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  1. #61
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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by ekkekan View Post
    To add what BertKu indicated I have used a cell charger from 220V or USB charger to add a bit of power into non rechargeable batteries. You can connect it to the 5V for a few sec and off for a few sec and repeat it a few times. The low current should prevent the 1.5V from exploding. Most of us would have a spare charger around. It will help in an emergency.
    Thank you, proves the point. Bert

  2. #62
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    Default Re: Charging AA, AAA batteries.

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  3. #63
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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by BertKu View Post
    Thank you, proves the point. Bert
    For those who like to understand more in what I am doing in an emergency situation and batteries are flat and no shop around. Here are the approx. calculations for charging a small battery.
    A 1mm2 wire of 1 meter has a resistance of 0,0227 Ohm at 25 degrees Celsius. At higher temperatures the resistance goes higher. Thus 2 lead wires of 1 mm2 copper has resistance of approx. 0.05 Ohm. A 0.75 mm2 has a resistance of 0.04 Ohm per meter.
    For this example we stick to 1 mm2.
    A 12 Volt battery, big car battery, minus the battery I like to charge is 12 - 1.5 Volt = 10,5 Volt. The 1,5 V battery is empty, but charges very quickly to 1,5 Volt or a little higher. The 2 meter 1 mm2 wire is 0.045 Ohm at 25 degrees.
    Thus 10,5 divided by 0.045 Ohm = 233 Ampere. I touch the battery for 0.05 second. (just sparking striking) This gives me 11,65 Ampere-second or 11650 mA-second /3600 = 3,236 milliAmphour I do it 20 times and my battery is charged by 65 mA-hour for a 2200 mAhour battery you need a lot of striking.

    Now we striking it longer on the 1,5 Volt battery, let say 1 second. This is not a good idea, too much energy is transferred. The energy increases and your temperature of your wire goes up but as long the intervals are longer let say every 5 second, the wire should not get too hot. If too hot, you have to wait. Also the battery should not get hot, but slightly warm is not a problem. The energy you pump into the battery does not let you battery explode if you strike short strikes.

    The same you can do on a 1.2 Volt, 6 or 9 Volt battery Nicads, MH, lead acid, but I haven't tried on a Lithium battery. Just the calculation is different, but the principle is the same. You regard me as a total idiot? Don't buy shares in a battery manufacturer should everybody start doing it
    Bert
    Last edited by BertKu; 2019/05/17 at 04:01 PM.

  4. #64
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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by BertKu View Post
    For those who like to understand more in what I am doing in an emergency situation and batteries are flat and no shop around. Here are the approx. calculations for charging a small battery.
    A 1mm2 wire of 1 meter has a resistance of 0,0227 Ohm at 25 degrees Celsius. At higher temperatures the resistance goes higher. Thus 2 lead wires of 1 mm2 copper has resistance of approx. 0.05 Ohm. A 0.75 mm2 has a resistance of 0.04 Ohm per meter.
    For this example we stick to 1 mm2.
    A 12 Volt battery, big car battery, minus the battery I like to charge is 12 - 1.5 Volt = 10,5 Volt. The 1,5 V battery is empty, but charges very quickly to 1,5 Volt or a little higher. The 2 meter 1 mm2 wire is 0.045 Ohm at 25 degrees.
    Thus 10,5 divided by 0.045 Ohm = 233 Ampere. I touch the battery for 0.05 second. (just sparking striking) This gives me 11,65 Ampere-second or 11650 mA-second /3600 = 3,236 milliAmphour I do it 20 times and my battery is charged by 65 mA-hour for a 2200 mAhour battery you need a lot of striking.

    Now we striking it longer on the 1,5 Volt battery, let say 1 second. This is not a good idea, too much energy is transferred. The energy increases and your temperature of your wire goes up but as long the intervals are longer let say every 5 second, the wire should not get too hot. If too hot, you have to wait. Also the battery should not get hot, but slightly warm is not a problem. The energy you pump into the battery does not let you battery explode if you strike short strikes.

