Boosting 2500mAh LiPo to 5V

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rubidium
 
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Boosting 2500mAh LiPo to 5V

Post by rubidium »

I'm using the Adafruit 2500mAh LiPo in conjunction with a TPS61230 boost converter to get a portable supply 5V @ 1-1.5A avg, 2A peak. Works well. But via resistor selections, the TPS61230 can be configured to have an undervoltage lockout threshold (with hysteresis), and I'm wondering what a practical value would be to set it at for long-term operation. According to the Adafruit description, the LiPo itself cuts off when its voltage hits 3.0V, so obviously that's a lower limit. But should I set the cutout for the TPS61230 notably higher than that, and why? I'd like to draw the most energy out of the battery between charges.
Thanks,
Jim

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Franklin97355
 
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Re: Boosting 2500mAh LiPo to 5V

Post by Franklin97355 »

The battery will shut off at 3.0v to keep from destroying itself and either exploding or catching fire but that is the "something is wrong" point and should not be the point you program into a system. 3.2v would be the minimum I would recommend and some batteries recommend 3.4 and I would respect any value stated by the battery supplier. The lower you go and the faster you charge the shorter the battery life.

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rubidium
 
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Re: Boosting 2500mAh LiPo to 5V

Post by rubidium »

Thanks. I had a cutoff of about 3.45-3.5 in mind, so maybe I can settle on 3.4 and get just a little more latitude.

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adafruit_support_mike
 
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Re: Boosting 2500mAh LiPo to 5V

Post by adafruit_support_mike »

3.4v is a good value. In terms of energy use, the difference between that and 3.2v is negligible.

The LiPo discharge curve has a sharp knee at the 'out of energy' end. By the time the voltage falls to 3.2v, you've used about 98% of the energy that was originally stored in the cell. 3.4v represents about 95% utilization.

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