Charged or Fried??? - Page 1
Forum section: electronics / beginners

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: September 04, 2014, 11:13:57 pm
content: Hello i have a question for a project.I built a simple circuit using a linear voltage regulator the LM7805.I filtered the input and output of the regulator using 2 * 10 uf electrolytic caps that have a tolerance of 16 volts and i supplied the circuit using a 9 volt power supply at 1 Amp.But it wont output 5 volts (thought the usb port i use as an output)Also all the connections are done right.I built this in order to charge my phone (Xperia SP) when im out of home using a 9 volt battery.But i dont want to fry the phone.So i would like advice on the circuit design what do i have to be careful about so i do not damage anything and about the connections to the female usb port... only VCC and GND or should i connect a data line to GND so the phone knows it is charging.Thank you in advance.

author: tautech
author_rank: Super Contributor
timestamp: September 04, 2014, 11:28:07 pm
content: Quote from: ChrisGreece52 on September 04, 2014, 11:13:57 pmPost a schematic.

author: mariush
author_rank: Super Contributor
timestamp: September 04, 2014, 11:35:21 pm
content: A 9v battery can not supply enough current to make most phones happy. A 9v battery is designed for... maybe peaks of 100-200 mA. The standard usb is 5v at 500mA and some phones use up to 1A. As the phone pulls lots of current, the voltage will drop from 9-10v down quite fast.A 7805 needs about 6.5-7v to output 5v, and the 9v battery will go down to 6.5-7v levels if you pull a lot of current.Post the schematic as tautech says, let's see how you connected everything.Some phones won't charge if the data wires/pins are not used in some way. Older apple phones want to see some voltage on those two data wires, which can be done with 2 sets of resistors. New usb charging standards say the two data wires have to tied together, other phones expect a resistor between those data pins.This page explains how to configure the data wires to simulate an apple charger :https://learn.adafruit.com/minty-boost/ichargingps. In addition, 7805 is a linear regulator, and a very poor way of providing energy to a phone. With linear regulators, current goes in, same amount of current goes out, just voltage changes. So the higher the voltage difference, the worse efficiency. With 10v in (fresh 9v battery), 5v out, you're looking at 50% efficiency, which is very bad, you're wasting half the battery as heat in the regulator.Even a basic mc34063 dc-dc converter will start from about 65-70% efficiency.

author: Simon
author_rank: Unknown
timestamp: September 05, 2014, 07:03:41 am
content: I'm guessing the 9V battery only has a total capacity of 2-300mA at best so your not going to get much life from that battery anyway it's not even worth using it.Your best bet is a pack of AA's and if you don't mind Li-ion cells you get 3x the power for the same space so two AA size batteries (for li-ion they have another name that means the same size) you get 7.2V 2A which is something worth having and will be able to deliver the current. Then you use a switchmode converter.For a switchmode converter if you go and find a controller, the MC34063 is easy to use and popular you will be given all the formula's on the datasheet for calculating components. With a switchmode converter you get 70-90% efficiency so less heat and more power for your money and space.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: September 06, 2014, 10:06:06 am
content: I am sorry for my ignorance. Here is the schematic.Edit : I am basically worried about the phone withstanding the charging current.I dont want my phone to fry so i need the most efficient and most safe solution.

author: amyk
author_rank: Super Contributor
timestamp: September 06, 2014, 10:16:21 am
content: Get the voltage right and it will draw however much current it needs.

author: fww
author_rank: Contributor
timestamp: September 07, 2014, 02:42:29 am
content: I find a same project with yours from a chinese website, just only for your reference.http://www.diyleyuan.com/index.php?m=content&c=index&a=show&catid=31&id=618------------But I'm not sure it is a valid, maybe you can measure voltage twice when it not load and load.

