2015 Subaru Outback - Mystery energy draw

subaru

#1

why does my 2015 subaru battery draw a 0.55 Amp current when the car is turned off?


#2

To maintain the electronic settings in your vehicle.
Whether 0.55 amps is high or low for your vehicle, I do not know.


#3

0.55 amps is WAY to high for any vehicle. If you measured this with the hood up and a door open then that is not an accurate figure. The car’s computers stay “awake” and draw current for a while when they think you are about to start and drive the car - doors open, hood open, ect. All must be closed up for a period of time before the current drops to a more reasonable 0.025 amps (25 milliamps).

This assumes you don’t have something that has gone bad and is pulling 0.5 amp when it should be pulling 0.005 amps. Suspect aftermarket stereo, or alarm systems.


#4

550 mA (0.55 amps) isn’t a normal off-state current draw. It should be more in the 50-100 mA range, or less. The off-state current draw measurement should be made by turning everything off, closing all the doors, and waiting 30 minutes or so. It could well measure 500 ma soon after turning the ignition off, as all the computers will be on, and actuators or electric motors may still be actuating something.

If you believe it is really drawing 550 mA, then it is a matter of detection to figure out why. There are several dozen circuits involved, each fused. So remove a fuse, and see if current drops to the 50 ma range or not. When it does, you’ll know which circuit is doing it. Then you have to figure out all the devices on that circuit, which is done by securing the car’s electrical schematics.

Newer cars like yours draw more off-state current. My early 90’s Corolla draws 7 ma.


#5

So is a dead battery problem the reason you ask this? Just wonderin’;…

Also, does this .55 mA occur immediately after shutoff or is it present an hour or so later?


#6

George, I keep telling you . . . 50 milliamps or less

I don’t know why you think the range is 50 - 100 milliamps

For example, just a few weeks ago at work, one of our vehicle operators forgot to retract the outriggers all the way, causing the “outrigger down” warning light to stay on

This caused a 130 milliamp current draw, which was enough to kill the batteries over a weekend

A 100 milliamp draw will also kill the batteries, might take a little more than 2 - 3 days, but it will happen

Once I fully retracted the outriggers, the “outrigger down” light stayed off, and I measured the parasitic draw again. It was now less than 20 milliamps

Honestly, I don’t know why you keep citing the numbers you do, because we’ve discussed it frequently, and all the professionals on this website say 50 milliamps or less

In this instance, I believe you’re not giving good advice

Would a doctor tell his patient it’s perfectly okay to be 100 pounds overweight . . . ?

I doubt it

:thinking:

No offense intended to anybody . . . I need to lose a few pounds myself


#7

I just found a way to lose 13 lbs so far. Have a Dental surgeon remove all of your upper teeth at one time .


#8

@db4690 … here’s what the Optima Battery Website says.

“What is “normal” for a parasitic draw?”

" a 25-milliamp draw is normal and anything that exceeds 100-milliamps indicates an electrical issue that needs to be addressed. Although I have checked the parasitic draw on my Excursion in the past, I’d never photographed that test. I did just that today and it indicated a draw of about 60-milliamps. That’s not too bad, considering I have some of the newer electrical accessories, like memory seats, mirrors and radio presets. "


#9

Then explain why I encounter so many newer vehicles . . . think vehicles from the last 2 or year model years, if not brand new . . . with plenty of luxury features, which draw 50 milliamps or less . . . ?!

:thinking:


#10

getting things into perspective…

let’s imagine one has a car with a 50 Amp-Hours battery

to start the car reliably, let’s assume it needs to retain 50% of capacity, so we have 25AH “to spend”

at 100 mA draw, we will get 25 / 0.1 = 250 hours to spend these 25 Amp-Hours, which is tad bit above 10 days

25 mA will give us a month and half to get to the same 50% of capacity

here we do not count the battery self-dranage, only the ideal scenario

10 days seem to be way too low for me, 40+ days is perfectly normal


#11

It depends on make/model/year/manufacturer options, and owner add-ons.


#12

Fine, George, think what you will


#13

But none of those should be contributing to current draw while in sleep mode. There is no reason to maintain any awake status for any of those features. Certainly, once you unlock or open a door, it’s going to wake up various modules and start drawing power but once the main system has determined that the timeout for sleep mode has expired, only the main computer is checking for a signal to wake up. Nobody uses RAM anymore to store settings. It all goes into non-volatile type memory (e.g. EEPROM) that does not need power to retain those settings. So radio presets, seat position, mirror settings etc all draw no power when sleeping.

60 mA seems high to me. How long did you wait before noting that reading? My TB has all the bells and whistles and only draws about 8mA when completely shut down. My prior TB started to drain battery within a week and I knew something was wrong. Traced it down to the power seats. The relay powering them wasn’t opening fully and creating a draw all the time. Even when asleep, the draw was around 80mA. I pulled the relay and it dropped to <10mA. Strange things can happen to cause higher draws than normal…


#14

True for some things, but some parameters in cars still seem to be stored in a volatile memory that’s lost when the battery is disconnected. If that weren’t the case, there’d be no need for the “memory saver” devices that plug into the cigarette lighter and allow you to swap out the battery without adverse effects.

Re the 60 ma, that wasn’t me talking, that was a quote from the battery manufacture’s website. I’ve never measured 60 ma myself. My truck uses 2.5 ma, entirely for the aftermarket radio, and my Corolla 7 ma. Like I say, it varies make/model/yr/options.


#15

That’s true, that’s why the ECM draws around 10-20mA. Most microcontrollers can go to sleep on less than a milliamp. I’m using one now that draws only 250uA in sleep mode. Settings like those mentioned in the article (my apologies for not realizing this and attributing the 60mA to you) that they attributed to the normal sleep mode draw do not change often and there is no reason they cannot be in non-volatile memory.