Thread: Fix for Discovery battery drain

The only certain conclusion of this reading is that the battery looses charge in time which can be caused by a minimal drain too or no drain at all if the battery is old and "tired" but you can't calculate the real drain from that

Originally Posted by sierrafery

The only certain conclusion of this reading is that the battery looses charge in time which can be caused by a minimal drain too or no drain at all if the battery is old and "tired" but you can't calculate the real drain from that

Funny this was 4 years ago and now the problem has started for me! As to calculating the real drain, that was not my intention, merely it was showing the fact there was drain for the half hour post key out...

Mentioned in a post yesterday as to the SLS being intermittently active whilst locked up, but tonight came out to find the interior light shining brightly in the D2 and the battery at a 12.3V after a solid day driving - thought the other night this was on but when I got close it was off. Removed the light but now have to stope that parasitic drain and researching came to this post.

Have tried for the last two days to turn off the SLS, the Nanocom allows me to go to coils but instantly reverts back to SLS when I leave the screen page, as I have the schrader valves in, may just disconnect the power to the tray. The battery was checked by the RACV and are only a few months old (optima blue top * 2) - maybe just take out the relay from the engine fuse box for the SLS?

Sure the D2 has not had much use over this year due to the shoulder but will have to try the solution on the 1st post unless there is another solution that has been found? The window switches do cease to function after 45 secs

baTTERY DRA8N.pdf

Any thoughts espeacially on the inability to turn of SLS??

You have to click on "write settings" at the end of menu before you leave the page then turn ignition off and wait 60 seconds before you unplug nanocom to retain the settings

Ohh the old turn the ignition off and wait 60 seconds, third time this week!
Did do the write settings as had to get an SD card to do so but didn't get the prompt as to turn off and wait etc.

Had to start the car with a touch on the starter solenoid... so looks like a bit of chaffing may have occured on the wire, hopefully not the switch tumbler.

This weeks task, to ensure all my grounds are patent.

Sorta relevant, mine would go flat after a couple of nights. After one night it would be a little low but would catch, but two and no start. Battery was absolutely fine. Drove me nuts, as I couldn't isolate it by measuring across fuses. Maybe I missed one. But it turned out to be the memory function of the original LR radio. Caught it when I approached the car in the dark and could just see the little LCD display weakly glowing. Radio, which I didn't use, is gone and no problems. Gets me thinking though, because it wasn't always so. Did the corroded fusebox cause this as well? Certainly caused many other issues. Worth a look?

Originally Posted by Tins

Sorta relevant, mine would go flat after a couple of nights. After one night it would be a little low but would catch, but two and no start. Battery was absolutely fine. Drove me nuts, as I couldn't isolate it by measuring across fuses. Maybe I missed one. But it turned out to be the memory function of the original LR radio. Caught it when I approached the car in the dark and could just see the little LCD display weakly glowing. Radio, which I didn't use, is gone and no problems. Gets me thinking though, because it wasn't always so. Did the corroded fusebox cause this as well? Certainly caused many other issues. Worth a look?

Did change out the fuse box a couple of years ago, but worth a check as well as the interior coming on and off makes absolutely no sense.

Originally Posted by RRT

Funny this was 4 years ago and now the problem has started for me! As to calculating the real drain, that was not my intention, merely it was showing the fact there was drain for the half hour post key out...

Mentioned in a post yesterday as to the SLS being intermittently active whilst locked up, but tonight came out to find the interior light shining brightly in the D2 and the battery at a 12.3V after a solid day driving - thought the other night this was on but when I got close it was off. Removed the light but now have to stope that parasitic drain and researching came to this post.

Have tried for the last two days to turn off the SLS, the Nanocom allows me to go to coils but instantly reverts back to SLS when I leave the screen page, as I have the schrader valves in, may just disconnect the power to the tray. The battery was checked by the RACV and are only a few months old (optima blue top * 2) - maybe just take out the relay from the engine fuse box for the SLS?

Sure the D2 has not had much use over this year due to the shoulder but will have to try the solution on the 1st post unless there is another solution that has been found? The window switches do cease to function after 45 secs

baTTERY DRA8N.pdf

Any thoughts espeacially on the inability to turn of SLS??

Based on the info in your posts, my guess is that your battery is probably Sulphated.

Especially as you say you are not using the vehicle that much.

Try putting a battery charger on your battery every night and leave it on all night and then remove it in the morning.

I would recommend doing this for at least a week, regardless of whether you drive it or not.

This is a slow process but it will reverse the Sulphation, if it is not to critical.

This will also help extend the life of the battery.

Originally Posted by Tins

... Drove me nuts, as I couldn't isolate it by measuring across fuses. Maybe I missed one. ...

After a lot of troubleshooting my opinion is that the best way to find a drain on a D2 is to remove the big fusibe links one by one while watching the drain on ampmeter then when it drops hard it's simple to identify the source based on which fuses are connected to that FL according to the power distribution diagram then remove those fuses one by one...and so on. Always start with maxi FL1(undo it from the bolt) cos a quite common but missed drain can come from the alternator itself as it has 8 diodes in the rectifier and if only one is shot it will still show correct charging with multimeter but once stopped there can be a backleak to earth through the faulty diode or it can hurt the battery in time and this is visible only with oscilloscope, many articles on the subject, one example https://autoedu.info/en/auto-electric/alternator/oscilloscope-alternator-test/

BTW to see the correct quiescent draw the vehicle must be locked with open bonnet(unplugged bonnet switch) dont open any door and wait at least 30 minutes(better 90) after it was locked, normal draw is like in the attachment: