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View Full Version : Whats the best route for batteries with the 3W Driver?



Ryma Mara
03-05-2007, 08:34 AM
I know you can stick rechargables in any of the holders and it would be just like you were using a rechargable pack but in the diagram it says for the 1W to use 4 AA's and for the 3W to use 5AA's.

Now is that regular non rechargable batteries or rechargables?

I plan on using rechargables.

Whats the voltage limit of the driver?

Jonitus
03-05-2007, 09:57 AM
Are you talking about Corbin's driver? If so, then it uses PWM (pulsed-width modulation) which varies the current from high to low, and the LED "sees" the average, hence needing approximately one more volt than normal.

I think, and don't quote me on this, that Corbin has gone as high as 9 volts on the driver, but I personally wouldn't do it.

LED's are more current dependent than voltage dependent, so as long as the outputs to the LED from the board are acceptable, you should be fine with four cells in a pack. If you want to play it safe and feed the LED plenty of current, get a 6 cell pack and a resistor between the pack and the board to step it down from 7.2 volts to 6 volts. Else, since Tim is making the packs "in-house", he could probably make you a 5 cell pack if you asked nicely.

Ryma Mara
03-05-2007, 11:42 AM
Yeah after all it is the only 3watt driver that I know of. :P

But yeah thanks for the info. I will just play it safe and go with the 4.2 pack. Wil make things alot easyer I think.

Thanks

LordArgyll
03-05-2007, 01:28 PM
It's 5 cells, rechargeable, for 6.0V. I've run 6V through it with nary a problem. More voltage is better, because as the current drops so will the voltage, and thus the brightness. 4.2V will do okay, but I think that's just a bit below the maximum voltage for a green 3W? So your voltage drop as the batteries drain might be more noticible.

Ryma Mara
03-05-2007, 01:45 PM
Oh yeah I forgot voltage and such is different from blues/greens and reds and ambers. but I plan on using a 3W amber.

Marsupial
03-05-2007, 02:20 PM
There are tons of 3W drivers out there, but the 3W driver here is from corbin's specifications.

Someone correct me if I'm wrong, but his PWM driver regulates the output current to be specifically what's needed for the LED, while pulsing it. With the PWM driver you won't see a lower brightness like in battery-operated circuits - the driver will delivers the maximum brightness untill there's not ennough juice in the batts.

Also, you can get more batteries - the minimum being 1V more then what's required (otherwise you go direct current and not PWM) and the max is around 9V IIRC.

I know I drive my 1W board with 6 alcaline AA (9V) with no problems - been doing so for more then 18 months already. The battery life is incredible with that.

hope this helps.

Ryma Mara
03-05-2007, 02:27 PM
BTW the driver here and corbins is the same thing :?

So If I understand this correctly, I could take the 7.2 Pack and not worry about supplying to much power to it then?

Cause the board will only take the power it needs and teh rest is used for insain battery life?

Jedi Ranger
03-05-2007, 02:33 PM
BTW the driver here and corbins is the same thing :?

So If I understand this correctly, I could take the 7.2 Pack and not worry about supplying to much power to it then?

Cause the board will only take the power it needs and teh rest is used for insain battery life?
You are correct! That's (one of) the beauties of Corbin's board(s)!!

Ryma Mara
03-05-2007, 02:34 PM
Well then no doute in my mind. I want one.

Thanks guys

xwingband
03-05-2007, 02:46 PM
Someone correct me if I'm wrong, but his PWM driver regulates the output current to be specifically what's needed for the LED, while pulsing it. With the PWM driver you won't see a lower brightness like in battery-operated circuits - the driver will delivers the maximum brightness untill there's not ennough juice in the batts.

Correct, you won't see a gradual dimming. I have noticed a step though... and depending on the battery combo and astuteness of the observer some will too.

There is a point where the batteries can't provide the 1V juice to use the PWM, but it still is enough to light it. If you use 4.8V Ni-MH this point is harder to see, but let's say you ran a 3.7V li-ion for a Amber/Red LED you'd see it... then bam it'd die pretty quick because of the nature of li-ions.

BTW for others knowledge... the limit of Corbin's board is maybe 12V. You can use a 11.1V li-ion pack and be okay.

Also it is a neat advantage of drivers. A 6V pack will have a longer run time over a 4.8V pack if amperage is the same. The funky part is think about things like a 4.8V Ni-MH at 2200mAh vs. a 7.2V li-ion at 1400mAh.

