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New battery dying after a week, 17mA standby load


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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?

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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.

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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.

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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.

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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.

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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.
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