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'03 outback limited, '01 Outback Limited, '01 Legacy L wagon, '96 Legacy Brighton wagon
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Discussion Starter · #1 ·
Have 2 01's - an OB and Legacy wagon - both 2.5 auto. Both will sit occasionally for extended periods of time, so I'm looking at various ways to minimize the drain on the battery, but will also keep a LiPo jumper battery in each for those "just in case" scenarios - neither will be parked where an electrical outlet is handy.

First off, both need new batteries, so after a bunch of research, I found that a Trojan 24AGM will fit with minor mods to the battery area - many comparisons tests have this one as the best available in that size, and it is a deep-cycle, not just a starter battery, with way more than enough CCA for even the coldest weather, and a decently high AH rating.

However, the measured parasitic drain on the OB that is keeping the ECU, clock, and whatever else stays live, is about 145 mA, so the car has maybe only 20 days before the voltage drops too low to start the engine.

So, I'm considering either a solid state battery disconnect, or a low-voltage cutoff.

Question: Does the '01 ECU care if it loses power? If not, the disconnect switch seems to be the best way to go.

If losing power IS an issue, then I'll have to look into minimizing the drain by identifying and wiring in a disconnect for everything BUT the ECU - resetting the clock and using the keys to manually open the doors is not an issue at all with me!

What are the experiences of others here, and what did you do to address the issue?
 

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On the Super Mod Squad
2002 3.0 VDC Wag + 2018 2.5 Leg Ltd
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how long are the cars going to sit?

what temps?
 

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'03 outback limited, '01 Outback Limited, '01 Legacy L wagon, '96 Legacy Brighton wagon
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Discussion Starter · #3 ·
Sitting time could at times be well past the 20 day mark mentioned, though I will at least TRY to make it no more than 2 weeks. Weather is central Indiana - and you don't know what it will be until it actually hits! :surprise: 95 is generally the highest in the summer, and sometimes 0 in the winter (with occasional days at 10 or more below).

Another question is in jump-starting this generation Sub - I've read of the surge issues that are possible with the new generation cars, and obviously want to avoid that! The owner's manual doesn't give any special precautions other than the sequence of cable attachment ( nothing different than I learned 60 years ago).
 

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Meh.
I has wagons.
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12,360 Posts
Kaylee (see my signature) would sit in a parking garage in Chicago for 2-4 weeks at a time when we lived there. Never failed to start.

If I was letting it sit a month or more I'd just unhook the battery.
 

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'03 outback limited, '01 Outback Limited, '01 Legacy L wagon, '96 Legacy Brighton wagon
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Discussion Starter · #5 ·
OK. To make life easy, in that case I'll go with the disconnect - easier and faster once it is installed.

That still leave the question about whether or not the ECU is OK with a power loss. Anyone?
 

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Meh.
I has wagons.
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12,360 Posts
Is fine. Will likely run a little funny the first drive cycle or two as the ECU resets, but no mechanical or safety issues to be concerned about.
 

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. . . However, the measured parasitic drain on the OB that is keeping the ECU, clock, and whatever else stays live, is about 145 mA, so the car has maybe only 20 days before the voltage drops too low to start the engine. . . .
Do both your 01s measure 145 ma "dark current"? That seems rather high.

In 2007 SOA issued a TSB that set the dark current limit at 150 ma, and more recently, 70 ma (but this might apply to more recent model years). My own measurement have been less than 10 ma, and a few other posts here are similar. I don't recall specific posts for the 2001, but it would seem odd that it would have normal drain that is more than 10 times larger, and almost at the SOA spec.

Ref: http://www.subaruoutback.org/forums...2-07-dark-current-excessive-battery-draw-.pdf
 

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'03 outback limited, '01 Outback Limited, '01 Legacy L wagon, '96 Legacy Brighton wagon
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Discussion Starter · #8 ·
I would expect that the newer generations might draw a bit more than mine, but 145 did seem a bit high. Doors were closed, no key in the ignition, everything off, except that the key fob WAS in my pocket. Once I've finished reconditioning the current battery, I'll check it again, with the fob a long ways away and wrapped in tin foil just to make sure. I need also to look at the wiring diagram to see what else is not turned off with the key out, and start pulling fuses to see what is drawing what - I'd like to get it to somewhere below 100mA if possible.

I guess that I'll find out about the ECU when i reinstall the battery! :)

the legacy drain has not been measured yet for comparison - when i bought it, the timing belt had snapped, so I'm almost ready to finish pulling the motor for rebuilding. probably won't get it back together until sometime this winter - have to concentrate on a new product that has to be out and tested well before the Olympics this winter.
 
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