12 Volt Car battery charger with ADC

rafael_jimenez · Joined: 26 Oct 2006 Posts: 27 Location: Wesseling

Hello People,
I'm doing a battery charger for my car,but can not get me as I wish functions.
in my code, I read the ADC status every two seconds, I think it is configured well timer1,
but the timer1 makes me blink on port B, 0 each interruption, when the battery is charging,
maybe you can tell me where my problem?
by the way,
under conditions( IF Then , I have tried in various ways) that would begin charging the battery when low volt 12.20
but I can not get the relay is activated when the battery is low volt 12.20,
maybe someone can lend a hand, please.

snipsnip · Joined: 10 Feb 2014 Posts: 66 Location: Melbourne

Try not using CLS, instead just print extra spaces to over write the longest text ie "hello world" will be replaced with "gone ........... "(dots are spaces)
CLS Takes a long time!!

Also - why you doing everything in the interrupt - do as little as possible. you've set it for two secs but have a wait 2 at the end of it before the exit ??

Id re-write the whole thing without using interrupts - You don't need it for "get adc". keep it simple.

i.dobson · Posted: Wed Mar 11, 2015 12:51 pm Post subject:

Hello,

Please do not put your program in the ISR. What you should do is keep the ISR and short as possible. What you should do is just set a flag in the ISR and the main program looks at this flag.
Something like:

albertsm · Joined: 09 Apr 2004 Posts: 4966 Location: Holland

- I removed your serial nr. from your post.

how do you connect the battery to the A/D converter input? I assume you have a resistor divider. Since you have a reference of AVCC, which is 5v ? make sure the maximum input is 5V. (use a zener to protect against overload).
I do not get this code :
For A = 1 To 14
Valueadc = Valueadc + Getadc(6)
Next A

if you want an average you need to divide it.

i also do not get the fact that you have an empty do..loop and use an ISR.
you can simply put your ISR code inside this loop.
Last, increase $hwstack to 40 when using an ISR.

rafael_jimenez · Joined: 26 Oct 2006 Posts: 27 Location: Wesseling

Thank you very much,

Hello Mr. snipsnip,
you are reason, but I did only to see Voltage State, because my code is for Attiny45 without display Very Happy

Thank you

Hello Mr.i.dobson,
I don´t have to much experience with Interrupt but I make change in my code now.

Hello Mr. Arbert, Sorry for my error ,
I Do Test with one Adjustable Power Supply from 11,80V to 16,80V.
Your are reason, I have Resistor divider but with Pot 10K, so
Ground 5K6 >>>Pot 10K<<<< 100K Resistor to 12V + Battery,
I Adjust with Pot the ADC to work fine.
Now my code Work.
But

[code]
'*******************************************************************************
'** 12 Volt Car Battery Charger Monitor
'** Battery 68Ah 560A.
'** Battery need 14,40 Volt constant current
'** Compiler version :2.0.7.8
'** Compiler build :2.0.7.8.004
'** IDE version :2.0.7.8.003
''** Windows OS :Windows 7 Ultimate
'** Windows Sp : Service Pack 1
'** Rafael B.Jimenez
'*******************************************************************************
$regfile = "m32def.dat" ' Atmega32
$crystal = 1000000 '1Mhz
$hwstack = 40
$swstack = 40
$framesize = 40
'$sim

Dim A As Byte 'for 14 x ADC
Dim Voltage As Word 'calculated voltage ADCvalue
Dim Valueadc As Word 'Battery Voltage
Dim Timecount As Word
Dim Displayvolt As String * 3 'convert number to string for decimal point value
Dim Voltstring As String * 4
Config Portb.0 = Output 'Switch Solid State Relay
Config Porta.6 = Input ' pin for ADC

'_______________Configuration LCD ________________________________

Config Lcdpin = Pin , Rs = Portc.2 , E = Portc.3 , Db4 = Portc.4 , Db5 = Portc.5 , Db6 = Portc.6 , Db7 = Portc.7

Config Lcd = 20 * 4
Cursor = Off
'---------------------Configuration ADC----------------------
Config Adc = Single , Prescaler = Auto , Reference = Avcc
Start Adc

Do
'__________________________________________________

Valueadc = 0
For A = 1 To 15
Valueadc = Valueadc + Getadc(6)
Next A

'---------display state ---------------
If Valueadc > 4176 Then ' if the value is over 14,40, 4176/14,40 = 29
Portb.0 = 0
Cls
Lcd "FuLL"

