Auxiliary battery draining while Parked / Ready

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LondonLass

Well-known member
Joined
Nov 19, 2014
Messages
66
With this hot weather I've sat a couple of times for a long lunch in the air conditioned comfort of the Phev while I eat my Tesco meal deal. Has anyone else experienced an issue with the Auxiliary battery being drained resulting in a dashboard warning about requiring a service and generally symptoms of low aux battery? I had made sure that the car was in Ready mode so that the main battery would be depleted to run the air con, and indeed excellent cold air, trickle of water under car and battery being used up over time. Used a jump starter battery pack to get it restarted and after a drive it seems to be ok.
 
AFAIK ... 12v battery can't be "discharged" when the PHEV is in ready mode.

I'm not sure AC can be running without ready mode (excluding the key fob trick)

Maybe the car was not in Ready mode ... but still the air flow was cold due to the previous usage of AC

Anyhow .. as jaapv point out ... you 12v battery possibly it is not anymore in a good shape

PS: On my cars I have always a voltage meter on the 12v plug ... so I'm monitoring all the time the voltage .. it is more easy to see when things are starting to go bad
 
This happened to me on the 2nd day I had the car. I was trying to get my phone to pair in the RemoteControl II app. Sitting for about 20 minutes with the car in and out of ready. AC was on for part of the time, temperature was around 85F. I finally gave up and went to start the car. Battery warning and Service light came up on the MFD. Being new to the car, at first I thought it was just part of ACC mode. I powered down the car and tried again and the message did not occur. I haven't seen it since.
 
There are actually 2 ready modes.

The first is by double pressing the start button...but without your foot on the brake pedal. This gives the appearance of being in Ready mode but it isn't and the car won't go.

The second is full Ready mode having pressed the start button with the brake pedal pressed. The car will go!
 
I totally flattened my auxiliary battery in around 15 minutes by leaving my power button in the 'second click' blue light position (ie. no foot on the brake pedal when pressing the power button so not the fully-live and ready to go position) with the heater on two blobs, side lights on and hazard flashers on (also with a trailer which may not have helped). I was at the time changing a flat tyre in a somewhat hazardous location in the snow.

The auxiliary battery was so completely flat that even the hazards wouldn't work. The only thing that worked was the rear wiper, intermittently, which at the time wasn't actually switched on. Re-pressing the power button didn't help either. The only thing I had to identify my position to oncoming (and mostly very inconsiderate) traffic was a small but powerful red flashing bicycle light (you know, the sort of thing that bicycles generally don't use when riding in the dark). Vehicle was eventually 'jump' started (Mitsubishi Breakdown) with conventional car jump-starting device (via fuse-box facility in bonnet provided for this very purpose) and was perfectly ok after that. Battery was tested and was at 100%.

I of course swore I would by a Li-ion jump-starter thingy as a result of this episode, but so far I haven't, so I've only got myself to blame if I manage to do it again. The thing is the Li-ion device also has to be in a fully charged state at all times. There seem to be mixed opinions as to how long a Li-ion device will remain charged.

I'm most definitely of the opinion, considering the amount of WARNINGS! that a PHEV is capable of that it should warn very severely and in no uncertain terms that the auxiliary battery is about to go flat. If you did happen to be stuck in a snowdrift in a potentially dangerous location (I kind of was) this could be a real life saver.
 
Tipper said:
There are actually 2 ready modes.

The first is by double pressing the start button...but without your foot on the brake pedal. This gives the appearance of being in Ready mode but it isn't and the car won't go.

5 second is full Ready mode having pressed the start button with the brake pedal pressed. The car will go!
The Ready light doesn't come on when the brake is not pressed. At least not in my car. So how does this give the appearance of being in Ready mode?

I think most relevant is whether the HV relay is engaged. When the AC or heater is working, it must be. To be honest I don't see how the DC/DC converter (that supplies the 12 volt circuitry from the main battery) could not be operational when the HV relay is engaged.
 
Yes the actual Ready light may not be on but I think I'm right in saying the colour of the start button light changes and you may be misled into thinking that two presses of the start button has put it in Ready mode.

Both my wife and I have inadvertently done this and then wondered why the car won't go! You have to turn it off, press the brake and press start all over again...
 
anko said:
I think most relevant is whether the HV relay is engaged. When the AC or heater is working, it must be. To be honest I don't see how the DC/DC converter (that supplies the 12 volt circuitry from the main battery) could not be operational when the HV relay is engaged.

Agreed, I didn't think the car was in Ready the whole time. In the process of debugging RemoteControl, I put the car in each of the three states to see if that fixed my problem. I still don't know why the low 12V battery warning came up, nor I have I seen it again.
 
NightPHEVer said:
I'm most definitely of the opinion, considering the amount of WARNINGS! that a PHEV is capable of that it should warn very severely and in no uncertain terms that the auxiliary battery is about to go flat. If you did happen to be stuck in a snowdrift in a potentially dangerous location (I kind of was) this could be a real life saver.

Well, in the second "position" you do get the red battery warning light and although the description at 6-43 of the manual does not specifically refer to extended time in this state, it does equate to the "ignition warning light" on a ICE. I assume we would not expect a normal car battery to take kindly to 15-20 minutes with the ignition on with stuff running but the engine not started? For example, I was always told to turn off headlights etc. when trying to start a car!
 
If the 'power' button is pressed once, the 'power' button shines an orange light. The radio and I think the wipers will work in this position but not much else (not even the windows!). Press the 'power' button again without the brake pedal depressed and the 'power' button shines a blue light, and all the dash displays and functions do to all intents appear to be fully live, but forward or reverse can't be selected.

