Member Since: 11 May 2006
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D4 charging querie
Right, where to start? What is the normal charging regime for a 11MY D4? If car hasn't been used much, starts higher (14.simething V) and drops down, sometimes as low as 11.8V if on a super long trip. Is this normal? I was getting concerned at the very low V numbers but the red light didn't come on and she didn't grind to a halt.
Now fast forward to today. After 400 miles, following 9 days at ~500 miles a day so pretty full battery, the volts were at 14.2 - 14.3V and didn't drop. Was a wee bit concerned re this and was watching it closely (nothing else to do on long drive), thought this wasn't right and did a BMS reset. This immediately meant the alternator was putting out 12.0V that gradually climbed up to 12.8V, more "normal".
What was going on and was resetting the BMS the right thing to do? Still getting to grips with the difference between the D3 & D4. All a bit complicated.
26th Jul 2017 5:24 pm
Gareth Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
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Mine is 13 model year, and after a few days standing it's at 12.0 on the cheap plug in volt meter I leave in the accessory socket.
My sockets are permanently live, as is my Blackvue which is powered through a power monitor. After a couple of days, the camera shuts off because the power monitor thinks the battery is getting too low.
When it's in this state, waking the car up drops the volts to about 11.0. During the start cycle it drops momentarily to 10.x but as soon as the engine starts it rapidly climbs. After a couple of minutes when the air is cool it climbs to anything between 14.5 and 15.9 volts. More likely to see over 15 in the winter when it's colder. Use of heated things like screens seats etc drops it a little but it stays over 13 all the time.
I know my battery is original and probably past its best, but it's never given an error or failed to start and I've never reset anything.
I thought you were only supposed to reset the BMS if you replaced the battery?
26th Jul 2017 5:45 pm
Gareth Site Moderator
Member Since: 07 Dec 2004
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Sorry meant to say that on long runs it's mostly at 13.8 to 14.5 depending on what's running.
Modern Land Rover and Jaguar vehicles run a Battery Monitoring System to allow them to smart charge the battery, this means that most of the time the battery is charged to about 80% capacity. This is to reduce the strain on the alternator as it doesn't have to charge it fully. Also means that it's not wasting energy charging a battery that doesn't really need it.
When the conditions change, such as outside temperature, lighting, heated seats, screens etc, it will modify the charging profile to compensate.1972 Range Rover Classic 2 door V8
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26th Jul 2017 5:54 pm
DSL Keeper of the wheelie bin
Member Since: 11 May 2006
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Agreed re BMS after charging but figured after 4,500 miles in 9 days it should be full to bursting. Batt is a fairly new (8 months old) Excide AGM battery. It was a bit worrying at first seeing 11.8v when it first occurred, but it didn't seem to cause any problems, saw that regularly on Road Trip, The Rescue. It was just seeing 400 miles of unchanging 14.2/14.3v that was unusual. Hence thought do a BMS reset, which put things back to normal.
I did think "what's the worst that can happen?".
26th Jul 2017 5:54 pm
DSL Keeper of the wheelie bin
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Gareth wrote:
Sorry meant to say that on long runs it's mostly at 13.8 to 14.5 depending on what's running.
I see typically a lot lower. Also use cheap ciggie socket voltmeter but it pretty much agrees with what the IID tells me.
Agreed re BMS after charging but figured after 4,500 miles in 9 days it should be full to bursting. Batt is a fairly new (8 months old) Excide AGM battery. It was a bit worrying at first seeing 11.8v when it first occurred, but it didn't seem to cause any problems, saw that regularly on Road Trip, The Rescue. It was just seeing 400 miles of unchanging 14.2/14.3v that was unusual. Hence thought do a BMS reset, which put things back to normal.
I did think "what's the worst that can happen?".
It will only charge to 80% of max capacity though, the voltage shows this. With regards to the reading, we regularly see that on cars in work, and it could be due to the contacts in the tool. I know I was concerned on my van when the radio (it displays voltage on startup) was only showing 10V, I cleaned the contacts on the battery and that's now up to 14V when running.1972 Range Rover Classic 2 door V8
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26th Jul 2017 6:00 pm
DSL Keeper of the wheelie bin
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How do I access the secret squirrel menu on the D4 to get what the car thinks the voltage is? I did compare the ciggie lighter readout and what the IID saw and they were pretty much the same.
26th Jul 2017 6:03 pm
Dudleydisco
Member Since: 20 Jun 2014
Location: York
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The IID and the ciggie lighter should agree as you've found. As Tiger says, the BMS will only charge the battery to 75-80%. It doesn't charge to 100% because it wants to leave some battery capacity for energy recovery!
Try travelling at 60 and then take your foot off the accelerator and see what happens to the voltage. On mine, it will slowly increase to about 14.5v and stay there until I touch the accelerator. Once I do, it'll drop back down to about 12v, assuming that my battery is 80% SOC or over.D4 MY14 XXV - RLD/IID BT
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26th Jul 2017 7:23 pm
BAZ8046
Member Since: 26 Feb 2010
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I have had this issue with my MY16 D4.
I use a plug in volt meter to keep an eye on the battery and charge rate.
The first time I noticed it had dropped down to 11.8v I was convinced it was about to break down.
I've noticed it a few times since over the last six months and the car has never presented any issues.
In the end I just put it down to the BMS system as each time the battery has been in a good state of charge.
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26th Jul 2017 9:48 pm
Gareth Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
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Dudleydisco wrote:
The IID and the ciggie lighter should agree as you've found. As Tiger says, the BMS will only charge the battery to 75-80%. It doesn't charge to 100% because it wants to leave some battery capacity for energy recovery!
Try travelling at 60 and then take your foot off the accelerator and see what happens to the voltage. On mine, it will slowly increase to about 14.5v and stay there until I touch the accelerator. Once I do, it'll drop back down to about 12v, assuming that my battery is 80% SOC or over.
This is interesting. I have noticed this exact behaviour on longer runs, and like you I had reckoned it to be part of the smart charging and energy recovery strategy. However, I've not seen it happen for quite some time now. So maybe an early sign of the battery getting tired is the loss of this smart charge function? I keep a volt meter in all the time, so it's easy to monitor.
26th Jul 2017 9:53 pm
DSL Keeper of the wheelie bin
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Hardware17 wrote:
Del ... are you just looking for things to worry about ? is there actually an issue ???
Only noticed coz the voltage stayed so unusually high (unusual for my car), was wondering if the reset routine after a couple of edits to my CCF had done something funny to the BMS. It was as if the alternator had just reverted back to becoming a "dumb" alternator.
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27th Jul 2017 5:50 am
D4mation
Member Since: 29 Jul 2011
Location: Ruralshire
Posts: 593
I thought one of the features of the "smart" alternator was to provide multi stage charging of the battery, in order to increase battery lifespan.
Once fully charged a lead acid battery will last longer if it's kept at a float charge of about 13.7 volts, rather than over charging at 14.5 or 14.7 volts.
I could be completely wrong though - it has been known MY12 D4 HSE Ipanema Sand
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