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Help needed - electrical problem when refitting battery

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More electrical woes.........

 

@d_a_n1979 's part went in a treat and all was well last week.

 

Went away for a long weekend without the car, got back in it today and found a totally flat battery. :sad:

 

Waited for the rain to ease and have just put it on overnight charge.

 

Any initial thoughts from anyone??

 

Oddly the tailgate will not now lock back shut , which it has always previously done even with the battery removed:???:

 

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1 hour ago, Hippy said:

More electrical woes.........

 

@d_a_n1979 's part went in a treat and all was well last week.

 

Went away for a long weekend without the car, got back in it today and found a totally flat battery. :sad:

 

Waited for the rain to ease and have just put it on overnight charge.

 

Any initial thoughts from anyone??

 

Oddly the tailgate will not now lock back shut , which it has always previously done even with the battery removed:???:

 

 

Oh hell :(

 

When I was chasing the electrical drain on my touring pal, I left the multimeter connected and watched it either with the tailgate open (light knocked off and catch flicked, so the car thought it was all locked up) and then car locked and saw how much it dropped to.

 

I then started to unplug items (DVD/CD changer, sat nav unit, stereo related fuses, heater valve, HVAC control panel etc - obviously one at once) and left the car for an hour or so, until whichever item I'd unplugged stopped the battery drain... You'll soon see that the battery drops to a voltage and then stays there if whatever you've unpligged is the drain

 

It's a faff and ballache, but it does work and if you've a trickle charger, least you can leave that plugged in overnight so it doesn't go dead :) 

 

I used the permanent battery connection for my trickle charger, so it was simply a case of just plugging it in rather than having to faff connecting to the the terminals etc

 

Worth doing, if I can do it, anyone can ;) 

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This method should work and has the benefit of being able to use a cheapish multimeter.  The downside is that it's measuring the gradual reducition of battery voltage as a result of slow discharge current.

 

Another way would be direct measurement using a dc clamp ammeter.  You can clamp over wires and see in real time what current is going through them if you can get access.  No disconnection needed.

 

The problem is the meter must be capable of reading dc which makes it more expensive.  Here is an example still cheaper than an hour of diagnostic time at a garage.

https://www.amazon.co.uk/BSIDE-1mA-Clamp-Meter-Auto-Ranging/dp/B07MXDW677/ref=asc_df_B07MXDW677/?tag=googshopuk-21&linkCode=df0&hvadid=309950309033&hvpos=1o6&hvnetw=g&hvrand=11252450989575176605&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=&hvtargid=pla-646764951748&psc=1

 

I've never actually done this on a car though  so views from others would help.

 

You would want to clamp over single wires if you can and woukd probably get zero if you clamped over a pair of wires containing the positive and earth return for a device feed even if current were flowing though you might not as earth returns in cars can be interesting.

Even if you can't then clamp over battery connection and see the current change as you disconnect things.

Edited by Dbcrd

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Alternatively get a multimeter that will measure current, pop in series with battery supply or earth lead and disconnect fuses one at a time until current drops. I had a 300mA (0.3amp) drain on the battery that turned out to be a bad LED in the interior lighting circuit (fuse 2 or 4).

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That is a cheaper alternative.  They will all measure dc current.  Just make sure it's set on the right range take care not overload or short anything.  Most have milliamp ranges that would be good for spotting low current drain but if something high current gets switched on like headlights you can damage the shunt in the meter at the 10A or bigger  range it's less easy to spot a low current. Definitely don't start the car obviously that pulls a massive current.

Edited by Dbcrd

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Thanks for all the input so far gentlemen - much appreciated!

 

This morning before going to work I took the battery off charge, as the charger was telling me that the cycle was complete.

 

The battery measured 12.95v. Left it disconnected on the bench in the garage.

 

Managed to get home just now for lunch. The battery now measures 12.52v. I also borrowed the Clarke battery load tester from work. The battery comes up as being weak.

I assume from this that the battery has been drained one too many times and is giving up the ghost.

