I used this method and it worked. I only charged the battery up to 13.6V, the voltage then drops down to the normal resting voltage of 12.6V. This method saved me from buying an immediate replacement battery, and a dedicated battery charger, or the possibility of having to call for an emergency jump start service. Thank you for the video.
Brilliant it works, my battery died after I left it in the for 2 months. I charge using this method only light bulb and 19 volt laptop charger. After an hour I start the car with the battery
Thanks, you are a genius. I did the project with 2 light bulbs in parallel. I used it on a battery that was very old and dry as a bone. I filled it up with distilled water and a bit of liquid from another battery. I hooked it all up and it started to charge the battery. At first, the light bulbs didn't go on at all. But as time went on they started to glow a bit and the voltage started to go down from 19v to 17v. The power adapter started to get a little warm as the glowing increased, but not hot. I then swapped the adapter for an actual battery charger and the battery started to charge. Awesome video. Thank you very much.
My alternator and battery charger is down and on a small island in the Caribbean there's no replacements due to pandemic. This idea has saved the day and has enabled my 50 year old Land Rover to start, make a trip into town and get me home again. I've taken the ammeter off my defunct battery charger and wired it into the circuit. With a 40W bulb I'm charging at 2.5amps.
I like your videos. Here is a comment that I share. All the energy through the light bulb is effectively wasted as heat, probably around 50% of the power from the power pack. Would it be not better to introduce a low cost buck converter ( under $10) to change the 19.5V to 12V, at an efficiency of typically 85-90%? The benefit of the buck converter will be to significantly reduce the emitted heat and charge your battery nearly twice as fast, too.
How did I not see this?? I knew there is a way aside from those ludicrously priced battery chargers and then you happened. Thanks so much! Will try it this coming weekend. Been worrying about my battery as I don't have time to go out and have it charged somewhere due to bad weather. Hopefully this can help me solve the problem and hopefully finally let me have a home battery charger! 😍
This will work without a bulb but you need to charge for short bursts of time eg 5-10mins to avoid overheating the battery. Your 12v battery should take 19v for short periods with rests in between to allow for cooling. Aim to get enough juice into it to get your car started then allow the battery to fully charge on the car with all unnecessary accessories off (eg lights, radio, fans) to avoid straining your alternator. I just charged mine straight (positive to positive etc) from a 19v 3.42amp laptop charger for a total of 35mins over several charges and it started the car no problem. Only issue was the charger itself was making a whining noise so it could be damaged but it was a spare so be aware you could shorten life of your charger or cause it to overheat. Take suitable precautions against acid and explosions, monitor battery and charger, I accept no liability if you follow this advice and are injured or there is damage.
I've improved the system a bit i've put a powerful headlight lamp and a weak one in parallel, when shorting the + and - both lamp work, but when plugged to my discharged battery only the weak lamp lights up ! Meaning the powerful one will light up when the battery is gonna be charged. Thanks for the tutorial even with electrical knowledge you sometime need a heads-up ! Great channel !
This is a good emergency charger .... but .... NEVER ! connect this to any sealed gel battery , because the voltage must NEVER exceed 14 Volts ( gassing ! ) you might fit a 13.8 Volt regulator after the lamp to avoid ruining your sealed or gel battery , and then the charger can be connected for long periods , without worries ...... DAVE™🛑
ok, I've read a lot of your replies so I'm going to assume it's just better to use the 18.5 V or 19 V charger with a light bulb, which gives out about 1.5 amps, that seems to be the best way of doing it. so guess you won't have to answer this if you prefer not to, but thanks for putting this info on you tube. it's great.
Yes, you are correct. Here is one more way to explain why we need a light bulb: a charger and a power supply actually are two different devices. A battery charger limits current, but a power supply doesn't limit current at all, and that is why we need a light bulb. Moreover, in order to fully charge a battery, we'll need to reach 14.2V on its terminals, which is impossible using a 13.5V power supply. Anyways I am glad that you find my video useful.
