Not sure of exact figures for your V6, but for late XMs, the total "quiescent" (parked up) current drain is approx. 40mA, maximum.Northerner wrote:Got a 77AH Bosch Silver 5 in my V6. Goes flat every couple of weeks cos the car's not running so something must be eating juice at a fair rate while she's idle?
If you check yours (IGN off, doors closed, everything off and quiet) by putting a multimeter in line with one of the battery connections, and you get something like 50mA or less, everything is probably in order.
If the current drain is anywhere near 100mA, this is very high, and something is sapping current. You can selectively remove fuses to pinpoint the culprit. (It's not unknown for cheap recon alternators to drain battery current through their permanent-live (BAT) connection, but this is eaily checked.)
With a 77Ah battery, there will be something like 50Ah useable capacity (before the voltage drops significantly), and theoretically a drain of 50mA should be suppliable for around 1000h (40 days). This corresponds with real life, where you could expect a parked-up car still to be startable after one month, or so.
If the car is being used intermittently, one of these is a great device to keep the battery is good condition, and avoid the over-charging that basic chargers don't prevent. The CTEK units get particularly good reviews.
CTEK MXS 3.8
They can be left connected to the battery indefinitely.