Can my car kill a battery in 2 weeks?
Yes, but it should not drain to zero in two weeks. And now it will not even charge.
You have no reason to assume that. Drains come in all shapes and sizes. Have you actually CHECKED for a drain?
Also depending on what your battery tender "is" it may have LESS power than the DRAIN. So it would NEVER charge up. Even if the tender puts out more current than the drain, it may be such a small tender, and or such a large drain, that the charge level just doesn't matter
On top of that, once a battery gets so far 'dead' a small charger may not be able to re-activate it. The heavier the battery, the worse this is, and the colder the weather (battery) the worse it is.
NEVER try to charge a frozen battery, by the way.
HOW TO diagnose a drain
1...Assume nothing.
2...Check everything you can think of that might be "on." Trunk light, glove box, do you have a modern stereo? Stereos can drain two ways---the "keep alive" for the program memory, and the output amplifier circuits are often "hot" at all times. So a bad cap/ other component can create drain--at various levels
Alternator. Sometimes alternator can have a drain, partially bad diode, etc
3A....HOW TO CHECK. Start out with an incandescant test lamp. Remove battery ground, and hook test lamp from engine ground or ground cable to the NEG post. If the light glows at all, there is a drain. If it lights really bright, be careful-------with your meter
3B...Now get your meter and set it up for the high amps scale, 10A, 20A whatever. Now put the meter in series with the battery just like the lamp. If it shows noting on the high scale, drop down to milliamps, etc. Allowable maximum opinions vary, but it should be WELL under .1A (1/10 of 1 amp) and should be more like less than 50ma (50 milli amps)
