Battery Drain - Fuse Check inconclusive.

stuadh · 11th April 2012, 21:37

Hi,

I have just put my ZT-T 190 back together after some extensive maintenance, including removing the engine, replacing the clutch and timing belts and renovating the LPG system. The battery is draining overnight. Here are some points:

-I don't have Satnav
-I don't have any electrical modifications or additions (other than the showroom fitted LPG system)
-The car is completely dry having been stored in a heated garage since October.
-There are no lights or machinery sounds that indicate anything obvious sticking on.
-The car started easily first time and runs well on petrol and LPG (LPG is more likely to manifest wider engine management faults)
-The battery is a year old, having been unused far nearly half this time. It has been regularly trickle-charged during the maintenance. I charged the battery for the afternoon before I started testing and it showed a steady 12.5V.
-Although I didn't test the alternator, it seems to be charging adequately. After two days of driving 80 miles plus, the car was easier to start in the evening than in the following morning. This morning it would not start at all.

I conducted the fuse test, having a DC ammeter placed in series at the neg terminal. The drain started at 380mA, dropping to 190mA after a few minutes. I usually waited until the drain settled to 190mA before doing any testing. I noted the following:

-Fuse 22 (Audio Amp) caused a 10mA drop. I have an afermarket radio/CD but the original Amp fitted.
-Fuse 5 (BCU and wipers) caused a 40mA drop. A 40mA drop was also noted by unplugging the wiper motor connector. The wiper motor was untouched during my work, although the wiring loom, nearby was.
-One of the two additional fuses linked to the LPG ECU caused a 10mA drop as did unplugging the LPG ECU.

This left around 150mA of drain (the wiper motor being a possible partial culprit) which is well in excess of the at-rest power use for the car. I resorted to unfoccussed wiggling of connectors and looms in the engine and plenum areas, the areas I was working in an effort to see if I had shorted something, but to no avail.

I seek inspiration for where to look next.

Yours Aye

Stuadh

rover54 · 12th April 2012, 04:22

In the past I have had a battery discharging overnight through the alternator. It happens if the diodes in the rectifier pack go U.S allow back-feeding of current from battery to alternator. Disconnect alternator overnight and see what happens.

Have you charged the battery off car and then left it overnight off car to see if it hold charge. It might be discharging internally. A battery discharge test might help.

Other than that, it is a case of pulling fuses to isolate the circuits.

lovema75 · 12th April 2012, 06:47

I would try the simple things first like checking the boot light isnt staying on when the boot is shut - my last Rover (a 400) did exactly that, confirmed by removing the bulb.

HarryM1BYT · 12th April 2012, 08:43

Quote:

Originally Posted by lovema75

I would try the simple things first like checking the boot light isnt staying on when the boot is shut - my last Rover (a 400) did exactly that, confirmed by removing the bulb.

That cannot (should not) happen on a 75, they are fitted with a battery saver circuit which means that even if you deliberately leave an interior light on, the BCU will isolate the supply after 20 minutes or so.

Your discharge rate once everything has gone into sleep mode should be nearer 30mA in total. Your readings all seem a little high and I cannot really imagine all of those items to be at fault. Rather than pulling individual fuses, start at the under bonnet fuse panel to find the main areas of discharge. That main panel serves the glove box panel, so you should be able to trace it that way a bit quicker.

As someone else has suggested, disconnect the alternator, just to eliminate that as a cause.

I would suggest waiting an for an hour after turning everything off, to get an 'at sleep' reading.

stuadh · 12th April 2012, 21:31

Cheers. I'll try the alternator test tomorrow night (I need the car through the day). I've just checked the Rimmer site and I can't find a seperate rectifier. I take it that it is integrated into the alternator? My motorbikes has all had seperates.

Yours Aye

Stuadh

HarryM1BYT · 12th April 2012, 22:22

Quote:

Originally Posted by stuadh

Cheers. I'll try the alternator test tomorrow night (I need the car through the day). I've just checked the Rimmer site and I can't find a seperate rectifier. I take it that it is integrated into the alternator? My motorbikes has all had seperates.

Yours Aye

Stuadh

Yes, it is an integral part of the alternator along with the regulator. The first alternators had the rectifiers integrated, but with an external regulator - now it is all in one.

Be aware that the large main terminal is live all of the time. Maybe you could disconnect and put your meter in between terminal and its cable? I also heard that there is a fuse in the main battery to alternator cable somewhere, perhaps you could find and pull that fuse- might be easier than disconnecting at the alternator?

stuadh · 13th April 2012, 19:01

Hmmm,

I have just disconnected the alternator and there is still 190mA draining through the system. I'm waiting for it to go to sleep to see what that reads.

I left the car on charge all night and it started fine in the morning. I left it through the day on a solar panel charge and it started at lunchtime. It wouldn't start after lunch (battery reading 9.9V) but did after 45 mins of high charge.

So, not the alternator. I'll just keep plugging away at it (ha ha, see what I did there?)

Stuadh

stuadh · 13th April 2012, 19:31

Battery at 12.5V - After an hour, ampage is a 20mA which is much better. Focussing on the battery, now.

Battery and alternator unplugged.

We'll see how it looks in the morning.

Stuadh

rover54 · 13th April 2012, 22:59

Sounds like battery is discharging internally. Charge it up off car and leave it 24 hrs and check voltage.

stuadh · 14th April 2012, 09:09

Interesting.

After 14 hours, the battery is reading 12.7V. Allowing for reading error, it hasn't lost any charge overnight suggesting that the batery is sound. I'm checking the "at sleep" reading in an hour then I'm going to take voltage readings every couple of hours to see how quickly it discharges.

This is doing my nut in.

