1. Simple and minimal parts thus good for beginners and hobbyist.
2. Can be used to charge Ni-Cd of different voltages (2.4V, 3.6V, 7.2V, and other battery voltage)
3. Automatic with battery over-voltage protection. Current limited and voltage controlled.
4. Visual led indicator. Charging (red) and full-charge (yellow) indicator.
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| charger schematic |
R1 - 1.2 kilo ohms 1/4W
R2 - see R2 and D2 table below
R3 - 2 kilo ohms 1/4W
Q1 - TIP41C or any NPN transistor min 1A current and 3W power
Q2 - 2N2222, CS9013, or similar NPN transistor
LED1 - Red or any LED with forward voltage around 2V (see LED)
LED2 - yellow or any LED color except Red
D1 - 1N4001 or similar diode
D2 - see R2 and D2 table below
DC supply - 12V to 15V DC supply or battery
Parts diagram/pins: click picture to enlarge
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| TIP41C pins |
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| 2N2222 pins |
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| LED pins |
Current = 8mA + (2/R2)
Table below is the list of values of R2 and zener diode D2 depending on the charging current you need and the voltage of your Ni-Cd battery.
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| R2 and D2 table |
USB Battery Charger for NiCd - USB based charger
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12V charger - automatic type, current and voltage controlled
Universal charger - charge any battery voltage form 1.2V up to 12v
Mobile phone charger - very simple charger for phones
24V battery charger - simple and automatic charger for 24V lead-acid
Sir, can i use this charger for nimh batteries?
ReplyDeleteNo you cant charge it using this charger. It might damage your battery.
ReplyDeletethank you, sir
ReplyDeleteHi, can this charger be used with 12V NiCd battery??
ReplyDeleteIf so, what value of D2 should I take; 14V?
Regards.
The idea is take the maximum voltage that your battery can hold without damaging it. Example if the battery is rated 12V but its maximum voltage is 13.3V, then use 13.3V zener. If there is no 13.3V zener, you can series two zener diodes like 5.1V and 8.2V or any combination.. The important is you protect your battery from damage.
ReplyDeleteThank you.. :)
ReplyDeleteCan I use a 6 VDC supply in this circuit? Will I need to change any resistor values? I am trying to charge 2 cells (2.4V)
ReplyDeleteThanks.
you can use 6V dc, just use 2.7V zener diode. No need to replace the values of resistors
ReplyDeleteim using a 12v 1.2A tranformer and a bridge rectifier to get a 12vdc supply from the 120v ac for you circuit. do i have to change any of the components to charge a 7.2v nicd?
ReplyDeleteNo need to replace any component if you are using 12V transformer but make sure you add heatsink to transistor Q2
ReplyDeleteActually i dont have any problems with Q2, Q1 is the one getting really hot is proper heat sink the solution?? Also im using the 1n3747 7.5v zener for D2 would that affect in anything?
DeleteTry increasing the value of R1 to 3.3K to 5.6K. That heating is normal because the DC supply is high (around 16VDC for a 12V transformer). If heating is still present try replacing Q2 with transistor of higher power rating.
ReplyDeleteAlright sounds good thanks alot . Also how does your circuit know when the battery is fully charged??
DeleteThis charger has very simple design. Yellow led will light when the "full charge voltage" is reached.
ReplyDeleteThe only way we cant tell that the battery is fully charged is when its voltage is equal to its rated full charge voltage.
When the battery reaches full charge what causes the current to go through Q2 to stop charging?
DeleteAssuming your battery is rated 7.2V and its full charge voltage is 7.5V. When the battery voltage reaches 7.5V, the zener diode D2 starts to conduct (below 7.5V, diode is off) and it will turn transistor Q2 on. When Q2 is fully on, Q1 turns off and so is the charging
ReplyDeleteThank you soo muuch i understand now !!!
ReplyDeleteSir, Thank you very much for sharing a very useful circuit like this.
ReplyDeleteI want to charge a 3.6v nicd battery(3 cells in series) of 1000mAH each. What will be the best input voltage?(4v or 5v or 6v or any other). How can I choose different input voltages according to different battery packs of different voltages. Kindly explain that.
I have one more doubt. You said in one of your previous post, that the D2 will not conduct till the battery is full. Is it because, there is a easy path through battery, so the current will flow in that direction. And after when the battery is full, that path will not be easy and the current flow through D2 causing the Q2 to switch and stop the charging.
3.6V battery needs atleast 6VDC input. Initially D2 is open and will not conduct, as the battery is charged, its voltage starts to increase until the "conducting voltage" of D2 is reached. When D2 will conduct, charging is off.