 

I guess a plan would be to replace the battery so I have a known good item to continue the search , or could it have caused the original problems ( constant blower and dead HVAC ) in the first place?

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Doesnt sound right as a cause of the symptoms but in any case worth changing as it is a huge headache when they fail when away from acess to a charger.  I had a failed battery a couple of years ago and due to circumstances the RAC sold me a new one (not too bad a price).  It also turned out that the battery in the car at the time was the wrong one and wasn't big enough so worth checking the type carefully when replacing.

 

Edited by Dbcrd

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@Hippy - Deffo replace the battery first

 

This is what I run: https://www.eurocarparts.com/p/bosch-s4-car-battery-019-4-year-guarantee-444770197 - with their 'MID60' code it's £123

 

I've also run this in previous E39s too with zero issues: https://www.halfords.com/motoring/bulbs-blades-batteries/car-batteries/yuasa--hsb019-silver-12v-car-battery-5-year-guarantee

Edited by d_a_n1979

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4 hours ago, d_a_n1979 said:

@Hippy - Deffo replace the battery first

 

This is what I run: https://www.eurocarparts.com/p/bosch-s4-car-battery-019-4-year-guarantee-444770197 - with their 'MID60' code it's £123

 

No sooner said than done!!

 

Managed to get the above on the way home from work.

 

Just fitted - reading 12.3v on install and 13.98v with the engine on at idle, so assume that the alternator is ok.

 

Thought I would measure the voltage before start up tomorrow morning and again after the car has been sat at work all day.  Would that  be a good indication of any potential battery drain?

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30 minutes ago, Hippy said:

 

No sooner said than done!!

 

Managed to get the above on the way home from work.

 

Just fitted - reading 12.3v on install and 13.98v with the engine on at idle, so assume that the alternator is ok.

 

Thought I would measure the voltage before start up tomorrow morning and again after the car has been sat at work all day.  Would that  be a good indication of any potential battery drain?


Ideally it needs to be over 14v when running...

 

Give the car a good run & see what the alternator is putting out during and when you’re back and it’s idling.

 

Personally I’d leave your multi meter connected to it overnight and see what the measurement is when you leave it and then get to it.

 

As yours is a touring, leave the boot cover open so you can see the meter through the glass ;) 

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On 15/10/2019 at 20:16, Clavurion said:

If the vehicle is with auto gearbox check that the lighting on selector lever goes off after 16 mins so vehicle goes to sleep mode correctly.

 

Can confirm that this happens.

 

Installed the battery on Tuesday - reading 12.3v.

Checked Wednesday morning before work - reading 12.1v.

Checked at work mid afternoon Wednesday - reading 12.1v

Checked this morning - reading 11.97v

Checked mid afternoon - reading 11.98v

 

Is the drop due to the alarm, or do we think there is something causing a small drain on the battery, which I guess at that rate would be a sod to find?:???:

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3 hours ago, Hippy said:

 

Can confirm that this happens.

 

Installed the battery on Tuesday - reading 12.3v.

Checked Wednesday morning before work - reading 12.1v.

Checked at work mid afternoon Wednesday - reading 12.1v

Checked this morning - reading 11.97v

Checked mid afternoon - reading 11.98v

 

Is the drop due to the alarm, or do we think there is something causing a small drain on the battery, which I guess at that rate would be a sod to find?:???:

 

There's a small drain

 

Next time you do it try as I've already said:

 

Unplug HVAC control panel;  lock car and read voltage once the orange light is out by the auto selector; leave overnight and then read voltage before you unlock the car (as said, as you've a touring, leave the multimeter when you can read it through the rear glass)

If not that, do the same with the heater valve in the engine bay unplugged (on drivers side suspension turret)

If not that; try it with the stereo fuses removed (56-58 IIRC)

If not that; try it with the heater washer jets unplugged

If not that; try it with the FSU unplugged

 

It's a faff, believe me I know, but you'll soon get there :) 

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Ok, I've managed to find time this morning to hook up a multi meter in series to the battery to measure current draw.

