Batteries - Rechargable and non rechargable

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15 years 1 month ago #308 by max2
Can anyone tell me the difference between rechargable and non rechargable batteries? Why are we not "supposed" to recharge non rechargable batteries?

why do rechargable batteries have a shorter charge life?

We seem to go through an incredible amount of AA (esp the digital camera) and so I have bought a variety of good rechargable batteries (which I don't think are that great either) but why is there a warning not to recharge shop bought charged batteries?

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15 years 1 month ago #42782 by Kiwi303
SHop bought batteries can be of several different kinds, the most ocmmon is acid fill and carbon rod, where some sot of acid pulp surrounds a carbon rod and the chemical reaction releases electrons. tryin to recharge those causes it to react in a different chemmical manner that can cause expolsions, or galvanic corrosion of the case and resultant acid leaks. it can also cause heat from the resistance of the current flow going the "Wrong" way which could cause the wet pulp to boil, through that would require running almost wall current straight through them. Another cause is that when an acid eacts, hydrogen is usually given off, during current draw, the hydrogen is probably absorbed by the carbon rod to creat hydrocarbons and current, the other way around may cause enough free H2 to cause pressurisation and forcing the seams open.

I'm not sure about how Alkaline batteries work, but it's probably he same, galvanic corrosion/leaks or heating/explosion.

Rechargables are generally either Nickel/Cadmuim or Lithium Ion or Metal Hydride. All I know of that reaction is Metal hydrides use Hydrogen somehow. they're normally made of substances with 2 Ionic states, when discharging they release electrons which creates current. during charging they collect electrons and add them to the electron shell around the atom to create Ions, which are charged particles.

Rechargable last for a shorter period because instead of chemicly changing a substance to knkock off the electons that were binding the molecules together, they're only losing or gaining a few electons per atom to created charged and uncharged particles.

Theres probably enough big holes to drive a truckload of science textbooks though, But thats as best as I can remember from School science classes. I never paid much attention. I wasmore interested in how to make a taser out of a collection of batteries than how the batteries themselves worked. :D

You Live and Learn, or you don't Live Long -anon

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15 years 1 month ago #42783 by wyseyes
Digital cameras use a lot of power, especially the little (or not so little) screen, and the flash.

The rechargeable NiCad batteries which have been around for years have an inherent problem which is often called 'memory'. The jist of this problem is that they don't seem to keep their charge after being used for a couple of months (without a special charger which discharges and recharges to remove the 'memory').
Newer NiMH batteries have no memory problem, and a better suited to the high-drain products like cameras. They need a NiMH charger to do them justice.

On each battery is a rating, expressed in mAH, or AH. This is a measure of how long it will last before it needs recharging. Go for the highest you can. I recently bought 12 NiMH 2700mAH AA batts from TM, they work well.

The disposable batteries are usually 1.5 volt, so in my camera there is 4 batts, an it runs on 6v. I think it cuts out when the batts get to 4.4v.
Rechargable batts are only 1.2v, so total is 4.8v. The camera runs fine on this, but there obviously isn't so far to go before the 4.4v is reached. However, the NiMH hold 1.2v for a very long time, then drop sharply, whereas the disposable voltage slowly goes down from the start.
The voltage is also a good reason not to try to charge 1.5v batts, they use different voltage levels in the chargers to match the different composition of the batts.

I see you shiver in anticip......................................................................................ation

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15 years 1 month ago #42784 by reggit
I use my digital a lot for work and have rechargeable batteries. To cut down on the juice I need, I use the viewfinder rather than the screen (prefer that anyway) and try to avoid much in the way of tutu-ing around with zoom. I find battery charges last quite a long time that way.

Shop bought non-rechargeables are lucky to last a day [V]

Take a break...while I take care of your home, your block, your pets, your stock! [;)] PM me...

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15 years 1 month ago #42787 by witheze
Thanks for all that guys [8D]

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15 years 1 month ago #42788 by wyseyes
Another time when the batteries are drained is when you are getting the pics off the camera. Most just use the usb cable which comes with the camera, plug it all in, turn it on and they show up on the PC. Best case just copy all the pics across to the PC, then turn it off again. Worst case is perusing the pics, zooming, viewing and editing the pics while they are still on the camera, all the while using up the battery.

There is a better way. Buy a cheap ($20) usb memory card reader, and instead of using the cable and camera to access the card, remove the card from the camera and plug it in the reader. The reader uses the computer power, not the camera batteries.

When finished bung the card back in the camera.

Note: don't use the computer to delete the old pics on the card, do it on the camera. This ensures the camera knows there is lots more room for the new pics.

I see you shiver in anticip......................................................................................ation

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15 years 1 month ago #42789 by Kiwi303
Groan... just read my first post, So many typos and grammatical errors and other english language screwups that would make my english teacher go ballistic. Never try to type while half asleep, on a laptop with a small keyboard, while theres a cat snoozing on you chest hiding the keys on your lap...

Using the desktop may have been a better idea then the laptop [:P]

Hopefully y'all can understand what i typed tho [;D]

You Live and Learn, or you don't Live Long -anon

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15 years 1 month ago #42790 by Valmai
Nup Didnt understand a word!:D You lost me at 'Shop bought batteries...' And it wasnt the cat that did it.[}:)]

Carbon-based biological unit.

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15 years 1 month ago #42792 by reggit

quote:Originally posted by wyseyes

Note: don't use the computer to delete the old pics on the card, do it on the camera. This ensures the camera knows there is lots more room for the new pics.

I have my PC set so that once it downloads the photos, the card is automatically cleared. Have never had a problem doing it this way, and memory card is still holding as many pics as it should.

