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Old Aug 30, 2014, 07:22 AM
Faroe Islands/Germany
epilot's Avatar
Joined Nov 2000
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Cheap single cell charger

Banggood has 10 of these small USB chargers for just over $10:

http://www.banggood.com/10Pcs-USB-Li...-p-943765.html

The charge current is determined by the resistor marked R3. On the board it is 1.2Kohm which means the charge current is 1000mA (1A). By substituting this resistor for a higher value, you reduce the charge current. 5Kohm will give you a 250mA charge current. The values are in the datasheet which can be found here: http://dlnmh9ip6v2uc.cloudfront.net/...ing/TP4056.pdf

The boards have an overcharge protection circuit. As far as I can tell the lowest charge rate you can acheive is 130mAh.
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Old Aug 30, 2014, 12:31 PM
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United States, MO, KCMO
Joined Aug 2005
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I'm currently using this lipo charger which charges at 100mah. You can also solder a jumper on the back for 500mah. Plus its 6$
http://www.adafruit.com/products/1304
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Old Aug 31, 2014, 05:22 PM
Mark Harrison
USA, CA, Piedmont
Joined Jun 2010
2,299 Posts
Quote:
Originally Posted by epilot View Post
Banggood has 10 of these small USB chargers for just over $10:

http://www.banggood.com/10Pcs-USB-Li...-p-943765.html

The charge current is determined by the resistor marked R3. On the board it is 1.2Kohm which means the charge current is 1000mA (1A). By substituting this resistor for a higher value, you reduce the charge current. 5Kohm will give you a 250mA charge current. The values are in the datasheet which can be found here: http://dlnmh9ip6v2uc.cloudfront.net/...ing/TP4056.pdf

The boards have an overcharge protection circuit. As far as I can tell the lowest charge rate you can acheive is 130mAh.
Neat! Any idea what size that R3 resistor might be (e.g. 0603)?
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Old Aug 31, 2014, 06:07 PM
skumgummi dave
Gresham, OR.
Joined Mar 2004
1,991 Posts
Lurking...

Dave-
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Old Aug 31, 2014, 06:18 PM
Faroe Islands/Germany
epilot's Avatar
Joined Nov 2000
6,050 Posts
Don't know the size of the resistor but will let you know once the boards arrive. I'll probably hook it up to a switch and a couple resistors so I can change the charge rate.
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Old Sep 08, 2014, 01:55 PM
Max
Joined Jul 2006
411 Posts
Very cool find!

Does anybody have calculated R values for different currents?
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Old Sep 08, 2014, 01:56 PM
Faroe Islands/Germany
epilot's Avatar
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Maksim, look in the datasheet I posted the link to. It has a table with charge current/resistor values.
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Old Sep 08, 2014, 02:23 PM
Max
Joined Jul 2006
411 Posts
Thanks Epilot!

For those wondering, here's the table of resistor values (from the PDF).

Another question that I have is what is the minimal battery current that we could use this for? I don't think the specs show the absolute maximum value of Rprog.
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Old Sep 08, 2014, 02:32 PM
Faroe Islands/Germany
epilot's Avatar
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IIRC it says the lowest charge current you can use is 130mAh.
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Old Sep 11, 2014, 12:48 AM
Mark Harrison
USA, CA, Piedmont
Joined Jun 2010
2,299 Posts
Woo Hoo, mine just came in! Got a package of 10. Need to figure out what charge rates I need. I like your idea of offboarding to a switch.

This will be my first time swapping out SMD devices, kinda excited to give it a try!
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Old Sep 11, 2014, 07:19 AM
A.K.A sir Crashalot
methuso's Avatar
Ístersund, SWEDEN
Joined Sep 2005
927 Posts
it only says lithium charger. Is there no differences in charging li-ion to li-po ?
Since i bought a 5pack li-ion chargers a couple or years ago and thought i bought wrong and never use them

/Ulf
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Old Sep 11, 2014, 07:30 AM
Faroe Islands/Germany
epilot's Avatar
Joined Nov 2000
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Li-ion cells are 3.6V, Lipo are 3.7V. Worst that can happen is that you don't get a full charge.

EDIT: Both chemstries terminate charging at app. 4.2V so there shouldn't be any issues. The both use CC/CV charging.
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Old Sep 11, 2014, 07:46 AM
Faroe Islands/Germany
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Good video about the charger:

New TP4056 Lithium Cell Charger Module with Battery Protection (12 min 56 sec)
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Old Sep 11, 2014, 03:21 PM
A.K.A sir Crashalot
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Ístersund, SWEDEN
Joined Sep 2005
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Whoo. Then i have five more chargers laying around
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Old Sep 24, 2014, 01:46 PM
Faroe Islands/Germany
epilot's Avatar
Joined Nov 2000
6,050 Posts
Mine have arrived but then I realised I don't have any resistors of the appropriate values. No trimpots either. Oh well, order some from Banggood and wait another month.
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