amps - 840 Watts - Max BTU 14,028
SD24-4500 24 Volt - 45 Amps - 1080 Watts - Max BTU 18,036
SD36-2000 36 Volt - 20 Amps - 720 Watts - Max BTU 11,664
SD36-2500 36 Volt - 25 Amps - 900 Watts - Max BTU 15,032
SD48-2000 48 Volt - 20 Amps - 960 Watts - Max BTU 16,032
SD48-2500 48 Volt - 25 Amps - 1200 Watts - Max BTU 20,040
Taking the first line, that puts out 480 watts. That's like one of the small 110 electric heaters on low, just for comparison. Most people would say that's not much heat in cold weather, but it's all subjective of course. I have run a 110 electric heater in my Chinook when plugged in, and with it on full (1500 watts, or over three times as many watts), it kept things tolerable, if not super comfortable, in 35-degree-ish weather (nighttime low). 480 watts would take the chill off in 50 degree or so weather, for me (although I find that blown air needs to be warmer, if that makes sense, as the "drafty" feel makes it seem less warm than radiant heat).
So 480 watts, which is fairly minimal, heat-wise. But it's taking 40 amps from your batteries! And due to Peukert's law, using 40 amps for an hour is a lot "worse" than using one amp over 40 hours, so you have that "hammering the batteries" effect that Peukert gives you. The typical Chinook battery bank is around 200 amp hours. For longest life, you typically want to draw down to only 50%*, so that means you have 100 amp hours to work with. That's 2.5 hours of using the heater if you are not using ANY other power. And it might be less than that due to Peukert's law. Say 2 hours or less. Everyone is different, but I wouldn't want to give all my usable battery power to heat for two hours with a weak heat.
Now, there are a few caveats: You may have a much larger battery bank (I have 375 amp hours, but still wouldn't choose to heat with electricity while parked). You may have a lithium bank. With lithium you are still needing to supply the amp hours, but can go below 50% and there isn't a big Peukert effect. I still don't think I'd find it very practical, but you may. And of course if driving, or running the generator its a different story.
Just to compare, let's take the Wave 6 propane-fired radiant heater, because that's 6,000 BTU's and a reasonably close comparison to heater number 1 on the list. Since the above example uses the entire battery bank capacity for heating, let's see how long the entire propane tank would run the Wave 6 on full blast. With the 80% fill rule, we have around 14.4 gallons of propane to work with in our 21-footers with the 18.x gallon tank. Doing BTU conversion math, our installed propane tanks would run the 6,000 BTU Wave 6 heater for 219.6 hours. Of course that's the whole tank without leaving any propane for other appliances, but then we were using the whole battery bank too, for the previous example. This is also not a direct comparison of how much power is stored in a battery vs. a propane tank, but rather takes into account what most of us DO carry in our Chinooks.
So, even for my "largish" 375 amp hour battery bank, I have at most around 200 amp hours to burn (which I then have to put back!). That would run the first (electric) heater for five hours. OTOH, my propane tank would run the similarly sized Wave 6 for just about 220 hours. And even though 6,000 BTU's is a bit less than 8,000, I find the radiant factor to make it feel "warmer" vs blown heat, so I'd rate them around the same.
The numbers could change slightly with a larger lithium bank, a smaller propane tank or etc., but this example shows why I don't think too many people heat with 12 volts in an RV while off the grid. The other fuels (kerosene, diesel) are closer to propane for how much you can "get" with what you can store.
In my case, I've tipped things even more in favor of propane for heat. Reason is, with my larger battery bank and solar to re-charge it, I've gone to a compressor (DC/AC electric) refrigerator. So I use my battery bank for that, and now I have the entire propane tank (minus the tiny amount used for cooking) to use for heat. Our tanks in the Chinook are relatively "huge." I can easily run my refrigerator 24/7, on 200 watts of solar and 375 amp hours of battery bank (or more solar and smaller bank would actually be a better balance, but I'm set up for adding more solar, hence out of proportion battery bank for now). So for me, it's much more efficient to run refrigerator on DC electric, and heat on propane, than the other way around (and there are some other advantages to compressor refrigerators too, such as no problem with slants, quick temp recovery or start up, somewhat safer design, etc.). In other words, I think it's more efficient to run refrigeration on 12 volts, and heat on fuel (propane in my case), than the other way around.
That does look like a nicely made heater though. I can see it being really nice for some situations. It wouldn't work for me off grid, but it might for some people. What I carry, for when I'm plugged in, is a couple of $15 110 electric heaters from Wal-Mart. Yeah, they are cheapish, but they do the job and store small. What I used in a previous trailer, when plugged in more of the time, was an electric "oil filled radiator" heater. Takes up more space, but a MUCH more pleasant and "warm feeling" heat, plus no noise. Each one lasted about two years under full time use, and they are under $50. I'd buy one again if I were going to be plugged in for any length of time.
BG
*Another battery bank strategy is to have a smaller bank, run it down much lower than 50%, and just replace more often. This could be effective if, say, you only had room for one battery and had to make it do as much work as possible. OTOH, you can get 375 amp hours from three Group 31 batteries (but these are not the type you'd want to run as "disposables").
PS: Rooney posted while I was typing, but as usual, he makes lots of good points in a simple paragraph or two
1999 Concourse