Tutorial: Blu-Ray With TEC! - Step by Step

[dnar]

And allow them to cool after use before charging.

I work with very high power density batteries at work (Military), insane and expensive one use batteries that *can* leak poisonous gases if discharged to far... So dangerous you can't fly these things (unless via dedicated means). The power of a car battery but much smaller. We don't store them in the lab, they come in and out each day.

 

[ossumguywill]

How small exactly? What kind of chemistry do they use? I want to learn about that kind of stuff... I find a knowledge of batteries is always useful, especially in a portable hobby like ours

 

[dnar]

They are the work horse of the US/Aus/UK (and others) Military. Initially made by British Aerospace (hence the BA in the part number), the BA5590 is Lithium Sulfur Dioxide (Li/SO2) and Lithium Manganese Dioxide (LiMnO2). Around the size of a stack of 12 CD's, they are man carried in mini-me ammo pouches. Not quite the power of a car battery (approx 15A/h) but still impressive for the weight. Actually comprised of 2 x 12V cells, wired out to a connector permitting independent operation, series or parallel. Each cell has a diode in series to permit easy paralleling as required (some gear needs 24V).

The big bugger with these cells is their characteristics approaching full discharge. They become quite high impedance, so when low voltage cut-out occurs in the connected electronics, the terminal voltage rises back to 12-14 volts! Add to this, they are quite temperature sensitive so any real "charge monitoring" over time must factor in cell temperature... This is the sort of work that I do, smart microprocessor systems to deal with all that kind of difficulty. Low voltage electronics is one of my specialties, along with real time systems of sorts (comms, video, audio, DSP).

http://www.batterystore.com/Saft/SaftPDF/BA5590.pdf

You can also get rechargeable cells in the same form factor. These include inbuilt LCD charge indication.

 

[ossumguywill]

They are the work horse of the US/Aus/UK (and others) Military. Initially made by British Aerospace (hence the BA in the part number), the BA5590 is Lithium Sulfur Dioxide (Li/SO2) and Lithium Manganese Dioxide (LiMnO2). Around the size of a stack of 12 CD's, they are man carried in mini-me ammo pouches. Not quite the power of a car battery (approx 15A/h) but still impressive for the weight. Actually comprised of 2 x 12V cells, wired out to a connector permitting independent operation, series or parallel. Each cell has a diode in series to permit easy paralleling as required (some gear needs 24V).

The big bugger with these cells is their characteristics approaching full discharge. They become quite high impedance, so when low voltage cut-out occurs in the connected electronics, the terminal voltage rises back to 12-14 volts! Add to this, they are quite temperature sensitive so any real "charge monitoring" over time must factor in cell temperature... This is the sort of work that I do, smart microprocessor systems to deal with all that kind of difficulty. Low voltage electronics is one of my specialties, along with real time systems of sorts (comms, video, audio, DSP).

http://www.batterystore.com/Saft/SaftPDF/BA5590.pdf

You can also get rechargeable cells in the same form factor. These include inbuilt LCD charge indication.

very cool! Microprocessors are another one of my hobbies. Do you use a micro+ADC or the same kind of dedicated battery protection hardware found in high-end Li+ batteries?

 

[dnar]

very cool! Microprocessors are another one of my hobbies. Do you use a micro+ADC or the same kind of dedicated battery protection hardware found in high-end Li+ batteries?

A combination of MCU (Atmel), ADC and precision references/op-amps with 0.1% resistors.

 

[ossumguywill]

A combination of MCU (Atmel), ADC and precision references/op-amps with 0.1% resistors.

Hive five for the Atmel club! Atmel is so awesome, they sent me a bunch of tiny2313s for free so I did this Arduino Forum - 14 LED "knight rider" with hardware PWM there's a video as well.

 

[seoguy]

What is your battery supply when fully charged (laser on) and also at the threshold of unusable?

Was not asking in ref to a specific laser, just curious if the devices you had suggested to jayrob were also useful/available for constant-current designs.

But for sake of example, say a circuit with an optimal input voltage (LD + regulator drop-out + headroom) of ~8.5-9V, and say Li-ion cells with an output voltage (depending on amount of charge) of ~3.6-4.2V each.

Two cells are insufficient for the voltage required. But add a 3rd, and at a full charge, the overwhelming majority of the voltage added by that extra battery is being used (wasted) to generate excess heat in the linear regulator!

So when you said this...

I understand, however your preceding linear regulators are wasting energy (lost as heat). This loss could be minimized using the switching equivalents.

...For these reasons, linear regs are a poor choice for battery applications.

And indicated these devices solved that issue (at least for TEC's), you can understand why that got my attention!

While still linear series pass, this LED constant current driver looks to me as if it will also work as a LD regulator. It regulates down to around 1V output AND included a TTL enable line (321U model only).

I might grab a few and try them out. $0.62 each at Farnell for 1-24 units.

http://www.infineon.com/dgdl/bcr320...c04c4&fileId=db3a304324fc7f9a0125204353c942f9

Thanks for the link! Will check those out. I know some members have been talking lately about possibly using LED drivers to run the new power-hungry 445's, but one of the LD driver vendors chimed-in that they were not suitable for LD's, because they did not have the "proper filtering"?

Not sure if that wasn't something that a well-placed filter cap or two couldn't solve, or if the concern was more related to the massive $ dif. between LED drivers such as the ones you mentioned, and the popular LD drivers being used today?

 

[dnar]

Two cells are insufficient for the voltage required. But add a 3rd, and at a full charge, the overwhelming majority of the voltage added by that extra battery is being used (wasted) to generate excess heat in the linear regulator!

So when you said this...

And indicated these devices solved that issue (at least for TEC's), you can understand why that got my attention!

Yes, ideal.

Thanks for the link! Will check those out. I know some members have been talking lately about possibly using LED drivers to run the new power-hungry 445's, but one of the LD driver vendors chimed-in that they were not suitable for LD's, because they did not have the "proper filtering"?

Not sure if that wasn't something that a well-placed filter cap or two couldn't solve, or if the concern was more related to the massive $ dif. between LED drivers such as the ones you mentioned, and the popular LD drivers being used today?

I suspect so. LED's are able to take a lot of abuse, particularly peak pursts, unlike smalled devices such as LD. I suspect that a bit of C would suffice as usual.

 

[Flaminpyro]

Just because your PS is able to put out 10 amps dose not mean that your ckt will draw it all.
It's best to have a overhead of about 33% when selecting a PS for the load you want to supply, any thing above that is gravy

my only problem with using a driver is that it would be have to be high rated as im using an external power source possibly. it could put out upward of 10amps... not sure if i should just let it draw that much current or attempt to find a smaller supply