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Lead acid battery charging, is this a problem or not?

Discussion in 'Electrics UK' started by ericmark, 10 Apr 2021.

  1. ericmark

    ericmark

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    After the bulk charge stage my battery chargers are designed to maintain the battery, it is rather simple there is zero, 0.1 amp and 0.8 amp charge rates, and two voltages 12.8 and 14.4 if the voltage drops below 12.8 it ups charge rate, and above 14.4 it drops charge rate, this is claimed to be better than floating at 13.4 volt as it equalises cells better.

    I have three cars and another 6 batteries from caravan and jump-start set and some 7 Ah from old stair lift which will be used for my radio. Plus two which use a dedicated charger for mobility scooter, and all but one charge A1 the charge rate will in the end drop to zero with likely once a day charger switching back on to top up charge, even the 95 Ah AGM on the Jag drops to zero charge rate after some time, switching back on at 11:40 am every day, clearly some thing in Jag auto switches on at that time.

    Batteries which are older never switch off, they sit at 0.1 amp charge rate, but 95% of the time sit at 12.8 - 12.9 volt and get a pulse every so often to maintain them.

    The odd one out is on a Kia Sorento, flooded 95 Ah battery, to start with all seems normal, it goes through each stage until it drops to 0.1 charge rate, then like the other batteries maybe 10 hours latter it gets a ½ hour pulse at 0.8 amp, then drops back to 0.1 amp again.

    But as time goes on both the time between the pulse gets shorter and pulse length gets shorter, so I end up with some thing like this Jazz and Kia charging 55.jpg with loads of pulses per hour, only the Kia battery does this, no other, all other batteries will be left on charge for around 2 weeks then charger moved to next battery, and with a 0.1 or 0.8 amp charge rate I don't really worry about exactly when moved to next battery, if I had more chargers or less batteries I would not take them off charge, just this one battery that does this.

    So does the pulsing do any harm? I have read conflicting reports on pulse charging, and I don't think this is what is meant by pulse charging, some very cleaver chargers use the decay between pulses to work out charge state and so charge rate, common with canal boat batteries but looking at chargers able to deliver 120 amp and charging 400 Ah battery bank, so not really the same as my 3.8 amp charger with a 95 Ah battery.

    So what is going on, is it slowly removing a build up of hard sulphur, so I should leave it longer, or is the rapid pulsing damaging the battery?

    My intention had been to fit the old Jaguar XE battery into the Kia Sorento and put the Kia Sorento battery in the caravan, as think the old Jag AGM battery is better, and also may be damaged with the caravan power supply which seems a tad high on voltage, the flooded battery I can top up with distilled water. But not sure if I need a code for Kia on changing battery or if any reprogramming required? So was waiting until licence sorted and can take it to Kia agents.

    It is the problem of moving from paper to photo licence now 70 which has resulted in the cars not being used and sitting in the drives, seems on line renewal is done by letter! And I need some one who has known me for 3 years to sign photo, so waiting until I have been in this house for 3 years before I can get some one local to sign licence paper application called the on line renewal form before I can get licence renewed. And clearly since not using bus or train has to be within walking distance.
     
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  3. BS3036

    BS3036

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    Don't you still have a passport? I thought they would use that photo. Expect I'm wrong though.
     
  4. ericmark

    ericmark

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    No valid passport, never bothered to renew it.
     
  5. SUNRAY

    SUNRAY

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    The gel cells do not like 14.4V.
    I have chargers that do the similar sort of thing to yours [4 of them from Lidl] which have killed several of my 7Ah to 17Ah batteries.
    A constant voltage of 13.6 [2.27V/cell] has worked for me for many years with a great number of such batteries and using the 'new' chargers seems to have killed them within a few charges.
    They seem to work well with 80 & 115Ah leisure batteries, in fact I was on the verge of outing a pair of 115's as their capacity appeared to have dropped to 30-40Ah or so [ACT gold battery tester] but after a very few use/charge cycles the capacity appears to have risen to 80AH or so.
     
