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Technical UPDATE - How long can you safely charge a battery?

Discussion in 'The Hokey Ass Message Board' started by HOTRODPRIMER, Oct 23, 2019.

  1. Boneyard51
    Joined: Dec 10, 2017
    Posts: 4,009

    Boneyard51
    Member

    I , too, quit reading after a short time of really no information.
    After near sixty years of dealing with batteries, I have notice several “ general” things about batteries.
    1: New batteries have more capacity than old batteries.
    2: More expensive batteries are usually better than cheap ones.
    3: Heavier- larger batteries are better than lighter-smaller batteries.
    4: You can get more “ juice” in a battery slow charging than fast charging.
    5: If a “ dead” battery charges up quickly, it’s usually a bad battery.
    6: If you let a car battery go completely dead, it severely damages it.
    7 :A lot of “ battery “ problems are bad connections.
    8: Not every battery acts the same.
    9: The more/deeper you “ cycle” a battery, the shorter the life of the battery.
    10: Be careful, batteries can hurt you!







    Bones
     
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  2. squirrel
    Joined: Sep 23, 2004
    Posts: 46,081

    squirrel
    Member

    Those are most of the things you need to know
     
  3. After being on the charger for a little over an hour the needle is standing straight up and down, I'm going to give it another hour and see if it helps, the battery is not hot. HRP
     
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  4. squirrel
    Joined: Sep 23, 2004
    Posts: 46,081

    squirrel
    Member

    Where did the needle start?
     
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  5. Jim, it showed a slight charge last week but today when I hooked up the charger it was sitting on zero.

    I let the battery charger for just over 2 hours today and it was just shy of a full charge, I thought what the heck John told me he recently charged a battery for four hours so I charged it another 45 minutes and it showed a full charge.

    I put it back in the wagon and it fired up on the first crank.

    I drove the car around the block and everything is working as it should, it was showing 13 volts. HRP
     
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  6. upspirate
    Joined: Apr 15, 2012
    Posts: 2,191

    upspirate
    Member

    Tomorrow morning will tell. Hope it recovered for you
     
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  7. Boneyard51
    Joined: Dec 10, 2017
    Posts: 4,009

    Boneyard51
    Member

    If you hooked up the charger to your battery that wouldn’t start your car after a 45 minutes and five mile drive and it showed 0 amps at first, you have a bad battery!
    A completely “ dead “ battery will show 0 amps at first. Oddly enough the battery has to have some charge to register amps on a charger. After it charges a while you will see the amount of amps on the gauge that you have set on the charger. Then it should taper back.
    Like UPSPirate says, tomorrow or the next day, will tell.






    Bones
     
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  8. I agree with you both, tomorrow will tell the tale. HRP
     
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  9. Truck64
    Joined: Oct 18, 2015
    Posts: 4,056

    Truck64
    Member
    from Ioway

    Can measure either (or both) the voltage and current when charging with a charger you want to be "safe" about it, notice the current starts out high and the voltage low. As the battery accepts the charge the current will taper down and the voltage start to rise. This can take a long time, depending on the charger capacity, and how dead the battery is.

    Usually somewhere in the mid 14s voltage range the current will be very low, a fraction of an amp, and the cells will be moderately outgassing. It takes a lot longer to charge in cold temperatures the internal resistance increases. The battery is basically as charged as it will get at this point, though letting it cook for a little while longer is considered a good thing.

    There is also a voltage correction factor applied. Charging voltage figures are normalized for 77° F., to reach a full charge and is around 15 volts or more in extreme cold. Even higher voltages are used for "equalizing" cells. At high temperatures, the charging voltages are reduced. This is why the "dumb" chargers are dangerous. Not so much in the wintertime when battery resistance is very high but in the summertime, if someone forgets about it the end voltage will rise very high and boil out the electrolyte.

