Battery drainage when parked

[SebP10]

Due to the current situation, many cars are now sitting idle when they would normally be out and about. There have been a couple of posts about new-ish cars having a flat Battery after what seems a short period of time, so I thought I'd experiment on one of our cars (hers 😉, as it's barely been used since the lockdown started) to see the current drain when parked. This was purely for my own interest but I though I'd share the results here as they may be useful for somebody.

I connected an ammeter between the negative lead from the car and the negative terminal from the Battery on our (her) 2017 XV (2.0 petrol with keyless entry) and then monitored the current with the car in various states. The meter used was a Fluke 177, the current reading of which was cross-checked with a Fluke 8088A earlier in the day and found to be within 1 mA at 1 A (0.1%, or good enough for me!) The Battery is the OE 62Ah unit and was fully charged (according to the Optimate III charger that was connected prior to the tests.) Key was kept out of range unless required. The current readings were fluctuating so the approximate mean values are used (possibly due to the flashing alarm and immobilser LEDs.) Current drain results were:

Locked, alarmed - 80 mA

Locked, alarmed, welcome lighting on (wafted key by the door) - 2.25 A. This drops to 320 mA once the interior lamp goes off and then drops back to 80 mA after approximately 35 seconds. This current was monitored for 1/2 an hour.

Locked (with key, so no alarm) - 80 mA

Unlocked (doors opened and closed to prevent automatic re-locking) - 300 mA (once interior lamp goes out.) This drops to 70 mA after approximately 35 seconds.

 

From this attempt at a scientific (but mainly messing about in the garage) experiment, it looks as though the alarm has no effect on the current draw over the immobiliser, and that only draws 10 mA more than when the car is open and idle. But with only 62 Ah available even 80 mA could drain the Battery in 32 days (by my !Removed!-packet (but probably more to it than that) calc.)

For the XV, from now on I will be plugging it in each weekend, as well as taking it to work occasionally, to keep it topped up until all this is over. (Oh, and don't leave the interior lamp on as this reduces the life to just over a day 😖)

I hope this has been useful (or at least given you something to do for a couple of minutes!)

[Jay762]

Useful post - thanks and gives a benchmark, Ill complete the same process when mine is back together as I have some additional security and electronics in place to povide a comparison

[Mr B]

80mA is quite high.
average in the auto world is between 20 and 55mA .
When we test these we like to do a 24 to 48hr test with a Bluetooth logging meter to a laptop
(you sometimes find modules waking up for periods and drawing more current)

Subaru newer models got a known by owners issue on Battery drain if left standing for couple weeks .

Dealers and Subaru themselves seem be ignoring it, I would assume it engineered into car electric systems and not a easy resolve .

Is a nasty problem as besides potentially leaving you stranded it also going reduce Battery life drastically which means more manufacture and recycle pollution (batteries are one of worst for pollution in manufacture and recyle) and another hit for your wallet .

Modern cars are far from green , they consume ridiculous amount of parts, servicing chemicals in a very short lifespan .
What they have got really good at is parting you with a lot of money for poor engineering poor quality, poor warranty and poor service support . .

 

[SebP10]

Yes, 80 mA does appear to be high. I've haven't checked before as I didn't have to as our previous cars were 2001 and 2002, no way near as electroniccy as these are. Makes you wonder whats going on with them? As you say, this is becoming a known issue. I've had a browse around the club section and there are a few Forester owners that you've helped, inc a very new e-Forester.

Interestingly, Subaru sent a video a couple of weeks ago on how to keep your car in tip-top condition during the lockdown, which suggests, amongst other things, disconnecting the Battery on both normal and eBoxer models if parked up for a while. It's on YouTube, but not listed so you can't find it when searching. Hopefully the linky-thing below will work...

https://subaru.im-group.co.uk/2VDY-110RG-5EYW5V-N14DM-1/c.aspx

I'm going to repeat my "experiments" on the Levorg tomorrow and see how that fairs (plus double the sample size!). A data-logger would be very useful. I can bring one home from work but the DC current-clamp would output 8 mV for the 80 mA on its lowest setting, so the signal would probably get lost in the noise.

[flat6]

I'm lucky enough to have a driveway, so I've been using a C-Tek charger set to supply for my Levorg. The dealer me it could go flat in 3 days  so I was forewarned.

[Tidgy]

came out to mine back end of last week and i've seen more life in a dodo.

as flat6 says i chucked my ctek on it and its now always charged. i bought a cable extension for it so it now runs under my garage door and to the car without leving any connectors exposed.

[SebP10]

I've been wondering about what systems could be active when the car is parked to cause such a current drain, and I started thinking about the keyless entry system. This appears to be constantly "looking" for a key so therefore using power. The handbook (page 2-16 for both the Levorg and XV) alludes to a Battery drain issue, recommending that the function is disabled "When the vehicle is not going to be used for an extended period of time", so I thought I'd give it a go.

Since the original post I've discovered an average function on the meter so I don't have to estimate the current from the fluctuations. I used the Levorg as it was already nose-on to the garage after being on charge overnight. Results were:

Keyless enabled, locked, alarmed - 71 mA

Keyless enabled, locked with key (no alarm) - 67 mA

Keyless disabled, locked, alarmed - 60 mA

Keyless disabled, locked with key (no alarm) - 56 mA

So disabling the keyless entry will reduce the current draw by around 15%. The drain is still high but should buy a few extra days before it dies. But, as stated above, the best bet is to buy a decent Battery charger with a long lead and plug it in if possible.