Okay, I'm envisioning frying my cars electronics because I'm not qualified to do this. I'll wait until Monday morning and pay a guy to jump start me 😁Thanks for the video anyway.
Hello, I have a 19V laptop power supply and a 21W bulb, I have been charging the battery during all the day but the battery between its poles does not pass above 12.30V. Any suggestion?
There is a trick to install correct circuit ,when light blub On >> Connector of laptop has two sides Negative (one contact )positive (two contacts + and sens ,if you keep connector ) ,should wire bulb touch both contact positive of connector.
What did you mean by "sens"? My connection bulb (which was connected to my laptop charger position on one hand and to battery positive terminal) switch on (though low voltage) only when it wire makes contact with the negative in the laptop charger mouth.
That's great. I have a query: When I test voltage on CHARGING mode, it shows 14.2v, and when switched off the CHARGING, it shows battery voltage 12.x volts not 14.2v now. Here you have said to keep the charging till 14.2v battery voltage - Now this voltage you have said is while CHARGING or CHARGING disconnected? There's a difference of about 14.2v - 12.6v=1.6v when charging is off. Obviously on charging it shows 1.6v more than actually battery voltage. I am using 12v 21w bulb and 65W laptop charger with output of 1.xAmp
Hi, 14.2v is while charging (charger connected). When it reaches 14.2v while charging you can consider it fully charged, and you can disconnect the charger. Usually, it slowly drops to 13.0V, but I think 12.6V is fine.
@@ElectricalPro Thanks. I got it. I think 12.70v is default we get newly from market. so 12.6v is fine. But finally it dropped to 12.3v which shows the battery is holding 50-70 charge.
@@ElectricalPro Thanks once again for your response. Yeah I also think that all cells are not charged equally but I had to close the charging as it was reached to 14.6v and battery was showing 12.8v means it was reached to full charging level. But as voltage is dropped from 12.8 to 12.3v I believe it is no more holding the charging equally to all the cells. But it's running fine on 12.3 also and my car run daily so let's see how far the battery goes.
Did you try it without the light bulb? I ask, because a lithium battery charger should be designed to work in constant current mode until it's constant voltage point is reached. Then you would have an even simpler system and it would be more efficient.
Hi, there are a lot of ways to improve this system, it would be great to charge it with "constant current mode until it's constant voltage point is reached" but then the circuit will be much more complicated. Also, the light bulb is wasting a lot of energy... energy efficient charger should use PWM... BUT: The point of my video is to make a very simple charger using just components that most people have. It is "emergency DIY car battery charger", and it should be used in case you really need to charge the battery and you don't have a regular charger.
Because 'Laptop charger' is 19V and it is going to try to charge the battery to 19V immediately, and that will cause a very high current, which will trigger overcurrent protection. The lightbulb limits the charging current. Btw, 'Laptop charger' is not a charger, it is a power supply (or power adapter). The actual circuit that controls charging of a laptop is inside the laptop. P.S. Ok, right after you said "work in constant current mode until it's constant voltage point is reached" I started to think that you know all this well, and that you do not ask a simple question about the lightbulb. Got it now, sorry :)
Ha ha, no problem. Maybe other people were thinking the same as me? I didn't know that the laptop contained the charging circuitry, but that makes sense since the laptop should operate even if the battery is flat when the power unit is connected. btw. I realised that I had a power tool Ni-cad charger that works OK as a directly-connected charger to my car battery, it outputs 2.6A from zero volts up, with a 30 volt open circuit voltage. I have some DVMs to monitor the VA
How u increased charging current? I mean u said by adding load..?but do current flow be effected by adding load? U kept 12V bulb & droped ,doesn't the overall voltage is Lesss than the charging voltage range like 14V to 15V
Dear this will work on bike battery?? I tried it but bulb didn't turn on,so that is why now change in the volts, stays at 19v. Why the bulb is not turning on??
