Post by lamazoid on Nov 30, 2013 11:07:02 GMT -8
Recently, i have built a small device for camping, consisting of battery (lithium-polymer), flashlight, USB-output for charging various gadgets, and some protection & charging circuitry to charge battery itself from 12v automotive socket.
That was built occasionally, without thorough planning, using readily available modules from DX (dealextreme).
But the device has proved itself very useful, so i plan to develop "version 2" from zero point, and make complete plans, ready for mass-production.
(here i will post photos later on)
So what it should have onboard:
- Buck converter to convert automotive 12v input (and maybe, 24v too) to 5v out, to power internal electronics. Why 5v? Cause that is USB voltage,
so it should not be exceeded when direct-driving from buck converter, while the battery is being charged;
- Lithium battery charging controller. Currently i'm using TP4056 1A charger, but its not very convenient to charge 4 A/h cell with this, and i plan to further increase battery capacity.
So, something around 3-4 Amps should be set as goal;
- Boost converter to drive 5V USB out from battery. Currently i'm using FP6298 chinese IC. It can provide ~2A output, which is far enough even for f**ng I-pads and other modern gadgets. The only problem is ordering this IC directly;
- LED Driver. Now it's same FP6298 with some gimmick stuff added to stabilize current instead of voltage. I need boost driver because i use 3w COB led, rated for 9-11v at 300mA. It can be buck driver or even simple resistor limiting in case of using regular LEDs;
- A relay or another switching device to switch between battery and external power supply. The reason i use relay, is that i wanted to isolate battery from other circuitry when powering from 12V.
As we can see, that it pretty complicated stuff, even despite i had pre-made modules.
So the design goal is to simplify all this, and compile into single unit.
That was built occasionally, without thorough planning, using readily available modules from DX (dealextreme).
But the device has proved itself very useful, so i plan to develop "version 2" from zero point, and make complete plans, ready for mass-production.
(here i will post photos later on)
So what it should have onboard:
- Buck converter to convert automotive 12v input (and maybe, 24v too) to 5v out, to power internal electronics. Why 5v? Cause that is USB voltage,
so it should not be exceeded when direct-driving from buck converter, while the battery is being charged;
- Lithium battery charging controller. Currently i'm using TP4056 1A charger, but its not very convenient to charge 4 A/h cell with this, and i plan to further increase battery capacity.
So, something around 3-4 Amps should be set as goal;
- Boost converter to drive 5V USB out from battery. Currently i'm using FP6298 chinese IC. It can provide ~2A output, which is far enough even for f**ng I-pads and other modern gadgets. The only problem is ordering this IC directly;
- LED Driver. Now it's same FP6298 with some gimmick stuff added to stabilize current instead of voltage. I need boost driver because i use 3w COB led, rated for 9-11v at 300mA. It can be buck driver or even simple resistor limiting in case of using regular LEDs;
- A relay or another switching device to switch between battery and external power supply. The reason i use relay, is that i wanted to isolate battery from other circuitry when powering from 12V.
As we can see, that it pretty complicated stuff, even despite i had pre-made modules.
So the design goal is to simplify all this, and compile into single unit.
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