What load can I put on the battery overnight, and still start? (1 Viewer)

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aktundra

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I am not electrically inclined, in fact the opposite.

Currently thinking about winter camping, wondering what load I can put on my dual battery system overnight, and still be assured the isolated battery will start the vehicle in the a.m.?

Is the key measurement the number of amps?

Is there some kind of table that says "x" amps = "y" hours conventional or "z" hours deep cycle?

Here in Alaska it is pretty common to have plug-in water heaters to assist in starting vehicles in the a.m.. I am wondering if the equation can work out, where there is a pug-in heater powerful enough to keep the vehicle thermostat open, (run through an inverter while on the trail), and then wire the OEM fan switch to run only the fan (not all ACC). Essentially run the vehicle heater overnight off the battery.

Would this system be doomed to fail? Such a draw, it would only produce 1hour, 2hours of heat before the battery would be dead? What is the proper metric to see if something could be designed?
 
i would think your asking a lot out of your battery.

I don't know of a chart that will show true reserve amps left due to variables. Temp (outside/inside), Starting battery charge, length of draw time, continuity of wires and connections, amp draw of the heater as well as the inverter.............

I think your best bet would be to look at installing a dual battery system that allows you to isolate the starting battery from the reserve/acc battery.
 
You should hit the overlanding portion of this site. There's heaters specifically designed for in car camping, and I think they're much more efficient than artificially running the oem hvac system.
 
I believe he's talking about running a block heater for the engine so it doesn't freeze.
 
My dual battery system does isolate the two batteries.

So I guess I will always be able to start.

I guess I am really wondering if it is worth the trouble to buy the engine heater with this additional functionality in mind? How long would it run before I would have to start the engine and recharge the #2 battery?

1 hour?, 2 hours?.....no
4 hours?, 6 hours?.....hhmmmm that's as much sleep as I get most nights !

I am wondering about maybe spending a little more on the minimum necessary for a block heater, to also use it as cabin heat, for sleeping in the rig. And thereby not worry about CO2 while sleeping from other possible heating options.
 
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An alternative to consider may be a remote starter. One of my 80's had an Astrostart/Astroflex brand remote starter that could be programmed to run the truck for 5-10 minutes every hour once the temp hit a predetermined temp. I think I had mine set at like -5 or something like that, which was not uncommon at all while living in Minnesota, Maine and Montana and it always worked just fine. I am no expert on the subject, but I would think a block heater or the like would drain a secondary deep cycle pretty quickly in cold weather.
 
Look at espar fuel fired heaters

They make one for the coolant or one for in cab heat, they are the heater that semis use. I am in Canada and have similar winter conditions you do. I have the coolant heater and it is great it has a 7 day timer, temp sensor so it wont boil the coolant and a remote option.

They say it burns about .1 L of fuel an hour but it is closer to .2L an hour. So you burn 1 L for 5 hours of heat, if it runs constantly, which it will not as it turns off once your coolant reaches the cut off temp.

Last week I only needed to run it for 45min to get my coolant to 113 F, outside temp was 5 F. I love it, it makes it start like it is july.

The heater is super tiny and only weights 6 lbs, it fit under my hood in the engine compartment.

http://ww w.espar.com/

Shawn
 
It's been a few years since I lived where block heaters were needed, but as I recall, they consumed around 700-1000 watts @120v. Running an inverter to supply that much power, plus running the heater fan, would likely limit the run time to 1-1.5 hours for most batteries.
 
In simplest terms - which is about all I understand.

Batteries have a capacity rating measured in amp-hours.
Devices have a consumption rating in amps or watts.

So, say your battery has a 75 amp hour rating and the heater you want to run has a 5 amp rating. Doing the math, you get 75 amp-hrs divided by 5 amp equals 15 hours.

This assumes the heater is running full time. If the heater is only running 30 minutes of every hour you get 75/(5*0.5) or 30 hours of run time.

It's recommended you only run the battery to half its capacity before recharging or you will damage the battery and shorten its life. So your 75 amp-hour battery is really a 37.5 amp-hour battery. There are other factors that will affect battery life like temperature but this calculation should give you a pretty good idea how long you can use the battery without recharging.
 
Shawn686, those systems look perfect, 12v and gas powered.

Looks like I have some research to do. I wonder if there is an after market blower, that can be retro fitted on the rear heater, to really put out, and make a meaningful contribution to the cabin heat?

Thanks again everybody
 
The airtronic version is just that. It is made to heat the cab on semis so they don't have to idle. I would imagine you can install the thermostat and heat ducts any where you wanted. No need to add any other blower.

I think it will definitely make a difference in your cabin heat they can range from 4100 btu/h to 18000 btu/h. If you cant do it with that much heat you need to close the windows, lol

Beaware that these systems are not cheap, my coolant one I just had installed was $2114 installed. You may be able to do it cheaper yourself, but you need to drop the fuel tank, so I just paid them to do it.

I used my coolant one again today at -4F, it throw a code on the first attempt to start but started on the second attempt and heated the coolant no problem and my truck started like in summer. Best money I have spent for a diesel truck in the winter.

Hope that helps.

Shawn
 
This is a great read. The author is Harold Barre.
books.jpg
 
Shawn686 said:
I have a 98 GMC 6.5 L diesel and have the espar hydronic 5 the diesel version.


http://www.espar.com/html/products/hydronic5.html

Shawn
Click to expand...

I've wanted one of these for a while, its' really the only reliable way to run heat at night. It would be interesting if you could get one that not only worked as a heater, but also as a mini generator. That way you could wire it up to charge your battery while it is generating heat.
 
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