 

With everything switched off and the car locked the reading was 1.18A

 

In sleep mode this dropped to 0.74A

 

I removed each fuse in turn and recorded the readings ( with doors shut but not locked ).

 

Most of the time removing an individual fuse still gave a reading of 1.18A , with two exceptions.

 

With fuse 4 removed the reading was 0.8A

 

With fuse 9 removed the reading dropped to 0.16A

 

Looking at the fuse card.....

20191020_123705.thumb.jpg.6f758dffcc915b78f5668eeecec58a73.jpg

 

 both fuse 4 and 9 relate to more than one item.

 

I concentrated on fuse 9 functions, as this seems to be where the current is being drawn the most.

I disconnected the heated washers - the reading stayed at 1.18A

Reconnected the washers and disconnected the HVAC unit and the reading dropped to 0.16A

 

Is it safe to assume that this unit is causing the problem?  If you recall my initial problem that started this thread was my blower constantly on and my HVAC devoid of power. This occurred after reconnecting a recharged battery. Prior to the battery going flat the HVAC was working ok. The HVAC unit was replaced with what was thought to be a good item and indeed normal functions returned.  

Should I replace this unit again, or could something else in this circuit potentially be causing the problem?

 

Thoughts as always appreciated!!

Edited by Hippy

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Good detective work narrowing it down to the HVAC system.

 

I wouldn't have thought the HVAC panel itself is consuming the 1A of power (could be wrong), I'd be tempted to start disconnecting things beyond the HVAC panel/that the HVAC panel controls to see if the current drain drops.

 

Looking at that IKHA wiring diagram I'd start with the usual things - aux cooling fan, heater valves, FSU/hedgehog and rear screen demister.

 

It's worth repeating the experiment a couple of times/in a different order - I mistakenly thought the drain I had was on another circuit because the car 'woke up' halfway through testing the different circuits for a current drain.

 

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Fuse F9 is Terminal 30 (continuous voltage) supply for IHKA, nothing else. 

 

Like suggested you could try eliminating the parts IHKA controls. (Aux fan is controlled by engine control unit so that can't cause drain via fuse F9.)

 

In sleep mode the current consumption should be below 40 mA.

Edited by Clavurion

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2 hours ago, Hippy said:

Ok, I've managed to find time this morning to hook up a multi meter in series to the battery to measure current draw.

 

With everything switched off and the car locked the reading was 1.18A

 

In sleep mode this dropped to 0.74A

 

I removed each fuse in turn and recorded the readings ( with doors shut but not locked ).

 

Most of the time removing an individual fuse still gave a reading of 1.18A , with two exceptions.

 

With fuse 4 removed the reading was 0.8A

 

With fuse 9 removed the reading dropped to 0.16A

 

Looking at the fuse card.....

20191020_123705.thumb.jpg.6f758dffcc915b78f5668eeecec58a73.jpg

 

 both fuse 4 and 9 relate to more than one item.

 

I concentrated on fuse 9 functions, as this seems to be where the current is being drawn the most.

I disconnected the heated washers - the reading stayed at 1.18A

Reconnected the washers and disconnected the HVAC unit and the reading dropped to 0.16A

 

Is it safe to assume that this unit is causing the problem?  If you recall my initial problem that started this thread was my blower constantly on and my HVAC devoid of power. This occurred after reconnecting a recharged battery. Prior to the battery going flat the HVAC was working ok. The HVAC unit was replaced with what was thought to be a good item and indeed normal functions returned.  

Should I replace this unit again, or could something else in this circuit potentially be causing the problem?

 

Thoughts as always appreciated!!


Id unplug the HVAC panel and see what the drain is, if any.

 

If it is that, I’m so sorry for sending you a duff replacement :oops: it was fine in my car, but wondering if it being sat in the garage has caused corrosion of something in it?

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49 minutes ago, Clavurion said:

(Aux fan is controlled by engine control unit so that can't cause drain via fuse F9.)

 

Agreed, but IHKA calculates a/c pressure or measures evaporator temperature and sends a signal to the DDE/DME engine ecu to activate the aux fan (to cool condenser with aux fan when A/C is running). So there is a potential cross over here.

