lithium charger circuit

[Andrew Borg]

I saw this lithium charger circuit instructable. Can I use a pot instead of the 1ohm 1w resistor to make current variable?

https://www.instructables.com/id/How-to-make-Lithium-charger/

Thanks

 

[Willen]

Hi, R4 is a 1k pot already there, from where you can get variable voltage output. 1 ohm is a power resistor which limits and sense the current.

 

[spec]

To make the current limit adjustable put a 100 Ohm potentiometer across the 1 Ohm resistor and connect the transitor wiper to the base of the transistor. When the potentiometer is at the top of its travel the current limit will be 600mV/1 Ohm= 600mA. At mid travel the current limit will be 1.2A and at the bottom of the potentiometer travel the current limit will be solely dictated by the current limiting of the three terminal regulator.

spec

(PS: this LiIon charger circuit has a few issues and is not recommended)

 

[Andrew Borg]

Hi, R4 is a 1k pot already there, from where you can get variable voltage output. 1 ohm is a power resistor which limits and sense the current.

Hi Willen thanks for response I was referring to R1 for current adjustment.

 

[audioguru]

The issues with that horrible circuit are serious:
1) It is an Instructable that might have been designed by a kid who is only 10 years old and who knows nothing about electronics like some Instructables.
2) It might set your home on fire! Its resistor between the Out pin and the Adj pin is 470 ohms which is much too high. The datasheet says the minimum load current (for some LM317 ICs) is higher than 470 ohms plus the very small charging current of a fully charged Lithium battery creates. The datasheet says it causes the output voltage to rise. But the absolute maximum charging voltage for two cells is 8.40V. When the charging voltage goes above 8.40V then the Lithium becomes unstable and bursts into a very hot fire.
3) It does not shut off when the battery is fully charged. A Lithium battery must never have a trickle charge.
4) It does not detect if the battery has been discharged too low. A lithium battery discharged too low can burst into flames when charged.
EDIT: 5) It does not balance-charge two cells. One of the two cells might become over-charged and set a fire.

 

[spec]

6) It also needs a IN400x diode: anode to LM317 output and cathode to LM317 input or the LM317 may blow.

spec

 

[MikeMl]

The issues with that horrible circuit are serious:
1) It is an Instructable that might have been designed by a kid who is only 10 years old and who knows nothing about electronics like some Instructables...

Most of the circuits i have looked at on Instructables are put there by designers that know nothing about electronics, regardless of how old they are...

 

[chemelec]

Most of the circuits i have looked at on Instructables are put there by designers that know nothing about electronics, regardless of how old they are...

I Also AGREE!

 

[audioguru]

One horrible Instructable had a TIP31 medium-power transistor driving an LED without any LED current limiting and without any base current limiting. The author admitted he was only 10 years old and knew almost nothing about electronics.

 

[Andrew Borg]

Thanks guys for your help. So what about this charger is it worthed for safety? Cause if it's good I buy this instead of building.
**broken link removed**
hash=item3609d67538:g:GIIAAOSw~uhUq6U-

 

[chemelec]

Yes it is probably OK.
If it Doesn't work, Complain and PayPal will Refund your Money!

 

[Andrew Borg]

Yes it is probably OK.
If it Doesn't work, Complain and PayPal will Refund your Money!

Ok Chemelec

The issues with that horrible circuit are serious:
1) It is an Instructable that might have been designed by a kid who is only 10 years old and who knows nothing about electronics like some Instructables.
2) It might set your home on fire! Its resistor between the Out pin and the Adj pin is 470 ohms which is much too high. The datasheet says the minimum load current (for some LM317 ICs) is higher than 470 ohms plus the very small charging current of a fully charged Lithium battery creates. The datasheet says it causes the output voltage to rise. But the absolute maximum charging voltage for two cells is 8.40V. When the charging voltage goes above 8.40V then the Lithium becomes unstable and bursts into a very hot fire.
3) It does not shut off when the battery is fully charged. A Lithium battery must never have a trickle charge.
4) It does not detect if the battery has been discharged too low. A lithium battery discharged too low can burst into flames when charged.
EDIT: 5) It does not balance-charge two cells. One of the two cells might become over-charged and set a fire.

As I read regarding the 18650 batts are not that sensitive as lithium polymer and can be charged without balancer.
Ok they should not over charged but if one regulates the voltage to certain hieght I don't think it will exceed that voltage.