  6. bernardgreen

    bernardgreen

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    That is my experience as well. Just last week an 8 year old 12 V 7 Ahr battery ran a 10 Watt lamp for 5 hours and still had 11 Volts on it's terminal
     
  7. ericmark

    ericmark

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    It does seem Gel batteries have a typical absorption voltage range 14.0 to 14.2 volts; typical float voltage range 13.1 to 13.3 volts.
    I have not really worked out the difference between AGM and VRLA for AGM it seems the typical absorption voltage range 14.4 to 15.0 volts; typical float voltage range 13.2 to 13.8 volts. And for VRLA the typical absorption voltage range 14.2 to 14.5 volts; typical float voltage range 13.2 to 13.5 volts.

    It seems to say "Actually, the AGM batteries are a variant of Sealed VRLA batteries, just a more advanced design." when hunting the internet for information and it does seem the Lidi and other cheap "Smart" chargers are designed for the AGM battery.

    Why a lead acid battery without ability to top up (AGM) should have a higher typical absorption voltage range 14.4 to 15.0 volts, to a flooded typical absorption voltage range 14.4 to 14.9 volts although only 0.1 volt.
     
  8. flameport

    flameport

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    Your batteries are old and need to be replaced.
     
  9. ericmark

    ericmark

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    Could say the same about me. However it does seem temperature related.
     
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  11. Harry Bloomfield

    Harry Bloomfield

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    I don't think the pulse charging, is of the pulse type from your little charger. Rather it is a charger of a type I designed and built many years ago, where it put out a large pulse of large current, then checked the battery voltage between the pulse to decide whether to continue with the pulses. My charger pulsed at up to 60amps and could start a car with a completely flat battery, in just a matter of minutes. I built it when ECU's began to appear in cars, which for the first time, discharged batteries whilst cars were parked. My company car would do most of the mileage, with my car (then as now) spending many weeks just parked up unused. My batteries never suffered any obvious damage as a result of its use.

    Could you not tweak the caravan charger voltage down a bit, most use a pot, or 1% resistor potential divider to set the output voltage.
     
    Last edited: 10 Apr 2021
  12. JohnW2

    JohnW2

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    No, you're right. When I was in eric's position, a couple of years ago, I was able to 'grant permission' for them to use my passport photo for my first-ever photo driving licence.

    However, I'm not sure what happens when I have to renew it, in a bit over a years' time (they only last 3 years for us oldies!), since my passport expuired last year, and any attempt get it renewed results in their website telling me that unless I have a "very urgent need" to renew the passport that I should 'go away and come back after the pandemic' :)

    Kind Regards, John
     
  13. 333rocky333

    333rocky333

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    We could quote that to some of the posters here :)
     
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  14. JohnW2

    JohnW2

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    We could, but we might prefer to limit ourselves to the first couple of words :)

    Kind Regards, John
     
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  15. SUNRAY

    SUNRAY

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    Anyone in particular?
     
  16. SUNRAY

    SUNRAY

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    OK I get the message...
     
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  17. ericmark

    ericmark

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    Last time I charged the Kia it was Winter, and I had as shown nearly 20 pulses per hour, however this time we have has some warm days, and the pulses have varied in the cold 10 pulses per hour and when warm dropping to 4 pulses per hour. The last time I was unaware of the temperature causing a variation.

    I have seen how a sulphated battery can sit doing nothing for 10 days, then as if a switch has been flicked, start to take charge and seem to fully recover, with this in mind don't want to remove charger too soon, however also don't want to damage battery leaving it on charge too long either, clearly under 13.4 volts no worries, so with the Honda Jazz the charger has automatic switched fully off, so no hurry removing, but this pulsing not so sure, likely leave one more day to see what happens.

    Update at 14:30 the Kia had dropped to 5 pulses per hour with outside temp at 11°C.

    Further update, snowed over night and pulse rate was 8 an hour, then warmed up and dropped to 4 an hour, so clearly temperature related. It also explains why it was not noticed in the summer months.
     
    Last edited: 12 Apr 2021
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