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LI-ION protected or unprotected?

A

alx

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i found this one:
http://www.dealextreme.com/details.dx/sku.722
which is 3.6V Li-Ion unprotected.

i would like to use 2 of them to power my laser.

Question: is any danger if voltage will drop under 3V or it drop to low? I know that recommended charger for unprotected batteries should be the one with auto-off function, to not overcharge it because is possible to explode. But what's happen if voltage comes to low? Will destroy battery? If yes, how low to be, in order to not generate problems?

regards,
alx
 





Danjoo

Danjoo

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Yes correct if the power from lithium batteries comes down, close to 0 Volt the cell is broken. Normally
Lowest voltage which is ok is around 2,75 Volt. Protected ones cut there.

Best choice is Protected for lasers.
This one for example:
http://www.dealextreme.com/details.dx/sku.8683

Loading is normally not a problem IF you use a lithium charger they stop when fully loaded.

Unprotected ones, I use only for High Power Flashlight where high discharge rates are required.


Hope this help you a bit

Daniel
 
Razako

Razako

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The problem with unprotected Li-Ions is that if you accidentally use them too much and the voltage drops below 2.7 Volts then they can't be recharged and are effectively broken. Unless you know what you're doing you should use protected cells.
 
Switch

Switch

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Some devices have protection circuits (like the RPL as I recall) but in diy lasers, unless you build a protection circuit, protected cells are recomended, like everyone said.

Of course , if your laser only takes one battery you could rip the circuit off a protected cell and build it in the laser.And then you can use unprotected cells safely :D (that would work wouldn't it?)
 
billg519

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I use unprotected cells sometimes. 10440's and CR2's for example. They can work well, but you must have the discipline to check their voltage regularly. If mine read less than 2.9 volts, I will recharge them. Switch has an excellent idea for single battery lasers, take a protective circuit from a battery and incorporate it into the laser. Also, some googling will find you info on low voltage cutoff circuits, and how to build them.
 
A

alx

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hi guys,

thanks for answers. If 2.7V is minimum voltage required, i think that i can use sku.72 without problem. Why? because i am using 2 x 3.7V unprotected cells to power up ddl driver which require a minimum voltage equal with 5.5V (3V for regulator + 2.5V minim for LD). Does it mean an average of 2.75 voltage on each cell at minimum. I never tried to see if laser diode will really light if is used 5.5V power source, but don't think so... afaik 6V is min voltage, else LD will not work...I am wrong? In last scenario....we have a bigger voltage (average 3V/cell) then minim required 2.7V... so my cells, will never go under 2.7V :)

regards,
alx
 
potatorage

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It is quite slow at charging the li-ion batteries, it is best to buy a "real" charger because sku 1251 does in fact have auto cutoff, and if li-ion batteries are overcharged, they are quite dangerous. The money you save by buying one of those is not worth it as you have to monitor the voltage continously so that they aren't overcharged. It would be okay if you bought protected cells, though. Just my thoughts
 
Switch

Switch

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Linkreincarnate said:
I found http://www.batteryjunction.com/li18322mahre.html

Protected cell 3.6v and 2600 mA. I d'ont know how those protection circuits will hold up with multiple batteries though. You may need to build your own protection for a two cell pak.
Click to expand...

That's the typical 18650 cell, DX has them too_Of course the protection circuit these come with will only work with one battery, or 2 or more in parallel(assuming equal capacity and discharge rate).If you have 2 or more in series , they're sum must be below 2.75V before the circuit shuts them off. :p
 
A

alx

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[ch12290 said:
]It is quite slow at charging the li-ion batteries, it is best to buy a "real" charger because sku 1251 does in fact have auto cutoff, and if li-ion batteries are overcharged, they are quite dangerous. The money you save by buying one of those is not worth it as you have to monitor the voltage continously so that they aren't overcharged. It would be okay if you bought protected cells, though. Just my thoughts
Click to expand...


I saw it and i would like to buy sku.1251. Is comming with 12V input compatibility for car use. I have only one problem: it does not charge 10440 battery (AAA format). This is strange, because it can charge 14500 models (AA) which are very closer to 10440 in size. Did anyone tried 10440 inside?

regards,
alx
 
L

Linkreincarnate

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I have a question about Li-ion batteries too. Can I safely charge a li-ion with a built in protection circuit inside of a standard smart charger? (In specific the one that comes with skylasers)
 
A

alx

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i found the answer:
10440 batteries should be charged at 200-220ma (with maximum peak at 320mah)!

Ultrafire WF-139 it goes really up to 500mA (http://www.dealextreme.com/details.dx/sku.1251) which is really dangerous for an 10440 battery.

An option to have all in one 3.6-3.7 battery charger for:
1. 10430
2. 10440
3. 14500
4. 16340
5. 17670
6. 18500
7. 18650
is to use Trustfire TR-001, see here:
- black version http://www.dealextreme.com/details.dx/sku.12594
- white version http://www.dealextreme.com/details.dx/sku.4151

Even it is rated 500mA too, really, TR-001 is working at 200-220mA and is much slower (2-4 times slower) then WF-139. Due to this reason, TR-001 can charge 10440 batteries and WF-139 not!

Did anybody own/use black version of TR-001 (sku.12594)? I am curious to hear his opinion.

regards,
alx
 
A

alx

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and another question:

how to translate "protected battery": stop/prevent the charger to overcharge battery over 4.2v or prevent other applications to discharge under 2.7v or booth?

regards,
alx
 
A

alx

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and for Universal Smart Quick Charger discussed above,

http://www.dealextreme.com/details.dx/sku.14885

i am not sure at all that is not having auto-off function enabled. i studied its description, read reviews and found this picture belongs to it:

http://www.dealextreme.com/productimages/sku_14885_3.jpg

as you see, it contain a LED! does it mean that is possible to HAVE auto-off function built-in (led is changing color when battery is fully charged).

can somebody confirm/infirm my version?

alx
 
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