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-   -   Slightly Confused By 18650 Batteries (http://www.bikeforums.net/electronics-lighting-gadgets/648997-slightly-confused-18650-batteries.html)

Ridire123 05-26-10 07:06 PM

Slightly Confused By 18650 Batteries
 
I recently purchased these batteries:
http://www.lighthound.com/AW-18650-P...on_p_3125.html

And this charger:
http://www.lighthound.com/Ultrafire-...er_p_2279.html

For use in this flashlight:
http://www.shiningbeam.com/servlet/t...h-C8-II/Detail

I got the batteries and chargers today and am slightly confused. This is my first set of non-AA, AAA, D batteries... I'm used to batteries having the little protruding part on the positive (or is it negative? Whatever...) end -- these clearly do not. When I put the batteries in the charger, the LEDs on the charger show green, but if I twist the batteries around a bit, they flash red. How do I know if the batteries are making contact with the charger properly?

Someone please help a clearly electronically challenged newb.

Thanks in advance!

ed 05-26-10 08:25 PM

You may need to make some spacers or buy some of those little magnets to stick on there for charging.

socalrider 05-26-10 09:34 PM

I have an older UF 18650 charger that does the same thing.. I have to rotate the batteries a small amount to get solid contact.. When I have a used cell I rotate until the light turns red and then come back and take off charger once it turns green..

These batteries are not like aa nimh, do not just leave them on the charger until needed.. Once you get the green light for a full charge, promptly take them off of the charger..

Ziemas 05-27-10 12:53 AM

The end of the battery with the small raised bumps is the negative side. They don't have a nipple on the positive side to ensure that they conform to the proper size.

ItsJustMe 05-27-10 06:57 AM

The UltraFire chargers with those sliding things to contact the batteries are notorious for making cruddy contact with the batteries. You need to poke and twist the battery to get it to go red so that it'll start charging.

I used to have that one (from DealExtreme) but I eventually bought this one instead, and it works great without the fiddling with the sliders:

http://www.dealextreme.com/details.dx/sku.6105

dougmc 05-27-10 11:47 AM

Quote:

Originally Posted by socalrider (Post 10872350)
These batteries are not like aa nimh

That much is true -- these are LiPo/Li-ion, not NiMH ...
Quote:

do not just leave them on the charger until needed.. Once you get the green light for a full charge, promptly take them off of the charger..
... however, this is wrong. Well, it's not bad advice, but it's not needed.

Lipo/Li-ion chargers stop charging when the battery is fully charged. Once they hit 4.2 volts/cell, no more charging. So the batteries can stay in the charger forever. Anything else and the battery will be quickly ruined (within minutes) and it could even cause a fire.

NiMH and NiCd cells can be overcharged at a low rate and they will be fine, as long as it's not done for days or weeks. Good fast chargers can detect when the batteries "peak" and will turn off at that point, often switching to a trickle (slow) charge. Cheap chargers just charge at a low rate forever, or turn off after X hours.

Overcharging a NiMH/NiCd cell at a low rate won't hurt it for a few hours or even a day or two -- but keep it up, and it will slowly damage the battery. But LiPo/Li-ion chargers MUST know how to turn off, or they'll ruin the batteries FAST and could start a fire. Therefore, ALL LiPo/Li-ion chargers shut off at the proper time, and leaving the batteries in them for an extended period does no damage.

Ziemas 05-27-10 11:55 AM

Quote:

Originally Posted by dougmc (Post 10875079)
That much is true -- these are LiPo/Li-ion, not NiMH ...
... however, this is wrong. Well, it's not bad advice, but it's not needed.

Lipo/Li-ion chargers stop charging when the battery is fully charged. Once they hit 4.2 volts/cell, no more charging. So the batteries can stay in the charger forever. Anything else and the battery will be quickly ruined (within minutes) and it could even cause a fire.

NiMH and NiCd cells can be overcharged at a low rate and they will be fine, as long as it's not done for days or weeks. Good fast chargers can detect when the batteries "peak" and will turn off at that point, often switching to a trickle (slow) charge. Cheap chargers just charge at a low rate forever, or turn off after X hours.

Overcharging a NiMH/NiCd cell at a low rate won't hurt it for a few hours or even a day or two -- but keep it up, and it will slowly damage the battery. But LiPo/Li-ion chargers MUST know how to turn off, or they'll ruin the batteries FAST and could start a fire. Therefore, ALL LiPo/Li-ion chargers shut off at the proper time, and leaving the batteries in them for an extended period does no damage.

That's not correct. There are many threads on this topic over at CPF. The Ultrafire charger is known to overcharge and sometimes trickle after termination.

The only non-hobby charger that I know of that actually terminates at 4.20v (or a little before) is the Pila ICB.

dougmc 05-27-10 01:21 PM

Quote:

Originally Posted by Ziemas (Post 10875140)
That's not correct. There are many threads on this topic over at CPF. The Ultrafire charger is known to overcharge and sometimes trickle after termination.

Then the problem is with the charger, not the batteries.

If the charger does not shut off (stop charging) at around 4.2 volts/cell, it should not be used. Unless you don't mind your batteries being ruined or catching fire, that is.

If your charger relies on you to remember to turn it off, and bad things happen if you forget, then the bottom line is that you need a better charger.

socalrider 05-27-10 02:05 PM

The reason I mentioned this is because that charger has been known to overcharge.. The Pila charger is the best on the market but a little pricey.. Just remember that Li-ion when overcharged have been known to vent with flame.. Although this is extremely rare, I always tell people to pull them off the charger once finished..

On a side note, what is the OP's opinion of the light??

dougmc 05-27-10 02:20 PM

Quote:

Originally Posted by socalrider (Post 10875965)
The reason I mentioned this is because that charger has been known to overcharge.

OK, and the warning makes sense, but it's not the batteries -- it's the charger.

After all, your cell phone, your iPod, your laptop, etc. all have similar batteries (Li-based) and are ruined and can even catch fire when overcharged, but nobody is saying to take them off their chargers when charged.

And again, you can't rely on people to watch a for light that will light up in a number of hours and remove the batteries quickly when it goes green -- if that needs to be done to avoid a fire, then there's going to be a fire, sooner or later.

I do have the same charger. I checked it's voltage -- mine maxes out at about 4.15 volts, so I see no need to watch it so closely. (But I don't have it charging on top of a pile of clothes either. And I have seen others talk about how their chargers put out higher voltages.) If it maxed out at 4.25 volts or higher -- I'd replace it. I wouldn't rely on myself to turn it off at the right time. And either way, I wouldn't rely on the green light, either -- if you can't rely on it to stop charging at an appropriate voltage, how do you know you can rely on the green light to tell you that it's time to remove the battery?

Fortunately, the 18650 batteries have metal cases and have protective circuits (though you can get them without -- don't) so even if your charger malfunctions, it's not likely to start a fire. But requiring people to remove the batteries at the appropriate time is a disaster waiting to happen -- and fortunately, it's not needed with LiPos that have proper chargers.

ItsJustMe 05-27-10 06:03 PM

If you use protected cells, it shouldn't matter if the charger keeps charging, the cell should stop the charge on its own, right?

I mean, I'd still prefer the charger to do it TOO but most people are going to run protected cells. I have shorted these cells out before (on purpose, to see what happened - if you try this at home, do it by remote control, outside, and behind a substantial barrier) - I would NOT even think about running unprotected cells.

davidad 05-27-10 06:36 PM

I have the DX 6105 and it takes another three hours after the light turns green to get to 4.19 volts on my batteries.
So far it does not over charge, but I bought protected cells.


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