You can try for example 10 Watt 10 Ohms. But such powerful resistor is not easy to find, that is why I've used a light bulb. With 10 Ohms, the current will be less than 1A. For the higher current you will need even more powerful resistor, with lower resistance... for example 20 Watt 5 Ohms.
It is not a good idea. Well, if it is 5 Ohms and can handle 2 - 3 Amps then maybe yes... but in this case, we don't use it as an inductor, we use it as a resistor. The only reason why inductor may work is because it uses a lot of wire, and wires have some resistance, therefore in some cases inductor may work as a resistor. But finding such inductor is even more difficult than finding a resistor.
I have one question. Currenly have laptop charger from premium class notebook. 19.5V and 12A (o think it 230W is ti gona work wih bulk lamo, to dcrease currency?) planning to charge to batter battery is 100ah. One camples , can i dro curenvy wiih potenciomert?
Hi there! Tried the same technique but for some reason, the bulb does not light up in this particular circuit. When I connect the bulb separately in power socket it lights up and when the same thing is connected to the circuit, nothing happens. Any advice on what I might be doing wrong?!
maybe because the voltage go thru the bulb 7v so not enough, or +ve side of bulb must connect with +ve side of charger and -ve side of bulb connect with +ve side of battery due to current flow.
Ingenious way of using existing hardware 2 solve y'r problem, BTW.. my damn laptop charger (TUM-90WAUT) (9.5-22V; 5A max outp.((90W)), shouldn't need this, should by its own downrate itself, but only after adding the serial resistor of the lamp switches to 12 Volts, ripping my hair out.. any idea?
Excess voltage cut the life spam of the battery or disfigure the sharp of the battery. Best voltage to charge 12v battery is 13.8. For fast charging depending on the ah.
1:26 Be carefully, because the diagram on the right is may be wrong, looks this type of chargers have 3 pins: outer cylingdical shell is minus, innher cylingdical shell is plus, and pin in the center is data pin, that is used by laptop to speak with charger brick and detect its power limit, that is why when you connect not supported power supply (for example: 40W charger instead of 60W one), it will write a notification and will not charge the laptop. At least my Dell laptop charger has this pinout.
Hello, that was a great video and idea!!! I’ve got three options to charge my battery (the first one is your idea) and I’d like you to comment on the other two options, just in case they are easier or more efficient. 1. Your Video. 2. I’ve got a power tool Ni-Mh/Ni-Cd charger rated at INPUT:220/240V - 60W, OUTPUT: 7.2-14.4V - 2.6A. The true voltage output is, two pins of 22.50V and another two pins of 27.50V (I guess they use the same circuit/different box and pinout, to charge the 14.4V and 18V series of their batteries). 3. …and finally the charger from a car air-pump, with an internal sealed Lead battery. It’s rated at INPUT:220/240V - 0.8A, OUTPUT: 12V - 1A. The true voltage output is 13.75V. My car battery is at 11.95V right now and it’s a 12V - 52Ah Calcium Battery. Before I start a charging session with any of the three, would you care to comment please? Many Thanks
Hello. All three should charge. But about 2 it's not clear to me, 22.50V seems too much. I would go with 3 or with 1. The cool thing about 3 that it is a complete charger, I like it, but charging will be relatively slow, it's 1A.
Hello, thanks for answering. No. 2 measurements are 100% correct but there is another pin in there I didn’t mention, that maybe it regulates the circuit as well as the voltage because inside these chargers (it’s a Makita one) there are overload and temperature sensors as well. For example they never start charging if the battery is too hot. If you think No. 3 is also OK as an alternative to your video, slow charge is not a problem and actually it’s better as far as I know. Thanks again.
That is the problem with 2, there is too much I'm not sure, and it's for Ni-Mh/Ni-Cd, it is probably ok, but I am not sure. 3 seems to be a complete charger, so use it, it is for a Lead battery, 13.75V is ok as well.
i did same, but my battery charging is below 1volt, so can i do the same to get charged, but bulb connected in series not getting blow and voltage at battery terminal is 19 volt, please help
I think you can use a potentiometer instead of a light bulb and check the voltage with a meter. Am I right? And can I charge the batteries eg 3V or 6V with this power supply?