 

Unplugging these things with HVAC panel still connected would rule them out.

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@Clavurion and @ttrw2 - thanks for the info.

 

So to clarify - if I plug the HVAC unit back in, what are the other items that this controls that I should be checking? I did replace the Hedgehog with a new Meyle item a few weeks ago when this problem first occurred.

 

53 minutes ago, d_a_n1979 said:


Id unplug the HVAC panel and see what the drain is, if any.

 

If it is that, I’m so sorry for sending you a duff replacement :oops: it was fine in my car, but wondering if it being sat in the garage has caused corrosion of something in it?

 

The reading dropped to 0.16A  when I disconnected the HVAC, but it looks like there are other checks I can do to see if this item is faulty, or it is something else down the line, so to speak. Hopefully @Clavurion and @ttrw2 will confirm what I need to check.

 

If it turns out to be the HVAC unit don't worry, and certainly no need to apologise. It was sent in good faith and your efforts were, and are , appreciated ;)

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This document gives an overview of the IKHA system and all it interacts with

 

Based on this I'd check what happens when you remove fuses that control the supply to the aux fan (fuse 75 on flying lead up behind glovebox) and the rear screen demister (fuse 20).  I would then also consider disconnecting the FSU (footwell) and the heater control valves (engine bay).

 

Do all the above with the HVAC panel connected, in a methodical manner as you've done before, looking for the reduction in current drain.

 

If these make no difference then it would be on to the other items the IKHA/HVAC system influences (but are harder to get to).

 

*Note it does say in that doc that the IKHA/HVAC panel must be coded to the car if replaced.

 

 

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Had some time again today to do some further checks.......

 

HVAC unit replaced . Multimeter reading 1.19A

 

Unplugged FSU -  still reading 1.19A

 

Unplugged fuses 75 and 76 one at a time - reading 1.19A in both cases

 

Unplugged heater control valves - reading dropped to 0.47A

 

Can I assume then that the heater valves are causing some of the drain? 

 

However, when the HVAC unit was removed  yesterday the reading dropped to 0.16A . Would this then indicate that the unit is faulty as well as the valves?

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1 hour ago, Hippy said:

Had some time again today to do some further checks.......

 

HVAC unit replaced . Multimeter reading 1.19A

 

Unplugged FSU -  still reading 1.19A

 

Unplugged fuses 75 and 76 one at a time - reading 1.19A in both cases

 

Unplugged heater control valves - reading dropped to 0.47A

 

Can I assume then that the heater valves are causing some of the drain? 

 

However, when the HVAC unit was removed  yesterday the reading dropped to 0.16A . Would this then indicate that the unit is faulty as well as the valves?

 

Balls; sounds exactly like I had pal!

 

I unplugged my heater valve when I was experiencing a battery drain and low and behold, no more drain. Replaced it with this and never any issues:

 

https://www.ebay.co.uk/itm/HEATER-CONTROL-VALVE-SOLENOID-FOR-BMW-5-7-SERIES-E39-E38-E53-X5-64128374995/232238550078?fits=Car+Make%3ABMW|Plat_Gen%3AE39&hash=item36127f0c3e:g:VwEAAOSwoA1bXvKe

 

I'd do that first; leave yours unplugged for now and it should be fine, swap it out with a new one and fingers crossed, that'll be it done :) 

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Good news that you've located 0.7A of the 1.2A drain and that it's not the new FSU or the aux fan.

 

I'd resist simply throwing more parts at this stage and try to determine why the heater valves are sinking that much current when they're off (strip and inspect electrical side of them). If you have no appetite for this then replace as Dan suggests, but you may find it is the HVAC panel (the controller) sending the current there rather than the heater valves demanding it and you need to repair/replace HVAC panel next. i.e. it becomes a process of elimination via part substitution instead of getting to the root cause.

 

Still ~0.4A drain from somewhere yet to be determined - this is enough to drain a fully charged battery below a cold start threshold in 10days or so. Did you try the rear screen demister?

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