Im using a 12V electric blanket that plugs into cig lighter. As it gets colder Im not sure how long I can run it overnight before it drains main battery , leaving the engine unable to start. Is there a tool to alert when the battery is approaching critical level?
How Long can I run my 12V electric blanket off Car Battery
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Not aware of one. But I’d consider using a jackery or some sort of power bank so your not using your car battery. Running that down puts more strain on your starter, even if it still starts and such. And takes life out of your car battery. Size of such a power bank would be determined by your needs. Best to get as big as you can afford. You can charge them while driving, from an AC outlet somewhere or from a portable solar panel. That would be my vote. I’ve got hundreds of thousands of miles on my truck and being diesel is has two serious batteries in it. I learned the best way to keep starters from failing is to keep good batteries operating it. I had no problem with warranty. But the hassle involved in changing starters and alternators out wasn’t worth it. At the first sign of weak batteries I’d change them out. I usually could find a home for at least one like in my old plow truck with a smaller gas engine. A good power bank will save you in the long run.
If you are going to do that buy an electric 12v blanket that has an automatic shutoff at 3 hours. That way you won’t wake up to a dead battery. Then if you wake up cold run your engine for a while to warm up your vehicle and recharge your car battery.
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rruff
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I slept in temperatures in the teens recently, and was impressed with how well a sleeping bag and couple blankets (fleese and fluffy) work. I was so toasty warm I didn't mind crawling out in the morning that much.
Car batteries aren't made to be deep cycled, and their ability to tolerate it will vary greatly depending on the model and how old it is. A 50W blanket that's on for 8 hrs will consume 400W-hr of energy. That's getting pretty close to the sensible limit of a 100ah deep cycle lead-acid battery (which is ~600W-hr), so I think a starter battery subjected to that would die pretty fast.
Car batteries aren't made to be deep cycled, and their ability to tolerate it will vary greatly depending on the model and how old it is. A 50W blanket that's on for 8 hrs will consume 400W-hr of energy. That's getting pretty close to the sensible limit of a 100ah deep cycle lead-acid battery (which is ~600W-hr), so I think a starter battery subjected to that would die pretty fast.
rruff
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To answer your original question, there are low voltage disconnects to prevent excessive discharge. Just don't think it's the best way to skin this cat, since your battery will still wear out fast if you drain it regularly.
https://www.amazon.com/dp/B07WDLFFF...industrial&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw
https://www.amazon.com/dp/B07WDLFFF...industrial&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw
eDJ_
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There are any number of apparatus available for this problem. Some are cheap...$20 dollars...others up .to $150+
This one cost around $20 dollars and even offers a factory recalibration option for a nominal fee if you want the warning voltage level set higher or lower.
I know a guy who uses the deep cycle battery from his fishing boat for the starting battery in his diesel Pickup Truck during the cold winter months while the standard battery sits in his garage on a trickle charger.
12vtechnology #BA3
This one cost around $20 dollars and even offers a factory recalibration option for a nominal fee if you want the warning voltage level set higher or lower.
I know a guy who uses the deep cycle battery from his fishing boat for the starting battery in his diesel Pickup Truck during the cold winter months while the standard battery sits in his garage on a trickle charger.
12vtechnology #BA3
mpruet
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I wouldn’t use my vehicle starter battery for anything other than starting the vehicle. If you want to run an electric blanket, then get somthing like a Jackery 500 or Bluetti.
I'm pretty close to rruff on this one. Why not use the electriblanket to warm the bed up, then add an unzipped sleeping bag (or bags) over it to keep the body heat in, and shut if off after you're in your "cave"? That way you're putting minimal strain on the battery. If you got enough layers you don't NEED that blanket on all night. That's how I work the system, anyway.
Bkwithlove
Active member
My 12v throw size electric (medium heat setting!) from Walmart drains my Jackery portable 150w size within a few hours. low heat i get maybe 4 hr.
car battery ingredients aren’t meant for this kind of use (although if the engine is running that is a slightly different story).
no matter what, as a solo traveler I deeply recommend an $80 jump start kit. Just for various reasons Ive needed it 3x and Im a careful person (and i killed my car battery draining it that many times; doesn’t keep a charge if you accidentally let it go dead a few times).
wishing you warm feet and cozy nights!!
quilting22
Well-known member
Perhaps a small solar charged power station would be a good option instead of your car battery. I have a larger PS and run my electric blanket w/o a problem.
I have no trouble with my 12V mini blanket running the battery down. I've used it as my only heat all night when the outside temperature was 18 F. My secret is that I wrap the 12V blanket around my middle and put on a lightweight insulated jacket over it. Then, setting the blanket on LOW is plenty of heat to stay toasty warm. (But I also wear long Johns for my legs and thick socks for my feet, all of me being under a warm, thick blanket over the bed.
