Hi guys got some protected Trustfire batteries at 0v.
What is the best way the get them back to normal?
Thinking of buying Xtar VP4C charger in order to bring the back to life.
Whats the best price for this charger as Amazon UK sells it for £16.99 plus shipping
Okay, we got (part) of the message. A protected cell will normally stop discharging at 2.8V.
Zero Volt, because …………
1/ the protection tripped
2/ you found those in the back of a drawer, where they may have been for years.
In case of #2, recycle them.
(dis)charging is a chemical process. That does not stop when you turn off the light.
Overdischarging can lead to a serious and irreversible situation.
If a protected battery is at 0.00V, most likely it's protection got triggered. That does not necessarily mean it is deeply discharged (< 2.50V). Sometimes, if you use such batteries in a high-perfomance flashlight, this protection can be triggered easily by activating turbo mode. I cannot give you any recommendations concerning chargers but some (maybe most) of the popular ones can easily reactivate these batteries.
Some questions that maybe help in terms of risk assessment:
If you decided to charge them up, use a low charge current and keep watching carefully (do not leave them unattended while charging). Once charging completed to 4.20V, let them settle a day and measure and note their voltage (probably around 4.12V - 4.20V, depending on termination current in the CV-phase of the charger). Then measure their voltages again after a week of resting. If it's still the same voltage they should be okay but if their voltage has dropped, I would not risk using them anymore.
Saving a few quid on batteries is not worth your safety. Trustfire cells are NOT safe and you should grab some quality cells with the purchase of your charger. If you list some of the lights or other devices you use them for we can make recommendations.
Nkon is a trusted retailer for li-ion cells and chargers in Europe.
Unless you really really want to use them, I’d echo the other comments about recycling those cells and buying new from a reliable retailer like 18650.uk or fogstar…
Need to check if protection is tripped, not sure how to do that….
If you’re feeling risky and have a hobby charger or something to monitor realtime voltage, go ahead and put some voltage into it and see if it “wakes up”. (if you are not experienced in batteries, DO NOT try this.)
I have “woken up” a few 0 volt 18650s as well (about 10 of them), and I normally have to put my hobby charger in NIMH or NICD mode as lithium modes need a voltage before it starts charging.
Nothing exploded. Some cells would not hold a charge though and I could see it “self discharging” in realtime (internal short) and would get warm. Warm while charging = not good. In “waking up” these cells, I would charge to 2.5v - 3.0v and then test for high self discharge (Internal Short).
Your mileage may vary and if you are not experienced in batteries, DO NOT try this.
Trustfire batteries in general are like almost dead last as far as “quality” as well as other Chinese _fire batteries. I would only use them in low drain applications like a basic XML flashlight or less.
Isn’t it true that you should never buy a battery with the word fire in it?
I’d be careful putting those cells in a new charger —might burn up some channels if they have internal shorts —even if these cells were cut off by a tripped protection circuit I wouldn’t fool with them unless I’d know exactly how long they’ve been in this state —unwrap one- take off the protection circuit and see what the cell says in volts —for me anything less than 2.5 volts I toss
8 batteries , 2 working ,6 dead.
Got 4 working again.
Now waiting for my nitecore um2 charger
A fairly good rule of thumb. There are a few exceptions though.
Windy Fire is one of those exceptions. Last time I bought anyway. 
True, except for WindyFire and Thorfire.
deep discharge -> copper cathode partially dissolves into electrolyte
“revive”charge> copper gets deposited back onto cathode again, but not evenly -> dendrides form, sticking out toward the separator
if you get lucky-> you notice high self-discharge, the cell gets warm
if you get unlucky -> thermal runaway, sometime in the (not so) far future, preferrably when least expected.
so unless the cell has its own protection, charging it after it dropped below 2.5V gives you a (time)bomb with thermite-like properties.
but if it is protected, then that will have prevented dangerous discharging, it just turned off the output.
if you want to dispose of it safely, I’ve heard putting the cell into a bucket of salt-water for a few days (outside!!!) will take it down to 0.0V, but only do that if it isn’t at 0V already.
But 100 Ohm resistor should do that much more safely (no water), leave them outside for a bit
then recycle it (where you normally bring used-up batteries in your country).