Spec me an LED Torch

Can you post a quote? I can't seem to load cpf at the moment!

Edit!
I just read it on Google cache and I see what you mean, that guy got the trip on aw cells too so it could be that the protection circuit being used on various cells don't play ball with bc40 on long runs, may maybe testing by turning it off or on a few times during use would stop this happening?

The laptop batteries are still going 55mins in.
 
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down for me too!

if you over discharge a li-ion battery the cells pcb cuts in to protect it hence the reading you are getting of 0.

re-inserting the cell into a charger will re-set the pcb.

i was reading some other sections before the site went down about li-ion ... i don't think we should be running this test like this! :)
 
i don't think we should be running this test like this! :)

Heh I will stop after this last test because I kind of feel the same way now :p At least the protection circuits are doing the job correctly so don't have to worry about them exploding in our hands or something!
 
Heh I will stop after this last test because I kind of feel the same way now :p At least the protection circuits are doing the job correctly so don't have to worry about them exploding in our hands or something!

lol..before the site went down i was reading a link in the same thread to a forum section they have called smoke, fire and close calls :eek:

......some obvious advice was switching the torch off when it gets too hot. and one story of a torch hitting the ceiling with a 18inch flame coming out the front.

and don't laugh (and just as candle power went down) i was reading a thread about what to do if your torch turns critical:cool:
 
Did they say what torch they were using that went up in flames? :p

At least my confidence is kept with the BC40, it has various protections built in, I'd be cautious about your UF980L though!
 
Overcharging Lithium-ion

Lithium-ion operates safely within the designated operating voltages; however, the battery becomes unstable if inadvertently charged to a higher than specified voltage. Prolonged charging above 4.30V forms plating of metallic lithium on the anode, while the cathode material becomes an oxidizing agent, loses stability and produces carbon dioxide (CO2). The cell pressure rises, and if charging is allowed to continue the current interrupt device (CID) responsible for cell safety disconnects the current at 1,380kPa (200psi).
Should the pressure rise further, a safety membrane bursts open at 3,450kPa (500psi) and the cell might eventually vent with flame. The thermal runaway moves lower when the battery is fully charged; for Li-cobalt this threshold is between 130–150C°C (266–302°F), nickel-manganese-cobalt (NMC) is 170–180°C (338–356°F), and manganese is 250°C (482°F). Li-phosphate enjoys similar and better temperature stabilities than manganese.
Lithium-ion is not the only battery that is a safety hazard if overcharged. Lead- and nickel-based batteries are also known to melt down and cause fire if improperly handled. Nickel-based batteries have also been recalled for safety concerns. Properly designed charging equipment is paramount for all battery systems.

Over-discharging Lithium-ion

Li-ion should never be discharged too low, and there are several safeguards to prevent this from happening. The equipment cuts off when the battery discharges to about 3.0V/cell, stopping the current flow. If the discharge continues to about 2.70V/cell or lower, the battery’s protection circuit puts the battery into a sleep mode. This renders the pack unserviceable and a recharge with most chargers is not possible. To prevent a battery from falling asleep, apply a partial charge before a long storage period.
Battery manufacturers ship batteries with a 40 percent charge. The low charge state reduces aging-related stress while allowing some self-discharge during storage. To minimize the current flow for the protection circuit before the battery is sold, advanced Li-ion packs feature a sleep mode that disables the protection circuit until activated by a brief charge or discharge. Once engaged, the battery remains operational and the on state can no longer be switched back to the standby mode.
Do not recharge lithium-ion if a cell has stayed at or below 1.5V for more than a week. Copper shunts may have formed inside the cells that can lead to a partial or total electrical short. If recharged, the cells might become unstable, causing excessive heat or showing other anomalies. Li-ion packs that have been under stress are more sensitive to mechanical abuse, such as vibration, dropping and exposure to heat.

source
 
Updated results, the laptop 18650s did not trip, I don't even know if they are protected though (easiest way to check?), what did happen after 1hr 16mins though is that the BC40 started flickering slightly. At low brightness mode it was fine though. Voltage reading showed one cell had discharged quicker than the other.

batt_voltages.jpg


Resetting the Ultrafire 2400 showed it had discharged near enough the same as the other cell, all good there I guess, apart from the trip!

Edit* Thanks! the 2.69 of the laptop battery confirms the 2.7 cutoff for the over-discharge note you quote above.
Edit2* I will charge my batteries at 300mA from now on, just to charge them safely, even if it takes longer!
 
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interesting the results all being close to 1hr15 mrk?

just finished test at 1hour 36mins on the new set of trustfires.

both are still working in the uf980l so presume bc40 circuitry has tripped them?

would be interesting to know volts now.... need to get a multimeter.
 
Yeah seems to be all around the same time for all 3 pairs, it would be interesting to know your voltages before and after though because yours might be charging a bit higher than mine thus giving those extra 15-20 mins on your charge?
 
The BC40 ticks all the boxes apart from modes.

Only two! 11 hours maximum runtime on 2x18650.. you gotta be kidding me!

There should be at least 3 modes! Not including a moonlight mode! When will these manufacturers realise that it isn't always about max lumens!?

Regulated light + many brightness modes = YES.
 
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The BC40 ticks all the boxes apart from modes. Only two!

My 2 other torches have 3 mode with strobe and the other with 3 brightness modes. despite all having memory they can all be a bit of a handful with not knowing what mode you are in.

I prefer the bc40 2 mode design...solid and uncomplicated :)


Now i have got up early and after a 10min search in garage have located my caltex cm1100 multimeter ! (this saves me another $20 hong kong purchase :p )

I have some figures for last nights test


JETBEAM BC40 830LUMEN

2x Trustfire 18650 2400mah

both cells before test = 4.16v

after test = 3.45v and 3.40v

runtime 1hr 36m


although i did not have a multimeter at the time of the test these figures are the voltages for the used batteries taken this morning (though i don't know if the voltage may change after resting overnight). the 4.16v figures were taken from a freshly charged set of batteries.

the xtar wp2 seems to do a great job with charging the batteries to 4.16v which i put down to it's built in cc/cv circuitry.
 
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Without having the time to read this entire thread, what is the best LED torch for around £20?

You need to tell us more about your requirements.

What batteries do you want to use?
Big or small torch?
Flood or throw?
Multi or single mode?
 
I was greasing up my C8 threads and o-rings tonight and managed to touch the smooth reflector and now it's left a fine webbing mark on the lens as you'd expect. BAH! Another reflector ordered from Manafont now, this is the 3rd time I've guffed up the reflector on this lol.
 
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