DLTooley
Well-known member
Don’t do it, except in an absolute emergency. Starter batteries are not designed for this use, rather to provide maximum amps when starting. Doing so will quickly destroy the starter battery, money better spent on a proper solution.
Short of a full solar system a portable power station is your best bet. There are better values than Jackery. You want a lifepo4 lithium based system for longevity.
As to how big, you’ll need to do the electricity math. The blanket label will have a watt rating, roughly how many hours you want to run the blanket times those watts is how many watt hours of power station you need. You will need to adjust for lower settings and there is also inverter conversion loss of ten percent or more.
If you need to replace your starter cost wise they do make deep discharge specialty starter batteries. These are commonly used in public safety vehicles, etc. Optima and Odyssey are two brands that come to mind.
Short of a full solar system a portable power station is your best bet. There are better values than Jackery. You want a lifepo4 lithium based system for longevity.
As to how big, you’ll need to do the electricity math. The blanket label will have a watt rating, roughly how many hours you want to run the blanket times those watts is how many watt hours of power station you need. You will need to adjust for lower settings and there is also inverter conversion loss of ten percent or more.
If you need to replace your starter cost wise they do make deep discharge specialty starter batteries. These are commonly used in public safety vehicles, etc. Optima and Odyssey are two brands that come to mind.
You do not NEED an electric blanket to stay warm at night.
Buy a good sleeping bag so you do not need to run heat at night. If you are short on funds look for one in a thrift store or on Facebook marketplace,Craigslist etc.
Have plenty of really thick fleece pajamas plus some thermal underwear to sleep in. Also have a pairs of wool socks, mittens and a fleece baclava, the type skiers wear. Your feet, hands and head need protection from heat loss and keeping them covered makes a huge difference on cold nights. A fleece pillow case is a lot warmer to sleep on than a regular fabric one.
Also make sure any walls and windows next to your bed have a thick blanket draped down them to keep cold drafts from the exterior off of you. That is an easy way to add a lot of extra insulation that you never see mentioned in DIY build threads. You will need to add some hooks or rods at the top of the vehicle to hang the blankets from. Blankets are a good thrift store purchase. They can store on top of your bed when not needed adding extra cushioning. Or fold them up into a backrest for sitting on the bed. Some ribbon ties will keep them in the right shape or if the folded up blanket fits into a pillow case that is another way to store them.
Buy a good sleeping bag so you do not need to run heat at night. If you are short on funds look for one in a thrift store or on Facebook marketplace,Craigslist etc.
Have plenty of really thick fleece pajamas plus some thermal underwear to sleep in. Also have a pairs of wool socks, mittens and a fleece baclava, the type skiers wear. Your feet, hands and head need protection from heat loss and keeping them covered makes a huge difference on cold nights. A fleece pillow case is a lot warmer to sleep on than a regular fabric one.
Also make sure any walls and windows next to your bed have a thick blanket draped down them to keep cold drafts from the exterior off of you. That is an easy way to add a lot of extra insulation that you never see mentioned in DIY build threads. You will need to add some hooks or rods at the top of the vehicle to hang the blankets from. Blankets are a good thrift store purchase. They can store on top of your bed when not needed adding extra cushioning. Or fold them up into a backrest for sitting on the bed. Some ribbon ties will keep them in the right shape or if the folded up blanket fits into a pillow case that is another way to store them.
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There's something satisfying about waking up in a nice and warm coccoon when you can see your breath and the temps are below freezing. On those morning I'd give anything for a catheter.
Learning to manage your power consumption and production is an essential if you want to be using electrical devices.
Last night for the first time since spring I needed to get my down sleeping bag out of storage. It was getting into the 30s some nights. A few more weeks of that cold will happen before I move down in elevation. But right now the daytime temps are in the 80s here in Northern AZ and triple digits in Western and Southern AZ. So it is much easier to use a sleeping bag than to deal with triple digit weather as Ido not have air conditioning. You choose your compromises. I can easily stay very warm while I sleep without needing extra power.
Last night for the first time since spring I needed to get my down sleeping bag out of storage. It was getting into the 30s some nights. A few more weeks of that cold will happen before I move down in elevation. But right now the daytime temps are in the 80s here in Northern AZ and triple digits in Western and Southern AZ. So it is much easier to use a sleeping bag than to deal with triple digit weather as Ido not have air conditioning. You choose your compromises. I can easily stay very warm while I sleep without needing extra power.
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Here's a battery monitor for under $20. It tells you how much power is left in your battery, and sounds an alarm if you are draining it too low.
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