Stuadh

11th April 2012, 21:37	#1
stuadh Regular poster MG ZT-T 190 & GSX1100G Join Date: Jun 2008 Location: Here Posts: 76 Thanks: 0 Thanked 0 Times in 0 Posts	Battery Drain - Fuse Check inconclusive. Hi, I have just put my ZT-T 190 back together after some extensive maintenance, including removing the engine, replacing the clutch and timing belts and renovating the LPG system. The battery is draining overnight. Here are some points: -I don't have Satnav -I don't have any electrical modifications or additions (other than the showroom fitted LPG system) -The car is completely dry having been stored in a heated garage since October. -There are no lights or machinery sounds that indicate anything obvious sticking on. -The car started easily first time and runs well on petrol and LPG (LPG is more likely to manifest wider engine management faults) -The battery is a year old, having been unused far nearly half this time. It has been regularly trickle-charged during the maintenance. I charged the battery for the afternoon before I started testing and it showed a steady 12.5V. -Although I didn't test the alternator, it seems to be charging adequately. After two days of driving 80 miles plus, the car was easier to start in the evening than in the following morning. This morning it would not start at all. I conducted the fuse test, having a DC ammeter placed in series at the neg terminal. The drain started at 380mA, dropping to 190mA after a few minutes. I usually waited until the drain settled to 190mA before doing any testing. I noted the following: -Fuse 22 (Audio Amp) caused a 10mA drop. I have an afermarket radio/CD but the original Amp fitted. -Fuse 5 (BCU and wipers) caused a 40mA drop. A 40mA drop was also noted by unplugging the wiper motor connector. The wiper motor was untouched during my work, although the wiring loom, nearby was. -One of the two additional fuses linked to the LPG ECU caused a 10mA drop as did unplugging the LPG ECU. This left around 150mA of drain (the wiper motor being a possible partial culprit) which is well in excess of the at-rest power use for the car. I resorted to unfoccussed wiggling of connectors and looms in the engine and plenum areas, the areas I was working in an effort to see if I had shorted something, but to no avail. I seek inspiration for where to look next. Yours Aye Stuadh

12th April 2012, 04:22	#2
rover54 Retired rover 75 v6 Auto Conn. SE 54 plate LPG and 2006 Rover 75 v6 Auto LPG , 1.8 r75 Manual Join Date: Aug 2010 Location: London Posts: 3,379 Thanks: 0 Thanked 6 Times in 6 Posts	In the past I have had a battery discharging overnight through the alternator. It happens if the diodes in the rectifier pack go U.S allow back-feeding of current from battery to alternator. Disconnect alternator overnight and see what happens. Have you charged the battery off car and then left it overnight off car to see if it hold charge. It might be discharging internally. A battery discharge test might help. Other than that, it is a case of pulling fuses to isolate the circuits. Last edited by rover54; 12th April 2012 at 04:29..

13th April 2012, 19:31	#8
stuadh Regular poster MG ZT-T 190 & GSX1100G Join Date: Jun 2008 Location: Here Posts: 76 Thanks: 0 Thanked 0 Times in 0 Posts	Battery at 12.5V - After an hour, ampage is a 20mA which is much better. Focussing on the battery, now. Battery and alternator unplugged. We'll see how it looks in the morning. Stuadh Last edited by stuadh; 13th April 2012 at 20:52..

12th April 2012, 06:47	#3
lovema75 This is my second home 75 Tourer CDT Join Date: Dec 2011 Location: Enfield Posts: 3,925 Thanks: 63 Thanked 431 Times in 237 Posts	I would try the simple things first like checking the boot light isnt staying on when the boot is shut - my last Rover (a 400) did exactly that, confirmed by removing the bulb.

12th April 2012, 21:31	#5
stuadh Regular poster MG ZT-T 190 & GSX1100G Join Date: Jun 2008 Location: Here Posts: 76 Thanks: 0 Thanked 0 Times in 0 Posts	Cheers. I'll try the alternator test tomorrow night (I need the car through the day). I've just checked the Rimmer site and I can't find a seperate rectifier. I take it that it is integrated into the alternator? My motorbikes has all had seperates. Yours Aye Stuadh

13th April 2012, 19:01	#7
stuadh Regular poster MG ZT-T 190 & GSX1100G Join Date: Jun 2008 Location: Here Posts: 76 Thanks: 0 Thanked 0 Times in 0 Posts	Hmmm, I have just disconnected the alternator and there is still 190mA draining through the system. I'm waiting for it to go to sleep to see what that reads. I left the car on charge all night and it started fine in the morning. I left it through the day on a solar panel charge and it started at lunchtime. It wouldn't start after lunch (battery reading 9.9V) but did after 45 mins of high charge. So, not the alternator. I'll just keep plugging away at it (ha ha, see what I did there?) Stuadh

13th April 2012, 22:59	#9
rover54 Retired rover 75 v6 Auto Conn. SE 54 plate LPG and 2006 Rover 75 v6 Auto LPG , 1.8 r75 Manual Join Date: Aug 2010 Location: London Posts: 3,379 Thanks: 0 Thanked 6 Times in 6 Posts	Sounds like battery is discharging internally. Charge it up off car and leave it 24 hrs and check voltage.

14th April 2012, 09:09	#10
stuadh Regular poster MG ZT-T 190 & GSX1100G Join Date: Jun 2008 Location: Here Posts: 76 Thanks: 0 Thanked 0 Times in 0 Posts	Interesting. After 14 hours, the battery is reading 12.7V. Allowing for reading error, it hasn't lost any charge overnight suggesting that the batery is sound. I'm checking the "at sleep" reading in an hour then I'm going to take voltage readings every couple of hours to see how quickly it discharges. This is doing my nut in. Stuadh