Charging issue

Update on this.

I've spoken with the BMW stealer who sold me the battery and they are saying that if I bring the car in they will check it and if the battery is faulty will replace it FOC but if there are other issues they will charge me, which is fair enough.

However, in the meantime I will get the battery load tested independently, and if it is at fault I will book it in with BMW and get them to change it FOC :) save me the hassle.
 
I'm still trying to sort this bloody issue :x

I've had a load test done on the battery now, but it was inconclusive. So I've now disconnected the battery and charged it with a CTEK fully.

After it stabilised properly overnight it was resding 12.8v first thing this morning and it's still reading the same now. I'm gonna check again tomorrow evening but it appears the battery is holding the charge ok.

I've then got to set about finding the cause of the discharge.

It's most odd because prior to this earlier in the week I took it for a run of 35 - 40 miles and when I got back it was reading 12.9v I checked it 20 minutes later and it was down to 10.5v. Before starting it Friday I checked and had 10.5v but it still started fine. Could I have a short rather than a parasitic fault?

I might have to concede I'm beaten and take it to an auto electrician.

Cheers.
 
RayM said:
I'm still trying to sort this bloody issue :x

I've had a load test done on the battery now, but it was inconclusive. So I've now disconnected the battery and charged it with a CTEK fully.

After it stabilised properly overnight it was resding 12.8v first thing this morning and it's still reading the same now. I'm gonna check again tomorrow evening but it appears the battery is holding the charge ok.

I've then got to set about finding the cause of the discharge.

It's most odd because prior to this earlier in the week I took it for a run of 35 - 40 miles and when I got back it was reading 12.9v I checked it 20 minutes later and it was down to 10.5v. Before starting it Friday I checked and had 10.5v but it still started fine. Could I have a short rather than a parasitic fault?

I might have to concede I'm beaten and take it to an auto electrician.

Cheers.
Click to expand...

I'm not sure why a load test would be 'inconclusive', they either pass or are under performing, given that load test and your reading I'de be pressing for a replacement battery before shelling out on an auto-electrician,

Anyway, if your battery reading after a run dropped from 12.9 to 10.5 in 20 mins that's a LOT of juice in a short period and the offending component will be getting pretty warm (feel the battery, starter and alternator they will be warmer that the surrounding components if faulty, low current items would be burning out at that rate!) - are you sure your earths are clean and tight and readings right? a battery at 10.5V is considered 'flat' and that reading is pretty typical of a battery with one defective cell so I'd still suspect battery, connections or earth points first.
 
Ewazix said:
RayM said:
I'm still trying to sort this bloody issue :x

I've had a load test done on the battery now, but it was inconclusive. So I've now disconnected the battery and charged it with a CTEK fully.

After it stabilised properly overnight it was resding 12.8v first thing this morning and it's still reading the same now. I'm gonna check again tomorrow evening but it appears the battery is holding the charge ok.

I've then got to set about finding the cause of the discharge.

It's most odd because prior to this earlier in the week I took it for a run of 35 - 40 miles and when I got back it was reading 12.9v I checked it 20 minutes later and it was down to 10.5v. Before starting it Friday I checked and had 10.5v but it still started fine. Could I have a short rather than a parasitic fault?

I might have to concede I'm beaten and take it to an auto electrician.

Cheers.
Click to expand...

I'm not sure why a load test would be 'inconclusive', they either pass or are under performing, given that load test and your reading I'de be pressing for a replacement battery before shelling out on an auto-electrician,

Anyway, if your battery reading after a run dropped from 12.9 to 10.5 in 20 mins that's a LOT of juice in a short period and the offending component will be getting pretty warm (feel the battery, starter and alternator they will be warmer that the surrounding components if faulty, low current items would be burning out at that rate!) - are you sure your earths are clean and tight and readings right? a battery at 10.5V is considered 'flat' and that reading is pretty typical of a battery with one defective cell so I'd still suspect battery, connections or earth points first.
Click to expand...

Ewazix

My voltage readings are defo correct.

When we used the load tester the battery was only on 10.5v ( confirmed by two meters) so the load meter reading only showed a marginal change when connected. The car also starterd at this point after being stood for 3 days.

