Using a compressor for tyres off battery

[Notebook]

I wondered if this is going to flatten the Battery?

should I leave it in park and start it?

help

[Mooly]

Lets put some numbers in...

I know the 12v Battery capacity of a Hybrid is lower (a smaller battery) than a conventional one but it is still in the 30 amp/hour or above region. That means you can draw 30 amps for 1 hour, 1 amp for 30 hours and so on.

A lighter socket could supply around 10 to 12 amps continuously (100 to 120 watts) and 10 amps would discharge a 30 amp battery in 3 hours. Your compressor will draw less current than this, perhaps around 5 amps and so you could inflate tyres continuously for around 6 hours.

So two or three minutes or  even 10 minutes running of the inflator takes a minute percentage of the available Battery charge.  

 

 

[Notebook]

Won’t my tyres be huge by then? 🤪

should I have the car started or just in radio mode - single press - to get the output from the socket. 
 

thanks

[Gerg]

I'm stealing Mooly's thunder here.  I think he means in your 'radio' (accessory) mode. 

If you have the car 'started', then the compressor running-time is really only limited by how much petrol is in the tank!  In that situation the car is turned into an 1800cc, petrol, air-conditioned, generator.  A little bit like this chap is using his Prius for.  At around 2:15 the video is especially relevant:-   https://www.youtube.com/watch?v=W86B-6BHrJA&ab_channel=CourtRye

Mooly's answer, as usual, is perfect, but don't you C-HR owners have some 12V Battery issues of your own - like the owners of other hybrids, only more extreme, which is yet to be resolved?

 

[Mooly]

Lol, thanks Gerg 🙂

On a Hybrid and I'm not sure what you actually would do or press to activate the lighter socket but it will be something similar to the old 'accessory' position on a conventional key ignition. So radio mode as Gerg mentioned sounds good. 

[Notebook]

Thanks all

pressed the start button and plugged it in. 
afterwads the car beeped and wouldn’t lock/ mirrors go in etc. 
looked in car to see I hadn’t pressed the start button again to cancel. Took it for a drive and starter no problem. 
thanks all

[Gerg]

On 10/1/2020 at 11:40 AM, Notebook said:

afterwads the car beeped and wouldn’t lock/ mirrors go in etc.

This sounds like the 12v Battery state of charge is marginal.  As per Mooly's maths, it shouldn't be a problem at all. 

Sadly, I think you have some underlying issue with your 12v Battery and charging system.  Until this is investigated or fixed then best to use the tyre compressor with the car system fully 'on', that way the traction (high voltage) Battery is topping up the 12v battery at same time as the compressor is drawing power from it.

[Mooly]

Just thinking outside the box for a moment... the compressor motor will possibly be quite 'noisy' electrically speaking meaning it may generate lots of electrical interference that superimposes onto the 12 volt line. That could conceivably 'spike' the electronic systems running in the background and perhaps cause some lockup or systems crash of some sort. 

Now that sort of thing shouldn't happen of course... but I certainly wouldn't bet against it.

[Satsuki]

1 hour ago, Mooly said:

Just thinking outside the box for a moment... the compressor motor will possibly be quite 'noisy' electrically speaking meaning it may generate lots of electrical interference that superimposes onto the 12 volt line. That could conceivably 'spike' the electronic systems running in the background and perhaps cause some lockup or systems crash of some sort. 

Now that sort of thing shouldn't happen of course... but I certainly wouldn't bet against it.

I agree with you. Electronic circuits does not like any noise or spike on the power lines, although in the cars they usually have a lot of filtering and protection circuit on their power line.

I would test the voltage level with a multimeter (if you have one) or a cheap car Battery level tester to make sure about the Battery itself. Measure the voltage across the Battery terminals when the car is *not* switched on and if you read any value below 11.5V then the battery is flat (the fully charged battery should read something between 12.5V to 13V). It also could be that the charging system is working fine but the battery itself is damaged and cannot hold the charge.