Very Cold Freezing Temps Parked with Stuff in Sportsmobile

[SkinnyRV]

Getting ready for first trip in cold country in new 2010 Sportsmobile LB Sprinter. Incomplete, but usable.

Starting from San Antonio working my way North for skiing in Utah and then near Bonners Ferry in Idaho where I have friends. Not planning on camping.

Have winterized water system, drained and added a little antifreeze. Not planning on using water system.

Do want to keep drinking water, cans, etc while parked overnight, skiing, and at the airport in Salt Lake City and Spokane for up to a week at a time while I make runs back to San Antonio to check on my wife who is in an Alzheimer's facility..

Have the dual 100 amp batteries and am thinking about a big ice chest with either a 12 v heated sleeping bag, mattress pad, electric blanket, or holding tank pad --or-- a small 12 watt light bulb on a thermostat or ?. If something bursts and makes a mess, it will at least be contained.

Is this a goofy notion or what?

Would not make friends if I burn the Sportsmobile while parked next to a bunch of other vehicles in the airport parking lot so need to minimize fire risk.

My only experience in cold weather is in an 2006 Itasca Navion (Sprinter chassis) with a bunch of sources of heat (Propane furnace, engine with boost heater, 3600 watt propane generator). Was OK down to -15. Spent a few winters living in Utah and had the Navion there when they set a record for consecutive days with HIGH temperature below freezing. It always started right up, as did the genset. I am spoiled.

Did have some cans freeze and burst in the Navion while it was parked in Salt Lake City and powered down.

BTW, ran a test an overnight test with the 2010 Sprinter motor at idle and burned 1/4 gallon of diesel per hour per Scan-gauge and produced plenty of heat and fresh air, so am thinking if I boondock on the road, I will idle the engine. No furnace, just ordered catalytic propane heater with thermostat, but won't run that while I am parked for extended time until I get comfortable with it, and probably won't get it installed before I leave. Will be installing low power computer fan to bring fresh air into the fan (details TBD but have a couple of notions).

BTW2 - a good way to dry out the inside if the humidity gets to high is to run the vehicle heater. After you heat the cold outside air it is very dry. That dry air causes me sinus problems, hence prefer something that produces water -- like burning propane.

[daveb]

No solar? I don't know how long your battery will last with a load for that length of time. The AH rating of your bank, air temp and load will make the difference. Maybe purchase a window solar panel and hope for good sun. If you plan to add much load, the panel will probably need to be able to put out a few amps and the load just cycle on and off at a very low draw. The icechest in a icechest might be the best solution...as for water, it's cheap, why not just buy it when you come back? For that matter, why not just restock when you get back?

Temperature Effects on Batteries
Battery capacity (how many amp-hours it can hold) is reduced as temperature goes down, and increased as temperature goes up. This is why your car battery dies on a cold winter morning, even though it worked fine the previous afternoon. If your batteries spend part of the year shivering in the cold, the reduced capacity has to be taken into account when sizing the system batteries. The standard rating for batteries is at room temperature - 25 degrees C (about 77 F). At approximately -22 degrees F (-27 C), battery AH capacity drops to 50%. At freezing, capacity is reduced by 20%. Capacity is increased at higher temperatures - at 122 degrees F, battery capacity would be about 12% higher.

Battery charging voltage also changes with temperature. It will vary from about 2.74 volts per cell (16.4 volts) at -40 C to 2.3 volts per cell (13.8 volts) at 50 C. This is why you should have temperature compensation on your charger or charge control if your batteries are outside and/or subject to wide temperature variations. Some charge controls have temperature compensation built in (such as Morningstar) - this works fine if the controller is subject to the same temperatures as the batteries. However, if your batteries are outside, and the controller is inside, it does not work that well. Adding another complication is that large battery banks make up a large thermal mass.

Thermal mass means that because they have so much mass, they will change internal temperature much slower than the surrounding air temperature. A large insulated battery bank may vary as little as 10 degrees over 24 hours internally, even though the air temperature varies from 20 to 70 degrees. For this reason, external (add-on) temperature sensors should be attached to one of the POSITIVE plate terminals, and bundled up a little with some type of insulation on the terminal. The sensor will then read very close to the actual internal battery temperature.

Even though battery capacity at high temperatures is higher, battery life is shortened. Battery capacity is reduced by 50% at -22 degrees F - but battery LIFE increases by about 60%. Battery life is reduced at higher temperatures - for every 15 degrees F over 77, battery life is cut in half. This holds true for ANY type of Lead-Acid battery, whether sealed, gelled, AGM, industrial or whatever. This is actually not as bad as it seems, as the battery will tend to average out the good and bad times. Click on the small graph to see a full size chart of temperature vs capacity.

One last note on temperatures - in some places that have extremely cold or hot conditions, batteries may be sold locally that are NOT standard electrolyte (acid) strengths. The electrolyte may be stronger (for cold) or weaker (for very hot) climates. In such cases, the specific gravity and the voltages may vary from what we show. NAW&S

[SkinnyRV]

Thanks. Did some math and am Running a test with a 3.8 watt 12V light bulb and an ice chest just to see if it can hold a temperature. Not that cold here, but will get some notion of the efficiency of an ice chest.

