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
Boosting 2500mAh LiPo to 5V
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Please be positive and constructive with your questions and comments.
- Franklin97355
- Posts: 23911
- Joined: Mon Apr 21, 2008 2:33 pm
Re: Boosting 2500mAh LiPo to 5V
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.
- rubidium
- Posts: 43
- Joined: Sun Nov 18, 2012 10:36 am
Re: Boosting 2500mAh LiPo to 5V
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.
- adafruit_support_mike
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Re: Boosting 2500mAh LiPo to 5V
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.
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.
Please be positive and constructive with your questions and comments.