I have noticed that my P300 seems drawing ~250 mA when it is sleeping. I wonder if that is normal? The other cars I had before draw much less, say, less than 50 mA. Any one paid any attention on this? I figure, with the loads of newer electronics installed on the new defender, it should draw more power when sleeping.

I should worry for this sleeping current draw, or should I?

 

I always double lock the defender to put it in the lowest possible energy draw state. What do you mean by sleeping?

 

thanks for asking. I did not get to actually measure it with an amp meter. I did some quick dirty calculation and estimated it.
This is how I did it. I made an unswitched 12 v port and hooked up a LET volt meter. So it is directly connected to the battery all the time. Then I parked the vehicle and started charging the battery with a AGM compatible charger and reached 13.0v, then I took off the charger and start counting hours. After about 95 hrs, while the car was "sleeping" all these hours, the voltage reading drop to 12.4 v, which equals to 75% charged. So 25% of the power inside this fully charged battery is drawn through 95 hrs.

The battery is a group 49 with about, say, 96 Ahr power when fully charged ( so 100% power = 96 hrs x 12 V x 1 A)
then in 95 hrs while the car sleeping, the power drawn is (25% which is roughly 95 hr x 12 v x 0.25A)

thus, I estimate the average current the car draws while "sleep" through these 95 hours, it is about 250 mA.

I could actually measure it after I install a kill switch to the battery. I will do it down the road, but not right now yet.

Again. I am a bit supprised to see 250 mA draw while sleeping. I think it is a bit too high, but I am not sure if it is supposed to be this high.

Thoughts? comments? Please?

Thanks

 

Telematics alone would draw that. It goes into sleep after few days of inactivity.

 

That’s a lot of math to come up with a theory on current draw. A clamp on ammeter should give you the current draw with much less wrangling.

 

These PowerFulUK videos have some interesting info related to battery consumption and parasitic power draw analysis:

• Defender L663 - Low Battery Warning - Static Power Drain Investigated
• Battery Drain Analysis Defender 90 - Low Battery Warning Problem
• Defender 90 Gets Flat Battery Review

Might be helpful in the context of sleeping time current draw. Edit: Sorry I have no idea why the links are posting as text and these full size video previews

 

The parasitic draw on the battery after the vehicle is asleep should be 40mA or less. An inductive amp clamp is not very accurate at this low of a measurement, so installing a multimeter set on amp setting and running it in series with the negative battery terminal will provide an accurate measurement. This takes a bit of skill to not blow the fuse in the meter, but it is really the best way. You can also use an oscilloscope set to record and it will show momentary wake up spikes, which is normal. If the 250mA is an accurate measurement, it is too high.

 

Thanks all for your insights.

Telematics certainly draws power, but probably in form of "bursts" at every now and then. Not sure how its current draw would look like after being averaged out.

Simon's videos are helpful, but he's more focused on who draws how much, while the car is awake. I some how remembered his clamp meter reads ~300 mA at ~15 mins after closing the door. That is close to what I estimated.

Agree that a clamp meter is not suitable for measuring the parasitic current ( now I learnt to use this right term, instead of making my own. ​Smile ).
I would like to add a kill switch at the negative post of the battery, Then I can attach my multimeter to actually measure the parasitic current. Later for sure.

I will for sure report back once I have my measurement.

Again, thanks a lot to you all.

 

Hi Can-Giu,
as said by other users, it would be advisable to use a current clamp meter for direct current, however 12.4 volts after 96 hours of stationary car is an acceptable value.
Some Defenders drained the battery very quickly because the door ECU module did not go into sleep mode, therefore requiring a software update.
A recall has been created for some cars.

marco

 

For this level of draw a clamp isn’t going to be a great method to measure… you need a shunt inline on the negative cable. This is how LFP batteries and similar measure state of charge. Otherwise the settling of the voltage after charging or even the change in temperature can shift the voltage around enough to mess up your calculations significantly.

Not that you want one of these but you can find some good info if you read up on the Victron Energy BMV-712. It’s the gauge I used in a travel trailer that introduced me to all this stuff a few years back.