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Thread: At rest Voltages. Post start voltages on a 1999 S type 4.0 V8.

  1. #21
    Senior Member Jim_S-V6_2004's Avatar
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    Quote Originally Posted by 04str View Post
    That's all great (or not) but as I posted people just aren't having the problems that ought to be occurring all the time if what you posted is all correct.

    I don't know which part(s) is/are wrong or misleading but by now we'd be seeing endless issues wouldn't we rather than the sporadic ones which then are readily fixed and stay fixed.

    Do bear in mind most of the cars are 3.0 and so vast numbers should be suffering all the time due to never having anything like a fully charged battery. They're not suffering so I think either the voltage is OK or the batteries just don't need as high a voltage as you say. Or something.
    .
    04str it's simple to understand,

    As long as the battery is in good condition and its voltage stays above 12.2 volts the 3.0-litre and 2.5-litre and now we know, the 4.0-litre too (thanks Lost One), S Types won't normally have any problems.

    But when the voltage drops below 12.2 volts, the S Type starts to give those random false errors, because the control modules won't have enough voltage to operate reliably.

    Other cars show different symptoms like warning lights flickering and other symptoms.

    If you don't have time to read all of this post, jump to the video.

    To continue...

    In those cases even a good mechie can be mislead because even a normal battery load tester can show the battery is good when it's not.

    Remember that until the early 1990s batteries' plates were made of lead/antimony alloy and would fully charge at 13.6 volts. We used to have only 3 basic types for cars, 55Amp/hour, 66Amp/hour and 77Amp/hour.

    Later, higher capacity was squeezed from lead/antimony batteries by adding more plates to each cell but the size got bigger so there was a limit to that method.

    I used to fit 77Amp/hour to my automatic gearbox cars because they were often difficult to start and could not be bump-started.

    Then from the late 1990s we needed more battery power (capacity) for newer cars and the current technology lead/calcium alloy plated batteries were produced to give that extra power and capacity without increasing the size of the battery, still with liquid acid in them.

    But most manufacturers still continued to fit the old lead/antimony batteries.

    Calcium batteries don't like being fully discharged, nor being frequently discharged. They can die any time when that happens. Maybe that's the reason.

    So car charging systems were still not upgraded to supply the 14.4 volts needed to fully charge those new batteries. This requirement can't be changed, it's 14.4 volts. A calcium battery cannot reach 12.6 to 12.7 volts, nor the higher "surface charge" of over 13.0 volts, without being "dragged" up by a higher voltage, and 13.6 or 13.8 volts isn't enough.

    There are figures on the net explaining how much higher the voltage needs to be for the calcium plate cell to "accept" charging to its full capacity.

    This video explains testing and diagnosis quite well using the latest testers in comparison to the older load testers etcetera, but note that the presenter doesn't know that "SLI" means a battery designed for "Starting, Lighting and Ignition" so he calls it "standard lead/acid":



    This is part of 3 videos, it's worth watching all of them.

    .

  2. #22
    Senior Member Jim_S-V6_2004's Avatar
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    It's prudent to keep an eye on your battery voltage in winter especially.

    You can buy a plugin monitor for your cigar lighter socket for 3 on eBay and leave it in as it turns off with the ignition.

    Remember that in the S Type we have a voltage drop of around 0.4 volts on the long cables to the control modules, so 12.2 volts will show as 11.8 volts, so don't worry!

    When the engine is running the true charging voltage is shown at the cigar lighter socket as it's in the control module circuit. Measure at the battery terminals with a DVM to see what voltage is delivered to the battery, on my S Type it was only 0.1 volts different when charging, but check yours. If there's a bigger difference check your long battery cables' connections for cleanness and tightness at all points to the front of the car.

    Remember the 4.2-litre and 2.7-litre S Types provide 14.0 to 15.3 volts variable, so they do fully charge and maintain all calcium and AGM batteries.

    But, they will kill lead/antimony plated batteries because those will overheat and evaporate their electrolyte if they don't drop to 13.6-13.8 volts. I don't know if these models can drop below 14.0 volts.

    I don't think you will easily find new lead/antimony batteries but if you do, remember this if you have a 4.2-litre or diesel S Type.

