What you're asking for now is completely different than what you had in your first post:

Sorry if i confused you , if you want more information i ll be happy to give them .

In the other hand what are the options available ?

 

In the other hand what are the options available ?

I'd buy one. There's nothing particularly special about a 9.6V NiMH battery pack. I googled for chargers and it didn't take long to find half a dozen different chargers at All-Battery.com; no affiliation...

 

I'd buy one. There's nothing particularly special about a 9.6V NiMH battery pack. I googled for chargers and it didn't take long to find half a dozen different chargers at All-Battery.com; no affiliation...

Is it possible to use a 19 v laptop psu and turn it into a charger using a diy circuit ?

 

Hello everybody .

I have a laptop psu delivering 19 v and 4.7 amp .

Now i need to replace a battery charger PSU but the original one was delivering a 10 v / 1.5-2A at the output . also the 10 volts was regulated with the tl431 , and the psu was used to charge a 9.6 v/ 3800 mah battery pack .

Is there a way to get the same output from a laptop PSU ( 19v/4.7A) using the tl431 or any other regulator but getting at least 1.5 A ??

You do not need any regulator. We are all making this unnecessarily complicated.

If you need a fast charge and 100% full charge then forget it and buy a commercial charger. It will be better than anything you can build and it will still stress the heck out of your batteries.

OTOH, if you can get by with slow charge and do not really need an absolute maximum charge then you can use the simplest of chargers you can make yourself.

You have a 19 VDC power supply and want to charge a 9.6 V 3.8 AH pack. So you have about 8~9 volt difference. Put a 15 ohm resistor and you'll be charging at about C/7. Do that until the battery is about 70% charged and then increase the resistor to 27 or 33 ohm so that you are charging at C/15 and then just don't leave it charging forever but take it off the charger roughly when you calculate it to be full. Or, if you are not in a hurry just start at C/15 from the beginning. You can use a timer for all this but I just eyeball it.

There is no easy way to detect a full charge. You can't do it and fast chargers that think they can do it do a lousy job and fry the batteries anyway. Charging slowly is the best way to not stress the battery.

I have seen my friends have all sorts of problems with fast chargers and, as I said, I prefer just to have an extra set of batteries and slow charge them.

 

Put a 15 ohm resistor and you'll be charging at about C/7. Do that until the battery is about 70% charged and then increase the resistor to 27 or 33 ohm so that you are charging at C/15 and then just don't leave it charging forever but take it off the charger roughly when you calculate it to be full.

Thuis method seems a bit hazardous .

I will anyways upload The original psu pictures just to give you an idea on the design , and then i will troubleshoot it .

 

Thuis method seems a bit hazardous .

Why? Please explain in detail what you think happens if you connect a 19 V supply, through a 33 ohm resistor, to a 9.6 NiMH battery pack. Or to a 12 V car battery for that matter.

I have been charging batteries like that for decades. What do you think a commercial charger does?

 

Why? Please explain in detail what you think happens if you connect a 19 V supply, through a 33 ohm resistor, to a 9.6 NiMH battery pack. Or to a 12 V car battery for that matter.

I have been charging batteries like that for decades. What do you think a commercial charger does?

The problem is that the client wants professional work .

Your method is good but the operator needs automatic charge turn off.

 

The problem is that the client wants professional work .

Your method is good but the operator needs automatic charge turn off.

You are looking in the wrong place then. You are not going to get a complex, high-quality design here. And it makes no sense anyway. As has already been pointed out to you there are chargers out there ready to be bought for little money. Anything we could design here would be worse and cost more in terms of time and effort. It just makes no sense.

 

The problem is that the client wants professional work .

Your method is good but the operator needs automatic charge turn off.

better off buying 'off the shelf' supply to do the job. that will fulfil the 'professional work' requirement.

'modifying' instantly makes it 'unprofessional' unless your doing a production run of them.

 

better off buying 'off the shelf' supply to do the job. that will fulfil the 'professional work' requirement.

'modifying' instantly makes it 'unprofessional' unless your doing a production run of them.

I have the feeling he's not listening but, yes, it just makes no sense to be trying to use something which belongs in a dumpster for a commercial, professional project where the $20 he'd be saving is the least of it because you open yourself to all sorts of liability if something goes wrong. Buy a commercial charger and you are quite protected. Modify it and you are on your own. Look what all-battery.com say on their site:

DO NOT make any any changes to the charger and connectors as this may cause safety issues including but not limited to electrical short, heating or fire. We are not liable for any damage caused by any alteration of the chargers and accessories.

The whole premise of this thread makes no sense to me.

 

Okay then , thanks for your time , but the idea was just to learn about chargers as well as solving my problem.

I will buy a brand new charger .