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Topic: Lipo Battery feeding the DC Power Supply on power outages (Read 254 times) previous topic - next topic


Hi, For my project I am using MKRwan 1310 with 3.7 v battery and 5v DC Power supply. Normally, the MKRWAN 1310 is running from DC Power supply and charcing the Lipo battery, but when power outages happened on mains MKRWAN is still running but the battery reversely feeds the DC Power Supply to beacuse indicator led on it still lit on. This stution causes very fast battery drain. I thoght to put a diode on V+ of USB cable but as I reed it will cause voltage drop.  How can solve this?
I attached the diagram.


Use a Schottky diode like 1N5820. They have less than 0.4V voltage drop. Which should be OK for your application.
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Mkrwan 1310 specs says, input voltage must be 5v. Is 0.4v drop on input cause other problems such as battery charging or slowdown on samd21 chip ? 


The Mkrwan 1310 uses bq24195 battery charger which accept 3..9 - 17V input. So it will work with diode. However that battery charger should take care about USB back feeding. So most likely  your quick battery discharge related to some other problem. And apparently it's a SW issue. 
Don't say "Thank you", just click on 'karma [add]' instead.


However that battery charger should take care about USB back feeding.
Well, it certainly should, but if the LED on the Meanwell is illuminated, it is hard to deny that it is back-feeding to some extent!


I designed a shield to catch pulses from drycontacts, Is that be releated with shield?


The datasheet for that Meanwell supply says the output voltage is adjustable from 4.75V to 5.5V.


It appears there's a pot near the LED.

If that's the case, you could use a diode, and adjust the output voltage up to compensate.


As Sherman said just about every industrial power supply has a pot to adjust the output voltage a little. After installing the diode between the power supply and the MKRWAN, grab a meter and check the voltage at the MKRWAN terminals. Adjust the pot until the voltage at the MKWAN reaches 5V.

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