    The same you can do on a 1.2 Volt, 6 or 9 Volt battery Nicads, MH, lead acid, but I haven't tried on a Lithium battery. Just the calculation is different, but the principle is the same. You regard me as a total idiot? Don't buy shares in a battery manufacturer should everybody start doing it
    Bert
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    Last edited by Dungbeetle; 2019/05/18 at 07:01 AM.
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  5. #65
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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by BertKu View Post
    For those who like to understand more in what I am doing in an emergency situation and batteries are flat and no shop around. Here are the approx. calculations for charging a small battery.
    A 1mm2 wire of 1 meter has a resistance of 0,0227 Ohm at 25 degrees Celsius. At higher temperatures the resistance goes higher. Thus 2 lead wires of 1 mm2 copper has resistance of approx. 0.05 Ohm. A 0.75 mm2 has a resistance of 0.04 Ohm per meter.
    For this example we stick to 1 mm2.
    A 12 Volt battery, big car battery, minus the battery I like to charge is 12 - 1.5 Volt = 10,5 Volt. The 1,5 V battery is empty, but charges very quickly to 1,5 Volt or a little higher. The 2 meter 1 mm2 wire is 0.045 Ohm at 25 degrees.
    Thus 10,5 divided by 0.045 Ohm = 233 Ampere. I touch the battery for 0.05 second. (just sparking striking) This gives me 11,65 Ampere-second or 11650 mA-second /3600 = 3,236 milliAmphour I do it 20 times and my battery is charged by 65 mA-hour for a 2200 mAhour battery you need a lot of striking.

    Now we striking it longer on the 1,5 Volt battery, let say 1 second. This is not a good idea, too much energy is transferred. The energy increases and your temperature of your wire goes up but as long the intervals are longer let say every 5 second, the wire should not get too hot. If too hot, you have to wait. Also the battery should not get hot, but slightly warm is not a problem. The energy you pump into the battery does not let you battery explode if you strike short strikes.

    The same you can do on a 1.2 Volt, 6 or 9 Volt battery Nicads, MH, lead acid, but I haven't tried on a Lithium battery. Just the calculation is different, but the principle is the same. You regard me as a total idiot? Don't buy shares in a battery manufacturer should everybody start doing it
    Bert
    This sounds plain dangerous to me.

    Why tempt fate? If one gets it wrong (seems a second or two too long) and you have a battery explode in your face. Armgat solution if you ask me.

    I'll just spend a few rand extra and pack spares batteries and not run the risk of getting a disfigured face or being blind......
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  7. #66
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    Default Re: Charging AA, AAA batteries.

    Dear Bert, unfortunately your calculations are way off.
    Cheers

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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by Fluffy View Post
    Dear Bert, unfortunately your calculations are way off.
    Yup.
    I was trying to think of a nice way of putting it.
    If you make a noise or need music in the bush or on the beach, you’re missing the point.

  10. #68
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    Default Re: Charging AA, AAA batteries.

    Q=IT
    Q=CV

    Q is coulombs
    I current (amps)
    T time (seconds)
    V volts

  11. #69
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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by Paul Dold View Post
    I have given up using rechargeable AA and AAA's - far easier to keep a new pack or two at home or in the car. Today just about every supermarket keeps a choice of brands.

    I never found the rechargeables lasted very long and was always swapping batteries in and out of the charger. They are not cheap either.
    It all depends on what you want to use the batteries for. Rechargables for short "bust" use are ok eg camera or flashlight used briefly or movement detection light. But for a light that is on for a long time eg table lantern or using a flashlight on a fairly long walk - rechargables are not so great. Three main differences:

    Non-rechargables fully charged start off above 1.5v, hold their existing charge between trips, are cheap relatively speaking and can be kept for many years.

    Rechargables fully charged start off only just above 1.3v, tend to loose their charge between trips so need to be monitored and recharged from time to time when in storage, after a few years their run time does drop off, and eventually they do not hold their charge anymore and thats it, they do cost a lot and you need a 220v/12v charger like a nitecore D4 which is not cheap.

    Frankly, even non-rechargable AAAs and AAs for table lanterns and longer use flashlights and head lights are also not ideal and are also best used only for short burst use.