    It generally takes about 2 volts above the resting battery voltage to approach a full charge. If a battery sits for a long time in a partially discharged state the sulfation on the plates turns into hard, permanent crystals in a matter of several days. Charging a permanently sulfated battery has been described as like trying to wash your hands wearing rubber gloves. This is why periodic charging and maintenance maximizes service life and battery tenders are so popular. Batteries naturally self-discharge sitting on the shelf and high temperatures accelerate this process. So you'll hear things like "Batteries die in July, they just don't fall over till November".

    Test the battery for load capacity. Disable the ignition and crank it over for several seconds while measuring the voltage at the posts. It should not drop below 9.6 volts. This is the minimum for a "good" battery, but it should hold higher than that.
     
  10. 3W JOHN
    Joined: Oct 8, 2015
    Posts: 575

    3W JOHN
    Member

    Danny, if the car starts tomorrow you need to drive it more than just around the block.
     
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  11. upspirate
    Joined: Apr 15, 2012
    Posts: 2,191

    upspirate
    Member

    Very good fairly simple explanation to a complex process.
    I've checked into a lot of this as we have a small cruising sailboat and all the stages of charging,float,equalization etc are very important.
    We won't even get into the different rates per battery types here....
     
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  12. morac41
    Joined: Jul 23, 2011
    Posts: 532

    morac41
    Member

    There are good quality trickle chargers you can leave connected when not using vehicle ..will keep your Battery fully charged without damaging the Battery....I have an acid 15 plate 12V that is 8 years old in a Van I don't drive much probably once a month
     
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  13. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,536

    dirty old man
    ALLIANCE MEMBER

    This is a subject that I've dealt with for a long time. Nowadays, having an OT DD, an OT diesel pickup, and 2 hot rods, I put my trust in Battery Tenders Plus for the ones not being driven on a daily basis. I've accumulated all sorts of chargers over the years, from a big old service station type that will charge at over 80 amps on 12 volts down to little 1 amp trickle chargers.
    This thread is timely for me, as in the past 2 weeks
    I had to replace the Braille battery in my roadster after about 6-8 years and the 2 NAPA batts in my diesel pickup that were 4.5 years old. No complaints on either one.
    Back in the 60s old clunkers that would run and were driveable sometimes sold for about the same price as a new battery!
    I was working @ Fisher Body/GM assy plant in ATL on afternoon shift and bought, patched up and sold old cars during the daylight hours.
    Many times a new battery would have cost more than I could get for the old car, so I resorted to a trick I had read about in an old WWII US Army vehicle maintenance handbook.
    You could take a weak battery that would still show some voltage and often get it to hold a charge again with this technique, but I sure as hell don't recommend using it today.
    You needed 2 battery cables at least 3' long each, a serviceable 2 amp charger, and a battery hydrometer.
    You charged the battery till it no longer showed a further change,in specific gravity, attached the 2 cables and shorted them together to throw a dead short on the battery till you killed it down almost dead. Repeat till you no longer got an increase in hydrometer readings or sediment in the cells shorted out one or more of the cells and ammeter dropped off.
    Then you turned the battery upside down and drained all of the acid out, took a garden hose and washed out all the sediment from all the cells, leave the battery upside down to drain overnight, refill with fresh acid, charge with slow charger overnight, and you usually had a battery that would suffice to sell an old clunker, often for less than $100.
     
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  14. Until it runs out of electrolyte and catches on fire, then you just call your insurance company......
     
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  15. stanlow69
    Joined: Feb 21, 2010
    Posts: 4,310

    stanlow69
    Member
    from red oak

    Ironicly, left the lights on my daily driver truck(97 with 145,000).Had some errands to do. Jumpstarted it and proceeded to drive 35 miles to another town. Battery was charged and drove another 45 miles and then headed home(50 miles). Sometimes you have to give your vehicles a workout. If they break, you fix them.
     
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  16. Truck64
    Joined: Oct 18, 2015
    Posts: 4,056

    Truck64
    Member
    from Ioway

    Ya gotta do what ya gotta do, but an external charger is the way to go whenever possible after drawing a battery down dead.
     
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  17. Just to recap, last week Brenda got in her delivery van to go to work, the battery was dead, I pulled the battery out of the '54 Ranch Wagon and with the knowledge that the battery in the wagon hasn't been replaced since I got it on the road I figured I would just buy a new one for the wagon.

