Transformerless charger (20 Amp)

[myid123456]

transformerless battery charger

hi guys do you know if it is possible to make a 20 amp lead acid battery charger
without using the 240/24 transformer and using the angel trigering triack for steping
down the voltage.

if it is possible how is it possible and what problems may be involved?

 

[DrBob13]

rumus perhitungan batt.charger

Forget it!!
The transformer is needed to isolate the mains from the battery for safety reasons. You could probably do something using a switch mode power supply but this still needs a transformer of some sort to provide isolation and it will be a lot more complex and expensive than using a big mains transformer with its very simple rectifier circuit.
Triacs are great for motor speed control using phase angle firing but these motors are designed for AC and are fully insulated.
Bob.

 

[FvM]

20 amp battery charger circuit

I don't want to discuss the design of a transformerless battery charger seriously. According to safety regulations, a transformerless circuit could be used, if any risk of touching the circuit can be excluded. This would be possible for a small battery in an enclosure but surely not for a lead-acid battery with freely accesible terminals.

Apart from that, a controllable rectifier with 14V/20A output operated from 230V mains is basically possible. Considering a 50 Hz thyristor circuit, it would involve an inductor not much smaller than the transformer of a usual battery charger and produce a lot of harmonics in input current.

Clearly, such circuit had never been designed as a battery charger in the ages of thyristor power eletronics. But e. g. a thyristor DC motor controller designed for 200V/20A would be able to supply also 14V/20A if needed. So although it's basically possible it's not really useful.

 

[myid123456]

rumus perhitungan transformerless battery charger

What if I make a DC voltage with a diod bridge (300 Vdc) and then make a PWM based Buck or Flyback converter from it and use it?
I know it still need transformer but because the frequency is high the transformer will be small.

 

[DrBob13]

20 ampere battery charger schematic

You could use a switcher as I said earlier but not with the topologies that you suggest because a buck regulator uses an inductor so it is not fully isolated from the mains and a flyback design is above its recommended power limit when runnng at 280W (14V/20A). A forward or half bridge converter could be used if you really want to go that way.
Bob.

 

[rvionics]

perhitungan batt.charger

You can use Switch Mode power supply technique where the size of the transformer
will be reduced by 10 times so the weight & copper usage / cost.
All the new commertial light weight chargers do use this technique.

 

[darla1]

transformerless battery charging circuit

hi

if you dont want isolation u can charge the battery using ac/dc rectifier followed by buck converter, if you want isolation use ac/dc rectifier and single switch forward/push pull/half bridge but see the power limittaions of each topology

darla

 

[myid123456]

transformerless phone charger

thank you guys it was very kind of you to answer me. and I think you are right about SMPS. do you know any schematic in this topologies that you know it will work. I will apritiat if you suggest me some schematics. thank you very much.

 

[darla1]

20 amp transformer

yeh i ll give schematic tell me which topology do you want

1. with isolation
2. with out isolation

 

[myid123456]

transformerless isolation

thanks darla.
with isolation is very good. but if you can send me both will be better.
I will apppreciate if you send them to my email.(myid1234562003@yahoo.com)

thanks anyway.

 

[omshankar]

Can any one give me this ciruit diagram to me.....
my id is (pandeyom9@yahoo.com)


Thanks........

 

[kabeer02]

try this....

 

[omshankar]

@Kabeer02:
Thanks for ur reply....

But I need transformer-less power supply for my circuit.

 

[kabeer02]

well for that i don't think it safe but if you still need it i will try and design one if i have time or you try and Google search it...

 

[omshankar]

thanks Kabeer for ur post.....