How to make Lithium charger

You will need this project when you have an extra mobile battery or you need to charge any lithium, Lithium ion or Lithium Polymer battery.

Maximum current is about 650 milliamps. The circuit is designed for batteries of 900mah or higher. Power source can be a 12v Gell cell (Power panel), or can be powered by a car's cigarette lighter.
I use an old 12v DC wall transformer (800ma or more.)

Step 1 The Schematic

The Circuit is simple , you will need the following

LM317 variable regulator
2N2222A or any Transistor handles 800mA
2 Capacitors 0.1 uf
1K POT
1ohm 1Watt resistor ( current limitor )

Adjust R4 to the required output voltage
R1 controls the output current

Comments

[spooge]

it is possible to charge a 12V SLA battery with this circuit?

[snowluck2345]

Could this me adjusted to handle a 15 amp charge. I put together a small lithium pack that is 3.7v at 15amp hours, I would like to charge it at a resonable rate, I was thinking of just regulating the voltage to 4.1 and letting it go.

[applejuice1998]

You would have to either get a bigger version of the LM317, I know there's one that'll handle 5+ amps. Or check the datasheet for the lm317, there's some circuits in there. ;)
What do do you need a 15amp lithium pack for anyways? lmao, just wondering.

[applejuice1998]

I just made this circuit, with 1/8 watt resistors ( except for the 1 watt one )
& I'm just wondering how this circuit works. What's the purpose of Q1? I know what the regulator does, just confused about Q1.

[max308]

I am wondering will this circuit works for 12V Li battery?

[fordb91]

can i use BC548 or 9014 Transistor?

[wcheng2]

Can someone please explain to me what the purpose of Q1, C1, and R1 are? Why does R1 need to be rated at 1W?

[secretsather]

There's nothing wrong with this circuit. It is intended for 2 li ion cells. Just a few notes:
1. Check the voltages of each cell to make sure they are above 3 volts. Do not use this charger if your cells are below 3 volts.
2. If you are charging 2 cells, make sure the voltages match, otherwise charge each cell individually.
3. If you are charging 1 cell, set the voltage (via the potentiometer) to 4.2 (or 4.1 to be super safe) volts before connecting the battery.
4. Check the resistance of the one ohm resistor to make sure it actually is 1 ohm, or charging current may be increased. 1 ohm will yield approx. 600mA
5. The battery will never fully charge. As the battery charges, it draws less current. So if your voltage is set correctly, you should have no problems with overcharge.

[ahdai]

Never charge a lithium cell with a constant current. It is only a matter of time you forget and the cell gets overcharged and bloat.

There are many ICs designed for that purpose. 1555 1811 etc...

[alex-sharetskiy]

does it turn off when the battery is fully charged?

[jimtran93]

 No it doesn't. This charger is very basic.

[spike2fei]

is there a way to make a charger control for acid led battery it will help me to thanks

[shawnsoucy]

can you use this charger to charge capacitors

[lolzertank]

Capacitors are very easy to charge, just hook them up to a voltage source with a resistor in series.

[rc jedi]

over voltage condition=fire
over current=fire
out of balance condition=fire
overdischarge=damaged battery

use a real charger

[ReCreate]

laziness = fire
not waching the battery =fire
being stupid = fire

[hosam_eldin]

Thanks from your language, you gave much about yourself

[ReCreate]

Laugh out loud, I was joking you know

[ReCreate]

wha?

[trialex]

Why not use a simple controller chip that is DESIGNED for Li-Ion batteries? The MAX1555 is designed to prevent over-charging of Li-Ions, and it needs LESS support components than this design.

[samkim]

Hi Friends, I am new to this forum, well I am trying to make a Li-Ion charger using Max 1555, has any one tried out doing this, if so please do tell me, I have been unsuccessful many a times doing this experiment. I am enclosing the circuit used for this experiment.I have done all the circuit connections as shown in the diagram but still when the battery has been charged after being discharged till 3.55V, while charging the LED will be in ON state, when it reaches the maximum(4.15V), the LED has to turn off, but in my case it remain to be ON. Could any one know the exact reason behind this.I am using DC input instead of USB for charging.Is it okay with it.Thank You.

[rob_fed]

I need a simple current source like this, not necessarily for li-ion batteries, I was wondering if the Q1 could be replaced with FET like and IRF511?

