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Powerboost 1000C - Charging LEDs
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Powerboost 1000C - Charging LEDs

by MasterOfBiscuits on Thu Aug 06, 2020 10:56 am

I've installed one of these boards in an old handheld games console and it works great. I broke out the LEDS and I'm trying to work out whether my battery isn't being fully charged, or if my LEDs are not displaying correctly.

I've wired the Low Batt, Charging and Charging Complete LEDs to a single RGB LED which has separate anodes and cathodes for each. Red is Low Batt, Blue is charging and Green is Charging Complete. I've had the battery on the charger all day while not using the machine and the blue LED is still showing. I have checked the voltage on the battery and it's showing 4.17v and has moved about 0.04v in the past 3 hours or so. I'm using a 5000mah Lipo battery straight from China. The RGB LED will only display one colour at a time which I thought would be no trouble, but I'm now wondering if the charging light will stay on as long as the cable is plugged in, meaning the green LED will never come on. Is this the case, and if so, is there a resistor I can add to switch it off? I've read the datasheet which states that the status pins are open-drain, which I don't fully understand.

Or, could it just be that my battery needs to reach 4.2v before the LED goes off?

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Re: Powerboost 1000C - Charging LEDs

by adafruit_support_bill on Thu Aug 06, 2020 11:07 am

The full charge voltage is 4.2v. But simply getting to 4.2v does not mean that the cell is fully charged. The charge has not yet reached the far corners of the cell and if you were to disconnect it from the charger, you would see the voltage start to drop.

So the charge controller will not stop immediately when it reaches 4.2v. At that point, the charge controller switches to a constant 4.2v 'trickle charge' mode and starts monitoring the charge current. When the current goes to zero, that means that the charge has fully leveled off across the entire cell and the charge cycle will stop.

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Re: Powerboost 1000C - Charging LEDs

by MasterOfBiscuits on Thu Aug 06, 2020 4:50 pm

Thanks Bill, the light eventually turned green, so all is well. It did take a looong time to charge - what would be considered a 'normal' charge time for a 5000mah battery with this board?

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Re: Powerboost 1000C - Charging LEDs

by adafruit_support_bill on Thu Aug 06, 2020 6:28 pm

The total charge time depends partly on the initial charge state of the cell and partly on the design of the cell. The maximum charge rate of the PowerBoost 100C is 1000mA. In theory, if you were able to completely charge the cell at that rate, it would take 5 hours to take a 5000mAh cell from empty to full. But, as explained above, the charge rate needs to slow down as the battery nears full charge.

Cells that are optimized for ultra-fast charging and high discharge rates (e.g. those designed for RC race cars and planes) have more electrode surface area and need less time in 'trickle charge' mode to top off the cell. Cells designed for less extreme applications like mobile phones will trade off some of that high speed charge/discharge capability to pack more capacity into a smaller package. These cells may transition to trickle charge mode when they are only at around 80% capacity and will take much longer to reach full charge.

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Re: Powerboost 1000C - Charging LEDs

by MasterOfBiscuits on Thu Aug 06, 2020 6:45 pm

Very interesting, thanks for the info!

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