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Old 10-14-13, 08:51 PM   #1
RubeRad
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New 18650s: charge before use?

Hey,

I just got in the mail a pair of Tenergy 18650s (these) to replace the crap batteries that came with my Cree XML T6 1650lum (allegedly) flashlight, which I use for commuting in the fully-dark mornings. (At $23 for light, charger, and batteries, I still think I got a good deal even with batteries that work for only about 45min).

So I'd like to start using the new batteries tomorrow morning, but I can't find anything in the packaging that says whether I should charge before first use, or go ahead and just use them. I am vaguely aware that you need to be a little more careful with 18650s than your average n-tuple-A, and I didn't want to burn my house down or explode my handlebars or anything like that.

thx,

r
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Old 10-14-13, 10:14 PM   #2
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Do you have a volt meter? If you don't have time for a full charge you could at least make sure they are at 3.7V or more, then you'll know they're mostly good, then do a full charge to check cut-off voltage when you get the chance.
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Old 10-14-13, 10:54 PM   #3
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Yes, I got my voltmeter out, and each battery is a hair above 4v. So I guess I'm good to toss 'em in!

thx!
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Old 10-14-13, 11:52 PM   #4
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In general Li-Ion batteries should be stored partially charged (30-70%). You can certainly use it a little before charging, but charging before first use is standard practice.
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Old 10-15-13, 07:35 AM   #5
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It shouldn't hurt to put them on the charger. If it's a good charger it won't charge full batteries. If it does, it's junk.
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Old 10-15-13, 02:45 PM   #6
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Yeah, LiIon batteries are designed so that you can do just about anything dumb with them, and they'll be fine. The big exception is that you have to be careful not to let them get hot, because that's dangerous.
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Old 10-17-13, 08:19 AM   #7
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Many Lithium Ion battery sellers send their batteries at 3.7 to 3.8 volts because this is the best voltage if you're going to store your batteries for a long time. If your batteries came at more than 4 volts then the selling should have charged them to full (4.2 volts) before sending them to you. Anyway, charging them again before first use wont hurt - most of the time.

I'm saying most of the time because there are crappy chargers that don't cut off even if the batteries are already fully charged. So when you're using unprotected crappy lithium ions and combine them with crappy chargers then you might be at risk on an explosion. Things like these happen especially with crappy *&^%Fire branded cells like the UltraFire BRC18650.

If you plan again of buying 18650 cells then it would be a good practice to look for protected ones from renowned manufacturers.
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Old 10-17-13, 09:02 AM   #8
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Thx, these cells do say protected, and I think this time I bought from a somewhat reputable american website (batteryjunction.com), rather than getting crappy re-wraps from china on fleabay for 99c.

These ones came sealed in retail packaging (as described on the website), so the seller could not have topped them up for me.

So these showed up in the mail Monday @4v, I did end up popping them in the light without charging, I ran them Tuesday and Wednesday mornings, today is Thursday and it shut off right at the beginning of my commute today. So that's about 1hr. Now that I have these new batteries, my old ones were charged up in my bag for backup. After I charge up tonight, I'm hoping to get at least 2.5hr on a charge, that would be a week of mornings. Even better if I could also get five evening commutes in flashing mode.

I was surprised when the light just suddenly shut off; no tapering off or dimming at all. The other batteries would fade out gradually. Maybe that's the low-voltage protection kicking in? (And the old batteries are lying when they say 'protected'? -- check that, I just looked, and the old batteries don't actually have the word 'protected' on them. They say 2400mAh 3.7v and "the voltage of full charge and cut-off discharge is 4.2v and 2.75v")
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Old 10-17-13, 09:32 AM   #9
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Yeah, these modern lights insist on giving their specific levels of light. If there are several levels, it will step down by steps until voltage is too low for the lowest level. My 501b goes into rapid flash mode before the final goodbye. It's not a bad way to go.
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Old 10-17-13, 10:43 AM   #10
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Yeah, the ones you have are good batteries. Cutting off without dimming means the PCB protection is doing its job. Without PCB protection you over-discharge your cells (i.e. if your flashlight driver has no protection too) if you wait until the light goes dim. This is not good because you are exposing yourself to risk when your battery explodes during charging.
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Old 10-17-13, 06:19 PM   #11
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Thx, that's reassuring!
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