    Even some suppliers don't realise there were lead/antimony batteries and call calcium batteries "standard" batteries. Today, they are ("standard").

    .

  3. #23
    Senior Member Lost it's Avatar
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    OK. Take 2.

    Vehicle not used for 2 days:

    Standing battery voltage:

    12.10V

    After 3 minutes with ignition on, presumably drawing current for initial pump prime, the climate control, dash etc. is energised. Interior fan?

    11.87V

    Immediately after start:

    13.69V

    After 10 mins:

    13.74V

    After run to Chichester and back, approx 22 miles, including stop for shopping, ignition off, boot open.

    12.3V

    So. A run of 22 miles approx, at normal road speed, down the A27 and back, brought the battery back up to slightly higher than it was to start with.

    The better news, as far as I am concerned is that the fuel gauge is now reading well below 1/4 and the car is running as sweet as a nut, in fact much smoother, it feels, than it was before I pulled the tank pump apart. It's also gained a few more ponies feels like? Definitely more grunt.

    At that my car appears to be working exactly how Jaguar intended. I'll just have to use my Ctek every so often to boost the battery to full charge.
    Last edited by Lost it; 26-12-18 at 15:57.
    2001 3.0 SE Auto, Satnav, winter pack. Dark Blue, all the toys.
    2004 3.0 Sovereign Estate. Winter pack. Fixed. For Sale.
    2005 Estate X type 2.2 Sport.
    2000 V8 3.2 XJ8 LWB. "Prom" car. Lovely. Should sell this one too really...
    2005 "AllyCat", 3.0 XJ6 SE.
    2000 S type 4.0 V8. Latest toy.
    VFR800A and a VFR 800F

    Still beating cancer. Trevor 2, Cancer 0.

    Sure I took the Red pill....

  4. #24
    Senior Member Lost it's Avatar
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    Quote Originally Posted by capri v8 driver View Post
    The X type uses a different way to controle the alternator then the S type and it has less power draining electronics on board then the S type. Therefor there are less draining problems then with the S type.

    Maybe useful, from the jag repair manual:
    I'm aware of that, the X type immediately after start can easily show over 15V charging. First time I saw that I almost panicked thinking the alternator was over charging.

    My Xtype can also charge my Hella battery boost thing that needs at least 14V to initiate the charge cycle using the cigar lighter. The S type couldn't.

    Makes you wonder what the thinking was?
    2001 3.0 SE Auto, Satnav, winter pack. Dark Blue, all the toys.
    2004 3.0 Sovereign Estate. Winter pack. Fixed. For Sale.
    2005 Estate X type 2.2 Sport.
    2000 V8 3.2 XJ8 LWB. "Prom" car. Lovely. Should sell this one too really...
    2005 "AllyCat", 3.0 XJ6 SE.
    2000 S type 4.0 V8. Latest toy.
    VFR800A and a VFR 800F

    Still beating cancer. Trevor 2, Cancer 0.

    Sure I took the Red pill....

  5. #25
    Senior Member Jim_S-V6_2004's Avatar
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    Quote Originally Posted by Lost it View Post
    OK. Take 2.

    Vehicle not used for 2 days:

    Standing battery voltage:

    12.10V

    After 3 minutes with ignition on, presumably drawing current for initial pump prime, the climate control, dash etc. is energised. Interior fan?

    11.87V

    Immediately after start:

    13.69V

    After 10 mins:

    13.74V

    After run to Chichester and back, approx 22 miles, including stop for shopping, ignition off, boot open.

    12.3V

    So. A run of 22 miles approx, at normal road speed, down the A27 and back, brought the battery back up to slightly higher than it was to start with.

    The better news, as far as I am concerned is that the fuel gauge is now reading well below 1/4 and the car is running as sweet as a nut, in fact much smoother, it feels, than it was before I pulled the tank pump apart. It's also gained a few more ponies feels like? Definitely more grunt.

    At that my car appears to be working exactly how Jaguar intended. I'll just have to use my Ctek every so often to boost the battery to full charge.
    Excellent, thanks again Lost One.

