GarageBoy
Flashlight Enthusiast
I remember the BB NG having a safe mode and a "unsafe" mode /ubbthreads/images/graemlins/grin.gif How does the light select the modes? Thanks!
-
You must be a Supporting Member to participate in the Candle Power Forums Marketplace.
You can become a Supporting Member.
Safe Mode and Full Mode for NGs?
- Thread starter GarageBoy
- Start date
Edited to add:
Wheee. One of these days I'll learn to answer questions that I'm not 100% on while using the search function. Jump down to dat2zip's post for the correct information re: full-regulation/safe mode selection. I think my description of the operation of each of the modes was correct, at least.
Safe mode is a fallback if full constant-current regulation can't be maintained, i.e. if the battery is too weak relative to the drive current. For example, a fresh CR123A will start in safe mode with a NG1000, as the battery just can't handle the load. NG400 or 500 will start in regulation and stay there for a while. 2xAA NiMH or 1xLiOn can handle the NG1000.
I think safe mode is roughly the same as the MadMax driver, which regulates input current. Since emitter Vf stays constant (aside from heat effects) and Vbatt decreases, output current will decrease proportionately as the battery drains.
A two-stage switch will kick the NG out of regulation and into safe mode, so you're sort of selecting the mode.
Wheee. One of these days I'll learn to answer questions that I'm not 100% on while using the search function. Jump down to dat2zip's post for the correct information re: full-regulation/safe mode selection. I think my description of the operation of each of the modes was correct, at least.
Safe mode is a fallback if full constant-current regulation can't be maintained, i.e. if the battery is too weak relative to the drive current. For example, a fresh CR123A will start in safe mode with a NG1000, as the battery just can't handle the load. NG400 or 500 will start in regulation and stay there for a while. 2xAA NiMH or 1xLiOn can handle the NG1000.
I think safe mode is roughly the same as the MadMax driver, which regulates input current. Since emitter Vf stays constant (aside from heat effects) and Vbatt decreases, output current will decrease proportionately as the battery drains.
A two-stage switch will kick the NG out of regulation and into safe mode, so you're sort of selecting the mode.
GarageBoy
Flashlight Enthusiast
thanks!So a BB 750NG in a Mag will be in wide open mode for a few minutes, before dropping? How much dimmer will the LED be in safe mode?
I don't have any answers, but my new NG500 behaves exactly like this on Duracell alkalines: Full brightness regulation for 90-100 mins. (The whole time comparing it to a freshly started BB400 at 15min intervals) Then it all of a sudden dims just slightly (hafta be watching for it) and rides out about another 20mins with smooth decline. Burned 3 sets of alkalines, same performance every time. I guess the noticeable dimming is the DD mode. Or is it the safe mode. Maybe the safe/full modes are seamless blended? In any case, looks like the regulated runtime to be the same as a BB400 but with the added brightness of the 500amps, which does noticeably improve the output (slight but noticeable). Also, it didn't heat up as hot as a BB400 does toward the end of the alkaline batt life, when it really starts suckin hard. Seems like the NG doesn't suck so hard. /ubbthreads/images/graemlins/smile.gif
GarageBoy
Flashlight Enthusiast
Well, it should only go into DD when Vf is above the V out
I don't know the runtime numbers off hand, but I think the NG750 lasts longer than a few minutes on 2xAA NiMH. I believe the BB750 has a runtime of around an hour (of course, it got very hot in a few minutes), and the NG should be a good bit more (or maybe the same, due to the safe mode cutoff).
I believe safe mode will dim gradually, depending on how demanding high is. Since an NG750 requires more power than a NG500, the batteries will have more remaining charge when it enters safe mode, and will therefore provide longer runtime in safe mode.
I think the noticeable brightness change is the transition to safe mode, but I don't actually know.
I believe safe mode will dim gradually, depending on how demanding high is. Since an NG750 requires more power than a NG500, the batteries will have more remaining charge when it enters safe mode, and will therefore provide longer runtime in safe mode.
I think the noticeable brightness change is the transition to safe mode, but I don't actually know.
GarageBoy
Flashlight Enthusiast
How long before the NG 750 gets HOT?
So the NG will act like a BB until the batteries run out of current, then it goes into a Mad Max like regulated input current?
So the NG will act like a BB until the batteries run out of current, then it goes into a Mad Max like regulated input current?
[ QUOTE ]
GarageBoy said:
So the NG will act like a BB until the batteries run out of current, then it goes into a Mad Max like regulated input current?
[/ QUOTE ]
That's my understanding of it; I could be completely off-base. I'm sure I read it in a description of the NG somewhere in the Shoppe forum, but it's been a while.
The problem with the BB750 is that both the Lux and the BB generate lots of heat, whereas the NG board doesn't heat up too much, but the Lux still does. I don't have any experience with any NG builds, so I don't know how fast a NG750 would heat up.
GarageBoy said:
So the NG will act like a BB until the batteries run out of current, then it goes into a Mad Max like regulated input current?
