Hi all I've had fitted a couple of weeks ago a new battery for my disco 2 at first no issues battery strong and starting great but when I left the disco for 3 or 4 days the battery was flat , I've had all the wiring checked by an auto electrician and is showing no faults any tips on suggesting the culprit ?
sierrafery
Well-Known Member
Hi, unfortunately this thing can't be just guessed... there is a troubleshooting method for quiescent current draw which an auto electrician should know ... if there are no faults there should be no drain but if there is a drain it's impossible to not be a fault somewhere(unless the battery had a factory fault in it)... simple as that, a good electrician shouldn't have let you go without a clear answer.
So, first questions are:
1. what's the charging voltage?
2. how much is the current drain with locked vehicle?
3. from 1 to 10 at which level are you with auto electrics?
Do you know how to measure the drain? , if yes report how much it is more than 30 minutes after you locked the vehicle with open bonnet then i'll tell you what to do... if you dont know i can't help you much cos you need some skills to follow my instructions then better find a serious electrician who should find the source of the drain and fix it
So, first questions are:
1. what's the charging voltage?
2. how much is the current drain with locked vehicle?
3. from 1 to 10 at which level are you with auto electrics?
Do you know how to measure the drain? , if yes report how much it is more than 30 minutes after you locked the vehicle with open bonnet then i'll tell you what to do... if you dont know i can't help you much cos you need some skills to follow my instructions then better find a serious electrician who should find the source of the drain and fix it
Last edited:
Hi thanks for replying, I took my disco to an auto electrics company after £75 diagnostic fee I was told the battery output was 13.8 volts under load and all the wiring checked out with no drain faults sorry I have no auto electrical experience so am very limited in that field
sierrafery
Well-Known Member
Too bad... IMO you should get a second oppinion and ask them to tell you exactly what's the stationary drain in mA with locked vehicle or at least ask them insistently to explain why your battery goes flat in 3 days if there is no excessive drain ???... it's not normal to let a customer go away with this dillema... BTW what kind of battery did you fit? AH/CCA?
Last edited:
Hi the battery is 1000 (EN) 120Ah 12v I was told it is the correct replacement
sierrafery
Well-Known Member
Yes it is... that battery should crank after it stays a month in a locked D2 which doesn't have some parasitic drain
sierrafery
Well-Known Member
A parasitic drain can have various sources and some of them can get worst and cause more serious trouble while driving too so none of these options seem OK to me, one of a quite common cause of parasitic drain is the alternator if it has only on diode shot but if they go one by one at a moment it can kill a new battery too or hurt an ECU i explained here: https://parts.jaguarlandroverclassi...MS4xLjAuMTcyNDY4ODE0MS4wLjAuMTY4ODI0NzM4OQ../ ... on a rudimentary charging test this problem is not observed.Thanks Arad I have considered 2 options if I can't fix the problem which is a battery isolator or leaving the vehicle unlocked that's maybe not a sensible option
also it can be a slight current leak in the wiring somewhere which if it goes bad you can end up with the vehicle in fire... these are the risks if you just hide the issue with a battery isolator so your choice... a skilled electrician should find the problem in no time unless you are unlucky enough to be some very uncommon oddity
Good luck
PopPops
Well-Known Member
+1 ^^
Back in the Covid lockdown days I had a similar problem as I was using the car rarely. It took little time to discover which fuse had excessive idle current. Your “electrical expert” should have been able to do the same. The car must be idle for 30 to 90 minutes with no door activity for all systems to shut down. The idle current should then be around 20mA, or less.
Mine was water damage in the IDM (passenger compartment fuse box) which I fixed, but that doesn’t mean yours will be the same.
I’ve left mine for 6 weeks without the battery going flat.
Follow Fery’s advice and you won’t go far wrong.
And good luck….
