Toyota Repair: Battery Drain, toyota 4runner, resoultion

Question
I have a 1997 Toyota 4Runner with 74000 miles.  I've installed an Optima battery last than a year ago, now, within the last 3 months, the vehicle will not hold the charge if it sits idol for 2+ days.  There's not enough battery charge to unlock the doors with the remote entry.  I borrowed a battery and installed it in the vehicle with the same results.  BTW, the vehicle is usually driven on weekends only, so this recent event of the drained battery has me puzzled.

Many thanks for you help with a resoultion to this issue.

Steve C.


Answer
There are two possibilities for this, the alternator may not be charging the battery enough but I think it's more likely that there is an excessive draw on the battery when the vehicle is parked, this can be checked with an ammeter hooked up in series with the negative battery terminal, if the is an idle current draw of more than .2 amps there is an electrical component that is drawing current from the battery, if this is the case you need to isolate what it is that is using the current, it could something simple like a dome light staying on, maybe an audio component like an aftermarket amp,or the alarm system.