[/ QUOTE ]
That's my understanding of it; I could be completely off-base. I'm sure I read it in a description of the NG somewhere in the Shoppe forum, but it's been a while.
The problem with the BB750 is that both the Lux and the BB generate lots of heat, whereas the NG board doesn't heat up too much, but the Lux still does. I don't have any experience with any NG builds, so I don't know how fast a NG750 would heat up.
It's a little more complicated than that.
The determining factor if it's in safe mode or full regulation is when you first turn on the light. If the battery voltage is high enough the Nexgen will go into full regulation and stay that way till it drains the battery or drops below it's minimum voltage of 1.8V or so.
That's great for a runtime plot, but, in real life, you turn it on/off many times before you change the batteries. Let's say the first N times you turn the light on it will start up in full regulation mode. After you have used the battery some it won't be able to start up in full regulation. From then on till you change the batteries it will start up in safe mode.
To complicate things further, if you have a J bin LED and a pretty fresh battery, full regulation of 750 will be about the same as if the converter started up in safe mode since that is about 700-750mA to the LED (1A input). The only way you will be able to determine this is if you could measure the brightness over time as it will slowely drop if it is in safe mode, but, it is very gradual and like the Madmax WO you will have a hard time perceiving this unless you metered it.
Either way, it's a great setup. I wouldn't worry over it since semi-regulated in safe mode is almost flat and your runtime will be greater than if it ran in true constant current mode.
OK, To verify you understand what I said, please repeat it back to me so that I know you understand it. /ubbthreads/images/graemlins/nana.gif
Wayne
The determining factor if it's in safe mode or full regulation is when you first turn on the light. If the battery voltage is high enough the Nexgen will go into full regulation and stay that way till it drains the battery or drops below it's minimum voltage of 1.8V or so.
That's great for a runtime plot, but, in real life, you turn it on/off many times before you change the batteries. Let's say the first N times you turn the light on it will start up in full regulation mode. After you have used the battery some it won't be able to start up in full regulation. From then on till you change the batteries it will start up in safe mode.
To complicate things further, if you have a J bin LED and a pretty fresh battery, full regulation of 750 will be about the same as if the converter started up in safe mode since that is about 700-750mA to the LED (1A input). The only way you will be able to determine this is if you could measure the brightness over time as it will slowely drop if it is in safe mode, but, it is very gradual and like the Madmax WO you will have a hard time perceiving this unless you metered it.
Either way, it's a great setup. I wouldn't worry over it since semi-regulated in safe mode is almost flat and your runtime will be greater than if it ran in true constant current mode.
OK, To verify you understand what I said, please repeat it back to me so that I know you understand it. /ubbthreads/images/graemlins/nana.gif
Wayne
OK so a freshly charged set of batts in a NG500 will fire the thing into regulation and as long as the light is not turned off, will constant current regulate all the way down to 1.8V? Then it goes direct drive, no safe mode? But if it is started on weak batts, then it may use safe semi-reg mode so as not to suck so hard on the weak batts and give longer runtime?
GarageBoy
Flashlight Enthusiast
So, new batts- full reg-til it dies
The less energy/power the batteries have, it will turn on in safe mode?
The less energy/power the batteries have, it will turn on in safe mode?
Yes, Full regulation if:
1A * Vin <= Vf * ILED.
So, depending on your LED Vf and the drive current you set, the critical theshold the converter will go into full regulation is dependant on the equation above. This is an approximate corner point, but, will give you an estimation where the line between full and safe mode exists for various combinations of LED current and Vf bin codes.
Wayne
1A * Vin <= Vf * ILED.
So, depending on your LED Vf and the drive current you set, the critical theshold the converter will go into full regulation is dependant on the equation above. This is an approximate corner point, but, will give you an estimation where the line between full and safe mode exists for various combinations of LED current and Vf bin codes.
Wayne
GarageBoy
Flashlight Enthusiast
ILED= the current to the LED or current drawn by LED?
(Higher flux= higher voltage or current draw? sorry, I never fully understood electrical physics)
Wayne, also, why does will the circuit stay in full regulation if I leave it on til it dies, compared to on and off operation?
Thanks again!
(Higher flux= higher voltage or current draw? sorry, I never fully understood electrical physics)
Wayne, also, why does will the circuit stay in full regulation if I leave it on til it dies, compared to on and off operation?
Thanks again!
GarageBoy
Flashlight Enthusiast
Also, how hot does the NG750 get? Thanks!
The converter starts up with 25% maximum power. This is to prevent a shorted load from blowing the converter or dumping excessive current into a defective product.
In normal use the IC senses whether it has reached regulation or not. When it does it trips internally enabling 100% of the IC's available power. Once this trip occurs it remains in this state till power is removed.
As for heat. Assume worst case the converter is dissipating 15% of the output power. If the Vf of the LED is 3.5V and you are driving 1A then output power = V * I = Vf * Iled = 3.5 * 1A = 3.5W. 15% of that is 0.5W.
