Battery Goes Dead

My 2016 Legacy 2.5i Premium (original battery) has had some battery issues the last year or so with an occasional slow crank. The terminals were fuzzy this summer and I cleaned them before I got stranded.

 

Now, it seems to be going dead in a couple days if I don't drive it. I commute an hour so it gets good and topped off when I do. Initial tests show good charging system health, good idle (engine off) voltage.

 

I've borrowed a battery load tester, amp clamp, multimeter.

 

Does anyone know what the nominal amp draw of the car is in park with the ignition off and the doors shut or any common systems that create a draw?

Check for a TSB about battery charging. Also factory battery is undersized and weak. Probably time to replace it anyway. But get the tsb done first.

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Does anyone know what the nominal amp draw of the car is in park with the ignition off and the doors shut or any common systems that create a draw?

 

 

An article from 2014 says 70mA for all models at that time.

 

Current models shouldn't be much different I would think.

 

 

It also appears to be an excellent tutorial for testing:

https://subaru.oemdtc.com/583/measurement-of-dark-current-parasitic-battery-draw-subaru

Edited November 14, 2019 by waldguy

Does anyone know what the nominal amp draw of the car is in park with the ignition off and the doors shut ...

Given its age, your battery should be nearing the end of its normal lifetime. Just replace it and get on with your life.

 

The formal spec (per both the FSM and at least one TSB) for dark current in the Gen 6 Legacy is 70 mA (0.07 amps) maximum, with occasional short spikes higher. In my limited experience (personal measurements), 30 mA is typical.

 

Has TSB 11-176-17 (Nov 16, 2017), "Reprogramming to Optimize ECM for Improved Battery Life," been applied to your car yet? If not, do it.

Edited November 19, 2019 by ammcinnis

Dead battery #3 this morning. These suckers do not like extreme cold.

 

The only thing not included in the extended warranty coverage is the battery.

 

Save yourself the time and aggravation and buy a replacement at Costco or PepBoys. Both have great values.

 

Also, spend the extra $10 and buy an AGM battery. You'll be grateful when it gets cold.

I never had actual trouble or inconvenience till now really, will ask about the TSB. I have asked my closest dealership multiple times about any updates to the computers or recalls and they say they don't see anything I have to bring it in.

 

Thanks for the amperage specs.

 

Has anyone retrofit a larger battery?

Has anyone retrofit a larger battery?

There has been endless discussion of this topic here and over on the Outback forum. The OE battery size is BCI Group 25. Two common "larger" replacements are Group 34 (NOT 34R!) and Group 24 (NOT 24F!). Both are drop-in replacements for the stock Group 25 battery, but either will have significantly higher electrical capacity.

 

FWIW, when I replaced the OE battery in my 2015 Legacy last summer, I bought a Duracell Platinum 24/34AGM from Sam's Club for less than $150. The exact same battery is also sold as the Deka Intimidator 9A34 (Deka is a "premium" brand name) at a significantly higher price. There are lots of other good battery choices out there, at a wide range of price points.

 

N.B. The BCI Group Number of a battery describes its physical dimensions, terminal style, and polarity, but it tells you nothing about a battery's electrical performance capabilities.

Edited November 19, 2019 by ammcinnis

Be careful if you use a battery that is not the one that's recommended for your car in the parts store system.. Years ago advance auto parts in a different state rejected my warranty because I used a battery with better specs than my oem battery, and was virtually the same size. I know I probably got screwed, but what can you do. They know when someone comes in with a dead battery and needs a new one, they probably are less likely to put up a fight.

Ammcinnis sorry for the rehash on the question but thanks for the excellent answer.

 

Apexi, I usually buy batteries from the local station and they are pretty good batteries (interstate) and spot on with the warranty. The batteries in my diesel truck are from 2013.

 

Battery failed the test at 260 amps at 8 volts. Going to charge it overnight with a maintainer and try it one more time.

 

Amp clamp is showing .65 amps draw.

Seems an awfully short life. Check that your trunk lid isn't ajar!

