Kia Picanto parasitic battery draw

[SenileGit]

Hi, I have a Kia Picanto which I bought a few months ago. I used it for a few weeks and then left it in my garage, as my wife and I each have a car, so we alternate which car we drive every few weeks. After two weeks of not being used, I went to use the Picanto and found the battery was completely flat. I thought it was probably because the battery was on its way out when I bought it, so bought a new one. After not being used for four days, the battery had gone flat again. I realised that something was draining the battery, so I watched this video on Youtube:

and with my wife holding the multimeter, I saw that the car was drawing 0.7A from the battery, when everything in the car was turned off. I found that if I removed the 30A 'B+' fuse, as shown in the diagram below, the 0.7A went down to 0.3A, and went back up to 0.7A when I reinserted it. I tried all of the other fuses, and none of them made any difference. After spending a long time on the internet, trying to find out what 'In Panel B+' actually meant (I'm no car mechanic), I found out that it was the 'Battery Positive' going into the fuse panel in the car. (There is also a second B+ 30A fuse, in the lower right of the engine compartment fusebox, also shown in the diagram below - removing that fuse made no difference to the current being drawn. I'm not sure why there are two of them.)

I then removed and reinserted the fuses in the fuse panel inside the car. I found that the boot light was on, even though the boot was apparently shut. I pushed the back of two of the rear seats forward so I could see the boot light when the boot was shut, and the light was still on - so I removed the light bulb itself, so that at least I would have time to fix the problem with the boot door sensor, without draining another battery. I checked the multimeter and it said it was taking 0.3A, which was still too high, but after a minute, (exactly a minute), it went down to 0.01A. I took the multimeter probes off and then put them back on - it said 0.3A again, but after exactly a minute it went down to 0.01A. I thought that there must be something taking some current when you first connect the battery - probably the ECU, and I presumed it went off after a minute and that was it.

How wrong I was. The next day, I tested the keyfob, which opened the car, and turned on the headlights, and they worked fine. I didn't bother starting the car, because I was using my other car at the time, and I didn't want to drain the battery unnecessarily. Two days later I went back to the car and the battery was completely dead again!

This time I tested ALL of the fuses in the under dashboard fuse box, as last time I had stopped when I got to the rear light fuse, thinking that was the cause of the problem. None of the fuses caused the current to drop when I removed them.

I tested the current again, twice, and it was still taking 0.3A for exactly one minute, and then going down to 0.01A. I even held the probes on for seven minutes the second time, thinking that maybe the 0.3A draw would reappear after five minutes, but it didn't.

I have now left the battery disconnected, because I can't risk another one being ruined. Has anybody got any ideas what I should try next?

 

[Deleted member 142255]

Things like the central locking, clock and immobiliser will draw a current.

 

[Old Salt]

Modern cars all have a drain on the battery when standing idle and this will fluctuate if doors, boot, bonnet opened as the systems kick in ready for you to insert the key. So that would go some way to explaining the 0.1 to 0.3 amp draw.

Radio memory, alarms etc will all add to that. If your battery is discharging at 0.7a x 10 hours thats 7 amps, now leave it standing for a week thats 0.7 x 24 x 7 which gives 117amps.

My battery is 135 amps and will give 135a for 1 hour or 1a for 135 hours. You may well have a problem but if you are not using the car a fully charged battery could well discharge in 2 weeks and in this weather short runs and standing idle will not help.

You could try a battery isolator as used on classic cars which at least would make it easier to “disconnect” the battery when its standing.

https://amzn.eu/d/5XgO1p6

You need to fix the boot light/switch.

 

[Jurassicspark]

If the problem still persists after driving the car more frequently then it's possible it is an intermittent load. Things like wiper motors (usually rear wipers) will periodically try to park and draw ~5A for short periods.

Various modules sometimes wake up and create large current draws as well. If you can put a scope on it with a very slow sweep you might catch something (which I doubt you'll have.) If no scope, try putting a 1A fuse inline with the negative cable and leave it sit over night. If the fuse is blown the next day, you've got an intermittent load.

Is there any aftermarket stuff installed? Any dash cameras?

 

[Harry Bloomfield]

I have now left the battery disconnected, because I can't risk another one being ruined. Has anybody got any ideas what I should try next?

The 0.010amp / 10mA discharge, is well within the normal range. All modern cars, do have some small loads, when parked - to keep clocks, ECU's, and alarms active. When you lock the car up, at higher current demand (the 0.1amp/ 100mA) is normal, until the car goes fully into it's sleep mode. Because of this constant discharge, most modern cars cannot survive much longer than a month, parked up, and unused - because the battery will then be near flat.

Modern cars are designed to expect to be used regularly, which will top the battery back up, after these small discharges. If they are not used regularly, or kept on a battery tender, then what you have found to happen, is only to be expected. Another issue, which might be adding to the issue, is starting the engine, and the car then not being driven far enough, to replace the power needed to start the engine.

