Rover 45 '02 1.8 auto battery drain puzzle.

[Justengland]

Hi, I've looked at the many threads on this subject and tried a few things but hoping to get a bit of advice.

The battery is draining after a couple of days (it is brand new). I tried disconnecting the alternator (as that seems the most common issue) left if for a couple of hours and the voltage in the battery had gone down from 12.8v to 12.7v (if it is not connected to anything the voltage does not drop at all). Then I reconnected the alternator and disconnected the starter motor for a couple of hours and it still dropped from 12.7v to 12.6v.

So first question, have I eliminated both of these as the source of the drain (I suppose it is almost impossible it could be both)?

Could it be the alarm/immobiliser system? How can I switch that off (or which fuse to pull)?

UPDATE: The drain is 15ma I think. When I removed the small fuses it stayed the same or even jumped to 170ma!??

Anyway eventually took out the 60amp big screw-in fuse and the drained dropped to 7ma. That 50% drop could make all the difference I would guess? Left it out and tried to start the car but there was a regular warning beep going off so didn't try!? Also central locking didn't work. If the drain is on that circuit it looks like it could be a lot of things. Central locking, alarm I guess, immobiliser? Anyone know what the beeping warning is all about? Would it be safe to start the car?

Many thanks

[mogodon]

If it's a saloon, try disconnecting the boot light, that may be staying on without you knowing, other thing to dissconnect is the Heated rear window and see then.

[jensden51]

Hi, when this happened to me it was the radio, I disconned it, problem gone . Den

[jensden51]

Hi, just thought, if you disconnect radio make sure you have the code. Den.

[Andy400]

just a thought but when u leave the car make sure you turn the heater fan setting to off, had a car where a relay was sticking occastionally and the heater fan would stay on or kick in some times.

[Justengland]

Originally Posted by mogodon

If it's a saloon, try disconnecting the boot light, that may be staying on without you knowing, other thing to dissconnect is the Heated rear window and see then.

Should have mentioned eliminated that as well, took the bulb out.

[Justengland]

Originally Posted by jensden51

Hi, when this happened to me it was the radio, I disconned it, problem gone . Den

I'll try that, however been through all the fuses now while check drain with a meter and it wasn't the radio or any of the smaller fuses. The drain is 15ma I think. When I removed the small fuses it stayed the same or even jumped to 170ma!??

Anyway eventually took out the 60amp big screw-in fuse and the drained dropped to 7ma. That 50% drop could make all the difference I would guess? Left it out and tried to start the car but there was a regular warning beep going off so didn't try!? Also central locking didn't work. If the drain is on that circuit it looks like it could be a lot of things. Central locking, alarm I guess, immobiliser? Anyone know what the beeping warning is all about? Would it be safe to start the car?

Cheers

[Justengland]

Originally Posted by jensden51

Hi, just thought, if you disconnect radio make sure you have the code. Den.

Good tip thanks.

[Justengland]

Originally Posted by Andy400

just a thought but when u leave the car make sure you turn the heater fan setting to off, had a car where a relay was sticking occastionally and the heater fan would stay on or kick in some times.

I'll try that. Actually on this car the first two fan settings haven't worked at all for a while. Could that be related (never used to be a problem)?

[MGJohn]

Originally Posted by Justengland

I'll try that. Actually on this car the first two fan settings haven't worked at all for a while. Could that be related (never used to be a problem)?

No, unrelated problem.

You need to replace the fan resistor located behind the drop down passenger side glove box. Ten minute job to replace:~

One of these ~ less than 12 quid posted :~

Rover Fan Resistor

Originally Posted by Justengland

.
So first question, have I eliminated both of these as the source of the drain (I suppose it is almost impossible it could be both)?
.

No, don't think so.

Might be this as you appear to have eliminated most possible causes :~ except Dodgy Alternator. 12.7 to 12.6 fairly normal.

I have had similar battery drain problems in the past with two cars. In both instances it was the alternator allowing the drain from the battery. Fitted good used alternator, sorted.

[Justengland]

Originally Posted by MGJohn

No, unrelated problem.

You need to replace the fan resistor located behind the drop down passenger side glove box. Ten minute job to replace:~

One of these ~ less than 12 quid posted :~

Rover Fan Resistor



No, don't think so.

Might be this as you appear to have eliminated most possible causes :~ except Dodgy Alternator. 12.7 to 12.6 fairly normal.

I have had similar battery drain problems in the past with two cars. In both instances it was the alternator allowing the drain from the battery. Fitted good used alternator, sorted.

Good to know the fan is probably not related, reasonably happy with just two settings for now.

Right, I'll try disconnecting the alternator again and use the meter see if that is the 15mamp drain (or more 10mamp which is actual problem). Do you know if 15mamp is a big drain, it sounds fairly reasonable?

Thanks

[MGJohn]

Originally Posted by Justengland

Good to know the fan is probably not related, reasonably happy with just two settings for now.

Right, I'll try disconnecting the alternator again and use the meter see if that is the 15mamp drain (or more 10mamp which is actual problem). Do you know if 15mamp is a big drain, it sounds fairly reasonable?

Thanks

Radio code maintenance?

[jdhturner]

At a current drain of rate of 15mA, it would take 67 hours to drain a single Ampere Hour from a battery. A typical battery has about 50 AH capacity so it would take upwards of a year to go flat at that rate.

To put this in perspective, my battery will last about 1 month with a full charge if the car is left standing. I've never measured the drain on my car but I suppose it's about 100mA and I've always assumed it's the alarm - probably a good chunk of that is the volumetric sensor (now unplugged because it died a few months back).

[Justengland]

Originally Posted by jdhturner

At a current drain of rate of 15mA, it would take 67 hours to drain a single Ampere Hour from a battery. A typical battery has about 50 AH capacity so it would take upwards of a year to go flat at that rate.

To put this in perspective, my battery will last about 1 month with a full charge if the car is left standing. I've never measured the drain on my car but I suppose it's about 100mA and I've always assumed it's the alarm - probably a good chunk of that is the volumetric sensor (now unplugged because it died a few months back).

So maybe it was just a loose connection that I 'fixed' when disconnecting things and it is fine now. Will try trusting it again : )