0.5W is not too hot for that board that size. If the board is potted or thermally bonded to something else this will not be an issue. If the converter board and LED are part of the same assembly like a Sandwich or Light Engine then the total heat is dominated by the LED. In actuality for flashlights the heat is dominated by the LED and the converter board contributes an additional amount of heat or wasted power.
Wayne
In normal use the IC senses whether it has reached regulation or not. When it does it trips internally enabling 100% of the IC's available power. Once this trip occurs it remains in this state till power is removed.
As for heat. Assume worst case the converter is dissipating 15% of the output power. If the Vf of the LED is 3.5V and you are driving 1A then output power = V * I = Vf * Iled = 3.5 * 1A = 3.5W. 15% of that is 0.5W.
0.5W is not too hot for that board that size. If the board is potted or thermally bonded to something else this will not be an issue. If the converter board and LED are part of the same assembly like a Sandwich or Light Engine then the total heat is dominated by the LED. In actuality for flashlights the heat is dominated by the LED and the converter board contributes an additional amount of heat or wasted power.
Wayne
GarageBoy
Flashlight Enthusiast
Thanks, so why do guys say the BB750 gets wayy too hot? I need to catch up on terms
There a couple reason that BB's have heat related problems.
It's a non-linear relationship between the battery, regulator and LED that the combination gets iffy at some point.
That is to say, at some point drawing more current may be diminshing returns limited by the internal resistance of the battery.
In the case of the BB750, because it is not as efficient as the nexgen it needs to draw more current on a fresh battery to try to keep the output in regulation. This additional inefficiency with a 123 battery tends to crest over the diminsihing return curve.
Why? That's because the BB750 tries to suck 1.1A to regulate 750, but, at 1A input draw the 123 drops ~1/2 Volt from 3V downto 2.5. Now the regulator actually sees 2.5 on it's input and it needs to draw 1.4-1.6A to boost 2.5V to 3.5V @ 750mA. This tends to put the converter board under more stress than needed. If the 123 didn't sag, this would not be an issue, but, the fact is 3V is a low voltage technology and like processors in modern day computers, dropping a couple tens of a volt can make or break todays modern electronics.
So, why does nexgen not get as hot? Won't it do the same thing?
Funny, but, the nexgen regulates just a little better and the 1A draw + the internal switch voltage drops are a lot less and thus the converter doesn't have to work as hard and even as the battery voltage drops the converter stays very efficient close to 90% most of the time, so heat generated is more or less constant over time.
The Badboy as it draws more current becomes very lossy and the efficiency drops dramatically when it draws currents over 1.2A or so. The BB750 on a fresh 123 will actually do quite well, but less efficient. As the battery depletes the BB will get less efficient and the heat generated will go up.
Wayne
It's a non-linear relationship between the battery, regulator and LED that the combination gets iffy at some point.
That is to say, at some point drawing more current may be diminshing returns limited by the internal resistance of the battery.
In the case of the BB750, because it is not as efficient as the nexgen it needs to draw more current on a fresh battery to try to keep the output in regulation. This additional inefficiency with a 123 battery tends to crest over the diminsihing return curve.
Why? That's because the BB750 tries to suck 1.1A to regulate 750, but, at 1A input draw the 123 drops ~1/2 Volt from 3V downto 2.5. Now the regulator actually sees 2.5 on it's input and it needs to draw 1.4-1.6A to boost 2.5V to 3.5V @ 750mA. This tends to put the converter board under more stress than needed. If the 123 didn't sag, this would not be an issue, but, the fact is 3V is a low voltage technology and like processors in modern day computers, dropping a couple tens of a volt can make or break todays modern electronics.
So, why does nexgen not get as hot? Won't it do the same thing?
Funny, but, the nexgen regulates just a little better and the 1A draw + the internal switch voltage drops are a lot less and thus the converter doesn't have to work as hard and even as the battery voltage drops the converter stays very efficient close to 90% most of the time, so heat generated is more or less constant over time.
The Badboy as it draws more current becomes very lossy and the efficiency drops dramatically when it draws currents over 1.2A or so. The BB750 on a fresh 123 will actually do quite well, but less efficient. As the battery depletes the BB will get less efficient and the heat generated will go up.
Wayne
GarageBoy
Flashlight Enthusiast
Thanks! So I'll pick up a BB NG for NiMH use and a MadMax for full drain at primary cells
Thanks for the lesson on converts mr Wayne!
Thanks for the lesson on converts mr Wayne!
Dan C
Enlightened
One more question concerning safe mode and a two-speed setup. When using a NG with a two level tailcap like the Aleph or Firefly setups, how does it respond? What does the converter do when, by the design of the resistored tailcap, it always starts out at the 'low' setting? It almost seems like the converter would see the low setting as a weak battery and always start in safe mode, and stay there even though you immediately go from low to high. Could you elaborate on that? Thanks, I've been wondering about this for some time...
Dan C
Dan C
GarageBoy
Flashlight Enthusiast
I'm guessing you just turn it off then on in high for full reg?