[Keso]

While I'm not an expert on battery charging, especially with lithium chemistries, what I have read about them so far suggests that an overly simplistic approach to charging lithium cells such as described here will more than likely damage your batteries and quite possibly cause a fire / explosion.

This circuit may work fine for lead acid batteries but, for lithium, you're quite literally playing with fire.

I *strongly* advise anybody considering making this circuit to do their research on lithium battery chargers first.

[Myself]

Absolutely dangerous if left alone. A current-limited, voltage-limited supply will work for the bulk charging phase, but this design requires that you manually monitor charge current and terminate the charge at the appropriate point. Allowing current to "trickle" in past the termination point will plate out metallic lithium on the electrodes, and detonate the cell.

Powerstream has a good how-to on charging lithium-ion batteries, which I've done by hand successfully many times. It takes an adjustable power supply and two meters, so you can monitor voltage and current simultaneously.

The circuit detailed here will cap the voltage, and if you use it with an appropriately small wall-wart that'll limit the current too, but you still need to monitor the current drop and disconnect the charger manually. Leaving it connected will destroy the battery, period.

[klee27x]

Actually, leaving it connected is a bad idea, but if the voltage is regulated properly, just a hair below 4.2V, this should ensure some degree of safety. To ensure that the voltage of an LM317 circuit does not float high at very tiny loads... such as when the cell is fully charged, you ought to add a small load resistor to the LM317 output. An indicator LED is sufficient. If your battery is trying to pull too much current, you can dither add a power resistor in series, or you can charge it in stages. I.E. set the voltage to a midway point between the cell and 4.2V. After a while, bump it up to 4.2V. Use as many incremental stages as necessary for the size/ESR of your battery. For multi/cell batteries, you can certainly get a voltage mismatch between cells. This occurs because as cells die, the voltage they accept starts to get lower. So a 4.2V cell will no longer hold 4.2V... it might be 4.0V. So if you are charging an 8.4V 2-cell battery, the good cell is now being exposed to 4.4V. I've had this occur a couple of times. If you do not catch this, you will permanently damage the good cell, too. *To all the experts who have seen Kip Kay videos and other vids of li ion cells being connected to 2 car batteries in series or thrown in fires- thanks for sharing your knowledge. We all feel smarter for it.

[klee27x]

Oh, and I wouldn't use a cheesy trim pot. Use a high quality potentiometer or fixed resistors to ensure a stable output voltage.

[gege]

This little charger is a NICE , SIMPLE way to charge li-ion batteries . It has a current limiter , change R 1 value to adjust to your needs It has a voltage limiter (it should be adjusted with NO load to 4.1 volts ) What else ?? a timer ... a thermal sensor ? a micro processor ? a Pic can do all that..

[-Aj-]

heres an idea of the charge profile of a li ion charging Li ion battery
Very helpful, it explains pretty much all we need to know in regards to charging the little chaps, then you can decide whether the charger is suited to your job. Or youll atleast be able to understand everything thats going on.

[thatonekid]

is the circuit there designed to cut power to the battery once it reaches <3% current flow?

[thatonekid]

what is the lowest voltage-in possible?

[kicker109]

Complicated. could that charge a 7.4 v Lithium Polymer battery?

[hosam_eldin]

I didn't say that this is a perfect circuit, I'm agree with some comments but i have some comments also: ( Over voltage ) --> you should adjust the output voltage carefully according to your battery to avoid over voltage. ( The charging current ) --> Also had a max value which is safe to the battery, knowing that the current is reduced gradually as battery reached it's maximum voltage. the current will drop a very small amount when the battery is fully charged.

[rickharris]

Not wishing to throw a damp towel in here but Lithium technology is very VERY sensitive to charging issues and can quickly result in an out of control fire at best. i would stay away from DIY chargers and stick with the one that the manufacturers supplied or at worst NEVER leave the battery alone whilst charging.

[!Andrew_Modder!]

:-| .. i would NEVER mess with a lithium battery (charge), because a video on Kip-Kays website, shows the effect of charging a lithium w-o the real charger!!!! (it looks like an incinerary, and blowtorchie majigger and crap) ...goda love my descriptions :-P...!

[Zak]

T add to Keso: the voltage is critical. Overvoltage may turn a battery into an incendiary device. Google 'lipo fire'. That said the safe voltage is usually 4.1 or 4.2 volts. Lower voltages give much longer battery life as well.