harrychoo

thanks for the reply. Actually, i still not fully understand the statement "any series resistance will screw up the load regulation" Can explain further?

Just change the LM301 with TL081 without any modification? The reason i want to monitor is not want to know how far it is being charged but i want to terminate the charging once it full. Any idea? Actually i need to view the main because i will implement inverter later part and i want to check its waveform. And the question i mean previously is, the neutral and live line both also output sine wave simultaneously? Or 180 degree out of phase or others? Same here too, i need to built an universal UPS system with AVR and different input AC voltage and 50Hz/60Hz. So i need to detect the input AC voltage in order to do the AVR and i need to detect whether it is 50Hz or 60Hz so i will output the same frequency on the inverter side. Thanks

@audioguru I not sure where is Sasi ??? Is it mean that his circuit no longer work? Do you have any idea on how to monitor the charging process? Do we need to monitor the battery voltage OR charging current during the charging process? I might want to do this with microcontroller's ADC. Off-topic : Can I know how is the voltage waveform for our main AC? We have Neutral and Live line respectively but how the waveform gonna looks like in each of these lines with respect to time? Is it possible to view the 240VAC waveform by using digital or analog oscilloscope? Or do we need certain special equipments? What is the procedure? Can I know by using op-amp, can we built some circuit to determine the input AC and its' frequency with the usage of microcontroller? Thanks ya

Is that ok and what happens if i omit the 0.22R? Can u help me in this too? http://www.electronics-lab.com/forum/index.php?topic=5518.0 Actually, i plan to make a similar charger with monitoring either by using comparator or microcontroller ADC and will cut off off the charging process once the battery is fully charged. Any idea on this? Thanks ;D

Can i know what is the main difference between your "Battery charger 2" with my circuit earlier other than those protection diode? The pot in your battery charger 2 is used to set current but not voltage? Can u explain why this can happen? Let say, i confirm that i want 14.4V at the battery there, then can I just replace the 500R pot and 1k res with a single res? If that so, what is my current? Last question is what is the purpose of the 0.22R? Thanks again

If use the Full Wave Capacitor Load, from my circuit, the calculation is 0.71 x 16V or 0.71 x 32V?

Thanks audioguru and MP for the reply. @audioguru Is it possible to make it using only 1 LM317? This is because almost all the battery charger circuit in the end market UPS system that I traced, they only using single LM317. And also I want to reduce cost if possible. If based on my earlier circuit, can I know what is the output current? How much power that the LM317 need to dissipate in my circuit and your circuit? Thanks a lot. @MP Then from my circuit, is it consider as Full Wave Resistive Load? If yes, then it should contradict with audioguru circuit where the input voltage to his first LM317 is 21.8V. What is the input voltage to my LM317 then? If it is a Full Bridge Resistive Load, then the input voltage to LM317 should be around 14.4V (0.45 x 32V) but ain't it too low since the output voltage i also want 14.4V? Thanks

Hi all and Sasi if u see this. This battery charger circuit i think i get from my thread last time and i think want to implement this. Can i know how u control the chraging current in this circuit? Is it by the 0.22R/10W? And for the monitoring part, do u have other way to monitor the charging process and use TTL signal with a transistor to switch off the charging? Thanks in advance battery_charger_2nd.pdf

Hi, I want to ask a question about transformer as i very confuse about the multitap transformer. In the circuit i put below, can i know what is the voltage for V1 and V2? Is it 16V or 32V? And is it V1 still an AC? The diode is 1N5399. Then below is the transformer that connected to LM317 to regulate the output voltage to charge my 12V 7Ah SLA battery. D1,D2,D3,D5 = 1N5399 D4 = 1N4148 C1 = 0.1uF R1 = 0.22R 5W R2 = 240R R3 = 2.54k The charging voltage is to be set at around 14.4V from R2 and R3. So my question is how we set the charging current? Is it thru R1? If yes, then what is the formula to change R1 so that i can get different charging current? From the LM317 datasheet, i only can get the load impedance that related to R1 which is Z1 = R1 x (1 + R3/R2) Any realtion between this and the charging current? Thanks

I have been study this type of charger quite a while. Now i wish to charge 12V 7Ah SLA battery. To charge the battery, u need a constant voltage and current source. First, u need to charge the SLA battery for 2.4V/cell. Charging current should be around 0.1C. The charging current will drop throughout the charging process.. When it reach like 10mA-40mA, u need to stop the charging process or change it to float charge which is 2.35V/cell, else it will be overcharged. I had built the charger using LM317 and some pot. However, now i wish to do it in switching type charger. I try to use some switching regulator like HA17384/385 or UC3844 current mode PWM to do the switching and with some opto-coupler and TL431 to do the feedback. All this i wish to do it with flyback topology. But now i still in study stage. I had study quite some of the application notes but still I not too understand how to produce constant current source in switching type. I manage to do cosntant voltage but not constant current. Any idea?

Hi nura100, I also want to buy some books that related to UPS design (particular in inverter and charger design) similar to what u posted before. Is it possible for me to get it? Can PM me or email me ([email protected]) regarding this? Thanks

I also having difficulty to understand the high freq transformer. I dunno how to read their specs and which spec i should use. Any help pls? Thanks What core of the transformer and what switching frequency normally being used?

Is the feedback from the optoisolator is to let the PWM controller to properly adjust its duty cycle so it can adjust to the desired output voltage? If that so, how about current? How we gonna know or control how much current will reach the output? I know this related to the another thread that i post ;D cheers

Wow, after having not reading my own thread for 2 weeks, it end up with so many discussions. Bravo. For Arun > Is it possible for me to get the manual or reference book for UPS? I want focus in the battery charger and sine wave inverter study. My rough spec will be 12V 7Ah SLA battery charger(might be more than 1 piece) and for inverter is about 500W or more than that. If possible, i hope the reference book can cover every spec and explanation so i can see the difference from that. And yeah, i'm from Malaysia. So anyway for me to get this? Thanks. For all> Battery charger For the battery charger, I would like to know more about the charging voltage, current and charging time. Is it efficient for us to use LM317 to charge the battery? As far as i know, to efficiently charge a SLA battery, we migh consider the charging voltage and temperature as well. For the charging voltage, as i know, to charge a low energy SLA, we need to use cyclic charge 1st (2.35V-2.4V/cell) until the charging current drop to a minimum value (3% of the rated current), then we have to change the charging state to float charge (2.25V - 2.3V/cell)

If i using transformer to step down the main voltage, will the output AC waveform exactly same as the input AC from main?? I heard that floating can be done on the oscilloscope in order to probe the 240VAC main. Another method is using differential probe. Am i right? How to do the both methods above? Thanks