Battery Drain?
 

1997 Volvo V70:~
Does this sound right or do I have a battery drain.
Battery is fine & just to make sure the same symptoms apply to a good spare.
No lights are on to include glove box & door markers-all eliminated.
The battery will start the car well but does loose some charge over a couple of days – same if doors locked or left open.

I’ve done a test with a 21w bulb test light connected to the removed negative lead & terminal- the bulb remains out so no drain on this test.
I then used a much smaller wattage bulb maybe 3w – same procedure as above but this time the bulb does glow quite dimly and with a sort of pulsating glow.
With the above still connected I removed each fuse in turn together with the other fuse box items – No change to the light i.e. it remains on.

(The only exception to the above is the fuse marked—Power To Fuse Box 60A but I would think that this fuse removal is correct to extinguish the bulb)

Is it normal to have a small battery discharge on these cars when all systems seem to be off?
Many Thanks
Bob

I think it would be normal to get a very small current drain, radio memory, alarm, ecu memory etc but it shouldn't drain the battery.
Might be worth doing the test with a multimeter to establish exactly how much current is being used

Current Drain
 

It can be quite difficult to locate a battery drain such as this. I had this on our Golf and again on my 3 Series BMW.

There are several YouTube videos on how to track the fault down but you will need a decent meter and plenty of time and patience. Often on modern cars they do not shut down immediately but take several minutes to do so after locking the car. You may need to check each suspect circuit at a time with the meter locked inside the car and reading it through a window, although it would possibly not apply to a car of this age.

Possible causes can include faulty starter motor or alternator, although these are less common.

I have the same problem, if i don't use the car for a few days the battery is dead

This was an ongoing problem on my 1998 V70 Tdi for quite a few years.

I eliminated all the usual suspects because they were staying on and draining the battery.. ie.. door/floor courtesy lights, red door edge lights. Seemed ok for a while, but the car was being used daily and it was summer, so less use of lights, heater, etc.

I then had the same problem again come wintertime. Starter problems this time though. Changed the starter and once again all seemed well, until I didn't use the car for a week. Flat battery! I recharged the battery, and did not lock the car, as my alarm system is not functioning correctly, so thought maybe that was causing the drain.

Carried on not locking the car here in France where I'm based at the moment. Didn't use the car for two days, and that coincided with very icy cold weather. Flat battery!

I recharged the battery, but after a couple of days the alternator light came on intermittently, then stayed on. I put a new alternator on, and touch wood, despite some icy weather the car has been starting fine.

Now, has it inadvertently cured the flat battery problem, I don't know, but I'm hoping so.

As Volvo Again says.. "I think it would be normal to get a very small current drain, radio memory, alarm, ecu memory etc but it shouldn't drain the battery". It is going to be a bit of trial and error I'm afraid using a good multi-meter.

I wish you all the best anyway.. Dave..

Anything above 10mA to 20mA when car is asleep is too high

You cannot diagnose this stuff with a light bulb

You need to use a multimeter set to Amps.
Be aware that the car uses many amps (A) when the key is on, and only a few milliamps when off (mA). So make sure the multimeter can show a range of (say) 10A down to 0.001 A (1mA)

You need to understand how much time it takes for the car to completely shut down and go to sleep - a few minutes on my 2009 XC90. The CAN busses stay active for a while.


Start with a paper log book. write down the current consumed when car is asleep

Then start the long and painstaking process of pulling one fuse and waiting for the car to go to sleep, and writing down what the consumption is with that fuse pulled.

Start with all the devices that use power when the car is sleeping: alarm, central locking, remote control, on-call system, etc.
Before removing the fuse for the central locking, confirm your physical key still works in the driver's door. You do not want to lock yourself out.

Then move on to devices that should be shut down when the key is off and out (radio, engine, gearbox, etc etc)

A paper log is essential here as after a few hours and days, you will never remember what you have and have not checked.

A couple of possibilities in your case, Dave:
1. The alternator has not been charging the battery fully for a long time and that showed in marginal conditions (cold start) as it just didn't have the power.
2. In older cars if the diodes in the alternator were faulty they would allow current drain through them when ignition was off. I don't know if the V70 is still wired in that way but if so it would cause exactly these symptoms?
Joe

Thanks Joe.. appreciated..

I have a feeling you may well be right with your diagnosis. Only time will tell. The batteries fine I know that. Current drain.. as Swiss XC90 says cannot be traced with a light bulb. Over time I must have spent hours taking readings, only to be led down dead end paths. Both starter and alternator were shot though, and the courtesy lights etc became so untrustworthy I just pulled all the bulbs.

I do hope Bob has success in his quest to find the drain on his car. I'll be keeping an eye on this thread..

Not overly concerned at this stage Dave as the battery hasn’t gone flat & I have a second one (purchased with the car) that is on a conditioner charge.
I have completed a repair to the driver’s door lock actuator – motor just in case this was linked to the drain, I think the same is within acceptable limits but do intend to investigate further once I have my hands on a multimeter.
I generally fit a battery isolating switch ( Riley & 240) and may do the same for the V70- the battery terminal is cranked on this car so not a straight forward change because of the lack of room etc.
Will update the post with any progress.
Regards Bob