New USB LiPo charger

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altair
 
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Re: New USB LiPo charger

Post by altair »

Hi!
I bought LiPo Charger v1.1 (among other things) and i have a question, what are soldering points (don't know how to call them) st1 & st2 ? thank you in advance

(p.s. i will still have to do some testing, but it seems mintyboost works with samsung galaxy)

adafruit
 
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Re: New USB LiPo charger

Post by adafruit »

those are status outputs, for LEDs

ayhsmb
 
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Re: New USB LiPo charger

Post by ayhsmb »

If I want to break out the status LEDs so that they can be mounted to an enclosure where could/should I take 5V and is it alright to leave the onboard LEDs in place? If I have it right, I would place a 150 ohm resistor (to make ~19 milliAmps current, assuming 2.2 V forward) one side to the ST pad the other to the cathode side of a LED and then the anode side to 5v, then repeat for the second ST pad.

adafruit
 
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Re: New USB LiPo charger

Post by adafruit »

yes!

ayhsmb
 
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Re: New USB LiPo charger

Post by ayhsmb »

Thanks! Sorry for the novice question but where is the best place to take the 5 V from? It looks like there are three holes, one by the power LED, one by the USB connector and one off of pins 1 and 2 of the chip that form an L shaped trace on the back of the board. Is it okay to solder a wire to one of them?

adafruit
 
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Re: New USB LiPo charger

Post by adafruit »

mm, you can take ~3.7 from the battery out pins (+) you dont need 5V cuz the vf of the LEDs is well < 3V

ayhsmb
 
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Re: New USB LiPo charger

Post by ayhsmb »

Cool, thanks! That ought to be much easier as I'm not so sure I could have soldered well to something that small.

rgm
 
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Re: New USB LiPo charger

Post by rgm »

adafruit wrote:that will work fine, might want to bump up the charge rate by soldering in a new R4 (see the schematic for new values you may want to pick) for like 500mA so it doesnt take a week to charge
A little trick -- you can set the charge rate on the MCP73833 v1.1 LiPo charger to just above 500mA by soldering in a 3.3KΩ resistor right on top of the existing 4.7KΩ SMT resistor that's in R4 (labeled 4701), bringing the effective resistance to ~ 1.93KΩ.

kmyerskpm
 
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Re: New USB LiPo charger

Post by kmyerskpm »

A little trick -- you can set the charge rate on the MCP73833 v1.1 LiPo charger to just above 500mA by soldering in a 3.3KΩ resistor right on top of the existing 4.7KΩ SMT resistor that's in R4 (labeled 4701), bringing the effective resistance to ~ 1.93KΩ.
Hi - before I go ahead and do this, I just wanted to confirm that this is an acceptable modification (does it really work). If so, do I just need a regular 1/4 watt 5% resistor?

Thanks.

adafruit
 
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Re: New USB LiPo charger

Post by adafruit »

yes

kmyerskpm
 
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Re: New USB LiPo charger

Post by kmyerskpm »

Great! Thanks for the prompt reply.

muzica
 
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Urgent of Technical reply for USB LiPo charger

Post by muzica »

Urgent and would like to have some technical advice

I'm a newb in this LIPo Charger, and i would like to ask what is the required voltage and current to charge a 3.7V 950mAh LiPoly Batt by using the configuration of 100mA charging current for the LiPo Charger board?

Thanks

Snipeye
 
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Re: New USB LiPo charger

Post by Snipeye »

Simplest Answer: Lipos are dangerous if used improperly. If you're a noob, I would very much suggest using a different type of battery.

Answer you want: Just plug it in to a USB port, USB Spec is 5v at 500mAh. To use 100mAh instead of the default 200mAh, you'll need a 10k resistor soldered in, though that means it'll take 9.5 hours to charge your battery...

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adafruit_support_bill
 
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Re: New USB LiPo charger

Post by adafruit_support_bill »

@muzica, The data sheet has all the details. http://ww1.microchip.com/downloads/en/D ... 22005b.pdf
Your supply should be between 3.75v and 6v.

muzica
 
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Re: New USB LiPo charger

Post by muzica »

Thanks for the quick reply on the input supply part, cause i got a 5V supply for it. Sorry for the trouble to answer, just trying to learn and get some answer from this forums.....^^

Another question is if i where to measure the voltage at the battery in pin, what will be the voltage appear? Cause i got a quite low measured voltage of 0.7 ~ 0.6 V ( i did not plug in the battery when doing this measurement cause i would like to see how much voltage is it passing to charge the battery), is it a problem or it is just normal?

I remember seeing a post about the charging will stop at 4.2V, does it means that if the LiPoly battery is only 3.7V it will just kept on charging and will not stop drawing power?

Really thanks for the time spent, really appreciate it. I already bought the product, just thinking of understanding more about how it operates and stuff like that.

Thanks alot....^^

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