Recently, I came across nice promotion on ultrafire Z5 by local dealer, checked review Ultrafire Z5 Review . So I decided to buy !
As per the review, 99% of the thing is exact matching to the description, quite satisfy on the usage.
But today I suddenly thought, why is the 2 batteries are used series (>7.5V) while single Cree LED only require 3.35V forward voltage for maximum current (3A). Even with driver/circuit voltage drop give and take, it shouldn’t use more than 4V even in 3A Hi-mode. (my single battery range from 3.8V-4.2V)
The Hi-mode of Z5 at most is 1A, which in XML datasheet about 3V forward voltage, so translate into theoretically maximum 3.5V requirement ONLY.
So if battery provided roughly 8V, then those excess voltage will be dissipate into useless heat in the driver/circuit. So my idea is to either make it parallel or series.
Just have this thought, torch under heavy usage, still charging. Will try with one battery once fully charge, and see the output remain same or not, from there will try to change the configuration IF my theory is correct.
It may supply sufficient power and hold enough voltage for a mostly regulated discharge curve, but think about if you are going on a long hike. Would you prefer to be stuck in darkness trying to change a battery, or just keep marching on?
The configuration is in series and the driver is probably a buck regulation driver as opposed to a linear driver, the latter of which burns off the excess voltage you speak of.
The 1A rating is measured at the tail, with two batteries in series. Which means 8.4W into the driver so up to 2~2.5A into the LED.
Read more about the difference between two regulation modes here.
Yes indeed there is more wattage, thats why I said those excess wattage due to excess voltage will be dissipating into useless heat.
Because for my knowledge I learned, current driven devices are dependent on current to varies amplitude of output. According to the SPECIFICATION , the output is depend on current, which must be paired with certain voltage. Maximum of 3.5V could be applied before you blow up the LED, so excess voltage will be shed off as heat by driver/circuit.
Of course, I’m not expert of LED, but I have knowledge of transistorized circuit (on audio ampifier, higher supply voltage provide more heat dissipation on idle/silent condition, compare when they are used to half swing of voltage supplied)
I think you missed the bit about different forms of regulation. Technology has advanced significantly over the old voltage regulation circuits, especially with the new efficiency standards coming out.
And you also haven't met the crazies (aka regulars) around here which consider anything below 5amps to an XM-L2, underdriven.
I wouldn't know about amps at all. I'm just a FOH engineer.
The extra voltage is not being wasted at all, it's being converted down to a lower voltage, and the extra energy is converted to amps. So for example, you got 2 cells in series, measure 1 amp at the tail, the driver (buck driver) bucks the voltage down to 4v and converts that 1A to 2A to the LED - end result is nothing wasted. It's not a pure 100% conversion, but it's close. I've measured the amps both at the tail and LED and confirm this does in fact really happen.
Batteries in series
Advantages:
the voltage the LED needs can be maintained better and more evenly during the course of the cells being discharged. In general, the "buck driver"'s do a great job to buck down the voltage to the level the LED wants.
The higher quality name brand lights generally use this design of the cells being wired in series
It's generally thought the lower amps being produced from the cells is less wear and tear on components like power switch's, wires, battery carriers, etc. If you want 9A to the LED (or LED's) and have 3 cells in series, the power switch only needs to handle 3 amps as oppossed to 9A if the cells were in parallel. Common switch's in many lights are rated for 1.5A at 250v, so the advantage is to reduce amps, but you have a lot of room to run at a higher voltage.
Disadvantages:
batteries in series should be evenly matched (use the same type and charged to the same level, also should be the same age) because as the cells deplete and reach their low point, it cannot be guaranteed they deplete evenly, so you run the risk of running the light on one cell, and the other cell may be drained below the safety margin of the cell. Cells in parallel do not have this issue because the circuit will simply take more power from the cell that is stronger, keeping the discharge level of the cells even.
For any lights with LION cells in series, you need to take some basic precautions of always using better quality, matching cells. If you do that, the risk is reduced to nothing worse than cells in parallel.
I drained a SupFire M6 light (4 cells in parallel) down to 3.2v the other day, and when measuring the voltage of each of the 4 cells individually, the meter read they were within 1/1000th of a volt of each other -- amazing! Sometimes the theory works!! Parallel cell lights have the advantage of being able to run questionable cells (ex: better quality and tested laptop pull cells) in a SRK or M6 style light, and I'm not really worried about it.
Of course with this all said, the driver electronics has to be able to support the cell configurations, so if you are stuck with a driver, you may be limited in how to configure the cells.
I think i’m really mistaken about it I also had tested using single and 2 in series, result is double consumption as you said, TOM E.
Very well explained, thank you. I know about the opposite of buck converter, which step up DC voltage of supply battery, didn’t thought of it
However, parallel also had its problem, such as when initially joining them, mismatch voltage (especially big gap) will instant heat up the battery because they tend to even up voltage at the terminal.
