Member Since: 15 Jan 2010
Location: Stockholm
Posts: 773
Smart charging ?
Got a message now and then for low battery.
Changed the battery to a battery I know is good and would take charge.
Reset the battery with my IID.
I am now cheking charging with a battery monitor.
Daytime it seems to charge when starting the car with around 14 V. Battery gets 99% charge.
When driving at night with full beam and extra light ramp, heating on it is not charging. The charge % goes down and down and down and I get a message battery voltage low.
What can be wrong???Discovery 3, MY2008, TDV6 Auto, G4 Tangiers Orange
Discovery 4, MY2011, TDV6 Auto
7th Dec 2020 3:11 am
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4651
As your post suggests it is a "smart charging" system and so is regulated based on demand. From what you say I would be suspicious of that replacement battery, but it may just be an earth issue with one of the straps. Again, diagnostics should have logged something so start there and check carefully the earth straps, particularly the one on the engine block. yµ (idµ - eAµ) ψ=mψ
7th Dec 2020 5:24 am
urhunden
Member Since: 15 Jan 2010
Location: Stockholm
Posts: 773
No faults reported when consulting my IID!Discovery 3, MY2008, TDV6 Auto, G4 Tangiers Orange
Discovery 4, MY2011, TDV6 Auto
7th Dec 2020 9:34 am
urhunden
Member Since: 15 Jan 2010
Location: Stockholm
Posts: 773
"After the BMS is resetted, the BMS performs a self-calibration. To do this, the battery is first charged with maximum charge voltage while the engine is running and then discharged to 75% charge. Discharging can take several days if only short distances are driven. During this time the alternator does not switch on! Only after that the BMS works normally again and charges the battery normally again.
Note: The BMS should always be reset at the earliest about 1 hour after the battery has been charged. The voltage of a car battery drops significantly for a period of about 10-60 minutes immediately after recharging – the so-called voltage sack. The causes for this seem to be in the electrochemistry of the battery, but have apparently not yet been researched in every detail. The fact is, if the BMS is reset directly after charging, the BMS assumes an incorrect maximum battery voltage. (Thanks to Hannes F. for the hint)"In today's world, if you contribute something, you don't contribute enough. If you contribute nothing, you receive everything.
2014 Discovery XXV
1961 Series 2
14th Dec 2020 1:54 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4651
The timescale in your screenshot is a bit short, but I would say it appears to be settling in the right direction.
A longer period of measurement would help confirm this, but you should consider what elec systems are turned on/off during the test!
You could try a test both ways, first at low demand with everything switched off, and then try heavy demand (lights, demisters, heated seats, etc) and see what it looks like.
Bear in mind battery "state of charge" will have an influence on test results, as will temperatures!
A DMM on the battery terminals with ign off and car asleep should read around 12.6v or above for a fully charged battery, whereas about 12.06 will be around 50% of charge.yµ (idµ - eAµ) ψ=mψ
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