Flat battery - no obvious cause

Elfman · 7th September 2011, 12:38

My diesel tourer has suffered a flat battery twice recently for no clear reason and with normal running the rest of the time. Once was after packing to leave for the ferry after a very successful 10 days in France, the second time was yesterday after the car had been at the local garage all day being diagnosed as needing a new cooling fan assembly (weep!). I've heard that the SatNavs can sometimes drain the battery when parked but I have no SatNav and this has just happened twice. Are there any well known causes or places to look?
Incidentally the car has only overheated the once, in an hour long ferry queue at Dunkirk, but I can't take the risk, even with our summers!

David3807 · 7th September 2011, 13:03

Fuel Burning Heater ?? Try unplugging it.

And I think glow plug relay can go faulty especially if it gets wet. Near the main ECU I believe.

Rov5 · 7th September 2011, 13:16

Also worth checking that the alternator is puttin out approx 14 volts with headlights and fan on.

chrissyboy · 7th September 2011, 17:08

if the car was in for dianostics then the battery will lose a lot of juice as the gnition would of been on for a long time . it may be that this time .are the connections tight on the battery? with a multi meter check that your getting 14 volts with engine running, if you are saying your hving a drain problem the only way to find the cause is to clamp to the battery and start unplugging the modules one by one to see if there is any change in the reading its showing ,,,say you unplugged the abs module and the reading dropped ,them you woud have found the module that is draining the battery ,

craig8661 · 7th September 2011, 17:12

could it also be the battery failing ie it has enouth amps to fire first turn but any use like radio or lights leaves it flat that it cant output the ampage

dattrike · 7th September 2011, 17:59

Can't help with that, but I have a spare cooling fan complete with new 0.47 ohm gold resistor if you haven't had a new one fitted yet.I have tested it, works ok full and half speed. £60. I live in Tewkesbury. PM me if you want it.

calibrax · 7th September 2011, 18:06

Quote:

Originally Posted by David3807

And I think glow plug relay can go faulty especially if it gets wet. Near the main ECU I believe.

This happened to me. The glow plug relay was stuck on - no obvious symptoms, except the battery would be completely dead after a while. As a temporary solution I removed the fusible link for it (it's the 100A one in the underbonnet fusebox, held in by two screws).

Elfman · 7th September 2011, 21:57

Thanks to all who have offered advice so far! Much appreciated and will report on the final outcome!

Evansabove · 8th September 2011, 13:46

Have you checked the Plenums that no water is flooding the ECU. The first sympton I had when my plenum flooded was a flat battery.

HTH

John

Tatts · 8th September 2011, 14:25

How old is the battery? If it's about 6 years, then it's probably on it's last legs. The electrics on these cars require a good strong battery, or the car won't start. Just lots of clicking & flashing headlights.

7th September 2011, 12:38	#1
Elfman Newbie Rover 75 Tourer CDT Connoissseur SE Auto Join Date: Jun 2011 Location: Cheltenham Posts: 25 Thanks: 2 Thanked 0 Times in 0 Posts	Flat battery - no obvious cause My diesel tourer has suffered a flat battery twice recently for no clear reason and with normal running the rest of the time. Once was after packing to leave for the ferry after a very successful 10 days in France, the second time was yesterday after the car had been at the local garage all day being diagnosed as needing a new cooling fan assembly (weep!). I've heard that the SatNavs can sometimes drain the battery when parked but I have no SatNav and this has just happened twice. Are there any well known causes or places to look? Incidentally the car has only overheated the once, in an hour long ferry queue at Dunkirk, but I can't take the risk, even with our summers!

7th September 2011, 13:03	#2
David3807 Posted a thing or two 2002 R75 Conn SE 2.5l Auto Tourer, 2001 R75 Conn SE 2.5 Auto Saloon Join Date: Nov 2006 Location: Gravesend Posts: 1,897 Thanks: 0 Thanked 2 Times in 2 Posts	Fuel Burning Heater ?? Try unplugging it. And I think glow plug relay can go faulty especially if it gets wet. Near the main ECU I believe. Last edited by David3807; 7th September 2011 at 22:24..

7th September 2011, 13:16	#3
Rov5 Loves to post Rover 75 Join Date: Aug 2007 Location: Glasgow Posts: 290 Thanks: 0 Thanked 1 Time in 1 Post	Flat Battery Also worth checking that the alternator is puttin out approx 14 volts with headlights and fan on.

7th September 2011, 17:08	#4
chrissyboy This is my second home lovely little ford focus. Join Date: Jul 2009 Location: East Dulwich Posts: 7,877 Thanks: 2 Thanked 82 Times in 68 Posts	if the car was in for dianostics then the battery will lose a lot of juice as the gnition would of been on for a long time . it may be that this time .are the connections tight on the battery? with a multi meter check that your getting 14 volts with engine running, if you are saying your hving a drain problem the only way to find the cause is to clamp to the battery and start unplugging the modules one by one to see if there is any change in the reading its showing ,,,say you unplugged the abs module and the reading dropped ,them you woud have found the module that is draining the battery , __________________ [ I'm really confused. -I keep dreaming I'm an insomniac Last edited by chrissyboy; 7th September 2011 at 17:14..

7th September 2011, 17:12	#5
craig8661 Posted a thing or two rover 75 tourer cdt Join Date: Feb 2011 Location: Chesterfield Posts: 1,924 Thanks: 3 Thanked 4 Times in 4 Posts	could it also be the battery failing ie it has enouth amps to fire first turn but any use like radio or lights leaves it flat that it cant output the ampage __________________ http://i984.photobucket.com/albums/a...y%20se/sig.jpg spoilt as i own a cdt auto connoisseur se cdt auto member 829 mods so far synergy 2 heated washer jets cant really add anything else as it has it all lol

7th September 2011, 17:59	#6
dattrike Posted a thing or two V6 2ltr auto in copperleaf +CDTI Auto in Royal Blue on loan to Son Join Date: Jul 2010 Location: Tewkesbury, Gloucestershire Posts: 1,709 Thanks: 105 Thanked 476 Times in 267 Posts	Flat battery Can't help with that, but I have a spare cooling fan complete with new 0.47 ohm gold resistor if you haven't had a new one fitted yet.I have tested it, works ok full and half speed. £60. I live in Tewkesbury. PM me if you want it. __________________

7th September 2011, 21:57	#8
Elfman Newbie Rover 75 Tourer CDT Connoissseur SE Auto Join Date: Jun 2011 Location: Cheltenham Posts: 25 Thanks: 2 Thanked 0 Times in 0 Posts	Thanks to all who have offered advice so far! Much appreciated and will report on the final outcome!

8th September 2011, 13:46	#9
Evansabove Loves to post Rover 75 CDT Conn SE Join Date: Mar 2008 Location: Bournemouth Posts: 272 Thanks: 1 Thanked 6 Times in 6 Posts	Have you checked the Plenums that no water is flooding the ECU. The first sympton I had when my plenum flooded was a flat battery. HTH John

8th September 2011, 14:25	#10
Tatts This is my second home MG6 TL Join Date: Nov 2006 Location: Tarn Posts: 5,269 Thanks: 2 Thanked 46 Times in 37 Posts	How old is the battery? If it's about 6 years, then it's probably on it's last legs. The electrics on these cars require a good strong battery, or the car won't start. Just lots of clicking & flashing headlights. __________________ http://www.wcgsig.com/115562.gif