A while ago I asked about how frequently one needs to run a car so that the a battery will not run down. I had let our car (a 1995 Chrysler Concorde) sit for about 10 days and then when I went to start it, it wouldn’t turn over. The guys at the garage said that nothing was wrong with it: that some older American cars simply need to be run every 4 days or so. But I’ve heard other people say that this is crazy: that they let their car sit for two or three weeks and it starts right up.
Here is my current question: recently the car’s thermostat went and we have gotten it repaired. Could the thermostat problem and running too hot have been connected to the fact that if the car sat for more than 4 or 5 days it wouldn’t start? I can’t see how these could be connected, but is it possible?
“Running a car every 4 days or so” is generally not a great idea unless you’re running it far enough (as in not sitting still) to get everything warmed up to temperature. Starting it for a while, then shutting it down is a bad practice.
There’s no reason you shouldn’t be able to let it sit for 10 days and then fire up. Something’s putting a drain on the battery.
It shouldn’t be necessary to run a car every 4 days. My '97 Escort which is basically used only when going on longer trips of 200+ miles sometimes sits in the garage for months and sometimes nearly a year at a time without being started. I would suggest you take the battery had have it load tested you may be due a new battery.
My 1993 Caprice sits for 2 or 3 weeks between drives. However I drive it 40 to 50 miles over the course of the day. More importantly, I check the battery voltage on a regular basis to ensure it’s fully charged (~12.6V). A fully discharged battery will read around 11.9V. I use a Battery Tender on a regular basis to keep the battery fully charged, I don’t depend on the car’s charging system.
If the battery is OK, then you definitely have an unacceptable drain. Any car should be able to sit for a couple of months untouched and still start right up.
You will either have to take an ammeter and hook it in series with the battery lead and track down the problem, or invest in a battery tender.
If the ammeter says that the drain is less than 50 mA or so (wait several minutes for any on-board computers to go into hibernation mode), the attention turns back to that battery. If replacing the battery was the only thing that changed before this problem started, I would say that the battery is suspect even though it passes the standard shop tests for accepting charge and delivering amperage.
Afterthought: Try charging the battery, then leaving it a week or two without connecting it to the car. Then connect it and see if it will start the car. If it fails, it is bad.
Just because you have a new battery doesn’t mean it’s good. I’d have it load tested, this can be done with the battery in the car. If the load test results show the battery is in fact good, I agree you probably have something causing a drain on the battery.