Member Since: 17 Sep 2009
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AGM batteries and level of charge
Well no cure for the timed climate, yet.
In Garage today and they said battery good at 12.45 volts.
Thought this would indicate a 50 percent charge on AGM battery, and having driven 50 miles there would of expected a higher reading.
Any thoughts or have i got it wrong.D4 Landmark MY16 Santorini Black THE LAST
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23rd Jan 2014 10:50 pm
lespes
Member Since: 17 Sep 2009
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D4 Landmark MY16 Santorini Black THE LAST
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24th Jan 2014 1:59 pm
motolite
Member Since: 18 Mar 2013
Location: Sydney
Posts: 931
hi lespes, 50 miles ay not be enough to fully charge the battery. Apparently the D4 alternator is 'smart' and at least 8 hours worth of driving is required. Of course it may depend on the state of charge to begin with.
24th Jan 2014 7:19 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
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Testing batteries is difficult - and I mean really difficult. In fact so difficult the closest we get with modern and expensive tools is by using electrochemical impedance spectroscopy. This is the technology you find in high-end testers found at better garages. If you want to know to know more about EIS in modern applications try a quick CalTec or NASA paper.
A battery can be tested and found to be 'good' whilst the voltage is a bit low. The DIY methods we use by testing voltage alone is only indicative of the State of Charge and health of the battery rather than an absolute guide. Measuring the CCA via electrochemical impedance spectroscopy is a better way to test AGM batteries and I would guess this is how the battery was tested to give the 'good' reading as well as the closed circuit voltage.
Member Since: 17 Sep 2009
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for input.
Complicated stuff, even more so for a simpleton like me
Frustrating, was working, then after just towbar electrics enabled, not.
According to my research a reading of 12.45 on a AGM battery equals about 50 percent charge, when ctek charger attached goes to the 50 percent charge straight away.
Would seem that the battery whatever mileage or distance never gets a charge of more than 50 percent from the alternator.
I suppose my expectation of having it work probably is just unrealistic, dealers just seem to shrug it off and offer no solutions or action.
I see over on FFRR the fitting of the gel batteries seems to solved most issues relating to this.D4 Landmark MY16 Santorini Black THE LAST
D4 HSE MY12 Marmais Teal: Gone. Missed a lot!
Freelander 2 SD HSE MY11 Silver:Thankfully gone.
D4 HSE MY11 Silver: Gone missed !
Range Rover Sport MY06 HSE Buck Blue: Gone missed!
Discovery D2 TD5 Facelift MY Red Gone Missed!
Discovery D2 TD5 Cobalt Blue: Gone Missed!
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Discovery D1 Avalon Blue First LR! missed!
Now demoted to a VW
25th Jan 2014 12:51 pm
lespes
Member Since: 17 Sep 2009
Location: Sitting Down
Posts: 2232
Quote:
Apparently the D4 alternator is 'smart'
Not smart enough if you ask me D4 Landmark MY16 Santorini Black THE LAST
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Discovery D2 TD5 Cobalt Blue: Gone Missed!
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Discovery D1 Avalon Blue First LR! missed!
Now demoted to a VW
25th Jan 2014 12:53 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
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Simplistically AGM batteries hold more energy at a lower voltage. They also absorb a charge quicker too.
This makes them doubly attractive to car manufacturers. Not only can they recover from stop/start quicker they can be deliberately held at a slightly lower state of charge to avoid the load placed on the alternator to get to the last few % of charge. This reduction in load and increased capability to absorb a charge allows them to use energy recovery too.
Driving a D4 whilst observing the voltage is fascinating. Accelerate the car and the voltage/alternator output is low and very near battery voltage. Take your foot off the throttle to slow down and the voltage/output shoots up as it loads the alternator to take advantage of the free energy.
It took them a few years to get it right, but I think it is excellent.
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 13 Jan 2009
Location: Bavaria
Posts: 136
my dealer has reset the BMS some time ago and the the voltage on my cig voltmeters always remains within 14.6 - 14.8V whatever the load on the engine. Is this smart charging strategy a trick of later models or is something wrong with my MY10 I still use the LR calcium batteryLife in the slow lane
25th Jan 2014 3:37 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
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There is a slow progression along the model years, so that is probably normal for an MY10 with a lead-acid battery. I've not had enough experience with an MY10 to be sure; others on the forum will know more.
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Hi Lespes and it depends on when you took the voltage reading, as to what it actually means.
If you took the reading just after turning the motor off and everything else was turned off in the D3, then that is a VERY low reading. You should see 13+v straight after turning the motor off.
If the reading was take the next morning after the D3 had been sitting all night then it’s a good reading and indicates about an 85% SoC.