I like to see a draw under 50mA but if anything under 70mA is within spec, I'd have to assume the battery is not holding a charge.

you need to do a draw down test. the easiest way is amp clamp and a meter

I didn't follow the procedure in post number 3 to the letter but an amp clamp on the wire, either positive or negative results in around .65 amps which is about 10 times the suggested limit of .070 amps. I'm going to try to run through that test as suggested but it's written extremely poorly, especially on the part with the buss bar which my car has.

 

 

The battery also still tested as failed after 18 hours on a trickle charger. Did only slightly better, 280 amps at 9 volts.

 

A friend was charging his phone in my car an left a USB deal plugged in to the 12v socket, that could also be a part of the draw, remembered it just now.

 

A draw down test, will have to look that one up.

A friend was charging his phone in my car an left a USB deal plugged in to the 12v socket, that could also be a part of the draw ...

Nope. The 12 volt sockets are not powered when the ignition is off.

Do you have any aftermarket accessories hard wired in?

 

Charge it, take it to dealer, have them apply the tsb. Then go get a new battery from somewhere else. Or get a new battery then go straight to the dealer and make them apply the update.

 

Your battery will not survive this winter. It’s dead already.

I couldn’t get four years out of mine.

My battery kept dying in 2016.My wife got stuck at work so i put in a 34 the next day, 42 month ac delco. The stock battery is way undersized. Edited December 6, 2019 by WILLINH

Stock battery is undersized but it did OK for me. It cranked OK even when car was left in -30 degree weather for six hours. It never went dead. It kept everything going in our Canadian prairie winters, even with heated seats. I did put it on the charger a couple of times a year.

 

Given the time of 56 months in service, today I pulled it from the car. Tested 12.62 volts.

 

Replacement: Redtop Optima, which hopefully goes for as long as I own the car.

last winter it was -30F and the car started just fine on the stock battery, i replaced it because it was 5 years old and they are not known to last. Put in a Napa Gold (east Penn) and car has no issues Edited January 2, 2020 by YeuEmMaiMai

Got a group 34 Interstate at the local station for well under 150. The battery clamp took a beating from the acid, need to take it out and paint it. They didn't stock group 25.

 

My car also started at 20 below last year no trouble.

 

I want to hate this car enough to sell it but this SiriusXM trial right now and the fuel economy has me loving it again.

AGM battery is very good. I have it on my diesels. They have gel in them and the good thing about them is that they can be drained to empty and recharged to full many times before they die comparing to regular battery that looses most of its life one time it goes completely empty.

 

For parasitic draw test, disconnect your negative battery terminal, set your DVOM to mili amps, connect red to negative battery terminal and connect black lead to negative battery cable. World standard is 50mA should not be more, but if our specs say 70mA then go by what specs say. If you see more than 70mA, start disconnecting fuse one by one and see when the number drops. When you see number drop you have problem with that circuit.

I don't know how many times this has been posted but if you have Eyesight, cross traffic alert, Harmon Kardon system, etc., having Key ON or radio ON without running the engine is a big draw. It killed my battery after about 20 minutes.

2017 legacy. On my third battery. 12,400miles. Had to replace original battery at 3,000. Second battery just lasted 2 years. Car is kept in garage. Subaru batteries very poor CCP

 

 

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2017 legacy. On my third battery. 12,400miles. Had to replace original battery at 3,000. Second battery just lasted 2 years. Car is kept in garage. Subaru batteries very poor CCP

 

 

2016 Legacy (Liberty here) still on first battery. 23,000 miles. Car kept in garage. My Subaru battery OK.

I'm noticing that my new battery is having trouble after a few days sitting again. Still haven't been able to get into the dealership to get fixed.

Well I think my stock battery crap out already,I jump start it twice yesterday and drove car on frwy for 15min went back home and park it,checked voltage and was 14.3V and after 2 hours went to start the car and no start so I check voltage and it drop to 7.6V & ni there was lights,door,etc left open.

So I jump start it again and it started then drove car for 30min the park it at home and waited 2-3hours and again Voltage dropped to 8.3V

So I guess time for new battery:/