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I want to power a device with up to 4A at 5V from a single-cell LIPO battery of 3.7V 5000mAh and be able to charge it. The idea is to have everything packed up inside a case, so I don't want to rely on an external charger and instead be able to charge it from USB2.0.

To convert the power from the battery to the device (from 3.7V to 5V), I plan to use a boost converter capable of supplying up to 4A ouput current (such as a XL6009 converter).

However, I don't know how and where to add a charger (such as this one, or any other one that would fit).

I'm not very versed in electrical engineering. Please help :) Thank you.

EDIT: I found this charger which allow to charge the battery while offering a direct output connection to the device. How can I be sure that the output connection can support the ~6A @ 3.7V current drawn from the battery ?

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  • \$\begingroup\$ So - reading between the lines - you want to build a power bank? \$\endgroup\$ – brhans Mar 19 '19 at 12:51
  • \$\begingroup\$ Not really, I am building an electronic device, but I want it to be easy to charge with a USB or micro-USB plug. The device has many small screens and a power-hungry camera capable of running deep-learning algorithm, that's why I need quite a high current. Actually, I'm trying to build a functional Kanto Pokédex \$\endgroup\$ – Jérôme Bruzaud Mar 19 '19 at 13:12
  • \$\begingroup\$ so your battery will not last for more than 1 hour if you consume all the 5000mah ? \$\endgroup\$ – Hasan alattar Mar 19 '19 at 13:14
  • \$\begingroup\$ That is right, however, the 4A comsumption would only last a few ~10s at each use (when using the camera and the deep learning algorithm), then would go back to ~0.6A for main use. The device will be shutdown or set to "sleep mode" most of the time, consuming around ~0.1A when not used. All in all, it would probably last a few hours, maybe half a day with moderate use. It is a first prototype. \$\endgroup\$ – Jérôme Bruzaud Mar 19 '19 at 13:20
  • \$\begingroup\$ tps61088 ? would work? \$\endgroup\$ – Hasan alattar Mar 19 '19 at 13:44
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Yes the SparkFun board is designed for exactly that. The limiting factor is the JST connector, but as long as that 6A rate is fort short runtimes you should be OK.

Test the temperature rise in hot ambient conditions, inside your enclosure at the XH wires and plug, holding 6A for say 10x longer than you imagine.

The other issue is the very low charge rate, if the cycling usage minutes per hour gets too high for too long, might need a higher mAh capacity battery to carry through the high activity times until the quieter recharging times.

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