 

[Siluro]

I live in terrace house so bought a solar panel 7.5w and plugged it via OBD port fused. Panel open circuit kicks out 21v in decent sunlight. Overcast drops to 15-18v where I doubt it is producing much output (don't have a DC current meter). When connected to Battery the panel cannot supply the 21v as the Battery will draw lots current so voltage drops down to the Battery voltage (bit over). Seems to work but I would probably buy a 10 watt plus next time. RAC sell a 4.8w panel which I cannot see doing much unless in 24 hour sunlight. Only had it a few days so too early to tell if it does much we shall see. It will definitely slow the drain of the Battery but not sure if it will keep it topped up. In the winter I doubt it from what I am seeing on this 7.5 watt panel.

If I was to use a higher wattage panel I would consider a regulator (needs research) as the amount of power is starting to get towards being able to start a fire easily.

[SebP10]

On 5/16/2020 at 10:28 AM, Siluro said:

I live in terrace house so bought a solar panel 7.5w and plugged it via ODB port fused. Panel open circuit kicks out 21v in decent sunlight. Overcast drops to 15-18v where I doubt it is producing much output (don't have a DC current meter). When connected to battery the panel cannot supply the 21v as the battery will draw lots current so voltage drops down to the battery voltage (bit over). Seems to work but I would probably buy a 10 watt plus next time. RAC sell a 4.8w panel which I cannot see doing much unless in 24 hour sunlight. Only had it a few days so too early to tell if it does much we shall see. It will definitely slow the drain of the battery but not sure if it will keep it topped up. In the winter I doubt it from what I am seeing on this 7.5 watt panel.

If I was to use a higher wattage panel I would consider a regulator (needs research) as the amount of power is starting to get towards being able to start a fire easily.

I bought an AA 4.8W panel for the wife's XV because it came with an OBD connector. It's not going to keep the Battery topped up for long, but it should buy a couple of weeks and negate the need to nose it into the garage for a charge. I took some current readings (detailed in the XV forum), but unless the panel is pointing directly at the sun (which is tricky as it has a habit of moving!), and angled-up at around 45^o (so the sun is 90^o to it), the output is far less than the peak rating. Knowing this now I would have gone for a 10W panel, as long as there was an OBD connector available.

But, as you say, anything more and a regulator would be required, as a flat Battery is easier to fix than a fire!

[Siluro]

I agree. The current falls of a cliff below  some where below 167v from the panel. This would turn out to be 30ma, maybe enough to negate normal draw barely. It dishes out 21max with no load. Yes a 15 watt panel may do the job well but still depends on British weather. This just delays the flat Battery.

 

Halford sell a fused OBD connector which I used on a cheap panel from eBay.

[Siluro]

12 hours ago, Siluro said:

I agree. The current falls of a cliff below  some where below 167v from the panel. This would turn out to be 30ma, maybe enough to negate normal draw barely. It dishes out 21max with no load. Yes a 15 watt panel may do the job well but still depends on British weather. This just delays the flat battery.

 

Halford sell a fused OBD connector which I used on a cheap panel from Ebay.

Wow it was late, I need to proof check in future. The current produced from my 7.5W panel falls of a cliff when the panel produces some where below 17 volts without a load (not connected to battery). This is a cloudy day sort of light. This would then only produce 30-40 ma (rough calculation) so the Battery would still slowly drain if left for a long period of time. Normal Battery drain I believe is 40-60 ma but that is car dependent. More modern cars maybe a lot more. My Hawkeye draws 50 ma when in sleep mode. It draws 0.3 amps for 20ish seconds when the Battery is first connected then drops to 0.05 amps. Based on this then a better panel would really be required to keep the Battery topped up in the winter months (dull days). Then you get into regulators and bigger or more expensive panels. Gets to the point where it is easier and cheaper to just pull the battery and stick it on a mains charger.

My 7.5 watt panel this last week has managed to keep it topped up but it has had some good sunshine. This week the panel has kept the battery around 12.4 volts. I checked battery voltage last thing at night.. Worst day being 12.37v but that is in line with the amount of sunlight. Only tested so far for a week.

I cannot see a 4.8w or lower being of much use unless you live in Australia but it will buy you some time before the battery is flat.

 

Edit: quick calculation without panel: (60/0.05)/24 = 50 Days or around 7 weeks to a flat battery. Based on just a continuous 50ma draw on fully charged 60Ah battery. This is for an untouched car parked and does not include ECU wake up draw, or interior lights and so on...... So my 7.5w panel in mid to good light might work on my car. I will keep testing.

[SebP10]

I left the XV alone, apart from occasionally opening the door to pop the bonnet and check the Battery voltage, for three weeks and it started on the button without fuss. The Battery voltage was generally around 12.6 V, so the 4.8 W panel seems ok at this time of year, althought the car is pointing almost south so gets a decent amount of sun (when available!)

I agree it won't give a net charge to the Battery, but if it buys some time then holidays (when allowed) will have one less thing to stress about!

I may look at a higher power panel (size dependant) for winter use (Mrs could be working from home until the New Year so the car may be stood for a while.) Overcharging won't be as much of an issue once the nights draw in and the sun is lower in the sky (and sorry to bring winter up before the longest day)

[Siluro]

12.6v is fully charged. Your doing well. Did you measure it with the panel still attached?

I only get sun from morning to 2pm then car is in shade.

[SebP10]

It was with the panel connected so the voltage will be inflated slightly. If I remember correctly the voltage was around 12.55 V on first checking (after the 10 A spike of unlocking the doors and then interior lights whilst popping the bonnet) but rose steadily to over 12.60 V in 30 s as it recovered. The sun was high enough that the bonnet did not obsure the panel.

We're fortunate that the dashboard gets sun from around 1030 until 1900 at the moment, so I think it is breaking even over 24 hours at the moment (on sunny days.)