Site Search:
Speak Korean Now!
Teach English Abroad and Get Paid to see the World!
Korean Job Discussion Forums Forum Index Korean Job Discussion Forums
"The Internet's Meeting Place for ESL/EFL Teachers from Around the World!"
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Android Device Using Buck Converter (Voltage Regulator) inst

Post new topic   Reply to topic    Korean Job Discussion Forums Forum Index -> Technology Forum
View previous topic :: View next topic  
Author Message

Joined: 27 Nov 2017

PostPosted: Thu Dec 07, 2017 6:19 pm    Post subject: Android Device Using Buck Converter (Voltage Regulator) inst Reply with quote

Hi to all, before I start my project that I think about it's perfect of result at the end of, but it just my thoughts. The situation is following, I have a project that is basically replacing my car's instrument panel with an Android device (a tablet). I managed to make everything work except for one thing: the Li-Ion battery of the tablet was heating up in the hot days (I live in Brazil). The solution that I found was to remove the tablet's Li-Ion battery and try to use a voltage regulator to replace it.

My first try was to use a 2A buck converter to drop the 12V battery voltage to 3.8V and use this as a power supply for the tablet. I managed to remove the flat cable used in the battery and soldered 3 wires (the positive and negative leads plus another wire that is probably a thermitor). Carefully using a multimeter I measured the resistance between the thermistor wire and the negative lead of the battery, it showed up something like 80kOhm. Then I adjusted the voltage regulator for 3.8V, connected the tablet wires accordingly and put a 80kOhm resistor between the thermistor wire and the negative lead.

When I tried to power on the tablet, nothing happened. I then increased the voltage to 4.3V (I read in the battery that I removed that the charging voltage was max 4.35V, so I thought that it was not a problem to try to increase the voltage a little bit) and this time it showed the Samsung logo for 3~5 seconds and turned off.

I was able to boot up the device and keep it running for some seconds with the following: besides powering it using the voltage regulator, I also plugged a USB002 charger in it. The boot, then, succeeded, it stayed on for some seconds and then powered off again.

Talking to a friend of mine that is an electrical engineer, he explained to me that these kind of devices sometimes have current peaks and that this 2A voltage regulator may not be able to handle the current peaks on GSM bursts and so on.

What I did then was to buy a 12A buck converter with both voltage regulation and current regulation (through potentiometers). Today I tried to use it, expecting it would work, unsuccessfully. I adjusted the voltage to 3.8V (also tried 4.3V as before) and adjusted the current to max current. The same thing happened. This time I used the multimeter to measure the current passing through the tablet and what I got was that when I try to power up it draws something like 200~300mA from the voltage regulator for 3~5s and then it powers off.

If someone could help me figure out why the voltage regulator it not working as expected, I would be grateful.

The 2A buck converter:
The 12A buck converter:
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Korean Job Discussion Forums Forum Index -> Technology Forum All times are GMT - 8 Hours
Page 1 of 1

Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

This page is maintained by the one and only Dave Sperling.
Contact Dave's ESL Cafe
Copyright © 2018 Dave Sperling. All Rights Reserved.

Powered by phpBB © 2001, 2002 phpBB Group

TEFL International Supports Dave's ESL Cafe
TEFL Courses, TESOL Course, English Teaching Jobs - TEFL International