Ni-MH have a linear voltage curve, but li-ions hold there voltage really well then die fast. Which in that combo would run longer... it's a good question! :lol: One I'm not sure of, but it should be considered.

Marsupial
03-05-2007, 03:18 PM
Also it is a neat advantage of drivers. A 6V pack will have a longer run time over a 4.8V pack if amperage is the same. The funky part is think about things like a 4.8V Ni-MH at 2200mAh vs. a 7.2V li-ion at 1400mAh.

Ni-MH have a linear voltage curve, but li-ions hold there voltage really well then die fast. Which in that combo would run longer... it's a good question! :lol: One I'm not sure of, but it should be considered.

I'm not sure wich would have the best battery life, but I think it would be pretty close... but from a price perspective I'd take the 4.8V Ni-MH and for the size of the pack I'd take the 7.2V Li-ion one.

There's more variables to consider ;)

Ryma Mara
03-05-2007, 03:20 PM
What is the difference between Ni-MH and Li-ion ?

xwingband
03-05-2007, 03:24 PM
I hear you! That's the beauty of custom sabers. I like options!

Sitting and working out what is optimal for that saber is fun. Deciding on batteries is just like what board/driver I want. Planning is definately half the fun... keeps you from buying too. :wink:

neophyl
03-05-2007, 03:59 PM
After I picked up my first Corbin driver at C3 I did some tests of current vs voltage.

Current consumption between a 4.8v pack and a 9v supply is quite a margin. It uses approx half the current at 9v. Id still take a 4.8v nima AA pack though for the capacity compared to a 9v pp3 battery.

7.2v was a really good voltage vs current setup with Corbins driver.

btw I tested it up to 12v and it worked fine. I didnt however perform any long term useage tests at that voltage so I wouldnt recommend it.

xwingband
03-05-2007, 04:39 PM
Acerocket was going up to 14V with the Tri-lux and it kept burning out. 12 worked okay though.

elrond.406
03-05-2007, 09:10 PM
LONG POST ALERT!!!


What is the difference between Ni-MH and Li-ion ?
Nimh Battery specifications-
Energy/weight 30-80 Wh/kg
Energy/size 140-300 Wh/L
Power/weight 250-1000 W/kg
Charge/discharge efficiency 66% [1]
Energy/consumer-price 1.5 [2] Wh/US$
Self-discharge rate 30%/month (temperature dependant)
Time durability many years
Cycle durability 500-1000
Nominal Cell Voltage 1.2 V

---
Li-ion Battery specifications-
Energy/weight 160 Wh/kg
Energy/size 270 Wh/L
Power/weight 1800 W/kg
Charge/discharge efficiency 99.9%[1]
Energy/consumer-price (___?)Wh/US$
Self-discharge rate 5%-10%/month
Time durability (24-36) months
Cycle durability 1200 cycles
Nominal Cell Voltage 3.6 V

Pros & cons of lion:

Pros-

Lithium-ion batteries can be formed into a wide variety of shapes and sizes so as to efficiently fill available space in the devices they power.

Li-ion batteries are lighter than other equivalent secondary batteries—often much lighter. The energy is stored in these batteries through the movement of lithium ions. Lithium is the third lightest element, giving a substantial saving in weight compared to batteries using much heavier metals. However, the bulk of the electrodes are effectively "housing" for the ions and add weight, and in addition "dead weight" from the electrolyte, current collectors, casing, electronics and conductivity additives reduce the charge per unit mass to little more than that of other rechargeable batteries. The forte of the Li-ion chemistry is the high open circuit voltage in comparison to aqueous batteries (such as lead acid, nickel metal hydride and nickel cadmium).

Li-ion batteries do not suffer from the memory effect. They also have a low self-discharge rate of approximately 5% per month, compared with over 30% per month in nickel metal hydride batteries and 10% per month in nickel cadmium batteries.

According to one manufacturer, Li-ion cells (and, accordingly, "dumb" Li-ion batteries) do not have any self-discharge in the usual meaning of this word. What looks like a self-discharge in these batteries is a permanent loss of capacity, described in more detail below. On the other hand, "smart" Li-ion batteries do self-discharge, due to the small constant drain of the built-in voltage monitoring circuit. This drain is the most important source of self-discharge in these batteries.

