Using Lithium Rechargeables - Info?

Hi, I'm new here. This is my first post and the flashlight below is my first high end led light.

I just ordered a Zebralight SC600 which uses the 18650 rechargeable lithium batteries.

I'm reading alot of stuff about how these batteries must be treated just so or you'll have problems.

My intent was to just shove this flashlight into my back pocket so I could whip it out for use quickly. I'll be using it several times everyday mostly on low to medium power.

Also, I read that temperatures of 86 or higher are a no no with 18650's. Since I'm sitting most of the time and the flashlight is in my back pocket it will get rather warm from body heat.

Is this something I should be worried about?

As for charging, supposedly you should never let these batteries get too low. Fine I can live with that. I'll just recharge every day or two.

I also ordered 2 Trustfire 2500 mAh 18650 Protected Lithium Rechargeable Batteries and
a Trustfire TR-001 Lithium Battery Charger.

One will be in the charger while the other is powering the light.

Or is there something wrong with doing it like this?
Some of the things I've been reading seem a little like a pagan ritual to the battery gods.

As I said I'm a beginner at all this and a bit of a cheapskate as well.

A few weeks ago I would have been shocked to contemplate spending $100 for a smallish flashlight. But here I am excited to receive my new Zebralight.

Welcome to CPF, Randy. :wave:
I have renamed your thread title slightly to better reflect the queries in your post.
Best regards,

Mostly just learn some general battery safety. For example, don't carry bare batteries in your pocket where they can get shorted with keys or such. Also it is NOT recommed to leave batteries in charger. Just put in charger when charging is needed and remove when done.

Don't think you should worry about the battery getting too warm from being in your back pocket while sitting.

Also don't think you need worry too much about charging the batteries often (there is a bit of missinfo on the subject).
For example, if you do a full discharge of the battery every cycle you will get maybe 500 FULL cycles. But if you recharge the battery after a half cycle you may get like 1500 HALF cycles which would be like 750 full cycles. So yes, just using a half cycle may extend the life of the battery by 50%. But if you recharge the battery after only 10% cycles use you will get like 4700 10% cycles, which is like only 470 full cycles. So actually less use than doing a full discharge everytime...

If you really want to extend battery life, then the PROPER way to do this would be to lower the maximun charge voltage (say 4.1 volts instead of 4.2 volts) and raise the cutoff voltage (like 3.0 volts instead of 2.7 volts). But while this would increase battery life a bit, it will reduce the battery capacity quite a bit. So it is a trade off. But the battery is already designed for decent life (400+ cycles, which is really quite a lot) at it's rated capacity. So just use em they way both the batteries and the flashlight is designed to use em and don't worry about it!

Why yes, you will need to buy new batteries in a few YEARS if you use the flashlight quite a lot.


And as the SC600 has a 2.7 volt cutoff, you should be fine using the battery all the way to cutoff. Keep in mind that the resting voltage will always be higher than the in-use voltage. So if the SC600 cuts off and 2.7 volts, the battery voltage will rise and the resting voltage should still be well above 3.0 volts.

Thanks bleagh

Good info. I feel better about it now.
I'll just use the damn thing sensibly and all should be well.

Whoa here, in my years on CPF I have never heard that 86 degrees F is dangerous to an 18650. Also though 4.1 volts will extend the battery life of Li-poly Lithium Ions cells, most chargers out there terminate at about, or close to 4.2 volts. Unless you have a good Li-Ion charger with voltage readouts it is going to be difficult to attain 4.1 volts. Use the Flashlight Electronics, Batteries Included forum and do some searching re Li-Ions.

Bill

Bullzeyebill said:

Whoa here, in my years on CPF I have never heard that 86 degrees F is dangerous to an 18650.

Click to expand...

I could imagine 86 degrees C might be a problem, though if any human had a body temperature that high the battery would be the least of their worries...

I got this 86 degree F business from the Battery University. How to Prolong Lithium-based Batteries - Battery University

Just checked it again. Seems to be mostly when stored at full charge. Maybe I'm misunderstanding.

Yes, I figured the 86 degrees F was from the Battery University. I should point out that 86 degrees F is 30 degrees C, which is the point they say that the battery life STARTS degrading as the temps increase. Still nothing to worry about as it is just the starting point. About the only time my batteries get that warm is when the flashlight gets quite warm (hot!). But even then it is usually for a fairly short time frame (compared to the total life time of the battery), nothing to worry about.

It is also where I got the cycle counts for the Depth of discharge. But it is misleading because it tries to directly compare partial cycles to full cycles. Which is WRONG because a 50% DoD is only half as long as 100% DoD, and a 10% DoD is only a tenth as long...

The better way to look at it is...
Basically the batteries will last a bit longer if you keep the voltage around 3.6-3.8 volts. So by shrinking the charge-discharge window a bit you can maybe increase the life of the batterie a bit. But you will also lose capacity.

Charging the batteries too often can actually shorten the life of the battery. Charger generally charge to 4.2 volts. And charging the batteries often will keep the batteries at close to 4.2 volts. And keeping the batteries at 4.2 volts will actually shorten the life a bit.

Really, just charge the batteries when the need charging. And remove them from the charger once they are done charging. If you do 100% DoD every cycle you should still get 400+ cycles from each battery under normal use. Assuming 500 cycles, that is about 3 years from 2 batteries IF you need recharge one battery every day. About 6 years if you need recharge one battery every other day. And 10 years if you only need to recharge twice a week...

If you carry a spare battery around it IS a good idea to get a battery holder of some sort that will protect the battery from shorts and such.

A new user of 18650's here as well. I have been using some xxxfire batteries in some single cell lights with no problems so far. Just acquired an Olight SR51 that I am using the 2x18650 carrier in. Just got some AW2900's. I am a bit uncomfortable putting these in the noname chargers but have a PILA inbound. Should I wait until I get the PILA to charge the AW's? Just concerned about damaging the pricey AW's. Hope this isn't to much of a hijack..