my 2007 tribeca is not in use for 5-6 weeks, while I am out of town. It’s in my garage in Lancaster, Pa. When I return to lancaster, it won’t start because the battery is dead. The Suberu Dealers says I have to buy a device to havea trickle charge going to my battery to prevent it
from discharging while I’m out of town for 4-5 weeks. Does this make sense to you?
see http://www.aa1car.com/library/battery_runs_down.htm for more info.
“As a rule, the parasitic drain on most late model vehicles should be less than 50 milliamps one hour after the vehicle has been shut off and left undisturbed. But this is a rule of thumb only. Always refer to the vehicle manufacturer’s key-off electrical drain specifications if available (some vehicle manufacturers have no published specifications).”
If we take the 50mA number, over 6 weeks that comes to 50 amp-hours, which is enough to discharge your battery mostly. It the drain is 100mA (entirely possible) it comes to 100 amp-hours, definitely enough!
So the dealer seems correct. Another alternative is to disconnect the battery, but that resets the radio and all the computer functions.
Have they replaced it yet? It likely got drawn down is now simply weaker and gets worse with each draw down. It will get replaced under the Subaru 3yr/36k everything warranty that even covers windshield wipers, brakes pads/rotors etc(eg wear items). You could just have a weak battery to start with.
good point. When you deep discharge a car battery (run it down to dead) it damages the battery. One that sees several deep discharges is badly damaged.
I’m assuming that when you tried to start the car, you got nothing, no lights, no sound, totally dead?
Also I’m assuming this is your first 6 wk trip?
Does this make sense to you?
Yes. Modern cars have computers and other devices that use current even when they are turned off. 5-6 weeks is a long time for any car without some sort of charging. About two weeks is usually safe for most cars.
You can buy sun powered devices that can keep your battery charged, but will not work if you are in a garage and don’t get sun light.
Also as noted, car batteries are not designed to be fully discharged. Each time you even come close to fully discharging them, they are damaged and their life is reduced.
That solar-powered device will also not work if it is connected via the cigarette lighter socket, as Subarus do not have power running to the lighter when the ignition is off. If the solar device could be connected directly to the battery terminals (and assuming that the car is not garaged) this would be a viable solution to the problem, IMHO.