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  • avatar MrShift@Edmunds 08/27/11 12:26 am PST

    Slow charging is generally considered better, for various reasons such as generating less heat and stress on the battery, and for more technical reaons which I'm a bit shakey on but have to do with the "interface charge" and distribution of the charge to the electrodes and electrolyte.


    I wouldn't think fast charging is 'harmful" per se, but really, if it is charging overnight, I would think a slow charge would be just fine.

    And if your battery gets pretty badly discharged during the day, for sure a slow charge would be better. Heavily discharged batteries don't take a fast charge very well--they get a surface charge but not a lot of power to crank or run anything.

    Try 2 amps and see how it works during the day. If the battery is sluggish, then go to 6. I'd avoid continuous 40 amp recharges.

    Also make sure you have proper venting because of the hydrogen gas.


Answers

  • MrShift@Edmunds 08/27/11 12:26 am PST

    Slow charging is generally considered better, for various reasons such as generating less heat and stress on the battery, and for more technical reaons which I'm a bit shakey on but have to do with the "interface charge" and distribution of the charge to the electrodes and electrolyte.


    I wouldn't think fast charging is 'harmful" per se, but really, if it is charging overnight, I would think a slow charge would be just fine.

    And if your battery gets pretty badly discharged during the day, for sure a slow charge would be better. Heavily discharged batteries don't take a fast charge very well--they get a surface charge but not a lot of power to crank or run anything.

    Try 2 amps and see how it works during the day. If the battery is sluggish, then go to 6. I'd avoid continuous 40 amp recharges.

    Also make sure you have proper venting because of the hydrogen gas.


  • zaken1 08/27/11 12:27 am PST

    The best charging rate for a lasting charge and being good for the battery is a ten hour or slower charge. Most car batteries have capacities of 60 to 100 amp/hours. A 60 amp hour battery will be fully charged in 10 hours with a 6 amp charger. A 100 amp hour battery will be fully charged in 10 hours with a 10 amp charger. A 40 amp charger is too strong to charge a battery on a regular basis; it is mainly used for quick charges just to get a vehicle going, but it creates too much heat in the battery to be used all the time.

    Some chargers are called automatic chargers. They automatically reduce the charging rate when a battery becomes fully charged; so this type of charger can be left on continuously without overcharging the battery. Other types of chargers are called manual chargers; they cannot be left on after a battery has become fully charged without overcharging and shortening the life of that battery.

    But chargers which put out less than 1 1/2 amps cannot overcharge a car battery. They are called "trickle chargers." A 1 1/2 amp trickle charger will take 40 hours to fully charge a 60 amp hour battery, or 66 hours to fully charge a 100 amp hour battery. However, trickle chargers often will not work to revive a dead battery. Batteries need at least a 6 or 10 amp charger to get them started charging if they have become totally dead.

    Several battery chargers produce a high frequency pulse which they claim keeps the battery from becoming sulfated. One of the best brands is called CTEK. But these chargers are more expensive than regular chargers, a fully automatic 7 amp model 7002 unit sells for about $100 on Amazon; while their top of the line 25 amp model 25000 automatic charger sells for about $240. This is the best battery charger made.

  • MrShift@Edmunds 08/27/11 1:28 pm PST

    Well gathering all this good info together, and from what I've read, it sounds like a 6 amp charge is the best way for you to go then.

  • rollingpoet 08/30/11 11:13 pm PST

    Thank you folks for you're help. Another question is can I link two batteries together and charge them both at the same time? They are both 12 volt. One has 700 cold cranking amps and the other is 440 cc amps, if that makes a dif?

  • zaken1 08/31/11 3:55 pm PST

    In answer to your follow up question about linking batteries together to charge (which by the way must be done with the batteries in PARALLEL; unless you use a 24 volt charger) it is not a good idea, because the two batteries will often charge unequally; since they are different sizes, and also because two large batteries will require twice as much charging current; which will greatly increase the length of the charging time and possibly overload the charger. If one battery is partly sulfated or has poor internal connections; it will fool an automatic charger and prevent fully charging either battery.

  • rollingpoet 09/02/11 9:51 am PST

    Ahhhh, thx for the info, I have found that by charging them seperatly they get a better charge and last longer as well. Very good advise. Thx again folks for your help.

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