Cons-

A unique drawback of the Li-ion battery is that its life span is dependent upon aging from time of manufacturing (shelf life) regardless of whether it was charged, and not just on the number of charge/discharge cycles. So an older battery will not last as long as a new battery due solely to its age, unlike other batteries. This drawback is not widely publicized.

At a 100% charge level, a typical Li-ion laptop battery that is full most of the time at 25 degrees Celsius or 77 degrees Fahrenheit, will irreversibly lose approximately 20% capacity per year. However, a battery stored inside a poorly ventilated laptop may be subject to a prolonged exposure to much higher temperatures than 25 °C, which will significantly shorten its life. The capacity loss begins from the time the battery was manufactured, and occurs even when the battery is unused. Different storage temperatures produce different loss results: 6% loss at 0 °C/32 °F, 20% at 25 °C/77 °F, and 35% at 40 °C/104 °F. When stored at 40% charge level, these figures are reduced to 2%, 4%, 15% at 0, 25 and 40 degrees Celsius respectively.

Li-ion batteries can even go into a state that is known as Deep Discharge. At this point, the battery may take a very long time to recharge. For example, a laptop battery that normally charges fully in 3 hours may take up to 42 hours to recharge. Or, the deep discharge state may be so severe that the battery will never come back to life. Deep discharging only takes place when products with rechargeable batteries are left unused for extended periods of time (often 2 or more years) or when they are recharged so often that they can no longer hold a charge. This makes Li-ion batteries unsuitable for back-up applications compared to lead-acid batteries, and even to Ni-MH batteries.

Because the maximum power that can be continuously drawn from the battery depends on its capacity, in high-powered (relative to C, the battery capacity in A·h) applications, like portable computers and video cameras, rather than showing a gradual shortening of the running time of the equipment, Li-ion batteries may often just abruptly fail.

Low-powered cyclical applications, like mobile phones, can get a much longer lifetime out of a Li-ion battery.

A stand-alone Li-ion cell must never be discharged below a certain voltage to avoid irreversible damage. Therefore all systems involving Li-ion batteries are equipped with a circuit that shuts down the system when the battery is discharged below the predefined threshold. It should thus be impossible to "deep discharge" the battery in a properly designed system during normal use. This is also one of the reasons Li-ion cells are rarely sold as such to consumers, but only as finished batteries designed to fit a particular system.

When the voltage monitoring circuit is built inside the battery (a so-called "smart" battery) rather than the equipment, it continuously draws a small current from the battery even when the battery is not in use; furthermore, the battery must not be stored fully discharged for prolonged periods of time, to avoid damage due to deep discharge.

Li-ion batteries are not as durable as nickel metal hydride or nickel-cadmium designs and can be extremely dangerous if mistreated. They are usually more expensive.

Li-ion chemistry is not safe as such, and a Li-ion cell requires several mandatory safety devices to be built in before it can be considered safe for use outside of a laboratory. These are: shut-down separator (for overtemperature), tear-away tab (for internal pressure), vent (pressure relief), and thermal interrupt (overcurrent/overcharging). The devices take away useful space inside the cells, and add an additional layer of unreliability. Typically, their action is to permanently and irreversibly disable the cell.

Despite these safety features, Li-ion batteries are the subject of frequent recalls.

The number of safety features can be compared with that of a nickel metal hydride cell, which only has a hydrogen/oxygen recombination device (preventing damage due to mild overcharging) and a back-up pressure valve.

Li-ion is better, but more expensive... 8)

Ryma Mara
03-06-2007, 04:05 AM
I dont know reading the cons to me thats not worth it.

LordArgyll
03-06-2007, 06:30 AM
The biggest drawback (at least in regards to saber building) is that they tend to be big to achieve both higher voltage and the same amount of current as NiMH. You use fewer cells, but they still take up roughly the same amount of volume, just in a different configuration. If you plan on including a driver and sound, it can get very, very cramped.

But like xwingband said, the bonus is that the voltage stays very regular until the final dropoff.


Correct, you won't see a gradual dimming. I have noticed a step though... and depending on the battery combo and astuteness of the observer some will too.

I think this is more or less what I meant. It seems logical to me that you'd see some sort of difference (however minute) if the voltage dropped below nominal. Unless the driver also boosts the voltage? I was under the impression that it just regulated the available current/voltage between high and low. I admit my lack of knowledge here.

xwingband
03-06-2007, 07:08 AM
True, there are sometimes drivers that will not produce a drop. These are step-up drivers like the micro puck and the other "boost" pucks. Most drivers are not like this however, Corbin's included.