However, just now I measured, the series configuration use less current (5-10%) than the single battery configuration. (considered the double fold) and there is no visible difference in light intensity, so does this propose it is more efficient (which contradict the fact I known) or does it just operate on slight lower current that the intensity isn’t noticeable ?
Now I’m running Z5 using 2 different battery, one being ultrafire 3AH protected, another ‘claimed to be sanyo’ 3AH unprotected.
the 2nd battery is quoted :” new X ( high quality made in japan )sanyo 18650 3000mah batt not red ultrafire”
but it is just pink package without label nor writing, only a sticker of warranty. Most probably isn’t genuine sanyo.
I don’t always measure them, but just now I measure them, the fully charged voltage is quite consistent. (4.18-4.19V)
Is there much of a risk using them like this ? Z5 doesn’t heat up much either, even long usage.
General rule is always use protected cells in series, and matching cells. Didn't mention that in the above post, but reason to use protected in series is the cell will shut itself down under the low voltage threshold, assuming it has a good protection circuit. Even if the driver has low voltage protection, it can't monitor each individual cell.
I would say you have a significant risk there, and would monitor the battery levels very carefully and not let them get below 3.5v or so.
UltraFire or any xxxFire cell for me, is a strong NOT RECOMMENDED, specially for multi-cell light.s
Better yet, dedome that emitter, put it on copper, and up the amperage. Then you will need more voltage than one cell can provide. My laser build thread shows were the sense resistors are.
OK, I was serious above. It's hard for me to see a potentially powerful light so under utilized.
But, I can see you are very concerned about Li-ion safety. That is a very good thing. I, too, use to avoid serial configurations and would convert serial lights into parallel lights. Then more demanding emitters came out, followed shortly by copper emitter bases. Combined, they made it hard to properly drive using one or multiple parallel cells. Keep in mind that most cells sag to 3.8 volts under load. So I reevaluated a formulated these rules for series usage for myself. I am not saying they are fool proof. They satisfy me and you need to figure out what satisfies you.
Use healthy cells. The cells should not get more then warm when charging. They should charge up to 4.15 or higher and not loose more than .03 volts sitting. Cells that do not meet this criteria are relegated to single cell or parallel cell lights. I accept lower voltage cell for IMR cells.
If the cells are over a couple years old or have seem to have degraded, check capacity (using a hobby charger). Only use these cellls with other cells of similar capacity.
Every time you remove cells from a light, check their voltage. If they are not within .03 volts of each other, retest capacity to see if they should be together.
The third rule is probably the most important. If the voltages are similar coming out of the light, they are very likely similar in capacity. You are trying to avoid having a cell discharge more than the others and then reverse charge.
To me, the above is adequate because it is unlikely something will go wrong within an one cycle. With everything, there is always some risk. Especially, getting in a car and riding in traffic.
For now, I’m using series configuration for the time being, won’t be changing it until later.
I use Z5 for working, so I would be I will be charging it on daily basis which I work on particular day (unless I rarely use it), won’t wait until it ‘deflated’.
So essentially won’t be much of a risk (as it almost never flat before, never try on DMM before though) and I won’t charge overnight However try time before charging I will see is it similar capacity by measuring voltage differential on DMM.
Without risk it won’t be fun ? XD
As for modding, I won’t go as far to dedome emitter, nor changing circuitry (unless I have full schematic) of my Z5. Haven’t try soldering SMD before (although I have the minimal equipment for it) but for now I still like my Z5 even with it slightly lower output.
HOWEVER, I have few more extra emitter (in torch) which I could afford to accidentally ‘fry’ or mess it.
(i) Zoomable light (unknown Cree bulb) modded from 3x AAA to 18650
(ii) Zoomable XPE-Q5
(iii) Ultrafire 501b-T6 5-Mode w/ memory
High output, but poor dissipation casing (and its dropin compability).
Willingness to mod from 1 to 3. Maybe can use those (iii) into Z5 after modding (501B not good anyway)
What Tom E. said. And yes its more dangerous to use two in series for the reasons he said, so definitely dont use two different batteries, especially if one is an Ultra(houseon/handon)fire battery… please just don’t.
Reason being is this: you never know what is in your “Ultrafire” battery, some are recycled cells, some are smaller cells inside a metal 18650 shell, some are 1,000mAh batteries wrapped with 1000 for $1 “Ultrafire 3,000mAh” wrappers, and most have a total of 1/2 to 1/10th the claimed capacity. So, you may THINK you aren’t running your flashlight low, and your Sanyo battery is fine, using 1,000 mAh of charge up from each battery, but your crappy Ultrafire cell could be at maximal normal useable discharge at this level. Next, most Ultrafire “protection” is phoney, so it wont stop you draining it too far. So, in this scenario, if you have a 1/3 capacity (or lower) Ultrafire in series with your Sanyo real 3,000 mAh battery, you are quite possibly OVER DISCHARGING the Ultrafire even if you only use what you think is 1/3rd of the runtime up…and if you over discharge a battery over and over, it is very likely to vent or explode eventually.
