Intelligent battery charger circuit

[donkey41]

nicd charger circuit

hi,

I have a litte different problem.

Suppose, I have a charger to charge optimaly according to my need, and suppose
that I have an apropriate source of power, via AC-DC adapter, to drive my
intended load (led, motor, whtever).
I want to have a system which should run normaly from power source (AC-DC adapter)
and want to have the battery backup for the case when mains power is not there
(through which the AC-DC works).
I know, I can use a UPS for this purpose, but I want to build myself a simple
circuit which can switche from power source to battery backup.

I have tried to search the forum and google, but could not get my answer (perhap
because I dont have specific keywords to search this kind of topic).

If it is discussed already somwhere in this forum, kindly forgive me
and let me know the link.

regards.

 

[RenatoBR]

intelligent battery chargers circuits

I have made some tests with the charger_v1.2.hex.

One NIMH 2500 mA - current 1.13 A - fail peak many times
One NIMH 2500 mA - current 1.36 A - fail peak many times
With two cells, works very well with 1.13 A.

I have tried simulation with this last hex and Proteus, didn't work.

Error message:
FATAL: [U1] Program or EEPROM data has invalid address [2000] for this device
Real Time Simulation failed to start

 

[Dexter Dude]

irf 540 connection

Proteus can be quite silly sometimes .Hex file is "snapshot" from my PIC ,and it is working fine in my charger .

I tried to recharge an over discharged element (using previous version ).The charger refused to charge and displayed E+A .The charger started only when I recharged (outside charger) a little this ellement . So , I'v made some modification to software and now the charger works fine with these over-discharged elements <=> charger_v1.2.hex solves this problem.
If you like here is charger_v1.2.hex without config. bits .Proteus will be happy with it but is the same software as before.
https://depositfiles.com/files/2970624


"One NIMH 2500 mA - current 1.13 A - fail peak many times "

RE: Did you format these batteries ? (slow charge at c/10 followed by discharge at c/10 .Repeat procedure at least 3-4 times).

 

[RenatoBR]

battery charger+circuit+pcb

"RE: Did you format these batteries ? (slow charge at c/10 followed by discharge at c/10 .Repeat procedure at least 3-4 times)."

OK, I'm recycling the new one I have bought.

Coming back to charger from Eric Brower, I'd like to know if I'm doing the correct calibration.

The author wrote:

CALIBRATION: Apply voltage to charger output. Adjust R4 so that D4 comes on at 0.5V per cell. i.e. for four cells, calibrate at 2V.
NOTE: Suitable for 2 to 8 cells.

My procedure:
For 2 cells - power up the charger with batt in and calibrate pot (pic pin 1) a little
bit more then 1 volt.
For 4 cells - the same pocedure and calibrate pot (pic pin 1) a little bit less then 2 volts.
If I calibrate exactly at 1V and 2V. the charger does not work properly.

Calibration for 1 batt: I have tried several ways, with and without batt in, but the peak fails several times for each time I try to charge 1 cell.
What you say?

 

[TCPIPV6]

best sla battery charger circuit

Dexter,

After the discharge, the status on the serial monitor changes from Dch to Bin.
I assume Bin means batteries in and 35 seconds cooling down. After 35 seconds the charge starts but te status remains on Bin. Is this normal?

 

[RenatoBR]

intelligent charger avr

TCPIPV6,

Is your charger working?
If no, use this calibration from Dude that is easy and you don´t need pc to check.

"I made some tests .The ratio between (Charger output) / Voltage on Pin 17) should be 2.1:1 . So if you have 0.803V -> adjust Pin 17 to 0.382V ."

 

[TCPIPV6]

attiny26 nimh charger

RenatoBR,

So far I can see the charger is working. It discharge, waits 35 seconds and then starts charging. I didn't wait for the whole chargeprocess to complete. Is your charger showing a charging status via the serial port?

I'm not able to test the charger for a couple of weeks from now.

 

[TCPIPV6]

dexter charger

Dexter,

Is it normal that the charge starts but te status remains on Bin?

 

[Dexter Dude]

lithium charger lm7805

No .It is not normal . The charger stayes in Bin state only for 35sec. Please read previous discussions .

