Thanks Charles, really useful!!!
charle escribió: > All, > > About the battery charger. May I share my experience with you? > > With the Technical handbook. > http://www.gpbatteries.com/pdf/NiCd.pdf > With the Page 11, > 3.2.4 a). You may find the manufacturer suggest the -dV shound be 0~20mV per > cell. > > http://www.gpbatteries.com/pdf/NiMH_Technical.pdf > With Page 13, 3.2.3 b). You may find the -dV should be in 0~5mV / cell and > the suggested value was 2mV/cell. > > And check with another vendor - Panasonic. > > http://www.panasonic.com/industrial/battery/oem/images/pdf/Panasonic_NiMH_ChargeMethods.pdf > > With item (5). It noted the -dV on panasonic Ni-Mh battery should be 5~10mV. > > There are much other vendor datasheet you may check. > > > Base my experience, you should check the dV in 2mV per cell on open case > charging with Ni-Mh battery. > If your battery was packed you may set -dV to 4~5mV per cell due the Thermal > resistance from battery to air will be larger. > And plus 50% of -dV on Ni-Cd battery. (3mV and 6mV) > > Because the -dV was due the temperature rise caused by over charge. > > Control the over charge ratio was the key to extend the battery's life > cycle! > > Hope these information can help you to design a good charger! > > Regards, > Charles. > > >> ------------------------------ >> >> Message: 5 >> Date: Fri, 09 Mar 2007 23:21:46 +0000 >> From: Rod Boyce <[EMAIL PROTECTED]> >> Subject: Re: [Sdcc-user] [OT] - ADC Ideas >> To: sdcc-user@lists.sourceforge.net >> Message-ID: <[EMAIL PROTECTED]> >> Content-Type: text/plain; charset=ISO-8859-1; format=flowed >> >> All, >> >> Firstly a correction this is not my circuit I found this on Google and >> posted the link as a example of what somebody else did. Now some facts >> I have used a very similar design to charge a 7.2 volt battery pack with >> an 8-bit ADC my peek detect charger only had a resolution of 2 counts to >> detect the peek and switch from fast charge to slow charge it is working >> very well. It reliably detects using a delta slope detection method and >> I have decided to accept a 55.4mV over charge and use a count difference >> of -3 counts to detect the charged condition and switch off the charger. >> >> Below is the basic charging algorithm I used it is quite simple: >> * A battery charger that detects it has been plugged in to the charger >> power supply. >> * Obtains the current battery status, reads the current battery voltage >> and waits for a stable reading. >> * Begin charging >> * Takes the current battery voltage every second and decides what to do >> next. >> * If the charging battery is above the correct voltage threshold then we >> begin looking for a voltage peek. >> * Once the peek has been detected the charger is switched off. >> >> I wrote this for a customer so don't ask for the source and this is only >> for NiCad batteries if you are doing other batteries you will need to >> research your own charging algorithm. >> >> You need to make sure that your ADC has enough resolution to detect the >> switch off point if you don't think that 10-bits are enough then use >> 16-bits. But a 10-bit ADC wit ha range of 3.3-volts has a resolution of >> 3.2mV and a 12V NiCad pack will have a peek detect of 20mV per cell or >> 200mV divide this by the a resistive divider of 6 gives a peek detect of >> 33.3mV which will give you a count or 10 or 11 counts this should be >> more that enough resolution to peek detect a 12Volt NiCad battery. >> Because you don't have to measure the ADC very often you could even over >> sample the ADC reading to get a cleaner reading. >> >> >> >> Markos wrote: >> >>> Hi Rod, >>> interesting design! Thanks. >>> How do you decide when to finish the charge? By the delta Peak. Have a >>> look at this (Fig 2): >>> http://www.maxim-ic.com/appnotes.cfm/appnote_number/680 >>> It is a typical (fast) charging voltage plot. With the divide by 4 >>> voltage Vsense, I will be loosing resolution, isn't it? >>> I mean, suposing that we have 0-5V in Vsense, 10 bit ADC gives 4,8 mV >>> per bit (adc step). Your resolution is divided by 4, so 4,8 x 4 = 20 mV >>> per bit + we must add the +- LSB ADC accuracy, thats a 40 mV error.... >>> So I think I won't be able to detect the 10 mV delta Peak.... >>> >>> In the description of your circuit you mention an 84 mV delta peak. Is >>> that peak the result of Delta * Num of Cells? >>> >>> Regards >>> >>> >>> Jean-Paul escribi?: >>> >>> >>>> Hi, >>>> >>>> It looks like you don't think that the end-of-charge voltage is above >>>> the >>>> nominal voltage. >>>> On the schematics given in the link hereafter, it would be safer to put >>>> a >>>> zener diode across the lower resistor of the divider, to protect the >>>> controller. >>>> >>>> Le Jeudi 8 Mars 2007 21:51, Rod Boyce a ?crit : >>>> >>>> >>>> >>>>> Markos, >>>>> >>>>> It is very simple I have done this many times in my days job, use a >>>>> resistive divider and work out the error by calibrating the input and >>>>> fix any error in software. One thing you have to be careful of is that >>>>> you monitor the temperature as well as many resistors vary their >>>>> resistance with temperature, but it depends on your application if you >>>>> are charging lead acid batteries then you may only have to calibrate >>>>> the >>>>> circuit between the usable voltage range of interest. >>>>> >>>>> Have a look at >>>>> http://www.angelfire.com/electronic/hayles/charge1fig3.html note the >>>>> divide by 4 voltage sense connecting to the ADC input of the PIC >>>>> micro-controller. >>>>> >>>>> Regards, >>>>> Rod >>>>> >>>>> Markos wrote: >>>>> >>>>> >>>>> >>>>>> Hi guys, >>>>>> maybe this is a little offtopic, but i'm sure you could >>>>>> help me. I'm implementing a simple battery charger, and I need to >>>>>> messaure voltages ranges from 0 to 12 V. >>>>>> ?Could I use the PIC integrated ADC to messaure above 5 V (provided >>>>>> that >>>>>> I use the voltage reference pins tied to 0 and 12 V, for example)? >>>>>> Most >>>>>> external ADC have a 0 to 5V input range.... >>>>>> How would you guys solve this? Any Ideas? >>>>>> >>>>>> Thanks in advance. >>>>>> >>>>>> >>>>>> ------------------------------------------------------------------------- >>>>>> Take Surveys. Earn Cash. Influence the Future of IT >>>>>> Join SourceForge.net's Techsay panel and you'll get the chance to >>>>>> share >>>>>> your opinions on IT & business topics through brief surveys-and earn >>>>>> cash >>>>>> http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV >>>>>> _______________________________________________ >>>>>> Sdcc-user mailing list >>>>>> Sdcc-user@lists.sourceforge.net >>>>>> https://lists.sourceforge.net/lists/listinfo/sdcc-user >>>>>> >>>>>> >>>>>> > > > ------------------------------------------------------------------------- > Take Surveys. Earn Cash. 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