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Trying to develope Battery Bank for Mobile Charger.

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Sajjadkhan

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I am trying to make a battery bank. I have soldered 9 lithium polymer batteries of 3AH in parallel to give 27AH of total capacity. They are soldered and glued and i can not take them apart.
After doing that i found out that how hard is to make a boost circuit with decent Amps. did a lots of search and ended up with nothing. No diagram online, seriously. I searched for schematics but no circuit was able to boost from 3v to 5v at decent amps. By decent i means at least 2 Amps. I searched tear downs of battery packs and ic numbers were rubbed off.

At the end i ended up with Lt1370 and ordered 2 of them with the inductors and caps recommended in the datasheet. I layout the PCB exactly as the instructed. after 2 minutes of mobile charging, voltage was getting weird up and down (i was monitoring it on oscilloscope ). It was drawing 3Amp from Supply and sourcing 1.2Amps. five caps were put in parallel (100uf, ESR=0.2 ohms,16v) one of the cap blew. At this point i came to know that when tantalum cap blows, they get short. So now the whole circuit was drawing 5Amps which is the limit of my PSU. I removed the cap and power up the circuit again and the next cap blows. all did the same one by one. this time with no load. i checked the ic compared the other new piece i have and the Vsw pin = switching pin was being shorted with the ground. i tested it after de-soldering it. the new one was not showing the continuity. so i installed the new ic and this time is used almunium caps of 25v rating. After 2 min they started smoking so i shutdown the circuit. and now the new ic is showing the same symptoms like the old one. Now i gave up on these ics as they are too damn costly.

Now i am looking at MCP1650. in Datasheet the schematic can provide 5v @ 1Amps. My questions: is it possible to get 2Amps or more by replacing the components with some high current capability components. I would be happy if you guys Help me in building this battery bank charger.
 

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