Jimmy 0 Posted May 21, 2020 I have an interesting problem with my battery dropping voltage overnight on my Falcon BF MK11. When the car is parked overnight & the voltage is checked next morning it drops to approx 12. 3. Leave it for 2 days & it drops to 12V. Battery is 6 months old. The alternator appears to be charging correctly ( 14.3V ). I have checked all lights to see if something eg boot or interior is staying on, not so. I checked the current draw with everything off by putting a current meter in series with the negative lead & the -terminal on the battery. The current draw is 0.250A ( 250 mA ) with the boot light on it is approx 1 amp boot light off 250mA. Does anybody have a suggestion as to what the cause could be, I have tried the same test with a new battery & same result. My other car can sit for up to 2 weeks & the battery voltage is approx 12.5V . A perplexing problem I even thought about fitting another alternator but don't want to spend money for no reason. Thought about pulling various fuses for a fault finding exercise to see if the voltage drops. Any suggestions welcome as I at the moment have run out of ideas. Cheers Jimmy Share this post Link to post Share on other sites
hendrixhc 10,918 Posted May 21, 2020 Any chance you have a car alarm fitted? Share this post Link to post Share on other sites
SPArKy_Dave 8,831 Posted May 21, 2020 I would start pulling some fuses, to locate which circuit is causing the current draw. As with all modern vehicles, the immobiliser and other various devices, will flatten even the best battery after a few weeks or so of sitting. That's what happened with my BF wagon, when we were in self-isolation, only going out for essentials/food etc. My x-series, hold a battery charge for months, without being started or driven. Share this post Link to post Share on other sites
2redrovers 21,372 Posted May 22, 2020 If your battery isn't a maintenance free type, check the fluid level isn't low. I had to replace my battery just last week because I had no charge, turned out to be down way too far. You said only 6 months old but never hurts to check the basics before looking deeper. Share this post Link to post Share on other sites
Jimmy 0 Posted May 23, 2020 Thanks for reply's. I have pulled various fuses current draw stays the same , battery is low maintenance, no alarm system apart from the factory specs. I started pulling fuses & cleaning the contacts same result. I moved onto the relays inside the car & pulled & refitted interesting result from this. The current draw reduced to 200mA & after about 10 min there was a click & the current draw dropped to 80mA. So seems there is a relay with residual draw somewhere, what I intend doing is to start pulling relays one at a time & see what the voltage is next morning. Process of elimination seems the way to go as it is now becoming annoying & I would like to find the problem & solve it. I will take any /all suggestions & should I solve it shall post for someone else who may have similar issues. One final thought the car is dual fuel after market LPG might pull all lpg fuses & see what happens. Not running on LPG as it cost 85- 99 cpl in Perth, petrol is cheaper at the moment. Country LPG up to $1.45 pl Share this post Link to post Share on other sites