Shahab2142
Posts: 2
Joined: Wed Sep 21, 2022 4:44 pm

Plug in battery drains overnight for some reason

Hi all,

I recently bought a used 64 plate mitsubishi outlander phev in the uk and I've noticed that some nights I've completely charged the battery and then disconnected the plug, locked the car and gone to bed. Then when I come in the morning and start the car, for some reason the battery shows only around 80% full instead of 100% that it was showing the night before. Is this normal? Why is my battery draining for no reason? Or is it even draining as it might be the case that the computer is lying to me. There are no lights turned on or anything. I'm very confused. Is it to do with the weather as it gets cold over night these days in england.

Any help would be appreciated!
Thanks
AndyInOz
Posts: 676
Joined: Wed Sep 09, 2015 5:05 pm
Location: Australia

Re: Plug in battery drains overnight for some reason

Yay! This is my favourite problem.

There are a couple of factors that could be at play here.

1. When the temperature is low, the battery cannot provide as much power as when temperatures are more normal.
(In my case, I've seen the displayed range to be lower in the morning when I arrived at work, than in the afternoon when I'm leaving work)
This is because the battery has warmed up as the day warms up.

2. There could be a timer set up to pre-heat the car.
When I first bought my car, I was having significant power drain going on overnight.
One evening, I went out to retrieve something from the car and found the interior to be blazing hot.
Once I found the timer settings, I discovered that the car had been set up to pre-heat the interior first thing in the morning, and at 7pm in the evening. Naturally that was using a lot of power from the battery.
Checking for pre-heating (or cooling) timers is probably the most important thing for you to do now.

If you poke around in the forum, you'll find me banging on about this timer issue, this was my original post on the subject:

https://www.myoutlanderphev.com/forum/v ... hp?p=19759
2014 PHEV Aspire, Arctic Silver;
Black Interior;
Hayman Reese removable tow bar;
1.5kW Solar, grid connected.
littlescrote
Posts: 388
Joined: Fri Jul 26, 2019 3:52 am

Re: Plug in battery drains overnight for some reason

As Andy says, it's most likely a timer to heat or cool the car. Sometimes they're visible in the dash settings, sometimes only in the App.
greendwarf
Posts: 2508
Joined: Tue Aug 05, 2014 1:32 pm

Re: Plug in battery drains overnight for some reason

Unlikely to be just ambient temperature in the UK yet.

However, the charging procedure seems unusual given that a full domestic charge is going to take over 3 hours at least - why disconnect and then lock the car. I plug in when it is already locked and then leave overnight and never noticed a less than full battery no matter what the temperature - only the range fluctuating with the weather. Not using a CHADEMO? :idea:

But a hidden timer setting is the most likely on a second-hand car.
Shahab2142
Posts: 2
Joined: Wed Sep 21, 2022 4:44 pm

Re: Plug in battery drains overnight for some reason

Hi all,
Thanks for all the responses. I disconnect the charger overnight because I'm actually charging it from a window in my house as I don't have a garage so I don't want to keep the window open at night. Also I don't see any heating sign or anything on the dashboard and the car doesn't feel blazing hot or anything when I come in. I will check whether there is a timer but what's weird is that even if I charge the car fully at night and then disconnect and then come back lets say 5pm in the afternoon when its relatively hot and sunny, the gauge still shows a bit less than the night before when I charged it. I assume it might be something to do with the electronics and maybe the hybrid system doing something in the background overnight that might be drawing some power. I've had days however when I've come back and its only lost maybe 3% charge and days where its 25%. It might be because its an old battery or something as I've heard that it is something that does tend to happen especially to older and more used batteries.

On a side note, when i took the car to a mechanic the other day (private garage), they serviced it and everything was fine but they said that their testing apparatus showed one fault with the hybrid system that they cleared off. I'm taking it again to the garage soon to see whether this fault will show up again with further testing. Also is it normal to be only getting 24 miles on a full charge? I don't have the whatchdog app or whatever equipment you need to monitor the battery.

Appreciate all the help!
Regards
ChrisMiller
Posts: 604
Joined: Tue Jan 12, 2016 6:37 am
Location: Bucks

Re: Plug in battery drains overnight for some reason

24 miles is a reasonable number. My guessometer often shows less than 20 on a full charge, but I live in a hilly region, which the car has 'learnt' about. The range will go down by a few miles, as the weather gets cooler.
GX4h (2016) since 23/12/2015
greendwarf
Posts: 2508
Joined: Tue Aug 05, 2014 1:32 pm

Re: Plug in battery drains overnight for some reason

24 is better than I'm getting on my '64 plate but battery condition varies according to the number of full charging cycles (about 2000 over its lifetime). As you don't know, with a second-hand car, the mix of ICE to EV driving, mileage is of no help.

I still think it is a timer problem, as the whole point about lithium batteries is that they hold their charge if unused! If not for heating (although our tin boxes on wheels lose heat very quickly once it is off), then it could be for the aircon - previous owner had it parked in the sun during the day? It was very hot this summer!
littlescrote
Posts: 388
Joined: Fri Jul 26, 2019 3:52 am

Re: Plug in battery drains overnight for some reason

There is no other reason for the Drive battery to be used other than for a timed heat/cool event, or a 2pm Aux battery 12V charge which you will not notice as it's a fraction of the Drive battery capacity.

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