My own car, doesn't get that much use. It lives in the garage, on a battery tender, the battery tender turns on every day, for 20 minutes, to top the battery back up.

 

[ReganAndCarter]

As a slight digression, Eric The Car Guy is one of the best Youtube mechanics on there. A proper, time-served mechanic. Have watched his vids for years and learnt some things from him. Bodgeitandlegit is another one from the Emerald Isle and Rainmanray another excellent Tuber from Florida.

 

[SenileGit]

Thank you for all your replies, they give me food for thought!
Jurassicpark, I have dash cameras, plugged into the cigarette lighter socket, but they only come on when I turn on the ignition, and go off when I turn it off. I can try unplugging them to see if that changes anything.

The second time the battery went flat, was after I had removed the boot light, but it still went flat after only three or four days - four days tops. That doesn't sound right to me - I should be able to leave a car standing for four days without the battery going down to zero volts.
Harry Bloomfield - surely you aren't saying that I can't leave my car for only three days without having to start the engine, or recharge the battery manually. I explained that these were two brand new batteries, I hadn't driven the car, nor even started the engine once. They were both fully charged, new.

My 'idle' load was 0.01A, probably less than that, because I had my multimeter on the 10A setting. The next setting is 200mA, so a great deal smaller, so I didn't use that, because the 0.3A would be too much for it, and I don't know if it would 'reset' itself once the current draw went down to 0.01A.
In other words, I presume my idle load should be 0.01A, as the car clearly worked happily for five minutes with that amount of draw - so the central locking, clock and immobiliser would presumably all have been working throughout. So something is drawing a lot more than 0.01A, some of the time - I presume repeatedly, on and off. I will try to get some clamps and attach the multimeter probes so that I don't have to hold them, then I'll sit and watch the multimeter for half an hour at least, to see if it goes back up to 0.3A while I'm sitting there.

As it is, I don't feel it's safe to leave the battery connected even overnight, unless I am going to be using the car every day (I am retired and only go out one or two times a week in the car.)

 

[Harry Bloomfield]

As it is, I don't feel it's safe to leave the battery connected even overnight, unless I am going to be using the car every day (I am retired and only go out one or two times a week in the car.)

It sounds as if it may not be getting enough use, to replace what is lost whilst parked. Do you have a battery charger? Automatic ones are best - I would suggest that once every two weeks, the battery is put on charge, overnight.

 

[Deleted member 142255]

Check if the increase in current coincides with the red flashing immobiliser light.

 

[SenileGit]

It sounds as if it may not be getting enough use, to replace what is lost whilst parked. Do you have a battery charger? Automatic ones are best - I would suggest that once every two weeks, the battery is put on charge, overnight.

I put a new battery in last Friday, this Tuesday the battery was dead, after leaving the car in the garage.
Sparky3, the 0.3A stays there for the first minute of connecting the battery, then it goes down to 0.01A. I don't think it can be the immobiliser. Something is taking 4W for the first minute, but then turns off, but then I presume it turns back on later (how much later, I don't know) and uses enough to completely flatten a brand new battery within four days.

 

[Harry Bloomfield]

Something is taking 4W for the first minute, but then turns off, but then I presume it turns back on later (how much later, I don't know) and uses enough to completely flatten a brand new battery within four days.

You are right, something must be switching back on. My best guess, would be an intermittent connection somewhere in your system. The poor connection, keeps waking things back up. The only way to confirm it, is by monitoring the current, over a long period, but start by making sure your battery is fully charged, and the main battery connections are clean and tight..

 

[carmanmemoranda]

Just because you put a new battery on. Do not assume it was fully charged.

 

[Jurassicspark]

As a slight digression, Eric The Car Guy is one of the best Youtube mechanics on there. A proper, time-served mechanic. Have watched his vids for years and learnt some things from him. Bodgeitandlegit is another one from the Emerald Isle and Rainmanray another excellent Tuber from Florida.

Scannerdanner youtube channel is very informative too. Goes deep into diagnosing and always against the parts cannon.

 

[Stuart981]

Thats what happens with modern cars. What I do is a regular battery charge once a week. I just leave the battery on charge overnight every Sunday.

 

[Harry Bloomfield]

Thats what happens with modern cars. What I do is a regular battery charge once a week. I just leave the battery on charge overnight every Sunday.

A modern car, used almost daily, and doing a sensible mileage to enable them to recharge their losses, will do absolutely fine. A less regularly used car, doing mostly short runs, will struggle. Even in the old days, on dynamos, cars would struggle, in low speed traffic, so nothing new.

Quite a few years ago, I had a problem with a new battery, rapidly going flat when it was left parked a few days, unused. I noticed the discharged current pulsing to a high value, regularly. I eventually traced it through the system, to the tow socket, which was fitted with a voltage controlled relay. The relay's voltage was set, so it clicked on, then the tiny voltage drop the relay's current drew, caused it to drop out again - and so the cycle continued, endlessly, discharging the battery. Tweaking the voltage setting, cured the problem.