Join Date: 14th December 2016
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Battery keeps dying
Hi guys, joined the forum years ago but can't remember any of my log in details. I've had my civic for just over 4 years now (2008 plate), and it's been great and reliable, however, the battery keeps going flat lately. It started around May time with a flat battery, so I borrowed my dads battery charger and it was fine for a week or two then it was obvious that the battery was knackered so I bought a new one. In my 2nd job I leave my car at my bosses house for 4-5 days and use one of his cars, and my car always started fine. Several weeks ago when I got back to my car, my battery was so flat the cental locking wouldn't work and the dash lights were all off. I called the RAC out and they advised me that my new battery which was only a few months old had a dead cell and needed replacing, but the place I bought the battery from has since shut down so I bought one from the RAC guy. A couple of weeks later the battery was dead again after being left at my bosses house for a few days, and again the following week. The battery has been dead enough to need jump leads and a booster pack to get the car started. The following morning the RAC came round again (the previous 2 times it was one of their contractors) to check the battery wasn't dodgy, but their tests came back saying it's fine but it's showing there is an open diode on the alternator.
Now onto the fun bit, I have a current drain on the battery, but it switches on and off. It's running around 0.220 for around 10-15 seconds, then goes up to around 0.550 for around 5 seconds,then drops down again. All the fuses and relays have been pulled one by one and the drain was still switching on and off. My mechanic also disconnected the alternator but the fault still persisted (which I think would rule out the open diode the RAC said about). He then spoke to a friend who is an auto electrician and he has said it's now probably a job for the main dealer as it maybe the ECU. In a last ditched attempt before I do that, I've found and disconnected the HFT module, but surely when the fuse for it was removed that would have done the same thing? Just before the initial flat battery issue I noticed my phone kept either not being found by the car, or on the rare occasion that it did it then dropped the connection during a call (it probably held the phone connection for 2 minutes tops), and since the battery was replaced the HFT system doesn't work at all. I'm hoping the HFT was the culprit, and I've also got a new relay for the air con coming. If anyone else has any suggestions I would love to hear them! Looking of the forum and Google ito seems to be a common problem that I've been lucky not to have until recently.