    Bottom line is both forms of AAAs and AAs have a limited use. This is why most better makes of torches and lanterns and cameras etc now use the far better rechargable lithium ion technology batteries and that are charged via 5V USB cables and socket adapters (enabling charging from both 220v and 12v sources). These are the products to go for. Try to keep AA and AAA battery use to a minimum. Otherwise especially for lighting a popular alternative is using a 12v led strip or globe light with a 12v 7a motor cycle battery which also comes in deep cell form. They can pretty efficiently also be charged up via a 10 - 20w solar panel combined with a small pwm controller.

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    Default Re: Charging AA, AAA batteries.

    Any tips on resuscitating a pair of old 14.4v 1500mAh Ni-Cad batteries?

    I have a very low mileage cordless drill that I don't just want to throw out, and I reckon repacking the batteries with Li-Ion will cost more than a new cordless.
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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by jelo View Post
    Any tips on resuscitating a pair of old 14.4v 1500mAh Ni-Cad batteries?

    I have a very low mileage cordless drill that I don't just want to throw out, and I reckon repacking the batteries with Li-Ion will cost more than a new cordless.
    Replace with Ni-MH batteries..

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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by jelo View Post
    Any tips on resuscitating a pair of old 14.4v 1500mAh Ni-Cad batteries?

    I have a very low mileage cordless drill that I don't just want to throw out, and I reckon repacking the batteries with Li-Ion will cost more than a new cordless.
    For repacking before you toss it try the place that repack at great prices close to Wonderboom High School in Voortrekker Rd. They also do shrink wrap of bat packs.

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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by jelo View Post
    Any tips on resuscitating a pair of old 14.4v 1500mAh Ni-Cad batteries?

    I have a very low mileage cordless drill that I don't just want to throw out, and I reckon repacking the batteries with Li-Ion will cost more than a new cordless.
    If you look around on Google there is a trick you can do with Nicads and a welder or a few car batteries in series, you give them a short zap over the terminals and that can break down the crystals that forms in Nicad batteries. Apparently it can be quite successful, batteries can go from just about zero runtime to being able to hold a decent amount.

  17. #74
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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by ekkekan View Post
    For repacking before you toss it try the place that repack at great prices close to Wonderboom High School in Voortrekker Rd. They also do shrink wrap of bat packs.

    S & P Power Units?
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  18. #75
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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by jelo View Post
    S & P Power Units?
    Yes that is the place. Was out of town and could not get to look up the name.

    My Ryobi drill Nicad battereies lasted just about 2 years. After a full charge even without use the batteries would discharge totally. Ditched it and bought one with Li-Ion and the Li-Ion lasts about 10 times as long as the Ni-Cad in normal use.
    Last edited by ekkekan; 2019/05/25 at 06:46 PM.

  19. #76
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    Default Re: Charging AA, AAA batteries.

    Yeah a new 14.4v cordless costs around R1200, it will be pointless repacking for anything close to that price.
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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by jelo View Post
    Any tips on resuscitating a pair of old 14.4v 1500mAh Ni-Cad batteries?

    I have a very low mileage cordless drill that I don't just want to throw out, and I reckon repacking the batteries with Li-Ion will cost more than a new cordless.
    I just had my Makita cordless drill battery packs repacked by Battery Experts - R320 per pack.
    If you make a noise or need music in the bush or on the beach, you’re missing the point.

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  22. #78
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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by PRA View Post
    I just had my Makita cordless drill battery packs repacked by Battery Experts - R320 per pack.
    Did you send them off or how did you do it?
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  23. #79
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    Default Re: Charging AA, AAA batteries.

    Looks like a very useful service!
    Thanks for posting.

    Quote Originally Posted by PRA View Post
    I just had my Makita cordless drill battery packs repacked by Battery Experts - R320 per pack.

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    Default Re: Charging AA, AAA batteries.

    Quote Originally Posted by jelo View Post
    Did you send them off or how did you do it?
    I bought the batteries and had them sent to me via PostNet.
    I opened the casings (cracked the seam weld) and installed the replacement batteries.
    Massive difference - drill works like new again.
    If you make a noise or need music in the bush or on the beach, you’re missing the point.

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