I have re-uploaded hex file here :
http://depositfiles.com/files/4413624

 

[tiochico27]

pic intelligent battery charger

Hello 4 all

I need .hex files from this project why the site have been deleted the files upped by Dexter Dude, again...

Dude, can you send files to mais e-mail or up him to a site again?

THX Bro

 

[Dexter Dude]

atiny15 asm

I received some requests so here is new link ( naughty depositfiles ) :

This is the latest version on this thread
Update : March 07 2009

Minor hardware updates ( see schematic)

 

[tiochico27]

charger circuitry calibrating

thankyou so much

Added after 1 hours 56 minutes:

Dude, can i use other transistor to replace BC173? I don't find this here.
the BC549 work great?

Thanks.

 

[Dexter Dude]

eric brouwer batterycharger

BC549 is fine .

Any npn general purpuse transistor should work fine ( exemple from BC5xx series )

 

[DE2IS]

delta v charging circuit

Thats great guys.I wanted a charger schematic.

 

[fratello]

intelligent charger pic

Great schematic ! I want to do this !!!! I have all the pieces, but please post the PCB. Thanks in advance ! The links don't works.

 

[D_A_V_E]

discrete intelligent battery charger

if just charging a 1 cell Lithium use the Bq series is perfect and small and easy to use

 

[Dexter Dude]

battery loader atmega

Here is the PCB ( green wires are wire connections ).

 

[fratello]

acc charging solar panel pic16f

Thank You verry much DD ! You are one fine gentleman...

 

[wee85]

intelligent nicad controller circuit

is the program for the PIC in asm file?

 

[Wicked Witch]

application note bq2004

Thank you very much for sharing this project with us.
I have just build this project and it seems to run well.
But I will surely subject it to extensive testing in the followings weeks.

Nevertheless I would like to suggest a design modification of the schematic based on the problems I have already encountered.

First, using a scope I discovered that during a charge pulse the LM317 current source occasionally goes into oscillation. Older Cells with higher internal resistance or small AAA or 2/3AA size cells seem to favor these oscillations.
The remedy is (like with most linear regulators that exhibit oscillations) a 47-100nF ceramic cap from the output (i.e. pin 2 of LM317) to ground.
The same applies to the LM7805. To minimize the risk of oscillation on the 5V rail (see application and design notes on the LM78xx series regulators) which may interfere with the PIC operation/AD conversion, it would be advisable to have additionally a 100nf ceramic cap parallel to the 1u electrolytic already present on the output of the LM7805.

Second I assume that the 4K7 resistor from G to S of IRF530 is counterproductive when trying to get a MOSFET with quite high Gate Voltage Threshold like IRF530 to turn on with a low RDSon.
In discharge mode of one cell my scope showed 600mV voltage drop across the Drain-Source path of IRF530 during the discharge pulse which translates to roughly 800 mOhm RDSon. After removing the 4K7 the voltage drop across D-S of IRF530 dropped to 100mV. This is a significant increase in conductivity (which translates to lower RDSon) of the MOSFET.
So if your intention was to have the MOSFET operate at low RDSon, I would suggest omitting the 4K7 and lowering the 1K from PIC Pin 16 to G of the MOSFET to 220 Ohm when using IRF530. MOSFET with lower Gate Voltage Threshold like those from MoBos or "Logic Level MOSFET" like IRL3103 should work with this modification as well.
BTW some time back in this thread on 12 DEC 2007 you said that "For IRF530 using IRF540" was "not critical". My search turned up that IRF530 had a Gate Threshold voltage of 2,9V. With IRF540 it was 10V. So you may never get a IRF540 to work the way the IRF530 it is intended when driving with 5V Gate Voltage.

And finally I was wondering if you could please modify the code of the PIC to deliver a RS232 data stream during any operation mode. Especially during the charge modes S,H,F, since I would like to monitor the voltages/status during the charge period, too, and with this data make conclusions as to where and why peak detection or other criteria may fail depending on the type of cell, charge current, age of cell, manufacturer etc.

Thanks again for sharing this project.

Best regards

Wicked Witch