TD5 runs down battery

My 1999 TD5 runs down the charge in the battery over a couple of days and will not start some mornings, when I come to turn the key it is totally dead with just the SRS light flickering slightly. Happens whether the vehicle is stood for a few days or if it is used daily. Took it to kwik sh*t to get the battery and alternator tested ,the alternator is kicking out plenty of juice but I came away with a new battery just to be on the safe side as I was advised it was a little weak. This morning less than a week later same thing happens! Totally dead battery.
I've checked all the blindingly obvious things,checked the kids haven't jammed a lighter in the socket or left their light on , glovebox light ,unplugged the radio fuse in case theres a fault with the radio, checked all the fuses to check for short circuits , the only other thing I can think of is if the alarm system is using loads of power for some reason.
Anyone had a similar problem?
any tips or pointers appreciated

A relay stuck in the energised position perhaps, feeding a circuit continuously?
I don't know if the TD5 alternator has a bridge rectifier in it (perhaps someone could comment), but it has been known for one of the diodes in a bridge to leak and cause what you describe.

I'd be throwing an ammeter inline with the live battery lead and seeing what current drain there is, and if there was substantial current being draw i'd be whipping out fuses until i found the offending circuit.

I put an ammeter on mine and found that the alarm drew about half an amp which by my reckoning should run a fully charged god battery down in about 9 days without any use

I haven't measured my current drain with a meter but it must be considerably lower than 1/2amp. I have repeatedly left my discovery parked up for between 2 and 4 weeks at a time and never had a problem starting it when i've returned.

Things like aftermarket audio systems, moisture in an ECU or fuse box could cause extra current drain and have an impact on battery sustained charge.

I know this is a common problem on range rovers (current drain from faulty RF receiver ) but never heard of it in a TD5 - I've had no probs when I've left mine for a few days.

Is it kept in a secure place overnight - can you try leaving it with no alarm overnight & checking the battery before & after to see how much it loses, although I can't see the alarm or imobiliser draining that much out of the battery - more likely an alternator problem

I knew someone who had a similar problem with a Jeep - he took it to an auto-electrician & the alternator was recharging the battery OK when the engine was running but discharging it when it was switched off - best to get an auto-electrician to check it if you can't sort it - wouldn't really trust kwik fit blokes to sort disco electrics, not suprised they sold you a new battery rather than finding the problem, you old battery was prob OK!

just another thought - when you leave it parked up are you near an airport, petrol station, cctv cameras etc, or an other sources of RF interference ?

have heard of quite a few cases of RF sources interfering with the Becm & ecu's on modern electrics.

Galen said:

I don't know if the TD5 alternator has a bridge rectifier in it (perhaps someone could comment).

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ALL alternators have them, it must be rectified to DC, thats why dynamos were used in the early days. There was NO such thing as a diode, so when they were invented and small enough they started using alternators rectified by a bridge rectifer (4 diodes arranged in such a way polarity can be kept the same for any input polarity).

ALL alternators have them, it must be rectified to DC, thats why dynamos were used in the early days. There was NO such thing as a diode, so when they were invented and small enough they started using alternators rectified by a bridge rectifer (4 diodes arranged in such a way polarity can be kept the same for any input polarity).

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I knew the system had to have a bridge rec somewhere, but was unsure as to if it was an integral part of the alternator or an external part

Galen said:

I knew the system had to have a bridge rec somewhere, but was unsure as to if it was an integral part of the alternator or an external part

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They are built into the alternator... this way they are self contained ready to supply DC.

My td5 did this once! went out to it turned the key!..... nothing. phoned local landrover spanner man to bollock him for fitting a dodgy battery 8 months earlier! booked it in for a look over.

i got my pal net door to give me a jump, its started ever since! that was 18 monts ago!!

i never did take it in!

Probably not relevant this time, but I knew someone who had same problem on a Saab. Dealer couldn't fix it. Turned out he had a posh radio that picked up and stored traffic news when "switched off". So the radio was on all the time and drained the battery.

Thanks for all your replies. Problem sorted now, seems it was a dicky load sensor on the SLS , replaced last week and it hasn't had any problems since.

Hi! I have a 1999 TD5.The red security light keeps blinking, even when the car is unlocked.Also, the radio green light keeps coming on without the radio it'self.Any ideas out there? Sometimes the car won't start after just two days,and other times it's okay after 2 weeks! I'm in Germany and can't find a mechanic to sort this out.

Hi! I have a 1999 TD5.The red security light keeps blinking, even when the car is unlocked.Also, the radio green light keeps coming on without the radio it'self.Any ideas out there? Sometimes the car won't start after just two days,and other times it's okay after 2 weeks! I'm in Germany and can't find a mechanic to sort this out.I did recently have new brake lines installes and also brake brushes.Could that have upset the electrical system?

Galen said:

I haven't measured my current drain with a meter but it must be considerably lower than 1/2amp. I have repeatedly left my discovery parked up for between 2 and 4 weeks at a time and never had a problem starting it when i've returned.

Things like aftermarket audio systems, moisture in an ECU or fuse box could cause extra current drain and have an impact on battery sustained charge.

Click to expand...