At this point a graphic appears (and a 'bong' sounds) in the centre of the dash to tell you to depress the brake pedal and press the 'power' button again. You don't have to 'turn it off' and start again at this point. If you press the brake pedal, press the 'power' button and let go of the button straight away nothing happens, but press the brake pedal and hold down the 'power' button for around 3 seconds and the fully live position will be available - it only took me around six months to find this out! And only then is the car totally 'live' and forward or reverse can be selected.

Whether PHEV's from other parts of world are different to UK spec in the above respect I don't know. My power button was in the blue-light-but-not-able-to-select R or D positon when I flattened my auxiliary battery.
 
NightPHEVer said:
I of course swore I would by a Li-ion jump-starter thingy as a result of this episode, but so far I haven't, so I've only got myself to blame if I manage to do it again. The thing is the Li-ion device also has to be in a fully charged state at all times. There seem to be mixed opinions as to how long a Li-ion device will remain charged.

What I do is leave the Li-ion jump-starter plugged in at the rear socket and store it in the cubby hole area. So it's always been charged when you are driving.
 
Thanks for the replies, good to see as usual a range of informed opinions! I was so sure that I was in Ready, and I was sure that the air-con was nice and cool. In hindsight however, and under controlled circumstances I tried again and I did notice a difference so perhaps I wasn't in Ready!

There does seem to be a distinct hum when the air conditioner is running, while the car is in ready mode so perhaps I will just look out for that, or if the hot weather stays around I'll just pop the car into neutral and keep the handbrake on since I would expect that would virtually guarantee that I was definitely Ready.

Intrigued by comment on rear power socket, I don't think I have one of those! Must have another look.
 
LondonLass said:
Intrigued by comment on rear power socket, I don't think I have one of those! Must have another look.

There's a USB port inside the centre arm-rest cubby box - well there is in mine anyway. UPDATE ALERT! Hmm actually, further to this can Li-ion jump starting devices actually be charged themselves via a USB (they all seem to have USB outputs for charging other devices) or do they normally plug into the conventional cigarette lighter style accessory socket below the centre dash? Do some PHEV's actually have an additional accessory socket in the rear of the vehicle - maybe an optional extra?


Re. greendwarf: "I assume we would not expect a normal car battery to take kindly to 15-20 minutes with the ignition on with stuff running but the engine not started?"

I'd agree with you there, but the difference with a PHEV is that unlike a conventional car we're all used to the engine not running in normal everyday usage, so it's rather hard to decide at what time the engine should in fact be running, in order to prevent inadvertant flattening of the auxiliary battery. I don't actually know how a conventional 'stop-start' car copes when the engine is not running. Do they have much bigger 12v batteries than a non stop-start car? How long would the air-con run in a conventional stop-start car before the battery was flattened (if you were for instance stationary in a traffic jam)? Or does the engine management have the good sense to start the engine before the battery goes flat?

In fact, the more I think about this the more I wonder why there is a Power Button 'blue-light' On position that is not the 'ready' mode. Apart from the fact that the windows work in the blue-light position and not in the orange-light position would it not be a better idea if there were only two 'On' positions - ACC 'On' orange-light position (radio - and wouldn't it be helpful if the windows worked in this position too!) and 'On' blue-light position - which could only be achieved if the brake pedal was depressed and therefore the car would be 'ready' to go, as it already is in the 'blue-light' foot-on-brake position.

I'm still not entirely clear about this - do all auxiliary battery flattening incidents occur in the 'blue-light' non-ready mode? Can the auxiliary battery still be flattened in the blue-light 'ready' mode? Or will the amount of power left in the main battery or engine start-up prevent the possibility of this happening? I guess it would be possible to flatten the auxiliary battery in the orange-light ACC position but perhaps it would take quite a long time? How come the pre-heat/air-con option doesn't flatten the auxiliary battery?
 
NightPHEVer said:
... I don't actually know how a conventional 'stop-start' car copes when the engine is not running. Do they have much bigger 12v batteries than a non stop-start car? How long would the air-con run in a conventional stop-start car before the battery was flattened (if you were for instance stationary in a traffic jam)? Or does the engine management have the good sense to start the engine before the battery goes flat?

I have a 2014 BMW X1 sdrive28i with start/stop (thankfully with a button to turn this on or off) and can answer a few of these questions. BMW's battery specs are 80AH 800A CCA, whereas the Outlander's specs are 45AH 325A CCA (reference: https://www.yuasa.co.uk/batteries/automotive/yuasa-auxilliary-backup-specialist-batteries/hj-s46b24r-658.html). Management turns on the engine before the battery dies, how long depends on whether ECO mode is on or off. If ECO mode is on, and start/stop is on, and the car is running but at a standstill and the air-con is on, the a/c compressor will be on and off sporadically (basically alternating between regular fan and a/c), and will take about 10-20 seconds before the engine turns back on. If ECO mode is off, the a/c compressor stays on constantly, so at a standstill, about 5-10 seconds before engine turns back on. I'm sure there are variances to these seconds depending on battery load at the time.
 
LondonLass said:
Thanks for the replies, good to see as usual a range of informed opinions! I was so sure that I was in Ready, and I was sure that the air-con was nice and cool. In hindsight however, and under controlled circumstances I tried again and I did notice a difference so perhaps I wasn't in Ready!

There does seem to be a distinct hum when the air conditioner is running, while the car is in ready mode so perhaps I will just look out for that, or if the hot weather stays around I'll just pop the car into neutral and keep the handbrake on since I would expect that would virtually guarantee that I was definitely Ready.

Intrigued by comment on rear power socket, I don't think I have one of those! Must have another look.
When the aircon is running there is a pronounced fan sound from the engine bay.
 
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