M@tt 77 Posted November 9, 2007 I suffered from a non starter the other day due to low battery voltage, which i thought might have been due to a drain\short somewhere. I had a problem with my central locking the other week as well which blew its fuse and i thought it might possibly be the cause. So today after fully charging the battery and having it checked at Halfords (in case it was faulty) i put the battery back in the car with the positive lead attached and my multimeter between the negtive battery terminal and the negative battery clamp. I made sure all internal lights and the ignition were turned off. The multimeter was connected via the 10A socket and it gave a reading of 0.08 Now i'm not sure what a reasonble reading is or isn't. I then went through each of the fuses in turn and pulled them out one at a time to see which ones affected the reading. The only fuse which had any affect was fuse 7 which covers the fag lighter, stereo, central locking motors. Pulling out this fuse caused the reading to drop down to 0.03 I isolated that out of the possible wires that run through fuse 7 it was only the wire that went to the stereo that caused this additional drain, which would make sense as it would use some power to retin radio ststion settings etc Therefore there was just 0.03 left which was not fused and i could only put this down to the draw of the alarm system which isn't fused as far as i can tell (or remember) Now can any one shed any light on whether these readings are too high or if not any calculations as to how long you'd have to leave the car before the battery was drained too much to start. Cos i hadn't driven the car for a week or 2 but i wouldn't have expected the battery to have drained that much. Cheers Matt Share this post Link to post Share on other sites
paulh 0 Posted November 9, 2007 Now can any one shed any light on whether these readings are too high or if not any calculations as to how long you'd have to leave the car before the battery was drained too much to start. Cos i hadn't driven the car for a week or 2 but i wouldn't have expected the battery to have drained that much. Cheers Matt I had a very similar problem to yours a couple of years ago. Did the same test as you and found the interior light was draining the battery after a week. Have since left the interior light in the mid position (off) and its been ok since. Its probably just a faulty door switch - but there's always another job on these cars that has a higher priority Share this post Link to post Share on other sites
christopher 5 1 Cars Posted November 9, 2007 Check the fuel pump relay is not sticky Share this post Link to post Share on other sites
Toddy 7 Posted November 10, 2007 Remembering my GCSE physics! A 45A battery x 12v has enough power for 540 Watts 0.08A x 12v = 0.96 watts per hour 540/ 0.96 = 562 hours 562/24 = 23 days So if the battery was not fully charged and it drained it to the point where it wouldn't crank over it sounds possible? Or those numbers could be a load of b*llocks! Share this post Link to post Share on other sites
M@tt 77 Posted November 12, 2007 (edited) cheers dave right in that case assuming the starter wouldn't spin over when it had 10volts (which is what it was reading when it wouldn't start) we're looking at how long it would take to drop 2 and a bit volts say 3 volts to be on safe side so 45A x 3v = 135 Watts 0.08a x 12v = 0.96 watts per hour 135 \ 0.96 = 140hrs 140\24 = 5.8days So in theory if i left the car for a week without running it it would drain the battery enought that it wouldn't start. Thats seems to be about right in that case as i hadn't driven it for at least a week. That seems like quite a short period of time thought don't you think? i'm sure people must leave their cars for longer than that and find they still start Edited November 12, 2007 by M@tt Share this post Link to post Share on other sites
paulh 0 Posted November 12, 2007 So in theory if i left the car for a week without running it it would drain the battery enought that it wouldn't start. Thats seems to be about right in that case as i hadn't driven it for at least a week. That seems like quite a short period of time thought don't you think? i'm sure people must leave their cars for longer than that and find they still start Think the longest I've left mine was about a month and it fired first time. A week doesn't sound very long to me. Share this post Link to post Share on other sites
Toddy 7 Posted November 12, 2007 M@tt Yeah it seems abnormal to me, maybe disconnect the alarm feed to see if there is a drain anywhere else? Since I just bought the same alarm, which is handy! It says the drain is 18mA @ 12.5V armed with ultra sonics 10mA @ 12.5V armed without ultra sonics So max drain should be 0.018 and yours is 0.08 so about 4.5 times what it should be, i think. Solar power charger sat on the dash maybe, never used one myself, so they might be as much use as a choccy fireguard. Cheers Share this post Link to post Share on other sites
M@tt 77 Posted November 28, 2007 (edited) cheers dave, yeah i'm going to have to go through the fuseboard a plug at a time to find which one's the alarm feed cos i can't remember which one i used need to sort this as the battery was flat again at the weeeknd having not used it for a week again out of interest would anybody be kind enough to check what the standard drain is on their battery as a comparison? Edited November 28, 2007 by M@tt Share this post Link to post Share on other sites
