The Mitsubishi Pajero Owners Club®

KayakSteve · Newbie Joined: 03 Apr 2015 Posts: 9 Location: Bolton

A few weeks ago we went camping and my 2009 Shogun was left with the key set to the accessory setting for a while to charge up a phone. Came to start it Sunday morning and nothing - flat battery.

Thinking about it I realised that once the ignition is on everything is on - you can't switch off the sat nav and even with the radio "off" my guess is the amp is still being supplied.

So lesson learnt, we were away again this weekend and didn't leave it on for any length of time - enough to blow up a couple of airbeds and the doors were open for a while so the courtesy lights were on. But, another flat battery and a begged jump start Sunday morning.

I could leave my old Ford Ranger with the doors open & the radio on for hours with no issue, on its original 12-year old battery.

Anyone any experience with this? How long can the accessory setting be switched on without the gizmos sucking the life out of the battery?

Or is my battery at the end of its life? I guess it's the original so coming up for 6 years old. Not new but shouldn't be dead yet.

Ta,
Steve

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Simon_W · ******* Joined: 21 May 2013 Posts: 4881 Location: Watford

The length of time a battery will supply current is dependent upon its rating and the current drawn. So, for example a 90 Amp Hour battery will supply 1 amp for 90 hours. Or 0.5A for 180 hours. If you have an ammeter, you could measure the current with the key in the 'Accessory' position and work out how long the battery will provide current for.

Or just pop down to a friendly garage and get them to do a discharge test on the battery.

If the battery is OK, it implies the current drain is too great if it's going flat very quickly. Then it's a matter of pulling out fuses until you isolate the culprit prior to fixing it.

I had a similar problem a while back, but when the car was just left standing. I traced it to a dodgy alarm module, which I then replaced.

h4rri · Posted: Tue Sep 22, 2015 13:07 Post subject:

Pop a leisure battery in the bay, split charge system and use that to power a couple of USB and 12 volt sockets and avoid the issues in future.

I don't like leaving the radio on, doors open etc and if I have to then I turn the interior lights off to reduce the battery drain.

tom fenton · Posted: Tue Sep 22, 2015 13:18 Post subject:

6 year old battery knack'd is my vote. Get it discharge tested at a fast fit type place to find out for sure.

trekker · Posted: Tue Sep 22, 2015 16:58 Post subject:

+1.

Rare for me to have a 6 year old battery, can't in fact remember when, my Pay crank batteries are usually weak after 3-4 years.

Once a 12 Volt battery's voltage has dropped to 10.5 Volt it is deemed flat. At this level there will be some power remaining, but not sufficient to crank a Paj diesel engine.

I run a 100 amp crank battery and a 100 amp deep cycle, it's safer that way.

titan · Posted: Tue Sep 22, 2015 18:30 Post subject:

i would have though the mk4 would have a auto cut off, so when the battery get below a certain level it cut the power off to stop the issue of not being able to start. i haven't tried mine but i know my jetta had this but when i had a knackered battery on it this didn't kick in because it was never holding a charge high enough. if that makes sense.

peteinchad · Posted: Tue Sep 22, 2015 18:55 Post subject:

I have a 12v to 5V converter wired directly to the battery with an isolating switch. The output of the converter is wired to a USB socket.

To charge my phone I plug it in to the USB socket and switch the converter on.

When I have finished I switch off the converter so there is no battery drain when it is not being used.

You can use a similar system with an accessory socket for running other items that need 12V.

ja2_k · Posted: Tue Sep 22, 2015 21:20 Post subject:

I had to replace the battery on my 2009 shogun as it was loosing charge,especially on cold nights last winter.

assassin · Posted: Wed Sep 23, 2015 3:15 Post subject:

Its a common problem and both the MK 3 and 4 have a battery management system, with the ignition switched off it should only have power for the radio memory and for the alarm, if you have a tracker fitted this will be powered.

Several other things will work with the ignition switched off and these include the interior lights and sidelights.

Begin at the beginning, with all doors closed and the ignition switched off you remove the battery + lead and connect a digital multimeter between the + terminal and + lead and this will give current consumption, this should be about 100 milliamps, if it is much more then you have an issue.
Press the bonnet switch for the alarm down (if fitted) and activate the alarm with the key fob and see how much the consumption rises, it shouldn't be by much and if it a dramatic rise it is the alarm.

Check all the battery connections particularly the earths for deterioration and corrosion.

KayakSteve · Newbie Joined: 03 Apr 2015 Posts: 9 Location: Bolton

Thanks for the above comments.

There's no real problem when it's switched off unless the doors are open - it can be left for days with no suggestion of being discharged.

Just wondering if anyone had any idea how long the radio etc. can be left on for without killing the battery.

Probably a good move to swap the battery out before winter anyway.

Cheers
Steve

assassin · Posted: Wed Sep 23, 2015 12:39 Post subject:

Having built numerous expedition vehicles I would suggest a separate circuit with split charging and separate battery. You can get digital versions complete with battery monitoring quite cheaply now and the programmable types even shut off at pre-determined levels, this way you have no need to use your engine battery at all.