Spec me an LED Torch

What's the best process to multimeter them? before and after charge to see how much power is on them? or do you mean the charge itself?
 
i'm not rightly sure actually...

i was planning on just checking their voltage after the charger's done with them to make sure that it's not overcharging them. :confused:
 
I'd have thought you'd test the connectors on the charger to see what voltage is being output to the batteries surely? And then of course see what the batteries are outputting after!
 
the voltage the charger charges the cells at is somewhat irrelevant, their voltage is determined by their charge state and chemistry. the charger should be charging them at around 4.5v... ish.

i mean, checking the charger voltage once to ensure it's not one of the old-style ones that charged the batteries at 13v is a good idea - those tended to cause explosions.
 
Aod said:
errrr, that's a complex question. the XM-L is probably the most practical LED to use in a P60 dropin for maximum brightness, but the SST-50 and SST-90 LED's theoretically offer higher brightness...

XM-L's probably still your best bet though. Of course, it does depend on which dropin you choose... they vary considerably.
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Cheers for the info Aod.
 
that's encouraging :p
as long as the batteries don't get hot (i can't quantify hot - i'm not sure whether hot means boiling hot, warm etc) when you're charging them, and they measure 4.2v or less when the light goes green then you should be okay.

just want to make sure though, you have the Ultrafire-WF139 right? if so, you take the cells out of the charger as soon as the charge "finishes" (LED turns constant green) right?

the WF-139 trickle-charges the cells after the main charge finishes and Li-Ion cells don't like that...

jmc007 said:
Cheers for the info Aod.
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No Problem matey. as far as i know, the Manafont XM-L dropin is the only "stock" one that fully drives the XM-L to it's full 2.8A, but there are people who'll make you one custom if you don't like the china-option.
 
I just realised I have a multimeter at work...*facepalm*

Just tested the batteries as they've been in the torches in the boot for 3 weeks now and have been used once for a couple of hours in that time.

Battery 1 is showing 4.16v (was on Solarforce L2)
Battery 2 is showing 4.10v (was on the Ultrafire C8)

So it's looking pretty good :)

P.S.
The switch you sent me appears to have worked itself loose in the tail! I screwed the cap back on inside using tweezers, was sure I did it tightly last time but will monitor!
 
that's not unusual apparently - because the switch-retention-ring rubs against the rear-edge of the body tube...

Charger Just Arrived btw - i bought an Xtar WP2
 
Aod said:
Hello Mate,
It depends what you need the UV dropin for.
if you're looking to be fluorescing *bodily fluids*, then no UV dropins on the market at the moment currently dip low enough into the UV spectrum - you need around 365nm for that.

if what you're trying to fluoresce is a material that is commonly regarded as fluorescent (like Dayglo objects, highlighter/"UV ink" etc), then just about any of them will do.
the WF-502B you linked to uses a 18650 cell for power, i assume that this means that you're also using a 18650? if so, that's good, because most of the UV dropins i've seen are 4.2V max.

http://solarforce-sales.com/product_detail.php?t=RB&s=11&id=44
http://www.dealextreme.com/p/1w-390...wf-502b-and-flashlights-alike-3-6v-4-2v-16694
http://kaidomain.com/ProductDetails.aspx?ProductId=9046
http://kaidomain.com/ProductDetails.aspx?ProductId=10572
http://kaidomain.com/ProductDetails.aspx?ProductId=11095

take your pick really, i have no information on the specific wavelengths emitted by any of them though, so caveat emptor etc...
There was a guy on CandlePowerForums who made UV dropin modules which used the top-of-the-line Nichia UV emitters, but the emitters were over $100 each, so there wasn't much demand for the modules and he's now out of stock on the emitters, and won't get more in until there's enough demand for them.

I recently found a site selling supposed 365nm UV LED's for quite reasonable prices, but i need to investigate that further.

<edit>
Hold up hold up, i've found a review of this Kaidomain UV Light, Here which has a photo which shows it fluorescing the color-strip on a banknote, this suggests that it's much lower wavelength than the cheap 395-400nm lights - i'd say that's a good one to go for. it probably wont light up *fluids* but banknotes, passports and credit cards should light up nicely.
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Much appreciate the informative help thanks Aod :D
 
Oxide™ said:
Much appreciate the informative help thanks Aod :D
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Not a Problem, glad to be of assistance :)

Khaaan! said:
Ah how does it differ to the ultrafire charger?
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the Ultrafire charges at a constant voltage and current (about 350/450mA) until it detects the battery is at 4.2v and then the charge voltage drops to (iirc) 60mA.

