LithPoly Charging Rate

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mobilewill
 
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LithPoly Charging Rate

Post by mobilewill »

http://www.adafruit.com/index.php?main_ ... cts_id=280

Do I need to remove the existing resistor to charge at max rate? Can I short out the R1 pins and get 1.2A charging rate? I am trying to charge the 6Ah battery from sparkfun.com which has a standard charge rate of .2C.

http://www.sparkfun.com/products/8484

Thanks!

adafruit
 
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Re: LithPoly Charging Rate

Post by adafruit »

shorting Rprog is fine

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mobilewill
 
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Re: LithPoly Charging Rate

Post by mobilewill »

So that gives me 1.2A?

Thanks, right now the default doesn't charge enough to power my project and charge, the battery slowly still drains. This morning it has the error light on. So I will try charging shorted and see how well it charges.

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mobilewill
 
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Re: LithPoly Charging Rate

Post by mobilewill »

Is it okay that the chip gets too hot to touch when charging at 1.2A? Should I get a small heats sink?

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Re: LithPoly Charging Rate

Post by adafruit »

try to keep the voltage in low, around 5V in for best performance
but it does have a thermal protection.

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mobilewill
 
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Re: LithPoly Charging Rate

Post by mobilewill »

I am using a power supply from a Dlink AP that is 5v 2.5A

adafruit
 
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Re: LithPoly Charging Rate

Post by adafruit »

should be OK then

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mobilewill
 
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Re: LithPoly Charging Rate

Post by mobilewill »

Thanks. Seems to charge better with the arduino/xbee off (or course) they draw about 160ma for some reason.

When is gets close to being done does it slow the charging rate?

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ImaginaryAxis
 
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Re: LithPoly Charging Rate

Post by ImaginaryAxis »

It should. The charging profiles for Lithum-Ion batteries start with a constant current phase then switch to a constant voltage phase. During the constant voltage phase the charging current reduces. The intent is not to overload the Lithium battery as they are prone to such things.

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mobilewill
 
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Re: LithPoly Charging Rate

Post by mobilewill »

It seems that it doesn't get through a full charge and ends up getting the error LED sometimes. I thinking it is getting too hot running 1.2A charge rate. Should I put a small heat sink on it? What else causes the error led?

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Re: LithPoly Charging Rate

Post by adafruit »

it could also be timing out, there is a safety timeout on it, but its like 4 or 5 hrs. try again

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mobilewill
 
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Re: LithPoly Charging Rate

Post by mobilewill »

I thought it was longer. I need it to charge while its connected to my project. Somewhere I read 14 hrs. Hmmm. Sometimes after overnight it is still solid led. But twice had red. Once actaully flashing that it was done. Wondering if it can't finish charging because project drawing too much? About 260ma.

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Re: LithPoly Charging Rate

Post by adafruit »

you could try removing the timing capacitor, that may work

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mobilewill
 
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Re: LithPoly Charging Rate

Post by mobilewill »

Thanks, so what is the timer set to out of the box? I read up on the datasheet but I don't know how 3 timers are set with 1 cap. The info on your site says 14hrs is that the max? Or is that how they are shipped? How long would it be if there isn't a cap? I hate to mess up the charger.

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Re: LithPoly Charging Rate

Post by adafruit »

we've never tried removing the cap. its .47uF - check the datasheet for precise calculations

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