You can expect the battery to run dead and freeze. There are three things to consider. The first is simply to remove the negative cable from the battery. That will stop the drain on it, but I hesitate to do that, mostly because other people researching this topic might do it on their car. Chrysler has always been one of the top manufacturers when it comes to "customer-friendly" business practices, and as such, it is pretty likely you must just reconnect the battery cable, and reset the clock, and you are done. That is not the case with cars from manufacturers who put profits ahead of what is in the best interest of their customers. That includes BMW, Audi, VW, and GM. With those brands, simply disconnecting the battery to replace it causes multiple computers to lock up, requiring a tow to the dealer to have them unlocked. With some VW models that can cost over $1,000.00. I have never run into that scam on a Chrysler product, but it is something you should keep in mind.
Every car has a means of eliminating the normal current drain on the battery for those times the car is expected to be in storage, like at the assembly plant and before it is sold to a dealership. In the past, there was one smaller battery wire with a bullet connector that could be pulled apart. Then came the "ignition off-draw", (IOD) fuse. At the dealership, as part of the "new vehicle prep", we installed wheel covers and antennas, pulled plastic covers off the seats, and plugged in the IOD fuse. The car could be operated by the delivery driver and dealership people with that fuse removed, but many systems, like radio, power locks, and power seat did not work.
Over time, that IOD fuse evolved into the airbag fuse. With all safety systems, including anti-lock brakes, there is always two fuses so if one blows, the other circuit is there to run the warning light. You should find on your car there are two air bag fuses side by side, and they are in a bright yellow plastic holder that makes it easy to remove them. They usually will not come all the way out. The idea is emergency personnel can pull the holder out about 1/2" to disable the system. Your owner's manual will have a section on what to do to stop that battery drain so the car can be stored.
The third alternative is to install a solar-powered battery maintainer. Some of them plug into the cigarette lighter outlet or power outlet, but you have to be sure those outlets work when the ignition switch is off. If they do not, you will need to use clip leads to connect it right to the battery. You don't have to close the hood tightly, to prevent pinching the wires, but do not leave it open enough for an under-hood light to stay on. If the car is not in a secure location and you must fully latch the hood, run the cables through the opening in the grille.
Chrysler says there can be a drain on the battery of up to thirty five milliamps, (0.035 amps), to keep the memory circuits alive in the numerous computers. That is now the industry standard unless the manufacturer states otherwise. Cadillac is one of the more common exceptions. They allow up to 50 milliamps. At thirty five milliamps, a good battery will still be charged enough to crank the engine for starting after sitting for three weeks. I have a 1993 Dodge Dynasty that gets driven about two times per year. The battery in that car will still crank the engine after sitting for about six weeks, but that is it.
Also, for older cars, when the battery slowly runs down over those three weeks, computers will gradually start to turn off, and the drain will decrease. That means that while the battery can no longer crank the engine, the acid in it has not fully turned to water, yet. It may freeze at minus ten degrees, but not at thirty one degrees. Once you charge it at a slow rate for an hour, it should start the engine just fine. It is when the acid freezes that the battery becomes junk and must be replaced. Once that three-week period is past, a weak battery becomes more run down fairly quickly.
Starting in the mid 1990's, most cars have an engine computer that goes to "sleep" mode at up to twenty minutes after turning the ignition switch off. During that twenty minutes it can draw up to three amps. The problem with this design is anything that interrupts power for just a fraction of a second will wake that computer up, then it will draw that three amps again for another twenty minutes. Low voltage, as in a partially-discharged battery, can confuse that computer into waking up. Once that happens, it will continue to draw that three amps until the battery is fully discharged. That could take as little as a couple of hours, to perhaps overnight. At that point the acid will freeze within a day or two. Freezing distorts the plates in the battery and causes them to short and / or fall apart. Once thawed out, it will never be able to be charged enough to crank the engine. It has to be replaced for that.
Getting back to my story about the solar-powered battery maintainer, it only has to be big enough to make up for that thirty five milliamp drain which takes place twenty four hours per day. Since you might only get an average of two or three hours per day of good sunlight, the unit will need to charge at a higher rate when it does charge. I have never looked into these maintainers because I just remove the batteries to use in my winter cars, but I suspect you can find one rated at about one amp. That is the same amount of current one brake light bulb or one under-hood bulb will draw. One amp is about thirty times the allowable current drain, but remember, you are only getting that one amp for a short period of time each day. Also, most cars don't draw that full thirty five milliamps. That is simply the maximum a car is allowed to draw.
I have two cars that are driven so little, a half tank of gas lasts over five years. I have never had a problem with old gas, but from what I have read, that is a concern in different parts of the country where they use different formulations. Some people will tell you to store the car with the gas tank filled, presumably to prevent condensation. Well, every time you use up a gallon of gas, a gallon of air comes into the tank, along with the humidity in it. The more you drive the car, the more air, and the more moisture enters the tank. When the car is sitting, what little moisture in there is all you are going to get. Most metal fuel system parts are made from stainless steel, so corrosion is not that big a deal. I prefer to leave the fuel level real low so when I start driving the car again after it has been stored, I can immediately put in fresh gas. That will easily dilute the old stuff and avoid any running problems. Remember too that almost all gas has ethanol in it. That is alcohol and it absorbs moisture so it can go through the engine without causing a problem.
Wednesday, December 21st, 2016 AT 9:43 AM