Page 5 of 11 FirstFirst 123456789 ... LastLast
Results 41 to 50 of 102

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

  1. #41
    Senior Member Lost it's Avatar
    Join Date
    Jun 2012
    Location
    Hayling Island
    Posts
    7,843
    Post Thanks / Like
    98% charged according to the tester. And it doesn't have to be fully charged to do a conductance test, the test is to check the resistance between plates, if they are "furred up" the resistance is higher. From what I can gather if the battery charge is too low it advises you to recharge and test again.

    Ohms law is used if I understand the logic. You know two of the measurements, the third one is worked out by the tester to give you the info you need.
    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....

  2. #42
    Senior Member Jim_S-V6_2004's Avatar
    Join Date
    Jun 2013
    Posts
    17,215
    Post Thanks / Like
    Yep 98% is good enough.

    Oh dear, another bad one.

    I=V/R (AMPS)
    V=IR (VOLTS)
    P=IV (WATTS)
    R=I/V (OHMS)
    etcetera:



    In one of the videos the presenter said that the conductance tester injects a series of pulses but I've no idea what or why, I haven't thought about it.

    Another said that a battery resistance up to 0.5 Ohms is ok but over 2 Ohms means get rid. I'd have to check a few batteries to confirm that.

    .

  3. #43
    Senior Member Jim_S-V6_2004's Avatar
    Join Date
    Jun 2013
    Posts
    17,215
    Post Thanks / Like
    Ok, I watched the video and got a good idea of the system.

    As we see, the monitor line looked good so no error was generated, but the alternator is lying, it's not producing any charging voltage. So he had to swap it out on speculation to prove his hunch.

    So here's a video diagnosing a faulty one to complete our understanding of the Ford PCM system:



    I don't know if the Ford system is the same as the SC1 or SC2 systems used in our 4.2-litre or 2.7-litre Diesel. These are the only 2 which generate variable 14 to 15 volts.

    I doubt it because the Ford system generates 13.6 volts to over 14.4 volts as we saw, after a startup delay. I don't think any of our systems do that, no startup delay is described in the workshop manual.

    But I don't have a diesel S Type nor a 4.2-litre S Type to check it.

    I really would like the testers those guys have, wouldn't you?

    .

  4. #44
    Senior Member Lost it's Avatar
    Join Date
    Jun 2012
    Location
    Hayling Island
    Posts
    7,843
    Post Thanks / Like
    I have to be honest Jim I'm really considering fitting an X type alternator to my S type, bypass the ECM monitoring completely so that it charges the battery properly.

    This weekend I intend checking to see if there is the extra lead on the standard fit alternator on my S type and if there is I will take it off and see if it throws a fit and puts a light on the dash. I'll also check the voltages.

    I wouldn't say Eric "threw a speculative alternator on", way I see it he checked the whole system because it wasn't throwing a warning light up and was trying to figure out why the alternator can fail to charge without setting the generator light on the dash. He monitored every parameter he could think of, knowing the most likely problem was a duff alternator, and if he had simply stuck a new one on, then he would not have been able to do the testing that he did. I don't think there was too much editing done off screen...

    And there is still apparently no clue as to why this can happen, so the whole system is crock as far as I'm concerned, if it can let you drive a car on battery alone without even warning you that you have a none working alternator it's a very poor design outcome. Even a dynamo equipped 1956 Ford Anglia would give you that warning...

    My 2.2 derv started doing that, it would throw a light whilst driving, eventually I swopped the alternator and it still does it if I leave it ticking over with the engine running from cold whilst I scrape the windows if it's cold enough. So I suspect that there is an element of "wait a few" on the X type charging circuit especially. Certainly on a really cold day it won't even entertain turning on some of the systems until it has run for a few secoinds after starting. On ly the headlamps. Everything else seems to wake up bit by bit. My 3.0 has always done this.
    Last edited by Lost it; 03-01-19 at 03:33.
    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. #45
    Senior Member
    Join Date
    Nov 2014
    Location
    Norfolk, UK
    Posts
    442
    Post Thanks / Like
    Quote Originally Posted by Lost it View Post
    I have to be honest Jim I'm really considering fitting an X type alternator to my S type, bypass the ECM monitoring completely so that it charges the battery properly.
    I really don't see why you would want to consider this. If you have a charging problem with the original equipment, why not just address that & fix it?
    Your 4.0l Has the same charging system as my old 3.0l & in over twelve years & 160,000 miles it never gave me any battery related issues, despite often spending weeks at a time doing sub 5 mile journeys. As Jim well knows, I have contacted the Platinum Prestige battery manufacturers to get their take on things & have had it confirmed that in their opinion, if things are working as they should be, our cars charging systems are quite capable of looking after their batteries. They are happy to recommend their batteries for use in our cars, & have put in writing that they will stand by any warranties for their products if they suffer premature failure when fitted to our cars. In my opinion, they wouldn't do that if they thought our cars charging systems couldn't charge their products properly. I think some of our S types may suffer from some of the systems not going to sleep correctly & therefore putting extra stress on their batteries. If everything shuts down as intended, they should give no problems.
    I went out to my 2.5 yesterday after it had stood unused & untouched since December the 13th. I was unable to drive for a few days before Xmas & with Mrs O on holiday, her car was parked behind & easier to get out when we needed one. I have just treated myself to a new iCarsoft LR V2.0, so decided to have a little play. It has a battery voltage check facility which showed my 5 year old Platinum Prestige 019 had held on to 12.3 of it's precious volts. A little lower than ideal, admittedly, but still perfectly adequate under the circumstances, it was a bit cold. I do believe that once the voltage drops below a certain level, this does cause systems to wake up & put even more drain on things, so a weak battery will perhaps show it's self earlier than on other makes/models, but if the battery is reasonably healthy & the car gets a run every now & then, it should be OK.

