| Author |
 Topic  |
|
kivdenn
Nobel Prize Winner
Uganda
535 Posts |
 Posted - Dec 23 2010 : 2:37:53 PM
|
| Am going to make a 24Volts version of this charger but am simply going to double the values of the components because I dont know how to find the appropriate values. If any body can help me before I begin, I highly appreciate. Thanks Dennis |
 |
|
|
kivdenn
Nobel Prize Winner
Uganda
535 Posts |
Posted - Dec 25 2010 : 07:14:05 AM
|
I have made the circuit and it works fine but R4 to R8 get very hot in a short time. I used 162 ohms 2watts.Also resistor 2 seem not to be of the right value because the LED just blinks when adjusting for a higher voltage instead of completely turning off. Please help me find the right component values for these resistors. Thanks
Dennis |
|
|
|
audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Dec 25 2010 : 10:49:04 AM
|
| Don't you know that when you double the voltage across a resistor then its power (heating) is 4 times? If you double the voltage and double the value of the resistor then the power (heating) is double. |
|
|
|
kivdenn
Nobel Prize Winner
Uganda
535 Posts |
Posted - Dec 25 2010 : 12:28:52 PM
|
| Thanks how about variable resistor? |
|
|
|
audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Dec 26 2010 : 09:39:41 AM
|
quote:
Originally posted by kivdenn
Thanks how about variable resistor?
Although a very expensive huge wire-wound variable resistor can be used, most variable resistors are for low power (less than 1/2W) and can control the conduction of some transistors that can get hot.
Simply use ohm's Law to calculate the correct resistor value. |
|
|
|
erki112
Apprentece
11 Posts |
Posted - Mar 14 2011 : 09:20:00 AM
|
I just made that circiut but the output voltage is around 9 v . when i connect it to charger ,it discharges the battery ,i tried to adjust pot but nothing happens ,the led always is light up. i use 2,5A 12V transformer which ac output is 13,1V. could someone help me wit that ,what would be the problem. Sorry for my bad english.
|
|
|
|
erki112
Apprentece
11 Posts |
Posted - Mar 15 2011 : 6:20:01 PM
|
| i found my problem the Q2 pins were changed . it charges the battery about 13,8 v .but how i test this circiut,because i dont know when the charging stops ,led dosent light up.i dont want to plow my battery . sorry for my bad english |
Edited by - erki112 on Mar 15 2011 6:20:31 PM |
|
|
|
awt
Apprentece
Nigeria
9 Posts |
|
|
erki112
Apprentece
11 Posts |
Posted - Mar 16 2011 : 3:47:46 PM
|
| i connected a fully charged battery to the charger but led didnt light up and voltage meter showed 15,6 ,battery started boiling, why didnt it turn of charging ,i tried to adjust pot but nothing happens. would the problem in zener diode. i metered voltage from between r2 and D3 ,there was about 5,6-7V wich changed when i turned pot . how much voltage there would be in the other side of D3. |
|
|
|
awt
Apprentece
Nigeria
9 Posts |
Posted - Mar 17 2011 : 04:40:14 AM
|
Let's do it together, just few info from u will help. What did u use as:
Q1 =
Q2 =
R4 =
R5 =
R7 =
R8 =
and d zener voltage of D3?
|
awotol
www.simplecircuitsandprojects.com |
|
|
|
erki112
Apprentece
11 Posts |
|
|
awt
Apprentece
Nigeria
9 Posts |
Posted - Mar 17 2011 : 1:47:57 PM
|
| Good, open up R5 and R8. Then short circuit out R7 while replacing R4 with 680ohm and R6 with 560ohm. Adjust R2 at 'high voltage cut off' |
awotol
www.simplecircuitsandprojects.com |
|
|
|
erki112
Apprentece
11 Posts |
Posted - Mar 17 2011 : 2:46:13 PM
|
| im not good in enghlish,but do i have to remove R5 and R8.and bridge R7.and replace R4 with 680 ohm 2w resistor.and R6 with 560 ohm 1/4w resistor. and finaly set pot to the max and test |
|
|
|
awt
Apprentece
Nigeria
9 Posts |
|
|
awt
Apprentece
Nigeria
9 Posts |
Posted - Mar 17 2011 : 3:58:16 PM
|
| it doesn't matter, it will work. i only suggested that one with lesser wattage to reduce the cost. |
awotol
www.simplecircuitsandprojects.com |
|
|
|
Topic |
|
Automatic 12V Lead Battery Charger