author: meshif
author_rank: Newbie
timestamp: September 07, 2014, 08:51:11 am
content: Not sure what ever happened to my Eagle files but it should be pretty easy to recreate this based on the picture. It works for most phones and other 5V devices. Probably not the best way of doing it but this was my first design that made it all the way to the "mass" production stage. If you wish to recreate this, you would probably want to connect D1 to the output of the 7805 rather than the switch. This way you know if your battery has enough juice to run the 7805.Silkscreen designations are as follows:CON1 - Input (9V battery clip)SW1 - SPDT power switch (can also use SPST)D1 - Power indicator LEDU1 - 7805C1 - Input filter capC2 - Output filter capD2 - 5.1V zener diode (extra protection because why not)CON2 - Output (I bought a bunch of cheap cables off eBay and soldered the microUSB end to the board)Go ahead and rip me apart for the crappy design on this one. Like I said, it was my first real attempt at "proper" PCB design and production and it actually worked so I was happy with that. I was able to get 3 of these on a 5x5cm PCB and I ordered 5 PCB's from Seeed. All 15 went into service and are still going just fine.

author: Simon
author_rank: Unknown
timestamp: September 07, 2014, 09:05:42 am
content: With the capacity of a 9V battery and it's inability to source high currents using one is pretty pointless (and possibly dangerous if the battery overheats), why not swap the 9V battery for a pack of AA batteries, 4-5 of them will do it and if your lucky you could probably charge off just 4 if they are 1.2V....

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: September 07, 2014, 10:46:23 pm
content: To begin with thanks for your responsesI need something efficient so i threw the LM7805 out of the project and i am doing a research on how to use MC34063 the most efficient way and order some pieces i found cheap on ebay so i can get going ASAP.As for the power source i have an old laptop battery which uses LGES318650 Lion Batteries 6 of them and it has the original charging controller connected.http://www.batteryspace.com/prod-specs/icr18650nh-2200.pdfI am such a noob i have no idea how to charge the thing(what voltage and current should i apply and such)Here are some pictures of the pack.

author: Simon
author_rank: Unknown
timestamp: September 08, 2014, 05:47:08 am
content: The pack needs charging from it's original controller or you may end up with a firework on your hands. Most laptops charge off 18-19V 3.5A ish

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: September 08, 2014, 11:37:17 am
content: Cool but can i just connect the transformer to the charging controller

author: Simon
author_rank: Unknown
timestamp: September 08, 2014, 11:42:12 am
content: Yes as far as I know, I don't know if there is anything in the laptop between power in and battery connector.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: September 08, 2014, 12:14:53 pm
content: Not sure too.The combination of my minimal experience and the lack of equipment right here does not help the case.Anyway i have the motherboard of the laptop but i have removed some chips (i will link them below) from it.I dont know if this matters charging wise so i will highlight their locations on the boards photo.Ill get the photos up as soon as i can.

author: Simon
author_rank: Unknown
timestamp: September 08, 2014, 12:30:50 pm
content: Try connecting a meter in continuity mode from the power jack to the battery terminals, if you get a buzz from both negative and positive pins of the jack then you can connect power straight to the battery.

author: notsob
author_rank: Frequent Contributor
timestamp: September 08, 2014, 08:27:19 pm
content: Have a look at this phone charger - kit available from adafruithttp://www.adafruit.com/products/14

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: September 09, 2014, 05:03:13 pm
content: Cool but the thing is i do now own a multimeter .... i ordered a cheapo one from ebay and i am waiting for it righ now.

author: Michaelo
author_rank: Newbie
timestamp: December 31, 2015, 06:09:51 pm
content: I know it's an old thread but I ended up here searching for info on LGES318650 batteries Dec 2015...As there's not much info on these batteries and there's a lot of old laptop out there with LGES318650 batteries still being taken apart and reused, I just wanted to point out LGES318650 batteries are 3.6 Volts not 3.7as indicated in this thread...Apparently even a 0.1 voltage difference can cause issues with Li/Lp circuits...

author: alsetalokin4017
author_rank: Super Contributor
timestamp: December 31, 2015, 11:44:55 pm
content: Er......http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries