First, I am a NOVICE in this stuff….that means I know about as much as a 5th grader about pills, cells, protected, unprotected and so forth.
Anyway, I have about 4 or 5 lights that I have bought since nosing around here. They are all kinda cheap except for my favorite….a Convoy S2+.
When I got several of them I was talking to a couple members that were helping me. I decided to go with the 18650 cells for the lights I have that take them. I have 1 protected cell with a charger. I have a couple more lights that also take these cells and another member sold me 6 standard cells, I guess they are UNprotected.
I don’t use my lights much, they mostly sit on my nightstand. I DON’T run my lights all the way to complete DISCHARGE. In fact I am still on my first charge for the 3 lights I have that are using these cells, 2 of them un and the S2+ is with the protected one.
I understand that I should avoid running these unprotected cells to complete discharge. Is that true cause I already do that.
Are there other precautions I need to observe when using these cells?
There's a ton of reading around the forum on the subject, have a look with the search button
Anyway, basically what you have been told is correct. Never completely discharge a lithium cell, this will ruin the cell and the risk is when you will recharge it, if damaged the charging could turn them into fireworks... no good!
Never use unprotected cells in series, but I see you only have small single cells lights.
It's imperative to know what kind of cells you have: good brand cells are more secure than cheapo fakes from ebay, maybe you don't already know but many ebay batteries are recycled from laptops battery packs, with just a new coloured shrinkwrap and shiny label.
Avoid all brands which have a "...fire" in the name, them are the most known for being very often fakes or recycled.
And, use a good quality charger, which REALLY consider the battery parameters to regulate and stop the charge. Be cautious with super-cheap chargers, a charger which does overcharge may turn batteries into bombs.
If there’s a bad cell in the series, or one that discharges faster than the others. You can end up with some cells being at like 3.9v and one at 3.2v, think that’s what he means. If they are all the same type and good cells, they all discharge equal and you should be ok… Been my experience anyways- but I’m pretty new to this
If you stick in used cells with fresh cells too… The ones with the lower voltage will suck power from the charged and heat up real good. Could possibly end up on richard simmons lap
It means connecting two or more batteries together positive to negative (same mah, higher voltage).
As opposed to negative to negative, postitive to positive, parallel (more mah, same voltage).
As above, a dud cell in series configuration can be dangerous. It doesnt even need to be a dud depending on numerous factors. If it drains from other cells, that can be enough to cause failures if it exceeds their discharge rate. Note, failure isnt simply a dead battery, it can mean vent with flame, creating a lot of pressure in a sealed light that has to escape, making the light a pipe bomb with all that glass and metal shrapnel available for nasties. Then theres there gasses, shockingly bad for you. Cells with different life cycles can cause issues, they might be fine as single cell light cells, but add them in series, they might be a drama. People may say ‘nah Ive done it hundreds of times yadda yadda its all good’, and they might, but its still not wise. Cheap cells, again, potential nasties especially in series. This is where li ion becomes …very temperamental.
Read up on the batteries youre playing with. Its well worth the effort. Battery university is a good place to start, google ‘battery university’. If you dont know the cells, dont put them in series. A couple of phrases for you to look for, internal resistance, crystals and membranes.
“In series” usually means two or more batteries placed end to end in a long flashlight battery tube with the positive end of one against the negative end of the other. In parallel means that the batteries typically are side by side in the light and they all face the same direction. Batteries in series add their voltages together so two lithium ion batteries in series are used in a light which is listed as running at up to 8.4V or so. Batteries in parallel do not add voltage but add capacity and current providing ability. Two 2600 mAh 3.7 Volt batteries in parallel are the same electrically as a 3.7 volt 5200 mAh battery.
There are other lights though which have battery holders which hold three or four or even eight batteries and they may have the batteries electrically in series, in parallel or even in series/parallel if there are four, six or eight batteries in the battery holder. The Fenix TK75 and TK76 have the series/parallel arrangement for example.
Series is when two or more cells are connected end to end. In a line.
If one cell is bad, the other will try to charge it, which may cause a very bad thing to happen.
I run lights in series with unprotected cells, but I am experienced and use high quality matched cells, which I am always testing. Mostly these are show off lights where I’m just trying to see how bright I can get it. These lights usually get too hot to run more than two minutes on high.
In single cell lights, there’s not really a lot to worry about if using good cells. Don’t let them run down before charging, or they’re trash.
The main reason for using unprotected cells is to get the most current because they have less resistance without the protection circuit. This is great for direct drive, but there will be no advantage in lights with regulated current. If your light has a 2.5A driver, you won’t get any higher current than a protected cell will supply.
A lot of lights come with built in protection warnings that will flash or dim when the cell runs down to a certain point.
Unless you’re running a hot rod and constantly checking and testing your cells, use protected cells for your own well being.
Only charge them in good chargers, i.e. ones that stop charging at the correct voltage and use the right charging algorithm.
Only use them in Flashlights that have battery protection i.e. they will warn you when voltage is getting low.
All of my 18650 lights have Nanjg drivers with low voltage warning.
Use a cover or case on any LiIon that you carry in a pocket. If your keys short out a battery, you will have that key ring branded on your thigh for life (one of my friends did this with a NiCad battery pack for a UHF CB).
Mike