Occasionally the battery on my 99 XLE discharges very quickly. In the most recent case it was started (with no issues) and driven twice in the morning for short journeys and then after being parked and left for 15-20 minutes the battery was virtually dead (central locking worked but only clicking noise when trying to start). After a AAA jump start the van drove normally and has been fine for a couple of days. Interestingly the battery was checked when it was serviced by Toyota a few days before and was found to be fine.
Does anyone have any suggestions? What could be draining the battery so quickly but only very intermittently? Is there a way of tracking the problem down? Could this simply be a battery problem - can they deteriorate that rapidly?