    At the shop I remembered I had pulled the practically new battery from our old delivery van I was driving when we got T-boned a couple of years ago when a idiot decided the light didn't apply to him.

    Worst case, I can buy a new battery but since I have this battery why not try?

    This is the battery I have been trying to charge and it was completely dead, last week I put it in the wagon and did a quick charge and the next day it wouldn't start, later I flipped the switch to start and I fired it up and drove it around the block, came back home, parked the car. killed the ignition and fired it back up, next day the battery was deader than a hammer.

    That brings us to yesterday, I pulled the battery back out and put it on the workbench and I ended up charging it for a little over 2 hours at that time the needle showed almost a full charge, put it back in the wagon and the car fired up almost instantly and I again drove the car around the block, it was showing 13 volts.

    This morning I hit the switch and the car fired off on the first crank, loaded up Brenda & Melinda and we drove across town for breakfast, I had my eye on the gauge all the way and it never wavered.

    We left the restaurant and made a couple of side trips and when I pulled the car in the garage we had driven 62 miles, I'm cautiously optimistic, if the battery holds the charge that will be great, if not nothing ventured, nothing gained. HRP
     
  18. upspirate
    Joined: Apr 15, 2012
    Posts: 2,191

    upspirate
    Member

    Thanks for the feedback. You might like to have a back-up or jump battery with you on your runs until you are really confident:)
     
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  19. Boneyard51
    Joined: Dec 10, 2017
    Posts: 4,009

    Boneyard51
    Member

    Let it set for a couple of days, too be sure. Marginal batteries have a way of letting you down in the most unopertune time! Just my experiences.





    Bones
     
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  20. Truck64
    Joined: Oct 18, 2015
    Posts: 4,056

    Truck64
    Member
    from Ioway

    Cranking voltage test for maybe 10 seconds. Disable the ignition. Want to see 9.6 volts minimum but a good battery will exceed that by quite a lot. Let it sit for at least 10 minutes and measure voltage, should "bounce back" to the standard battery voltage.
     
  21. Better yet, use a load tester (carbon pile). Load battery to half the cold cranking amps for 15 seconds, should stay above the 9.6volts


    Sent from my iPhone using H.A.M.B.
     
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  22. Truck64
    Joined: Oct 18, 2015
    Posts: 4,056

    Truck64
    Member
    from Ioway

    That's true but $10 says he doesn't have a carbon pile. That will definitely tell the tale though.
     
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  23. I had my jump box with me today and I'll have it with me on my next trip out. HRP

    That would be a safe bet.:D HRP
     
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  24. BamaMav
    Joined: Jun 19, 2011
    Posts: 4,146

    BamaMav
    Member
    from Berry, AL

    I bought a load tester at Tractor Supply, about $25 IIRC. It has a spring like strip like used in electric heaters that glows when you put the battery load on it. Meter needle will point to voltage and has a scale foe good to replace on it.
     
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  25. UPDATE - We went out this evening in the wagon, fired right up, no problems, I honestly think I may get some mileage out of this battery, I did have my jump box just in case. HRP
     
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  26. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,536

    dirty old man
    ALLIANCE MEMBER

    Agree on the carrying a jump box at least till you're sure that battery is OK.
    But a caution to all about jump boxes: When recharging them be sure to place them on a non flammable surface and away from other flammable objects, because like most all electrical stuff, and especially those with lithium in the batteries, things can and have gone wrong and they can catch fire.
    Friend of mine was damn lucky when one blazed up on a wooden shelf in his carport and it didn't ignite the shelf before he found it. Since then, when I recharge mine I place it either on a steel work bench top or a concrete floor.
     
  27. trikejunkie
    Joined: Dec 2, 2011
    Posts: 54

    trikejunkie
    Member
    from Scotland

    If I have a "dead " battery I usually put a small wattage 12v bulb across the terminals when charging -some chargers (both of mine !) like to"see amps/volts? being drawn before they kick out charging power.I have also left batteries on charge for days by mistake!!
     

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