a repeating problem… after 2-3 weeks of not driving the car
(2000 Suzuki Vitara, 70,000 m) the battery is totally dead - not even a click. mechanic installed new battery to replace a quite old one and check the electrical componets - passed the test.
Dead battery again !!! Rechecked above - and looked for electircal drain w all systems turned off - no drain reported. Other than driving it more (it’s for bad winter weather) what else could be done???
You need to leave the battery disconnected when parked for a period, or get a battery tender that you can connect to the battery and plug into an outlet. These battery tenders are designed to keep a battery in good shape by giving a battery a pulsed charge with a low amperage pulse. This keeps a battery charged up, and helps prevent sulfurized build-up on the battery plates.
The battery should not drain in that short a period. Please check if the dome light inside goes off; this happened to me on a Pontiac when I left it at the airport on a trip overseas. These lights quickly run the battery flat. Otherwise there must be a short somewhere. When a battery is on its last legs it may not keep a charge, so a new battery is preferable to a charger; it makes sense for extended (several months)of no driving. I worked overseas for 4 years and asked my son to run each of the 2 cars every 2 weeks or so. He never encountered a dead battery, and sometimes did not drive the cars for 3 weeks. So, I would give the battery a load test first, and then check for shorts. The charger is still a good idea, but you should not need it routinely.
A new battery should not go completely dead in 2 or 3 weeks. If it does, then there has to be a draw on the system no matter what you were told.
Disconnect the battery negative terminal, charge the battery, and lightly touch the cable end to the battery terminal.
If you see a noticeable blue spark there is a draw. A very faint yellow spark may be the clock and is not an issue.
Of course, make sure all doors are closed, key off, etc.
That’s not a scientific method, more of a backyard deal, but it can work if you’re not electrically astute or have a VOM.
Does your car have a dusk sensor and daytime running lights? Sometimes, a sticky relay will cause the daytime running lights to stay on even when you pull your key out. This could cause an intermittently dead battery and it would run it down fast enough that if it happened during daylight hours, you might easily miss it. There’s an exponential decay in lumens to voltage so it wouldn’t take much to dim beyond obvious notice.
I would have the car rechecked, possibly at a shop that specializes in electrical repairs. There has to be a drain occuring somehow. Normally, a drain of more than 80 milliamps is cause for concern and the system should be checked for a problem.