Well, I’m not so sure about the fact with me, since the ultrafire I had use for quite some time, and it doesn’t seems to have low capacity. The seller also claimed to tested the battery capacity before shipping.
I don’t have equipment nor method to measure them though. (would be appreciate if someone can help me with it, like building DIY capacity tester, I’m good with building discreet circuit ) What is the cut-off voltage should have in those protected cell ? I can try measure before each charging though.
However I’m more worried about sanyo battery (new, only used few time, didn’t use alot/long enough to judge)
OK, well its not opinion what I stated, but fact about the common poor quality and false mAh in “Ultrafires” in the general markets. You MAY have gotten lucky and gotten an Ultrafire with OK capacity, maybe you got a “real Ultrafire”. You could have also gotten lucky by getting a recycled used 3100mAh Panasonic that was re-wrapped as an “Ultrafire”. Who knows really…including yourself! You also noted you weren’t certain the other was a Sanyo cell, and you have no way of measuring capacity…so really you have nothing to judge it from, and if both batteries are low capacity they both seem “fine” and your Z5 runs the LED on high at 1A say (most are far lower current and lumen output than you think, here a Z5 is measured at 1A tailcap current on this site: Review: TrustFire Z1 XML-T6 "1600 Lumen" Zoomable (a.k.a. Z5) ) for a relatively “long time” of say 2hrs, so from your perspective they seem “good”, but still have only 1,000 mAh capacity each… The thing is, if you have no “known” quantities, you cannot solve the formula. All I’m doing is warning you to be careful and you can do what you want.
An easy way to compare would be to buy two Panasonic cells of 3100 mAh from a reputable dealer, and compare run time to when it dims. Or with a cheap multimeter, take a tailcap measurement for how much current the led pulls, and run the light, monitoring voltage in the batteries every so often as it runs down in a timed manner, and you could get an approximation. You should never go below 2.5V, many batteries 2.7V, but you really dont know what you have so it would be hard to advise you…but best would be stop once you hit 3.0V, there is very little energy after that anyways, and batteries will always jump back up in voltage once you take the load off and take them out of the flashlight, so I really wouldnt run them further than that if you do this test, thats a pretty good approximation. And of course they could still blow up doing any of these tests, so do any of these tests at your own risk knowing Ultrafire cells are garbage and could explode and kill you! Probably wont, but its like a negative lottery, if you are willing to roll the dice knowing it could happen, its up to you, I wouldn’t. I’d buy some good Panasonics…in fact I did exactly that.
My first experience was with a Z5 (and a couple other lights bought for gifts) and crappy Ultrafire batteries. I found they drained quickly, and I started to do some runtimes on my batteries I purchased, and bought some known good Panasonics after finding out how bad the Ultrafires really were when I did some research. I had purchased several sets of red “ultrafire 3000mAh” and on comparing them with known good batteries I found that these had about 1/3rd the runtime on average…and as I used them a few times the capacity/runtime went DOWN in those. One other “bargain” group of “5000mAh” batteries I bought had 1/10th the claimed capacity. Luckily I was able to return many of the batteries and some sellers didnt want them back, so I recycled those, I have none left. I won’t touch Ultrafire/cheap batteries anymore, only Panasonics, Sonys, Samsungs, etc. Just isn’t worth it for the risk, run time or low max A output.
Thanks for your time for the long paragraph, I appreciate it.
In fact the ultrafire I had isn’t tested using Z5, it was by my 501B-T6 which had about 1.4A drain (alot brighter than Z5) and running hot due to poor dissipation of 501B, couldn’t continue testing battery capacity that way continuously.
~I once tried on for 12 minutes straight on high mode, the torch too hot to hold more than 2 second, then I switch off and never try again. Then I notice the output light is dimmer since then even it is cold…. is it possible permanent damage ? (compared to another new unit)
I had a moderate DMM which used for all my measurement, Z5 consumption was 0.4-0.5A using 2x cell, while ±1A using single cell. The problem is I don’t have method to ‘stick’ the DMM terminal to torch/battery for testing, I was holding my pointy lead to touch for measurement.
But according to their description about battery, the capacity is
4.2V is 100%
4.1V is around 90%
4.0V is around 80%
3.9V is around 60%
3.8V is around 40%
3.7V is around 20%
3.6V is empty
going to 3.5 volts will damage the cell.
So for safety measure and purposes, best to cut-off at 3.7 lodaded ? since it is the norminal voltage standard of li-lion. Will try and search for any circuit tester of Li-ion battery, or will come up with myself
I do agree there is alot scam/fake UF, or over-rated UF, so its time to test mine ? XD
