Disco 4 with keyless start, and a dodgy battery
My 2014 Disco, with keyless start, recently had some battery issues that took a while to diagnose. There were some unexpected side effects.
The outcome was the battery needed replacing, even though it charged to a normal voltage, started the engine quite well, and delivered “acceptable” cranking amps according to two tests. The new battery solved all the symptoms which were a constant 1.7 amp drain and “Low Battery, Start engine” messages on the dash.
The episode started with a classic flat battery after 2 days camping. I put that down to frequent opening/closing doors and locking/unlocking and no driving. Jump started it, drove the car to the next town where NRMA roadside assist checked over. Alternator OK, voltage OK, cranking amps down a bit, but the battery just needed a long charge according to the serviceman.
So after a 3 hour drive all seemed well, but suspecting that something may be draining the battery, a clamp meter showed a constant 1.7amp drain on the main battery cables.
Got home and confirmed that “parasitic” drain using a different clamp meter, and charged the battery using a solar regulator with an inline power analyser, which confirmed the battery needed about 40AmpHrs per day to keep up with the 1.7amp discharge. This as consistent with a 90AH battery going flat in 2 days.
During this period the car dash started constantly displaying “Low Battery, Start engine” despite being on the charger, or the car being driven for 40 minute trips or more.
A second battery test by Opposite Lock, who have some familiarity with Discos, advised the cranking amps while just OK, indicate the battery is not probably good enough for the Disco’s electronics. I took the car to a Land Rover service place that had the correct Varta battery in stock. They also tested the old battery and said it was not up to scratch. It was replaced, and the dash message and “parasitic” drain disappeared.
It seems the low battery causes the computer system to not fully go to sleep, causing the abnormal battery drain that ensures the battery does go flat! Subsequent clamp meter checks showed 0.4amp drain with the new battery. That would take 110 days to drain the battery to 50% charge.
So in my experience, if there is any evidence that the battery is low, such as dash messages, low cranking speed or unexplained “Parasitic” loads, get the battery checked, and replace it if the cranking amps are down. Use a genuine LR battery. Mine cost $620 fitted and the computer system reset. Not cheap!
Another revelation from all the monitoring, is that every time the car was unlocked or a door opened, the accessories were activated for 3 minutes before going back to sleep. This and the computer put a 6 amp drain on the battery for that period. I also discovered that the auto electrician that wired the DCDC charger for the auxiliary battery and the relay for the trailer Anderson plug, connected it to “accessory” rather than ignition. So that if the camper trailer was also connected with its DCDC charger, 50 amps could be drawn from the crank battery whenever a car door was opened or the car locked.
I will be getting both changed to only activate when the engine is started.
My message is that if you have an unexplained and seemingly parasitic battery drain, check the battery, and if the cranking amps are down, it may need replacing. The parasitic drain disappeared when the new battery was fitted.
Good one Land Rover! When the battery gets a bit dodgy, make the computer not sleep and ensure the battery goes fully flat in 2 days.