As I said, with the battery disconnected it has held the 12.8v charge for 12 hours so I'm gonna test it again tomorrow. If I do have a faulty cell this will prove it if the voltage has dropped surely?

If it maintains the same volts then the battery is ok? Otherwise I can do the load test again with the battery at 12.8v and see what that shows.

Can you tell me where the main earth connections are so that I can check them also please.

This is becoming a right pita.
 
There are several connections and grounding points on the car, the ones you can easily check are the + and - terminal posts on the battery which need to be buffed bright with a bit of abrasive like emery sheet and bolted tight, and the earth strap running from the - Neg terminal to the boot floor. It needs to be tight and free from rust on the mating surfaces. The other grounding points are located with significant components like the starter and alternator but are going to be tricky unless you have facilities to get under the car safely and are reasonably confident. http://www.bmwclub.lv/files/08_E85_Power_Supply.pdf

There are some tricky aspects to the power supply and main cable running under the car which are easy to balls-up if you are not sure what you are doing, including the BST battery safety terminal on the battery and B+ system which prevent electrics causing a fire in the event of an accident or damage to the looms. Good ol' Shipkiller posted a detailed reply re someone with odd discharge problems which explains the system http://www.z4-forum.com/forum/viewtopic.php?t=13765

Whilst I'm all for having a go at fixing stuff I know from experience that you can cause more expensive problems than you solve unless you are fairly competent and have the facilities in which case maybe find a recommended pro in your area, good luck and keep us posted :thumbsup:
 
Ewazix said:
There are several connections and grounding points on the car, the ones you can easily check are the + and - terminal posts on the battery which need to be buffed bright with a bit of abrasive like emery sheet and bolted tight, and the earth strap running from the - Neg terminal to the boot floor. It needs to be tight and free from rust on the mating surfaces. The other grounding points are located with significant components like the starter and alternator but are going to be tricky unless you have facilities to get under the car safely and are reasonably confident. http://www.bmwclub.lv/files/08_E85_Power_Supply.pdf

There are some tricky aspects to the power supply and main cable running under the car which are easy to balls-up if you are not sure what you are doing, including the BST battery safety terminal on the battery and B+ system which prevent electrics causing a fire in the event of an accident or damage to the looms. Good ol' Shipkiller posted a detailed reply re someone with odd discharge problems which explains the system http://www.z4-forum.com/forum/viewtopic.php?t=13765

Whilst I'm all for having a go at fixing stuff I know from experience that you can cause more expensive problems than you solve unless you are fairly competent and have the facilities in which case maybe find a recommended pro in your area, good luck and keep us posted :thumbsup:
Click to expand...

Thanks Buddy. I tinkered a little more last night and found that on reconnecting the battery (Which had still not lost any charge since Saturday) that the voltage dropped almost immediately and was down to 10.5v within 10 minutes. There must be a bad earth or short somewhere, so as you say, In the interest of me mot making a major F**k up I'm gonna get a local Auto electrician to check it out.

I will update once I've got it sorted.

Thanks for your assistance though.

Cheers.
 
This bloody saga continues on.

After the auto electrician gave the car the all clear last week I've took it in to the Stealers this morning to check it out.

Just got a call from them telling me the alternator is faulty and not charging the battery. very quietly told them that I thought that was a "crock of Shite" as both I and the auto electrician had tested the voltage when the car was running and getting 14.3v on tick over.

They confirmed that they could not detect any parasitic load and that the car was "going to sleep" fine.

So I said have you actually tested the battery? - met with silence, then..... we don't have the equipment to do that!!

So how the hell do they determine if my "New" battery supplied by them is faulty? However, they can test the new "clever" batteries apparently but that don't help.

I then explained at some length the tests I had done on the battery and that I had fully charged it both on and off the vehicle but as soon as you put it under load it drops 2 volts within minutes. Where is the correlation between this and their diagnosis that the alternator is not charging, when the battery is losing this much charge in such a short space of time with no evidence of a parasitic load?..

I don't pretend to be any kind of expert but I don't think they know what the hell they are doing :x .
 
You must log in or register to reply here.
Back
Top Bottom