SweetJustice Posted September 11, 2018 Share Posted September 11, 2018 My five-year-old battery was dying -- dead flat -- over the course of about a week of standby. I replaced the battery, but the new one promptly did the same thing. I've put an ammeter inline a couple of times, and found fairly typical results -- starting around 40 mA, dropping to 17-25 mA after a couple of minutes. The corner shop confirmed a 17 mA standby load. They put the battery on the load tester, and it tested out OK. Last week, I pulled the battery off the charger at about 13.0V surface charge. Today, five days later, it's at 12.65V. In my mind, this rules out an internal short. What am I missing here? Do I need to put the battery on a discharge tester? Link to comment Share on other sites More sharing options...
Tronic Posted September 12, 2018 Share Posted September 12, 2018 What is the brand of the battery ? A decent new battery should not be flat with that sort of load within a week. Batteries vary so much in quality its not funny. I had the AA replace a battery once, it lasted 18 months. When I pulled it out of the car it weighed nothing. I still have a Yuasa battery that is nearly 12 years old that is used to emergency jumpstart cars and the ride on lawnmower. Have you checked your car is charging properly ? it should have over 14V to the battery when you turn a few things on like the fan and lights. Link to comment Share on other sites More sharing options...
SweetJustice Posted September 13, 2018 Author Share Posted September 13, 2018 What is the brand of the battery ? <snip> Have you checked your car is charging properly ? it should have over 14V to the battery when you turn a few things on like the fan and lights. It is not a charging issue -- when I check after a drive, it tests at 13V. And the failure occurrs after trickle-charging and then *not driving*. It's a crap battery - Maxx brand, warranty replacement. But the fact that it's behaving exactly the same as the "failed" replacement is what has me thinking that something odd is happening here. Link to comment Share on other sites More sharing options...
Underdog Posted September 13, 2018 Share Posted September 13, 2018 I had this problem after performing the FPCM mod as originally detailed here: https://legacygt.com/forums/showthread.php/upgrading-your-fuel-pump-wiring-4th-gen-213570.html My troubleshooting and resolution is detailed here: https://legacygt.com/forums/showthread.php/fpcm-wiring-upgrade-relay-staying-switched-w-key-off-242295.html Even if your car doesn’t have the same modification, the process of elimination should still help identify the parasitic drain. The Crimson Dynamo Link to comment Share on other sites More sharing options...
SweetJustice Posted September 13, 2018 Author Share Posted September 13, 2018 I had this problem after performing the FPCM mod From your link, it looks like you had about 100mA parasitic drain -- much more than the 17mA I'm seeing, which I understand is well within spec for maintaining clock and radio memory. I'm out of ideas though, so thanks for the tip -- I'll start by isolating where my drain is going. Link to comment Share on other sites More sharing options...
08SpecB_DE Posted September 14, 2018 Share Posted September 14, 2018 Are you able to pop the caps to check the fluid with a hydrometer or is it a sealed battery? Sounds like you have a bad cell or one going bad and its not holding a charge. If the fluid is low, top off with distilled water. 17mA is well within the acceptable range. Link to comment Share on other sites More sharing options...
Underdog Posted September 14, 2018 Share Posted September 14, 2018 You’re right, I misremembered. Once the issue was resolved it would pull .01A (using a cheapo meter) so your 17mA sounds totally within reason. I wonder if its something intermittent, like a faulty door switch, that is increasing the drain while the car is not being observed. The Crimson Dynamo Link to comment Share on other sites More sharing options...
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