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SLA Battery Charger help?

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I checked out your website, Mr. chemelec.
Really cool stuff you got there!
About your circuit diagram, ..........
1) RX is rated at 4K7, and according to the formula, RX= 06V / 0.120A, which should be 5 OHMs, right? Or am i a bit mixed up? The circuit i came accross first, turns out to be just about identicle to yours, only it has an led between the collector of the transistor, and the adjustable pin of the v-reg (goes off when fully charged / minimum current is reached)
. they use a 1 ohm resistor (in the same place as your diagram) for a 650mAh charge, which complies with you formula.
2) i want to use your circuit to charge higher current batteries, of between 25 and 45AH. im assuming i could get away with an LM338, on a large cool rib, but i doubt the transistor will survive. Can i use a TIP41C instead (15A Rated, as opposed to the 0.6A of the 2N4123) ? Other substitutes? ideas?
 
ziyad said:
I checked out your website, Mr. chemelec.
Really cool stuff you got there!
About your circuit diagram, ..........
1) RX is rated at 4K7, and according to the formula, RX= 06V / 0.120A, which should be 5 OHMs, right? Or am i a bit mixed up? The circuit i came accross first, turns out to be just about identicle to yours, only it has an led between the collector of the transistor, and the adjustable pin of the v-reg (goes off when fully charged / minimum current is reached)
. they use a 1 ohm resistor (in the same place as your diagram) for a 650mAh charge, which complies with you formula.
2) i want to use your circuit to charge higher current batteries, of between 25 and 45AH. im assuming i could get away with an LM338, on a large cool rib, but i doubt the transistor will survive. Can i use a TIP41C instead (15A Rated, as opposed to the 0.6A of the 2N4123) ? Other substitutes? ideas?

Sorry about that TYPO. It should have read 4R7, Not 4K7.
(4R7 = 4.7 Ohms.)
This is Now Corrected.

Yes you can use an LM338 for higher current.
But the 2N4123 is still OK.
Its the Resistor that Needs to be Greatly Increased in Wattage.
The Transistor is only a Low Currents Switch.
 
Thanks for that. i figured there was a TYPO Boo Boo.
I,ve used a 2N2222A transistor in place of the one you use, as i just could'nt get hold of the 2N4123.
it seems to work fine.
.....Now, back to the questions.......
Can i stack v-regs in parrallel to double or triple current handling?
If so, i suppose i would have to accomodate for about 2Volts more on the input side for this for each reg? :confused:
 
ziyad said:
Thanks for that. i figured there was a TYPO Boo Boo.
I,ve used a 2N2222A transistor in place of the one you use, as i just could'nt get hold of the 2N4123.
it seems to work fine.
.....Now, back to the questions.......
Can i stack v-regs in parrallel to double or triple current handling?
If so, i suppose i would have to accomodate for about 2Volts more on the input side for this for each reg? :confused:

Any Small NPN Transistor is OK.

Paralleling Regulators is not really recommended.

But Adding a "Pass Transistor" will work.
Check out the Data Sheet of the LM317 for info on doing this.
 
i need 48V 2A gell battery charger.kindly any one can help me out. i am using 12V 20Ah * 4 batteries to be charged
 
SLA chargers

Morning all.

So I've been reading lots of information/opinions (some scientific, some not) on SLA charging and am quite impressed by the wide range of information given. I fully understand the sulfisification issue/challenge but, obviously there is a great deal of flexibility seen several products are sold that claim to be 'intelligent chargers' to fit many charging needs.

The big question from and EE prospective is: if I can design a power supply that provides constant V and can regulate current flow A (cowbar power supplies have done this for decades) why can I not design a charger that one can set the charging current based on the battery need?

A.
 
Krumlink,

Here is the schematic for a PowerSonic 12v SLA battery charger that I drew up while repairing one. D4 is on during fast charge, and goes out when the charging current drops below about 100mA.

Ken

is that a outomaticaly stop when the battery is fully charge..... pls reply asap
 
For anybody needing a 1.5A max charger for 12V SLAs, I bought a couple of these switchers. They are mis-marked by the manufacturer, but what they do is charge with a current limit of ~ 1.5A until the SLA voltage gets up to ~14.8V, at which point they hold the voltage constant at 14.8V until the charge current drops to about 100mA, at which point the LED goes from Red to Green, and the voltage drops to ~13.7V where it stays until a load is applied to the battery, or the 120V input is recycled.

Not bad for $10.00
 
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