    Regards, OW
    1999 S Type 3.0L SE, A truly lovely old girl that's served me well. Probably the best car I've had. Now retired.
    02.5MY (X202) S Type 2.5L SE, 58,000 miles, full Jag s/h, all papers, MOT's, receipts etc from new when purchased.
    2006 X type SE 2.2 Diesel. Supposed to be Mrs O's economical commuter car.
    2004 (X202) 2.5L Sport plus, to replace the 3.0L

  6. Likes Lost it liked this post
  7. #46
    Senior Member Jim_S-V6_2004's Avatar
    Join Date
    Jun 2013
    Posts
    17,215
    Post Thanks / Like
    That's quite correct OW - as long as the car is used even fairly regularly and doesn't have starting problems, it can put up with the battery being 75-80% charged.

    My 2.5-litre sat for over a month and still started. So I didn't have to worry about current drain.

    I think as you say, some owners do suffer from battery drain and should look into it.

    A quick voltage measurement at the battery terminals will show the battery state of charge, and you can look up the voltage in charts on the web to see the percentage of full charge.

    These conductance testers are cheap now and make it dead easy to check a battery, well worth spending the money.

    It's a shame that manufacturers won't tell you their batteries will be OK in any car which generates at least 13.6 volts, but won't clarify that they need 14.4 volts to get fully charged, to show 12.7 volts.

    Many sales people are blissfully unaware.

    All calcium alloy batteries need the same voltage, it's a chemical reaction. AGM batteries need 14.6 to 14.8 volts to fully charge, they go to 12.85 volts at full charge. Can't get away from this.

    When you watch some comparative videos of battery types you will see that even the presenters don't know this because they don't mention charging voltages.

    It's technical info which is available all over the internet and in some videos too. I've linked to many in the past.

    Just be aware and check now and then, as I've said many times.

    .

  8. #47
    Senior Member
    Join Date
    Jul 2009
    Location
    Yorkshire
    Posts
    10,218
    Post Thanks / Like
    Sounds like batteries are readily available which do not need 14.4V or higher but are fully charged at 13.6/13.8V.

    The same kind are used in many non-car applications i.e. 13.6/13.8V is the correct voltage, not least because it's been the right amount for decades and changing every bit of equipment is not viable.

  9. #48
    Senior Member Jim_S-V6_2004's Avatar
    Join Date
    Jun 2013
    Posts
    17,215
    Post Thanks / Like
    Quote Originally Posted by 04str View Post
    Sounds like batteries are readily available which do not need 14.4V or higher but are fully charged at 13.6/13.8V.

    The same kind are used in many non-car applications i.e. 13.6/13.8V is the correct voltage, not least because it's been the right amount for decades and changing every bit of equipment is not viable.
    .
    Point me at some please 04str.

    .

  10. #49
    Senior Member
    Join Date
    Nov 2014
    Location
    Norfolk, UK
    Posts
    442
    Post Thanks / Like
    Gave the X type a run today as that also had stood unused since before Xmas & thought I'd hook the LR V2.0 up & see what voltages I got. At rest with drivers door open & interior lights on, it registered 12.4 volts. When started, voltage rose to 12.6 & stabilised for about 30 seconds, then started rising very slowly & after about another minute & a half,stabilised again at 13.9. Nothing except heater/climate switched on, fan started to run as engine warmed. Took for 10 mile run watching voltage as best I could & it seemed to be around the 14 volt mark. When home, scanner reported highest voltage this test at 14.05 & lowest at 7.8, presumably when cranking the engine. On that basis, the X type is almost worse than the 2.5 S type, as it doesn't get the higher voltage boost after starting. I'll have to hook it up to the S type next time I go out in it & see what voltages that gives, & for how long.

    Regards, OW
    1999 S Type 3.0L SE, A truly lovely old girl that's served me well. Probably the best car I've had. Now retired.
    02.5MY (X202) S Type 2.5L SE, 58,000 miles, full Jag s/h, all papers, MOT's, receipts etc from new when purchased.
    2006 X type SE 2.2 Diesel. Supposed to be Mrs O's economical commuter car.
    2004 (X202) 2.5L Sport plus, to replace the 3.0L

  11. #50
    Senior Member Jim_S-V6_2004's Avatar
    Join Date
    Jun 2013
    Posts
    17,215
    Post Thanks / Like
    Thanks for this OW, it's interesting to know.

    .

Page 5 of 11 FirstFirst 123456789 ... LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •