45 w 12v/7.5 ah inverter shows 650 vac

Out is rectified and filtered dc. 227 volts seems ok. As earlier stated, you will see huge voltages if check dc with meter set to ac range. You can check this by testing 12V DC with meter set to AC range. It will read 24V or so.
There is no feedback loop to error amplifier circuit of sg3524 to regulate output voltage.With load it will drop.

You tested this with small load (mobile charger). Before any more suggestions, you should connect the output to a 20W bulb and see if the bulb lights properly. Also, check the output DC voltage.

Click to expand...

This is the way to go.
Most probably its made to lt a 40 watts florescent rod with electronic choke or for two 20 watts energy savers. Both of which can operate with dc. Use your charger in parallel with load and dont operate without load.

14 watt and 5 watt cfl is working with low intensity.fully charged battery with 12.4 v. drains to ~11.0v.within 10 min
with on load(14 w cfl) VAC=~400v,VDC=~178v (i have charged the battery all night)
battery voltage on load=11.80 and off load=12.57v
meter reads mains o/p voltage 248v.

and one problem is that when i measure inverter's o/p ac voltage it shows only with one polarity,means if i interchange the meter connection it will show only with one direction i.e ~400v only with one direction.
if i interchange connection it shows 00v(meter is on 750 ac)

so is that battery ,that i should change ??? battery is one year old and local made.
is there changes i have to make to make inverter more than 45 w?

---------- Post added at 14:56 ---------- Previous post was at 14:50 ----------

yes you are right ,at ac test it gives 27v with meter set to ac and for dc it shows 12.1v

what is the value of the 14 pin DIP IC next to the SG3524N IC?
Is it a LM324N?

burnt component is regulator LM317and next to 3524n is lm339

you can easily trace the whole circuit diagram from the pcb by reverse engineering.

saminda said:

14 watt and 5 watt cfl is working with low intensity.fully charged battery with 12.4 v. drains to ~11.0v.within 10 min
with on load(14 w cfl) VAC=~400v,VDC=~178v (i have charged the battery all night)
battery voltage on load=11.80 and off load=12.57v
meter reads mains o/p voltage 248v.

and one problem is that when i measure inverter's o/p ac voltage it shows only with one polarity,means if i interchange the meter connection it will show only with one direction i.e ~400v only with one direction.
if i interchange connection it shows 00v(meter is on 750 ac)

so is that battery ,that i should change ??? battery is one year old and local made.
is there changes i have to make to make inverter more than 45 w?

---------- Post added at 14:56 ---------- Previous post was at 14:50 ----------

yes you are right ,at ac test it gives 27v with meter set to ac and for dc it shows 12.1v

Click to expand...

It could be the battery. Use an ammeter to measure the current when using 19W load. That should give a better indication. Current reading should be less than 2.5A(worst case). If it is within this limit, then, most probably, the problem is with the battery.

After 10 minutes use, do the MOSFETs get very hot?

and one problem is that when i measure inverter's o/p ac voltage it shows only with one polarity,means if i interchange the meter connection it will show only with one direction i.e ~400v only with one direction.
if i interchange connection it shows 00v(meter is on 750 ac)

Click to expand...

The output of the inverter is DC, not AC.


Hope this helps.
Tahmid.

i ve lost my last multimeter while checking current from that 12 v battery .
so i bought new one.
that is why i didnt rply .
now problem is ,,,,, at full charge 14 w cfl only lightn up 20~ min,after that i again charged battery.I ve done this for 3 times and result is same. At the time of shut down cfl battery o/p voltage is 11.80 to 12 .
tell me about safely measuring current without destroying another multimeter...

regards

I don't know the current rating of your multimeter, but usually they aren't very high and I wouldn't measure more than 500mA with a multi-meter (unless you've got a very good one with the capability). I'd rather use a dedicated ammeter or do this:
Use a 0.1 ohm resistor. Disconnect the ground (negative terminal) of your circuit from the battery. Connect the ground of the circuit to one end of the 0.1 ohm resistor. Connect the other end to the negative end of the battery. Turn on the circuit. Wait for 5-10 seconds. Then, read the voltage across the 0.1 ohm resistor. Connect the +ve lead of the voltmeter to the end where the circuit negative is connected. Connect the -ve lead to the battery negative terminal. Then, current = (Voltage reading from voltmeter or multimeter)*10

So, if your multimeter reads 0.23V, then the current is around 2.3A.

This isn't a very accurate method due to resistor tolerance. However, you can read the resistance with the multimeter.

Then, current = (Voltage reading from voltmeter or multimeter) / resistance reading. This is better.

Hope this helps.
Tahmid.

i ve done this with 1 ohm 5 watt resistor. the voltage across it shows 0.91v , with 14 watt cfl load ,
so 0.91/1=0.91a is that true??????????

Yes. Thereabouts. So, taking tolerance of the resistor to be 10% gives min 0.9 ohm resistor. So, that's a max current of 1.0A. So, current is around 1A. That seems fine. So, the problem is most probably with the battery, which is most likely damaged.

Try with a 12V power supply or another 12V battery.

Hope this helps.
Tahmid.

but that battery is too costly around 600.I think the charging block of lm317 regulator is not charging battery
properly. is there any suggestion in mind to charge the battery properly?????
any idea to make it working long lasting????

While charging, measure the current using the method stated above. When battery is almost completely discharged, you should get a charging rate of 0.7A to 1.2A. Near the end of the charging, ie after 10 to 14 hours, you should get a charging rate of < 0.2A.

Also, I've noticed (from experience) that some sealed lead acid batteries don't charge below 14.5V. These were used in UPS-es. In these UPS-es, the charging voltage was 14.5V. If you see charging current is too low, try to increase the charging voltage to around 14.5V. If still, you get low charging current (lower than usual), then, you probably need to change the battery since battery is most likely completely damaged.

Hope this helps.
Tahmid.