Did I mention I hate grocery shopping?

[Roonie]

Originally Posted by SkinnyRV

BTW, ran a test an overnight test with the 2010 Sprinter motor at idle and burned 1/4 gallon of diesel per hour per Scan-gauge and produced plenty of heat and fresh air, so am thinking if I boondock on the road, I will idle the engine.

Surprised no one has commented on this part yet....

Hopefully at high idle since idling diesel engines is bad (do a search in this forum and others for the info). Also idling engine all night could produce CO while sleeping also very bad! I wouldn't do it even though I have a CO detector mounted inside from SMB.

[daveb]

Ya, I have to agree about running the engine while you sleep. Even a candle will produce CO. Not much of a problem to wake and run the engine for a time, but you should be able to use a good sleeping bag and survive during those short stays provided it doesn't get too cold. Chemical heat packs/wraps could be a solution to help keep you and other things warm. I've used those tent camping...kind of expensive but sure makes your back feel good. The problem is they only last a day. Maybe someone that frequents cold weather will come up with something for ya. [edit] you might look into the smaller alcohol heaters but they put out a lot of moisture from what I've read.

Dave

[Angel]

I have a 12 volt electric blanket that works for me. Uses 4 amps, shuts off after 45 min but you can push a button to turn it back on for 45 min as often as needed.

Angel

[SkinnyRV]

Results of using a 12 volt low watt light to warm an ice chest.

I used a 3.8 watt incandescent rated at 14 volts Sylvania 194LL light. That works out to 0.27 AMPS current draw.

Given I have 200 AMP-hour total battery and using a conservative 25%, the 0.27 AMPS for 168 hours is around 45 AMP. Continuous current draw of the light bulb for a week would work.

However, the light consistently keeps the old battered Ice chest 10 degrees warmer than the ambient temperature. Not enough to provide protection from the extreme cold for a week.

Will look at more options. Overnight stuff should be easy.

[SkinnyRV]

Against my better judgment, I am going to explain some thinking and research on Sprinter running at idle while parked.

Have heard the low oil pressure thing applied to various vehicles since I was a kid. I will spare you all the details, but it was certainly true for gasoline engines in the 50's and before, as well as the old air cooled airplane engines I flew.

However, I have read all the Mercedes-Benz Sprinter Engineering and Compliance documents and searched the online versions for cautions about oil pressure and idle and emissions and idle and have found no prohibitions. Same was true for the 5 cylinder that is in my 2006 Sprinter based Navion.

My 2010 Sprinter with the V6 idles around 680 RPM.

Per the Sprinter Engineering and Compliance alternator guide all 2010 Sprinters have the 220 AMP alternator and because the regulator connects to the computer you cannot use a different alternator. You can add a second on the power take off.

At the 680 RPM idle, the guide shows alternator output as 140 AMPS when the water temperature is cold (73F) and 119 AMPS when the water temperature is warm (176F). Assuming the alternator voltage is around 14, that is 1666 watts after the engine warms up. That is more than enough to run the house A/C. I ran both the house A/C and the Sprinter A/C at the same time (with the heat on max to keep the A/C from cycling) for an hour and did not detect any decrease in battery voltage. Can't wait to try it out next August. Scanguage fuel flow does go up to 0.38 GPH when I run both air conditioners.

On the CO issue,
whenever the Sprinter fan is running, fresh air is brought into the vehicle at the front, and exhausted through flappers located inside the rear bumpers. There is positive pressure in the vehicle and continuous air exchange. In case of problems, I have redundante CO detectors.

I MHO CO risks are less than when then fan is not running to bring outside air into the vehicle -- unless you are in an enclosed garage. Certainly safer than running a Heat Buddy or stove burner without a vent, or as in my case, a convection oven that was leaking air from the propane fridge vent (since fixed by Sportsmobile).

I have a 12 volt electric mattress pad and a 12 volt sleeping bag. The electric mattress pad works well. However in the very cold temperatures this born and raised South Texan sleeps more comfortably when the room temperature is above 60. I keep knocking off that stocking cap and cannot keep warm without it.

When the outside temperatures are near or below zero, the temperatures inside drop quickly and there is the risk of frozen water and burst beer bottles and food cans.

Maybe somebody should directly ask Sprinter Engineering and Compliance for their take.

[SkinnyRV]

Forgot to mention that the 2010 Sprinter has an infrared temperature sensor in the center of the dash that monitors the cab temperature and adjusts the heat to maintain the set temperature.

[jage]

For starters, how about getting a better cooler?

Once that is done, pack it with stuff and leave it one week, realizing you might have a mess when you get back. There is a big difference between fully packed and empty. I'd say everything you want to leave should not already be cold, and that you should always make a point to fully pack the cooler.

After that, I'd say real world testing is your only option. Maybe you can borrow someone's deep freezer, but likely you will have to just park there and try it.

Lots of factors, like ambient sun heat, that you might be able to take advantage of, but that can't be predicted so well. Hopefully you don't start on the coldest week of the year, and can see how things do through some not so bitter temps, and then make adjustments if things start to get frozen around the edges of the cooler.

If it doesn't work, get a Chilly Dog system. Mine will start and run the vehicle based on inside temps. You can set a high and low temp or to run on an interval.