The Xtar-WP2 charges at 600mA until about 4v, and then gradually reduces the charge current until it decides the battery is full (at about 4.15V - a bit early) and drops the charge current to 60uA.

the Xtar method is slightly better for the batteries, which prefer to be charged in that method. it's also better because the trickle charge is so low that it's almost inconsequential.
It does stop the charge at 4.15V, when the cell's about 93% charged, which is a bit annoying but is also better for cell longevity.

Pleasantly, the Xtar WP2 seems to be cheaper from UK suppliers than the Ultrafire for some reason...
 
Khaaan! said:
What's the best process to multimeter them? before and after charge to see how much power is on them? or do you mean the charge itself?
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Check the voltage before charging - if it's below 2.75v (2.5v for Samsung 2900mahs) bin them as the've been discharged too far.

After charge they shouldn't exceed 4.2v. If they do, you need a different charger.

Aod said:
the voltage the charger charges the cells at is somewhat irrelevant, their voltage is determined by their charge state and chemistry. the charger should be charging them at around 4.5v... ish.

i mean, checking the charger voltage once to ensure it's not one of the old-style ones that charged the batteries at 13v is a good idea - those tended to cause explosions.
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Incorrect - a true cc/cv (constant current/constant voltage) charger - as reconmended by the manufacturers, should never exceed 4.2v when charging.

A CC/CV charger should start charging at say 600ma all the time (constant current) the voltages are rising - say 3.6v to 4.2v over time. Once the voltage of the cell reaches 4.2v then the charger should switch to constant voltage and then the current drops off to zero over time.

Ultrafire WF-139 is a dire charger. Xtar WP2 is slightly better but for lions you can't beat a Pila IBC or hobby charger.

I have an Ultrafire WF139 and HXY Digital Li-Ion charger for sale - I wont use them any more - cc/cv only chargers for me now.
 
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amigafan2003 said:
Incorrect - a true cc/cv (constant current/constant voltage) charger - as reconmended by the manufacturers, should never exceed 4.2v when charging.

A CC/CV charger should start charging at say 600ma all the time (constant current) the voltages are rising - say 3.6v to 4.2v over time. Once the voltage of the cell reaches 4.2v then the charger should switch to constant voltage and then the current drops off to zero over time.
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i didn't say the charger should charge the batteries to 4.5 volts, i said the charging voltage, as in the voltage differential that the charger creates across the battery, should be in the region of 4.5v, as opposed to the 13 volts that some old WF-139's charged at.

the Charging voltage is largely inconsequential, i've used chargers which charge 7.4v packs at 12v and they're fine.

regardless of how a CC/CV charger operates, your description of the Li-Ion charging process is incorrect. if the charger uses the constant current until the cell reaches 4.2v and then reduces the current, it's effectively overcharging the cell.

Lithium-Ion cells should be charged fast for the first eighty percent or so of their capacity, and then charged at an increasingly slow rate for the remaining twenty percent of their capacity. this is behaviour that i've been taught about at University and also that i have observed in the charging process on my laptop (a modern thinkpad with extremely precise charging circuitry - overall battery capacity hasn't dropped a single percent in two years)

This is why a good laptop will take hardly any time at all to go from 0% to 85%, and then take ages and ages to finish.

Also, this is the voltage-levels that i go by when checking Lithium Ion cells:

4.2V Full 100%
4.1V About 90%
4.0V About 80%
3.9V About 60%
3.8V About 40%
3.7V About 20%
3.6V Empty - Stop using.
<3.5V Overdischarged
<3.0V Cell damage occurs (increasingly based on duration and how much lower voltage goes.)
 
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Checked the cells as I am home now using my multimeter which is newer than the one at work. 4.07v on one and 4.15v on another so some variation compared to work's device.

Just charging them now and will re-check voltages when the charger reckons they are full.
 
4.22V is a little worrying, it really shouldn't be charging them a jot over 4.2v

what that immediately after charging? if so, what did they read 30 minutes or so later?
 
That was immediately after charging. After about 30-45mins usage playing around I bunged them in the car again. Just tested them now and they read 4.10 and 4.16 respectively.
 
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