 

[spec]

You should always charge all LiIon batteries, LiIon and LiPo included, according to their individual requirements. LiIon batteries are very sensitive to charge and discharge voltages and, generally speaking, an accuracy of 50mV is recommended. This can be achieved by balancing or effectively providing a separate charger for each battery.

Here is a review of the charger you are considering: https://lygte-info.dk/review/Review Charger TP4056 UK.html

And for reference the TP4056 chip data sheet: https://dlnmh9ip6v2uc.cloudfront.net/datasheets/Prototyping/TP4056.pdf

spec

 

[spec]

By the way, you can get a similar charger with load protection too: https://www.ebay.co.uk/itm/1A-Micro...582642?hash=item3ac6c01e72:g:PboAAOSw6btXSwuQ

spec

(see post #3 @ https://www.electro-tech-online.com...ns-on-this-18650-charger.149100/#post-1274924)

 

[audioguru]

A Chinese charger sold on ebay with an unknown manufacturer? Do they have any quality control? Or are you guessing that it might not burn down your home? How cheap is too cheap?
I'll pass and buy a good charger from a local distributor that is made by a well known reliable company.

 

[Andrew Borg]

A Chinese charger sold on ebay with an unknown manufacturer? Do they have any quality control? Or are you guessing that it might not burn down your home? How cheap is too cheap?
I'll pass and buy a good charger from a local distributor that is made by a well known reliable company.

I think you are exagerating guys. I charged these types with only a regulator

 

[Willen]

I think you are exagerating guys. I charged these types with only a regulator

If the li-ion cell do not have any protection circuitry, it could be dangerous as they said. I think most of the cell has internal protection circuit. If you break the cellphone's battery, you will get that one chip inside. Maybe that's protecting in your case.

My two experience:
- Once battery's voltage was 0V. I broke the cell and removed the chip. Then measured the original output pole of the cell and it was upto 2V. So we can say that chip was disconnecting the cell to make safe us. Charging a cell having voltage lower than minimum in Li-ion can explode.
-Once bettery was fully discharged mistakenly and cellphone was not detecting it. So I charged it using cellphone's 5V power adapter directly. I forgot to disconnect charging and it was being charged whole night! I though it's about to explode because of OVER charging. When I put the battery in cellphone, charging is just 10%. It means the internal chip disconnected the charging process after few minute when it get something wrong charging voltage.
But be careful, the tiny chip always might not be able to protect our precious life.

 

[Andrew Borg]

If the li-ion cell do not have any protection circuitry, it could be dangerous as they said. I think most of the cell has internal protection circuit. If you break the cellphone's battery, you will get that one chip inside. Maybe that's protecting in your case.

My two experience:
- Once battery's voltage was 0V. I broke the cell and removed the chip. Then measured the original output pole of the cell and it was upto 2V. So we can say that chip was disconnecting the cell to make safe us. Charging a cell having voltage lower than minimum in Li-ion can explode.
-Once bettery was fully discharged mistakenly and cellphone was not detecting it. So I charged it using cellphone's 5V power adapter directly. I forgot to disconnect charging and it was being charged whole night! I though it's about to explode because of OVER charging. When I put the battery in cellphone, charging is just 10%. It means the internal chip disconnected the charging process after few minute when it get something wrong charging voltage.
But be careful, the tiny chip always might not be able to protect our precious life.

Hi Willen 18650's have no protection circuits cause these are not lithium polymer.
https://www.easyacc.com/media-center/what-is-the-difference-between-18650-and-li-polymer-battery/

 

[debe]

This is the module Andrew was refering to quite cheep on Ebay. I paid a whole lot more from a local electronics store $15. Set it up to day to see how it works & it appears to recharge a nearly flat cell. And yes its made in China as just about every thing else. The 4056 chip is quite cheep.

 

[Andrew Borg]

This is the module Andrew was refering to quite cheep on Ebay. I paid a whole lot more from a local electronics store $15. Set it up to day to see how it works & it appears to recharge a nearly flat cell. And yes its made in China as just about every thing else. The 4056 chip is quite cheep.View attachment 101368 View attachment 101369 View attachment 101370 View attachment 101371 View attachment 101372 View attachment 101373

Hi Debe yes I saw those on ebay. The thing is that I need this batts for my drill so I have to connect them in series as a small bank.
But I still think that the circuit on instructable can do the job for this types.
See this guy used them for his car:

Thanks guys.