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Discussion Starter · #1 ·
Is the system that recharges the battery different than the alternator? Lately I've been struggling with a battery not holding charge over a week of having the car sitting in my garage. I want to make sure I don't have some other problem before writing off the battery and just buying a new one. What steps should I take to make sure everything is okay? My ScanMaster3 displays 13.6-14.2 volts when the car is running so I assume the alternator is doing its job. Car ran fine after the battery was recharged the first time, it restarted when stopped the same day etc. Left it for a week, ran it for about 5 min and turned it off (no driving) left it for another week and the battery was dead again.
 

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07 FXT sport
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Maybe take it to a autozone/napa etc.. and let them test the battery.

My guess is the battery. Is it the stock battery? If it's from your 05 thats about 5 years which seems to be about the lifetime of the stock subaru batteries.


dm

I think i read in another thread it's a 5 year old optima red top. That's a shame if the red top is done in 5 years. I have one in my wrx but I believe when the FXT stock battery fails I'll be staying away from the red tops.
 

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2007 Forester Sports XT 4EAT
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There's always a slight drain on the battery for vehicle electronics. IMO the battery should not be dead in a week. Either your battery is failing or it's not getting a full charge. In addition, if you're running your vehicle for 5 minutes to charge the battery, that's not enough running time. IMO you need to run the vehicle until it's up to normal operating temperature & even that may not be enough to bring the battery back up to full charge. :confused:

If you're considering a battery charger, I'd recommend this one. The price is reasonable & it has 3 LED indicators that let you know what it's doing. I actually have one mounted permanently in each of my vehicles. :wink:

Bobby...

My MODding Journal
 

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2007 Mitsubishi Pajero 5spd Automatic
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^Agreed. starting the car for 5min only taps the battery more then you charge it. Alot more.
 

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Discussion Starter · #6 ·
A short? As in on the battery or some of my installed components? Wouldn't a fuse blow if there was a short?

Wow.. that charger looks great! I may have to pick one up after I get a new batt and leave it in the car.




Sounds like a short or battery is done.

Yea Autozone/Advance Auto.
 

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2014 CVT
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824 Posts
nope batterys them self can get internal shorts, which can keep them from working right, the 13.6-14.2 volts says your alt is working fine, there is a chance that you have a parasitic draw, either something being left on, or a fail component that is creating a draw that kills your battery, also do you have a optima??? cus that changes a lot
 

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Discussion Starter · #8 ·
The battery is a optima red top which I've had for about 4 years now.

I have a bunch of engine monitoring devices installed and also a amateur radio. All systems turn off when the ignition is turned off.



nope batterys them self can get internal shorts, which can keep them from working right, the 13.6-14.2 volts says your alt is working fine, there is a chance that you have a parasitic draw, either something being left on, or a fail component that is creating a draw that kills your battery, also do you have a optima??? cus that changes a lot
 

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2007 Forester Sports XT 4EAT
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A short? As in on the battery or some of my installed components? Wouldn't a fuse blow if there was a short?

Wow.. that charger looks great! I may have to pick one up after I get a new batt and leave it in the car.
There are lots of chargers to choose from, but this one had eveything I was looking for. :wink:

If you have access to a DC ammeter, you could disconnect the ground wire from the battery & insert the ammeter to measure the parasitic current drain. There should be some current flow, but much less than the cabin light. There has to be some current flow for devices like your head unit (memory), the ECM & the security system. :smile:

Bobby...

My MODding Journal
 

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just because you think all systems turn off doesnt mean that they all are truely off, and from a quick look at the optima site it would seem you would be better off with a yellow top.......... thats just i what i read, also i would read up on how to test for a parasitic draw, its to late for me to start that lol
 

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You had an internal short/bad cell in the optima. Pretty common lately with them. If the new one acts the same though, then its probably something shorted/grounded out like the security system or a light not going off.
 
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