battery charger circuit

[t_sanoop]

hi,

i am using a 6v,5Ah rechargeble sealed battery in my project. i want to make a charger circuit to that battery. kindly anybody can help me by providing proper idea for making that circuit...


thanking you

sanoop

 

[muki55]

here's a link for battery charger.
https://www.electronics-lab.com/projects/power/004/index.html

 

[Dr.EM]

This may be able to be adapted to your needs, there arn't many 6v designs around;

https://www.aaroncake.net/circuits/charger2.htm

 

[Hero999]

LM317 constant current source connected to a bridge rectifier with a 4,700uF filter capacitor and a 9V transformer.

 

[Pedro Martins]

For your needs!

 

[eblc1388]

Hi Pedro,

In your above design, what will be the approximate voltage:

a. across the 22 ohm resistor?
b. between LM317 input & output pin?

 

[Pedro Martins]

Across resistor +/- 1.32V
Across LM317 +/- 0.6V

You are going to tell me that LM has a dropout of more than 2V... and you are right.
But that dropout is for full load 1 to 1,5A.
At 60mA and @ 25ºC the dropout is +/- 1,6V...

So, The circuit must be corrected

Assuming a charge voltage of 6,9V and a current of 60mA:

Vbat + Ve1 + Vdropout + (Vdiode x 4) =
6,9 + 1,32 + 1,6 + (0,6 x 4) =
6,9 + 1,32 + 1,6 + 2,4 =
12,22V

To get the transformer voltage, we must convert this into RMS value:

12,22V / 1,414 = 8,64V

Finally, a transformer from 8V to 9V is sufficient

But... the first schematic also works, but not as efficient

 

[Pedro Martins]

Sorry!
Any moderator out there?!
Last attachment is wrong. Delete it for get more disk space

Here is the correct one:

 

[eblc1388]

First please pardon me for picking bones with the circuit. This is a public forum so I hope the discussion can be useful to somebody in a later date.

Ok, we have now cleared the question of low transformer voltage.

Now two additional points:

1. Did you work out the voltage across the 22 ohm resistor using ohm's law of 22*60mA? Then you will be surprised to know it is only 1.25V instead of 1.32V.

2. You have subtracted four diode drop(2.4V) whereas actually the rectifier circuit dropping only 1.2V at all times.

 

[Pedro Martins]

Hi L.Chung!

You are right!
I'm at work and only want to help! Time for thinking it's a thing I don't have at work! Get it ?

I wrote the text very fast, and counted all diodes.
Also, 1,25V it's a constant voltage no matter what value have R1.
I am pardoned? I can be a newbie here, but I work in electronics for more than 15 years.
It was a lapse of mine! My excuses to you and to all members.

Back to the circuit:

The 22R resistor gives 56,8mA, to get 60mA, the resistor must be 20,83R.
The transformer would be, ideally, 7,67V.

All this theoretical. In practice, the values don't alter much.

The aim is to get a working 6V battery charger.

New schematic:

 

[Pedro Martins]

And the PCB
50 x 20 mm

 

[ataul]

hi,

i am using a 6v,5Ah rechargeble sealed battery in my project. i want to make a charger circuit to that battery. kindly anybody can help me by providing proper idea for making that circuit...


thanking you

sanoop

Hi sanoop

I Hope this circuit help u

I make it, and working very well .this is on/off type charging system

best wishes to u

ataul.....

 

[abhaykanade]

But it takes long time[25-35 hr] to recharge battery

 

[ataul]

If u reduce the velue of 3.3Ohm 5W resister then u can reduce charging time.this resister use here as a current limiting purpose.

 

[Abdul3440]

hi all,

i'm sorry to ask maybe for correction since i have try to calculate the value given 60ma*22ohm = 1.32volt ( I * R = V ). please advice