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Wondered if you can help?  I value your Subaru expertise

I had a new Battery fitted in 5th November 2020, and had been using the car quite often.

When the last lock down kicked in I didn’t use the car much at all.

I experienced a flat Battery on 22nd Jan so put on a fast charge and had the Battery checked where I bought it. They said it was ok but need a full charge.

Out came the Battery charger again and trickle charged it over a 24 hour period, it was reading 12.6 volts on my multi meter.

Since then I have experienced Battery drain over a 2 -3 day period.   I have made sure all interior lights are off.  

A TV receiver that was under the driver’s seat, (left in when it was imported), was removed.

I checked if anything else was left on but couldn’t find anything


On 24th Jan the Battery was 11.9 volts , I had to go out in the car and after 9 miles it read 12.3 v. next morning it 11.82v

Next day 11.46v

Next day 11.27v

Next day 10.76v (the 28th) I charged the Battery 12.5v

Next day I  did 6 miles and it read 12.5 v

Next day 11.67v  we did 8 miles that day and it read 12.1v when I parked up.   

Over the next week I did 10 miles one day and 20 miles the second day.

When not using the car the Battery was losing around 0.5 to .08 v each day.  

Last Tuesday the Battery was charged and at 12.16v, I pulled the radio/clock fuse, (the radio/sat nav/phone etc. was fitted by the importer) and checked it the next day it read 11.4v , so not that.

Thursday it was 10.3v and wouldn’t start, it was very cold too. -4 degrees!

I fast charged the Battery , 12.7 v and went shopping after I got back it was 12.8v. I put the radio fuse back in and pulled the heated seat fuses (retro fitted)

Did a short run last night, to the chip shop! and when I parked up it was 12.3v.

This morning it was 11.65v. so not the heated seats!

As you will no doubt gather there is a drain on the Battery somewhere,.  Do you have any ideas?

The alternator charges at 14.6V so that seems ok.


Sorry for the long drawn out e-mail , just hope you can throw some light in it?? (no pun intended)

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Well you certainly got a parasitic draw, fairly large, likely close to 1 amp.
You would expect under 20mA draw on these once locked and modules all sleeping .

Don't overlook possibility of alternator being culprit, bad diode will cause it pull current when stationary .
You could check that easily with you multimeter in amp mode in series or just leave alternator harness and cable to Battery disconnected overnight .
Your best way beyond this is leaving bonnet and drivers door open with bonnet alarm and door latch moved to lock/closed positions and allow car modules to go fully sleep and measure voltage drops across fuses and use a voltage drop to amp draw chart find circuit that active then pull up some wiring diagrams of that circuit to search and test further to narrow it down .
You will find a huge amount of information and videos on doing voltage drop parasitic draw testing online  that be far more fast education training that what I can put in this reply.
Fast way we do it on what likely large current draw like yours seems to be is infrared thermometer (preferably imager), can pinpoint the hot fuse/relay/module/motor/solenoid in literary seconds .
Basically as you got a multimeter, you got good chance narrow this down with bit more work and mastering a technique . good luck ...

* Would be good putting your multimeter in series with Battery + to actually measure the current draw so you know figures you looking for (some good videos can be found on how easily do this )
An amp clamp meter useful for this sort of auto test work that cheap is UT210E, pretty good and under £30 mark and can be made a really nice cheap tool if modify the firmware a little, I got a couple of these meters and they useful and disposable to me at that cost .

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Full marks for taking the experimental data.  
Less marks because, like all of us, you only have measurements for when things were going wrong and don't know what normal looks like. 

I will not question Mr B's expert and experienced contribution but add this account of my own, to reassure you or  add to your doubts:

January 2015 new WRX, with new Battery
November 2015 went to Australia for a month [no, not in Suby]. Car turns over fine on return, but then left it a few more days before actually driving. Battery flat. Realised I really should have disabled the remote locking to reduce Battery drain, as the manual advises, and who knows what the Tracker uses?  Borrowed a charger for a day and all normal again.   

Monday 24 September 2018 car and Battery now nearly 4 years old.
"My car Battery empty and clicking like a woodpecker. Disconnected it. Scorpion Tracker called several times."
Remembering lessons from 2015 before going away for some weeks, I study the voltages and current draw (ammeter cautiously in series from the Battery terminal) over a cycle of charging / driving, much as you have done.   
Tuesday 25 September 2018 "Car starts again but losing 1 amp of current in dormant state. Leave it charging all night."  

Wednesday 26 September 2018 "Car charged but minimal retention of charge/voltage. Worked through all the fuses in engine compartment and identified "back up" circuit as all but 6 milliamps of drain. Assume it is the Scorpion Tracker circuit (but also door locking). Call Tracker [to learn anything about the current consumption / charging profile of their installations - but Tracker, rather unspecifically,  does not think their devices cause material drain] then Perkins to order a new Battery. Despite long charging now the ~900 milliamp  drain continues. - if it was recharging the Scorpion Battery it would have filled or slowed by now. Also the reserve alarm does not sound on removing the Battery lead now." 

Thursday 27 September 2018 "Collect Battery at noon... swap it over. .. Check Battery drain but still above viability for two weeks. Charge Battery to the end of the day."  

Sunday 14 October 2018 - returned from abroad. Car which had been left with remote locking and Tracker live for 17 days started fine. 

No problems since, though have charged Battery during various lockdowns.   


1) When batteries start to go, get a new one straightaway. [Nothing we don't all now there.]

2) The days when Battery drain was mostly from leaving the interior lights on are long gone. If your Subaru has a Tracker or remote door locking then see above.

3) You can measure an awful lot of current drain coming out of a newly charged weak Battery - but it doesn't represent an equilibrium state. Even when I bought a new Battery the dormant car drew nearly an amp from it - presumably charging the Tracker or other reserve Battery for the first few hours? At 1 amp a fully charged new Battery would be dead in 3 days. In reality it lasted at least 17 days (so average drain less than 150 milliamps, and I think actually below 60 milliamps from later measurements. 

4) If none of the above, follow Mr B.  

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lot of newer cars do fluctuate around 40 to 60mA, seem have lot of pointless module wakeups and users across lot of car manufacturers are suffering from poor Battery life, constant no starts and general buggy module software along with silly short lifespan faults from general penny pinching component quality.
In my opinion anything over 40mA is not good even if it engineered to be that level, Newer cars are killing batteries real fast from combination of higher drain pulling batteries down further and causing more deterioration in the cells and from fact most modern car Battery durability is about half of what it was a decade or 2 ago .
Older models was about 40mA max and we didn't like seeing it that high really, well under 30 preferred and good out the factory range was seen around 15 to 25mA .

A lot of poor engineering exists today unfortunately in poor choice of way too much unneeded electronics along with sloppy software and general poor quality from engineering to a minimal quality level which is putting most of the new stuff in the crusher while the older generation vehicles still going almost faultlessly .

Really is good environmental logic is newer cars ! (far from it if do lifespan equations and include amount of parts and consumables they used)

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One thing to remember is when taking a Battery measurement you should let it settle after use. It should slowly rise a bit.

Below 11 volts and it will start to sulphate, reducing it's life. Jumping is also not good for batteries as you can bend the plates, if you have to leave the Battery connected for 10 mins before jumping or longer


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