ReplyDeleteExample is a 3.9V zener diode will start to conduct when the voltage across it is 3.9V. Any voltage lower than 3.9V has no effect to 3.9V dioded D2.
I want to charge a 2.4v Battery. Can I use the circuit with a 5v usb port? The max current in a usb port is 500ma.
ReplyDeletethanks in advance!!
Hi DH-gm, great site, wondering if you could give some pointers to modify this circuit to charge cordles power tool batteries.
ReplyDeleteI have a 24v dc power supply rated at 6.5 A and want to charge Nicad batteries at 12V 14V and 18V
Appreciate your help.
hi i am Kiran can i turn this circuit to charge ni-mh batteries?if yes how?
ReplyDeleteif not do u have other circuit which can charge 7.2v ni-mh batteries?
thank u
i will be waiting for reply.
hi sir what if 1.2V battery will be used
ReplyDeleteUse any regular diode, plus a resistor between 300k to 560k , instead of the zener. Diode needs to be in forward direction. Remove R3.
Deletehi sir,,lately i made this project but i didn't work. i used 9volts supply 750mA to charge the battery of my flashlight using ni-cad battery with this specs; 2.4 volts 1900mAh.LED1 will turn on for few seconds then off, after LED2 will turn on. could you advice me how this happen?placement of all parts has been repeatedly check and everything is ok base on the diagram.
ReplyDeleteIm learning so much from your effort! THX
ReplyDeleteI have a 3.6V 800mAh NiCd I would like to add into this circuit a current control for different charging rates. In replacement of R2 would i put a 2.52ohm (100%of800mAh) --> 27.7ohm (10%of800mAh) potentiometer? or would i have to wire a switch into place for individual resistors?
Where is this formula from? Current = 8mA + (2/R2)
Thx again!
What if you changed R3 to a0 to 500 ohm Potentiometer, inserted a test port to set the current you want to charge at. That would allow you to "regulate the current" used to charge the battery and keep the remainder of the circuit for voltage control. Would this work?
ReplyDeleteVery Good Question !
DeleteI would be very interested in the answer to this, really hope the author replies !
Sorry I mean R2 not R3.
ReplyDeleteneed some help,i did this projenct and the yellow led it`s always on,the red is off and the output voltage is 3.3 v.
ReplyDelete12v 350 mah power supply
9.6 2000 mah battery
What should R2 be if I have a 600mah Nicd?
ReplyDeleteCan this circuit be made to disconnect when the power supply is removed? I need to be able to pull the power supply and not have the battery bleed charge through R3
ReplyDeleteGood day to you Sir,
ReplyDeletethanks so much for sharing this awesome little minimal parts count Ni-cd charger !
Just what ive been needing for months !
But i need a little guidenace please, im needing to charge a 1.2 Gumstick battery at 500mA but the values for R2 and D2 are not in your charts, please could you kindly let me know which values i would need for this low battery charging, also what would be a recommended input voltage for this circuit ?
By the way, AWESOME idea to add the LED's ! just what i needed to know the battery is charged !
Can I use BD 179 instead of tip41c? Please answer
ReplyDeletesir can you plz explain me the working .. from the scratch
ReplyDeletehow can i charge 3.6 v ni-cd what the value of r2 and d2
ReplyDeleteplease help
ReplyDeletethis circuit simply doesn't work no matter how fine your calculations are.
ReplyDeleteBatteries must be *dead* for it to work and then again only for a few minutes as the voltage rise on nim-cd batts is quite fast.
Dear,
ReplyDeleteIs there any type of circuit (Automatic) for charge NI-HM battery or can we done some changes to this circuit and take for charge NI-HM battery. Thanks.........
Hi,
ReplyDeleteI would like to charge 24V 30AH batteries, what are the components I need to change in this ckt in order to make the above mentioned battery charger.
Hello everyone,
ReplyDeleteThis circuit works but there is a miscalculation.
You have to add the forward voltage drop of the diode D1 to the desired final voltage of the charged battery.
1N4001 diode has 1V voltage drop at 1A. Usually its around 0.6V in most applications.
So for a 4.8V battery the desired full voltage should be around 1.4V per cell. Thats 5.6V total. Plus diode voltage drop 5.6V+0.6V=6.2V. So you should use 6.2V zener diode for D2.
can this be used to charge 12v SMF or 3.6v Li-on battery?
ReplyDeletecan this be used to charge 12v SMF or 3.6v Li-on battery?