    Yes I'd say your battery is fine but needs a full charge.

    Cheers.

    .

  6. #26
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    Quote Originally Posted by Lost it View Post
    I'm aware of that, the X type immediately after start can easily show over 15V charging. First time I saw that I almost panicked thinking the alternator was over charging.

    My Xtype can also charge my Hella battery boost thing that needs at least 14V to initiate the charge cycle using the cigar lighter. The S type couldn't.

    Makes you wonder what the thinking was?
    That's rather like the STR kind.

    It can probably cope with more than just ordinary lead acid, as you've found, whereas the majority of S-Types need a battery happy to be charged at 13.8V (nominal) for most of the time. (BTW that is like burglar alarms and the like.)

    That said, the profile the STR puts out is still aimed at lead acid. It can do a better job of anti-sulphation I gather.

  7. #27
    Senior Member Jim_S-V6_2004's Avatar
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    04str... don't worry so much!

    Fortunately the STR and the Normally Aspirated 4.2-litre S Type and the 2.7 diesel can all fully charge any battery type, old tech, calcium, and AGM.

    They are all "lead/acid". That's how they work. No acid, no lead... No battery.

    So you don't need to worry at all.

    Lost One, the initial 15 volts in the post-2002 3.0-litre and the 2.5-litre S Types is only present for a few minutes, to recover some of the charge used in starting.

    It would be good to know if that X Type does the same, just to compare?

    I'm wondering if different X Types have different charging systems too, but that's beyond my scope of interest until I get one.

    .
    Last edited by Jim_S-V6_2004; 27-12-18 at 17:00.

  8. #28
    Senior Member Lost it's Avatar
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    Well, after that I'm going to get me a conductance tester. I have three batteries that I have concerns about so I might as well find out what kind of state they are in. My X type estate, the XJ and the S type are all needing more and more "ctek" time to keep up. And it's not that cold yet...
    2001 3.0 SE Auto, Satnav, winter pack. Dark Blue, all the toys.
    2004 3.0 Sovereign Estate. Winter pack. Fixed. For Sale.
    2005 Estate X type 2.2 Sport.
    2000 V8 3.2 XJ8 LWB. "Prom" car. Lovely. Should sell this one too really...
    2005 "AllyCat", 3.0 XJ6 SE.
    2000 S type 4.0 V8. Latest toy.
    VFR800A and a VFR 800F

    Still beating cancer. Trevor 2, Cancer 0.

    Sure I took the Red pill....

  9. #29
    Senior Member Lost it's Avatar
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    OK, my "Conductance test" tool arrived, I followed the instructions and it says my S type battery is 92% healthy.

    CCA is rated at 800, actual measured CCA is 771. So over two years it's lost 8%. It's at 99% charge (it's on the Ctek and has been for 24 hours) and I doubt it will get to 100% charge.

    So. That one at least is fine.

    My wife's Fiesta is a 440CCA thing, that measures at 420CCA so that's fine as well, I actually used the Amp Hour scale to check hers.

    I'll get to the rest of the cars tomorrow, having a bite to eat then off to QA for my scan. This is the one I went for, battery that was flat and recharged seems to be in an XJ.

    Last edited by Lost it; 30-12-18 at 19:41.
    2001 3.0 SE Auto, Satnav, winter pack. Dark Blue, all the toys.
    2004 3.0 Sovereign Estate. Winter pack. Fixed. For Sale.
    2005 Estate X type 2.2 Sport.
    2000 V8 3.2 XJ8 LWB. "Prom" car. Lovely. Should sell this one too really...
    2005 "AllyCat", 3.0 XJ6 SE.
    2000 S type 4.0 V8. Latest toy.
    VFR800A and a VFR 800F

    Still beating cancer. Trevor 2, Cancer 0.

    Sure I took the Red pill....

  10. #30
    Senior Member Jim_S-V6_2004's Avatar
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    Excellent Lost One.

    By the way, CA (Cranking Amps) are measured at 32F, which is 0C.

    CCA (Cold Cranking Amps) are measured at 0F, which is? -17.8C!!

    That's not "Cold"! That's Very Cold!!

    .

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