Universal Battery Charger

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wizpic said:
What do you mean by updates ?
Has far has I'm aware there is none if your talking about software
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Hi wizpic,

i tried to click on the link shared by Felix on 4shared.com, but the link is not valid anymore.
I wish to review on his c code as what he did in PIC16F877A.

Thanks.

Regards,
Joe
 


Hello to all, this is my first message.
It's many times I would like to build an UniversalCharger. Some months ago I see this project http://www.seven-segments.com/index.php?action=menucats&id=43
I bought the IC ACS756 (evolution of ACS750), but I discoverd the sensibility is very low about 100mA. I tried to contact the author and I discoverd also a new IC ACS714 with better sensibility about 19mA with max 5A (perfect for me).
I began to adapt the PCB to new IC and also the source, during this work, I discovered the ACS714 has a better sensibility about 1mA with OpAmp as LM324.
There is many work to do. I done only some tests for now. I would like also to convert source code from Pascal to C and change PIC from PIC16F876 to PIC18F2550. USB with Emulation Serial so I can remove MAX232.
Today I discovered this Universal Charger with some difference by other project. No current sensor and buck converter.
Which is better?
I need to regulate tension from 1,2 to 20V with step 1V and for the current 100mA to 5A with step 20mA is good.
Can I charge LiFe battery? Universal Charger of Seven Segment permit to create other profiles so I can charge also LiFe without change the source code.

Thank you for your suggestions.
 

I know I know old post but....
did a schematic ever turn up or have a missed it somewhere ?


ok i found it in the left hand side of his webpage in Spanish
thanks
David
 
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Please help me. How can I program the 24lc256 (eprom) in this circuit. Sorry for my poor english.
 


Thanks a lot for your help. I tried so much to compile the code files but I could not do it. I have some questions;
1. Which program must I use to compile the codes? Mplab? Ccs, or whatever else?
2. How can I compile the files?
3. Which of the files is the main file and what is the purpose of "makefile".
So sorry for my ridiculous questions. I have no expert about programming. But I believe that I can solve the problems by your worthless helps.
 

faruk32 said:
So sorry for my ridiculous questions. I have no expert about programming. But I believe that I can solve the problems by your worthless helps.
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"Worthless helps":twisted:. What do you mean by Worthless helps. Wizpic gave you the answer. No wonder no one did not help you further.
 

eeye said:
"Worthless helps":twisted:. What do you mean by Worthless helps. Wizpic gave you the answer. No wonder no one did not help you further.
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And he has been here 2009 and only 2 posts :thinker:, No wonder he had no replies, mine is working great :lol:
 

wizpic said:
... mine is working great :lol:
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Great to know that you had success with the project. By the way, I managed to compile the sources and eventually program the controller and build the charger, but the voltages and currents being supplied by the charger were way off. For example if you put an ammeter in series with the battery and program say 900mA of current, you'll not get 900mA (the current keeps jumping between 920mA and 850mA, in my case). Check it out by yourself. Same is the story with the voltages. Be very careful when you charge LiIo/LiPo with this charger, the voltages on the battery exceed 4.5V, which is not good for the battery and sometimes this thing is feeding the supply voltage (due to the spikes in the MOSFET gate). I screwed up a few of my expensive RC LiPo batteries with this charger.

So eventually what I figured out was that the software is missing "PID" control. The charge algorithms if you see are purely "P" (i.e., proportional) governed. So if actual current is greater than controlcurrent, the duty cycle is reduced immediately and vice versa. What is needed is "I and D" components also. The integral and derivative of the voltage and currents. The integral will ensure that the system is damped and the derivative will ensure sudden load changes are accommodated.

If you have noticed, those MOSFET's are running hot when 1A is being pumped into the battery. Why because the MOSFET is not being turned on fully due to bad driver design. Ideally, the MOSFET in the schematic has Rds ON = 0.35ohm. So 1A current will give just 0.35W and the MOSFET should be luke warm. But I had to put a heatsink on the same :???:

In the schematic, the inductor value is not correct. See the app note by TI to calculate inductors for buck converters here

Overall I can say it is a nice hobby project to get understanding of how buck converters work :-D

See the theoretically calculated plots for the original charger and the charger with PID. The output of the original charger is oscillating while that with PID is nicely damped.


Cheers,
eeye
 
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Hi Eeye
I did notice that but only used it to charge a few NiCad's and a couple of SLA batteries, I did notice the voltage/current readings where slightly out, May be I was a bit over the top when I said working great only used a number of times, must admit I've not used it on LiIo/LiPo batteries, I've seen this video tear town from Dave jones of the Turnigy Accucell 6 he goes into with lot of detail, you may want to have a look you can also get the schematic.
https://www.eevblog.com/2012/12/12/eevblog-397-turnigy-accucel-6-charger-teardown/

There is some discussion's here about the voltage readings and how to calibrate here
https://www.rcgroups.com/forums/showthread.php?t=839657
https://github.com/stawel/cheali-charger
https://www.rcgroups.com/forums/showthread.php?t=1046318

I was pondering to have another go and thinking about using the turnigy-accucel-6 based hardware and controlling with a micro/arduino with 12 or 18 bit ADC converter, I've got the IB6 charger(which is what I use more) and hacking into that and remove the atmel controller and just hook up the micro/arduino, but don't seem to get a lot of time at the moment with lots of other projects on the go,
I agree the PID method is the better way to go, May be I will blow the cob webs of it and have ago at it. The IB6 does a good job (readings little more accurate but not the best), my thinking is it does the job ok and think sometimes why bother but then again on the other hand we would have no hobby if we did not do things like this as it makes it more interesting and fun along the way, plus you just use it has a building block and improve it and make it more to what you need and on the plus side if it breaks you have a good idea how to fix it, I like the idea that the IB6 use's a buck/boost converter so you can use other 12V batteries to charge while your out and about or upto a 20V PSU
 

wizpic said:
I've seen this video tear town from Dave jones of the Turnigy Accucell 6 he goes into with lot of detail, you may want to have a look you can also get the schematic.
https://www.eevblog.com/2012/12/12/eevblog-397-turnigy-accucel-6-charger-teardown/
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Wizpic: Thanks for the nice find. Exactly this is what I'm talking about, the closed loop control :thumbsup:

wizpic said:
I've got the IB6 charger(which is what I use more)....IB6 does a good job (readings little more accurate but not the best)
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Me too have the IMAX B6, got the original one from HK for US$50 (incl. shipping). Does a decent job, to keep my RC's going and the LiPo's safe.:grin:
 

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