ReplyDeleteSir can i use it for Li battery please reply asap?
ReplyDeleteyes you can use it for Li battery
DeleteI have 12v(NiMh) 1800mAh battery[which have 10 AA batteries] set. And I connect one female usb port with two wires that coming from that battery set. Now please help me how do I charge the battery set via usb port and also use the battery set as a power bank for my mobile.
ReplyDeleteplease reply as soon as possible.
yes, it will work for you
ReplyDeletesounds good.
@====}:::::::::::::::::::::::::::>
i have battery with 3.7v but i have a wii remote that work with 2 AA battrey 1.5 + 1.5
ReplyDeleteso do i charge the battery only to 3V or i just charge it with 3.7v and i add diode zener paralele with the wii remote so can voltage be 3V , if you suggest that i charge it with 3v , what i m gonna to choose with R2 an D2 ?thanks
If i want to charge a 3.6volt battery pack, what would i need to do to use a 12volt power supply?
ReplyDeleteinput voltage can change to 5 volt ?
ReplyDeleteSir can i use solar panel as input?
ReplyDeleteCool circuits, thank you :) are a little confused, but have a few questions that I hope you can help me with.
ReplyDeleteYou talk about this "battery is rated 12V but its maximum voltage is 13.3V" how do I find its max voltage?
Now the circuit is for NiCd, but can I not use it for NiMH and NiZn also? From what I've tried to find out, I do not see there are given any difference in the charging between them? If so, where should I change so it can be used for NiMH?
can anybody help me.... my red led doesn't light up it's just the yellow one... and i don't know if it's the transistors that are bad or if it is only something miss connected...
ReplyDeleteI face the same problem, input voltage is 15V and output voltage is 3.5V...
ReplyDeleteSeems like no cut off will happen for 3.6V battery.
Any idea? Anyone successful?
Good afternoon! My name is Ramiro. I'm from Argentina.My English is not very good,i'm sorry . I saw the circuit and looks very easy.
ReplyDeleteI have to build a battery charger for two batterys AA (1.2 V 1350 mAh ) with USB port. My question is: does anyone test this circuit with 5V power supply?
I'll wait an answer or advice from you.
Thank you for your time.
Ramiro
Hi Ramiro! My name is Milan, i'm from Serbia. Answer on your question is: Search on YouTube channel AKA KASYAN and find video Как сделать USB зарядное устройство для Ni-Mh.
DeleteHi DH-gm,
ReplyDeleteThanks for posting this.
I was wondiering how can I use it to charge a 4.8v Ni-Cd battery (1.2V x 4cells/1300mAh each). Do I have to change anything in the circuit and what's the best input DC voltage?
Hi, i have a new bright 9.6v NiCd battery and its charger (OUTPUT:11.6V and DC 165mA)which is broken and does'nt work.
ReplyDeleteShould I consider 11.6V zenner diode or stick to 9.6V only, and IMPORTANTLY what should be the specification of R2 to be used (ohms and voltage) here.
Hi DH-gm
ReplyDeleteI am using 12 volt 1 amp wall adapter. Any changes to the components to charge 3) 1.2v NIMH batteries in series (3.6 V total)
My yellow is on as soon as I apply power.
ReplyDeleteI have 3.7v on the cathode of the zener and 0.6v on the anode, yet it looks like the 2n2222 is conducting and the yellow led is on turning the TIP41C off I do not understand it.
If I remove the zener the circuit goes into charge and the red led comes on and if i remove the yellow led it also goes into charge and the red led comes on and I get about 100ma charge to the battery. I was surprised with the 100ma because I had selected R2 to be 2 x 20ohm 1/4 watt in parallel because I didn't have a 1/2 watt 10 ohm and expected a 200ma charge current.
Any help would be appreciated
IDK.. i have the same issue... i guess nobody wants to respond to this
DeleteI have made your curcuit and it only outputs 1.8v and the yellow LED is lighting all the time. The red is not on at all. I am charging a 2.4v battery. What can I have done wrong.
ReplyDeleteI have made a pcb with ExpressPCB. Any way to upload an image here?
ReplyDeleteI have made your curcuit and it only outputs 1.8v and the yellow LED is lighting all the time. The red is not on at all. I am charging a 2.4v battery. What can I have done wrong.
ReplyDeletetry a higher value zener diode. someone in above post spotted an error.
ReplyDeleteSir please I'm having 9v zener diode can it be used on the 9.6v ni-mh battery
ReplyDeleteHello. Please what do I do?
ReplyDelete