PIC12F683 Usb charger

[zed65]

Here is a simple USB charger for 2pcs of AA NIMH or NICD I made a while ago.
It uses an DS18B20 1wire sensor to measure the temperature of the batteries and shuts of about 32 degrees celsius.
The program is made in Flowcode and the schematics in Eagle.

If you find it interesting/useful, feel free to use it.
Be careful, the TIP122 gets a bit hot!

[alfonsoagama]

You can get a cheaper, and more sophisticated usb charger with:

MCP73123 for 2 pcs of AA NIMH or NICD with a Resistor Programmable Fast Charge Current: 130 mA - 1100 mA
MCP73223 for 4 pcs of AA NIMH or NICD with a Resistor Programmable Fast Charge Current: 130 mA - 1100 mA

[jamen]

NO SOURE CODE?

[alfonsoagama]

The .hex file is included in the attachment.

[pickit2]

WTF!   Why don't you say what your on about.

@ jaman to which post are you saying has no hex code?
@ alfonsoagama you did not post any link for your post? just some a vauge reference to a few ic's from microchip.
Then you say .hex file is in the attachment, your post don't have an attachment, so why respond to jaman's post?

[metal]

alfonsoagama meant that the hex is in the first attachment.

[Ichan]

MCP73123 for 2 pcs of AA NIMH or NICD with a Resistor Programmable Fast Charge Current: 130 mA - 1100 mA
MCP73223 for 4 pcs of AA NIMH or NICD with a Resistor Programmable Fast Charge Current: 130 mA - 1100 mA

The MCP's is Li-Ion charger, 2x in series of NIMH or NICD (2.4V) will be charged at about 4.2V on the constant voltage charging sequence, not a wise choice.

-ichan

[alfonsoagama]

The MCP's is Li-Ion charger, 2x in series of NIMH or NICD (2.4V) will be charged at about 4.2V on the constant voltage charging sequence, not a wise choice.

-ichan

The MCP's are Lithium Iron Phosphate (LiFePO4) Battery Charge Management Controller, 2x in series of NIMH or NICD (NiMH batteries normally operate at 1.2 V per cell but The charging voltage is about 1.8V per cell) will be charged at about 3.6V on the constant voltage charging sequence (not 4.2V).
The MCP73123/223 employs a constant current/constant voltage charge algorithm.


http://ww1.microchip.com/downloads/en/DeviceDoc/22191D.pdf

[Ichan]

...will be charged at about 3.6V on the constant voltage charging sequence (not 4.2V).

3.6 (or 3.7) volt is nominal voltage of Li-Ion (family) battery, after constant current charging will be continued with constant voltage at about 4.2 - 4.4 V (depends on the battery).

Try to measure the voltage of a fully charged Li-Ion (family) battery, it is not around 3.6 but 4.2 volt.

-ichan

[Magnox]

I'm fairly sure that the LiFePO4 cells are not 4.2V EOC, but 3.6V to 3.7V. They are the odd member of the secondary lithium cell family. The datasheet linked in post #7 specifically mentions 3.6V EOC limit.

That's why they are used a lot in flashlights that support CR123 cells (that's why I know about them) but cannot handle the higher voltage of the 'usual' RCR123 LiIon cells.

Here's a datasheet for an example LiFePO4 cell:

http://liionbms.com/pdf/goldpeak/GP45EVLF.pdf

[Ichan]

That is me who do not really know what LiFePO4 is, specifically it's end of charge condition - mixed it up with Li-Po perhaps.

Thanks for the new know-how.

-ichan