End If

If Valueadc = 0 Then 'when value adc cero , no battery
' Portb.0 = 1
Cls
Locate 1 , 1
Lcd " No "
Locate 2 , 1
Lcd "Battery "
End If

If Valueadc < 4177 And Valueadc > 0 Then 'If valueADC are under ValueADC and over cero

Portb.0 = 1 'Switch Relay ON

Voltage = Valueadc / 29
Displayvolt = Str(voltage)
Voltstring = Format(displayvolt , " 0.0")

Locate 1 , 1
Lcd "charging"
Locate 2 , 1
Lcd Voltstring ; "V "

End If

Loop

I mean:
I want that when the Port-B is low is kept low until the voltage of the battery reaches 12 volts, the battery should always be between 12.20 to 12.30 volt and then under 12,20 the PortB.0 go High.
I test divers Form but do not get fine.
maybe someone has a better idea than I.
Always thought as my code works, but want it
when the value reaches 12.20 adc disable relays

Thnak you very much.
Regards

Deanus · Joined: 26 May 2006 Posts: 188 Location: Adelaide

Hi Rafael_jimenez,

I agree with the others whe they say do the minimum abount possible sutch as set a flag and do the rest in the main loop.
A couple of things with battery chargers,

1) Turn OFF the charging voltage Before measuring the battery voltage else you will only be reading the charge voltage and the program will terminate the charge too early.

2) You don't mention what type of battery you are charging. NiMh, NiCd, SLA, LiIo all have different charging patterns.

3) I really would like to see the battery that requires charging anywhere from

rafael_jimenez · Joined: 26 Oct 2006 Posts: 27 Location: Wesseling

Hello Deanus,
Thank you for you answer,

My Battery is for Car, GigaWatt Calcium Technology and form manufacturer say need Constant 14,40 volt,
my Adjustable constant Power Supply is from 0Volt to 15Volt 4Amp

I do so
For A = 1 To 15
Valueadc = Valueadc + Getadc(6)
Next A
for better unit resultad,

Sorry, perhaps ye not understand my explanation, I use 2 Resistor and one Potentiometer in my Resistor dividir to Adjust the correct ADC Value for Battery and looking so,

GND<5K6> (to 10K Potentiometer here to adc(6) <100> to Battery Plus
please See Schematic circuit.
My code prepare for one Attiny45 with Led charging control.

My code it works, but only I nedd when Battery is to 14,40 Volt Switch Off and Waiting when Battery voltage come down to 12,30 Volt, my Code doe Hystery and continuous loading all,
I need a solution, when the battery is charged burdens stop and wait until it is depleted
I am no to much experiencie with bascom , I am I am an electrician
Razz

Thank you for you help
Regards

EDC · Joined: 26 Mar 2014 Posts: 671

This example show simple logic. You can set "name" for constans for better code readable and then use simple "state of unit mechanism"
State of unit You can change in any part/ place of code and then in next loop another part of code will be run.

P_Santos · Joined: 07 Jul 2011 Posts: 102

Hello,
I take this post to try to know how to properly do the evaluation of the percentage of the autonomy of a Litium battery.
I think that when we are measuring the voltage it must will have to be injected a load to the battery.
Will my reasoning correct?

Best regards
P_Santos

rafael_jimenez · Joined: 26 Oct 2006 Posts: 27 Location: Wesseling

Thank you EDC,for you logic Function, but no undestand to much, I Teste your code, but I can not find good results,
I test now so

EDC · Joined: 26 Mar 2014 Posts: 671

Try this joined code Smile

Ofcourse some bug can be..

rafael_jimenez · Joined: 26 Oct 2006 Posts: 27 Location: Wesseling

Thank very much EDC
Now you function , very nice Very Happy

I studie you Code .
I wannt now one Ask,
to see nummber in decimal in Display but so
00.00, I test with String but I do not get the point.
can you give me an example, Please.

Thank you to much.
Regards
Rafael

EDC · Joined: 26 Mar 2014 Posts: 671

If I`m understand what You want then instead of this

rafael_jimenez · Joined: 26 Oct 2006 Posts: 27 Location: Wesseling

Ok now i understand,
Thank for your clarification.

Regard
Raffi