Take a break...while I take care of your home, your block, your pets, your stock! [;)] PM me...

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15 years 1 month ago #42801 by Kiwi303
Cameras check the amount of SPACE ona card, not the number of slots free to stick a picture in.

A picture of a plain boring blank wall could use a quite small amount of byte to store, whereas a same sized picture of a hippie flower festival with lots of psychadeliac tie died shirts, different colloured lightbulbs and lots of objects, could be Very Large memory wise. As such, space rules :D

You Live and Learn, or you don't Live Long -anon

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15 years 1 month ago #42807 by wyseyes
Yes, but some operating systems don't delete files instantly, they simply move them to a different directory (mostly called the Trash), and they remain on the disk. Think of the windoze method of deleting a file, you also need to empty the trash. Depends on the OS settings for each disk. The files remain on the disk until you empty the trash.

If the pics are moved to the trash directory on the card, but not removed, then the camera will check the amount of space and find less.

The OS on the camera will always delete instantly.

I see you shiver in anticip......................................................................................ation

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15 years 1 month ago #42834 by ame

quote:Originally posted by swaggie

Can anyone tell me the difference between rechargable and non rechargable batteries? Why are we not "supposed" to recharge non rechargable batteries?

In a circular explanation, rechargeable batteries are designed to be recharged. Non-rechargeable batteries are not. Basically it's to do with the chemistry of the batteries. Certain chemicals, when mixed, will produce a voltage due to a chemical reaction, but the reaction is not reversible.

You are not 'supposed' to recharge non-rechargeable batteries for two reasons:

1) It might not actually work, so you'd be disappointed
2) The process might cause the battery to explode, which would also disappoint you.

However, you can buy chargers that will allegedly put some charge back into a non-rechargeable cell.

quote:why do rechargable batteries have a shorter charge life?

The capacity of a battery is measured in Ampere-hours (Ah), which basically specifies how long a battery will last with a given rate of discharge. The simplistic view of this figure is that a battery of capacity nAh will provide 1A for n hours, or nA for 1 hour. This isn't strictly true, but it illustrates the principle. Generally, to derive this figure, you discharge the battery at a low rate (say, 1/10th of its capacity) and measure the time until it reaches the 'end of life' voltage, which might be as low as 0.8V (and might not be any good for most things). You cannot then say, well, if I discharged it at 1/10th of its current capacity and it lasted x hours, then I can draw full current and it will last x/10 hours. It probably won't last half that long!

A Duracell AA battery (for example) has a nominal capacity of 2850mAh (or 2.85Ah). If you look at the label of your rechargeable battery it should say what the capacity is, but common sizes are 1800mAh and 2000mAh. Clearly, the rechargeable cells have a smaller capacity to begin with. Not only that, but rechargeable cells have a nominal voltage of 1.2V, whereas non-rechargeable cells are nominally 1.5V. What this means is that the power density of the non-rechargeable cell is greater, so even if you had a rechargeable cell of 2850mAh capacity it would contain less energy than the non-rechargeable one.

*BUT* the real answer is 'it depends'. You have clear evidence from experience that your rechargeables last for less time than a non-rechargeable. It could be the charge capacity of the cells, or it could be the type of load that is being put on the cells.

quote:We seem to go through an incredible amount of AA (esp the digital camera) and so I have bought a variety of good rechargable batteries (which I don't think are that great either) but why is there a warning not to recharge shop bought charged batteries?

See above. Mostly it's because it might explode, or the charger might catch fire, or acid (or other chemicals) might ooze out of the cell.

Google around for more. Unfortunately you might find some conflicting information...

HTH,

A

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15 years 1 month ago #42838 by max2
Thankyou everyone for your answers. I thought it had something to do with chemicals etc, but thought why don't they just make them all the same....

Anyhow a look at the collection of rechargeables in the house shows a BIG difference in size:

Duracell AA rechargeable ACCU 2100mAh Ni-MH
Powerbase AA Ni-MH rechargeable whopping 2600mAh

and finally the ones that Bunnings stock in Aust (no other brand on the shelves) and were quite expensive:
Varta 15 minute charge and go, Accu 2000mAh type 5306 NiMH

Now my next question is the Varta say I should only use the Varta recharger, is this fact or fantasy on behalf of the manufacturer who would wish me to purchase more of their product. (by the way, I have these in my Russell Hobbs salt and pepper grinders and they last about a week, not really happy with them).

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15 years 1 month ago #42851 by Kiwi303
I recharged varta in a generic recharger with no problems, they probably have a fancy charger that allows trickle charging once fast charge has topped them up, and don't want their batteries stressed by overcharging in a Fast Charge only-no cutoff type cheap charger.

I like Varta Zinc Oxide batteries for my hearing aid, 720mAh as opposed to the 650mAh to 680mAh of most of the other brands. It's a pity they can't make Zinc Oxide batteries in AA size, they'd pack in a fair whack of power. 1.4V 650mAh in a cell 1/10th the length and not as round would mean over 7000mAh at 1.5V if they could manage it direct volumetric :D
Of course the AA zinc cell would probably cost about $20 each going by what a pack of 4 hearing aid cells cost.

You Live and Learn, or you don't Live Long -anon

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15 years 1 month ago #42854 by max2
I wouldn't mind the cost Kiwi303 if I felt the product was worthwhile, but the AA Vartas are certainly not. Or not for the grinders anyhow.

Perhaps they are more suited to the remotes instead and I should put the Powerbase into the grinders. But that then means buying more rechargable batteries.... and I am back to the position I was, continually buying batteries again. I don't feel like I am saving any...

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