The chart below will give you a good idea of the batteries SoC once it has been left over night.
As Robbie pointed out, it’s not as simple as check the voltage, job done.
Hi viethson and if your voltage reading is a constant 14.6 - 14.8v, this either is too high depending on how long it stays there. Any more than thirty minutes and you have a problem.
Either the alternator is running too high for no reason, or it has a reason, your cranking battery may be on it’s way out.
Constant 14.7v or higher will eventually cook a battery, particularly on a long drive.
Click image to enlarge
2008 TDV8 RR Lux + 2009 D4 2.7
29th Jan 2014 10:54 am
lespes
Member Since: 17 Sep 2009
Location: Sitting Down
Posts: 2232
Drivesafe.
This was chart remembered seeing before
Managed to get Voltmeter this morning as old one broken.
Battery fully charged yesterday via ctek and had run this morn.
Voltage then 12.65 after 10 mins switched off.
When engine running between 14.5 and 14.7 similar to Viethson.
I have an AGM battery fitted in D4, wondered if voltages are the same as the lead acid batteries, have read that AGM batterywill produce a lower reading than lead acid batteries.D4 Landmark MY16 Santorini Black THE LAST
D4 HSE MY12 Marmais Teal: Gone. Missed a lot!
Freelander 2 SD HSE MY11 Silver:Thankfully gone.
D4 HSE MY11 Silver: Gone missed !
Range Rover Sport MY06 HSE Buck Blue: Gone missed!
Discovery D2 TD5 Facelift MY Red Gone Missed!
Discovery D2 TD5 Cobalt Blue: Gone Missed!
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Discovery D1 Avalon Blue First LR! missed!
Now demoted to a VW
29th Jan 2014 12:28 pm
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Hi Lespes and the chart above works for all lead acid batteries, AGMs, Gels and wet cell batteries.
The chart is for batteries that are in use, and even if the vehicle has been sitting unused for a few days, the battery is still providing power, even though it is very low currents, in the milliamps range, the battery is still in use and the chart above will give you a reasonable idea of whether the battery is near fully charged, is not fully charged but is OK or near flat and in need of a charge.
Note the green area is for cranking batteries and the green and yellow area is for deep cycle batteries.2008 TDV8 RR Lux + 2009 D4 2.7
29th Jan 2014 1:08 pm
CUCO
Member Since: 27 May 2011
Location: Spain & Oleee!!!
Posts: 609
if you do a long run, the voltage must be lower, the system get the volts high until the batt holds an aceptable charge (retrieving crancking effort and over night discharge)), and then it gets low to settle around the volts the BMS thinks are better for long life of the batt/maintaining of level of charge.
i observed too that it depends on external temp too, higher the ambient temp -> lower the voltage.
if your batt holds charge, volts should go down around 15- 30 minutes after you start driving. mine do this. starts high, gets lower as you go driving. as lower as 12,8-13,00 on flat surface (and after 6 hours non stop driving too..with more than 6 hours previously, just stopping to feed the beast...and pee )
one thing i saw was that depending on the conected items (accesories), the volts change too, getting higher as the number of accesories grow. if you turn on the defrosted, heated wheel, heated seats, light or whate ever, the volts rises ( except when just turned on engine, when it gets lower, to go up after very very few minutes...)
if yours dont go down. recharge the batt to top (overnight for example) and retest, maybe your driving habits dont recharge the batt enough and the car is putting its best trying to recharge the batt to adequate level..
29th Jan 2014 1:12 pm
viethson
Member Since: 13 Jan 2009
Location: Bavaria
Posts: 136
Thanks everyone for your inputs
The dealer did top up the battery over night, reset the BMS and installed it again. Even with the fully charged battery the volts won't drop below 14.6V. The battery is now 3 1/2 years old so maybe it is now just unable to hold the charge and the alternator is just unable to charge it to an acceptable level. I will fit a AGM battery soon. I expect to see some change in Volts afterwards. But is a BMS reset really necessary so that the BMS realizes the state of charge of the new battery and adapt the charging voltage? And if so can it be done with a faultmate or will I have to see the dealer again?
Thank you Life in the slow lane
29th Jan 2014 3:25 pm
SHARKYSHARKS
Member Since: 20 Dec 2008
Location: Saddleworth Oldham
Posts: 1954
I have always used an heavy battery discharge tester on all my batteries, to indicate how good they are !!
You can charge a battery to full capacity and it will read 12+on a volt meter but until you put that battery under a heavy load you will never completely know!
This is where a battery discharge tester would find a damaged or weak cell within the battery, to let you diagnose how it will perform under heavy load conditions and prevent failure or breakdown. MY18 D5 HSE LUX😎
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