Hi, yes, but you'll need a very powerful potentiometer. Depending on a desired current you will need a 10W or maybe even 60W potentiometer. For a 6V motorcycle battery I think it is better to use a 12V power supply, it will be more energy efficient. But please DON'T charge Li-ion batteries with this method, because they may explode.
HI, i just watch your video, i have a set of battery for my ebike 48v20Ah, when its full charge it will be 52 to 53v on my lcd, but lately, i charge it then my charger gets green, when i check my lcd its still the same but when i run my ebike, it just fall fast unto 42.7v that causes my ebike to crawl. when i check the batterys individualy (12v each set of 4) one of the batterys line just got burned due to the wire was jam. so im asking if i can do these procedure like on your video to fully charge my batterys? hope youl read my comment and help me thank you....
Dude you are a King Boss! Thank you for this video. Would this work as an adequate power source for an electrolysis tank? Since it wouldn't be used to charge a battery would I really need to use a light bulb? Could I just run the negative straight to my piece being cleaned and the positive straight to my sacrificial anode?
Hi, Yes, one bulb 12V 200W is good. But, before charging make sure that your power supply can provide 10A of current. If your power supply cannot provide 10A, then you need to use less-powerful bulb.
I have a question: I replaced a car battery recently as it was 3 years old and could not start the engine. I checked the voltage using a multimeter and it showed 10.45 Volts. Does it mean the battery is quite dead and cannot be charged?
Just try to charge it, 10.45 Volts just means it is discharged. If it is a new battery just from a store it is not good, because storing discharged battery is bad for the battery.
Hi, yes, the bulb needs to light when charging, and the brightness of the light will become lower and lower throughout the charging. Charging time will depend on many things, like the capacity of the battery, and how deeply it is discharged, and also light bulb effects charging time, a more powerful bulb will make charging faster. The best way to tell whether the battery is fully charged or not is to measure the voltage while the battery is charging. If the voltage becomes higher than 14.2V the battery is fully charged.
Hi, you mean that if i use two bulbs the charging will become faster because it will also double the amphere , or let me say 1 bulb is to 2 amp and 2 bulb become 4 amp, i am right?
Yes, you are right. Small clarification: it will double the current when you connect the bulbs in parallel.... but if you connect bulbs in the sequence you will decrease the charging current in half instead of doubling it.
Hi there. I have the suply of 19v 3.72amps laptop charger ..and I used a dual wire bulb with a wattage of 5Watt 12V and What is the thickness that the wire must be or is it okey if the wire stays cool cause I have a 0.5mm wire for the stream
Hi, If you use 5 Watt 12V bulb then the charging current will be less than 0.5A, I think your 0.5mm wire will handle such current fine, but a thicker wire is better of course. Thicker wire can handle much more current. The thicker wire you use the cooler it will be.
Good day, u mentioned the light bulb is to limit the ampere output from the power supply/laptop charger. If without the light bulb then it will kill the power supply just in case the battery is totally drained. U also mentioned can replace the light bulb with a 12V CPU fan. I have this CPU fan has a sticker stated 12V 0.18A (R). Does it means that 0.18A will be the ampere to charge the battery OR it is actually 3.82A output to the battery ? Which 3.82A = Max ampere output of the power supply/laptop charger (4A) deduct (-) CPU Fan ampere (0.18A) ? Thank you.
Good day!, It will be 0.18A, maybe even less... your 3.82A just is the maximum your power supply can provide. Imagine that you have 40A power supply, it will still charge your laptop fine, but you can also connect 10 laptops to it simultaneously without any problem, and one such power supply can charge them all at the same time. Your 12V 0.18A means that the fan is designed to work with 12V and in such case the current will be 0.18A. The real question is "what voltage the fan will get?" in our case it will be 19V(PowerSupply) - 12V(Battery) = 7V (voltage at the fan). So the fan will get 7V instead of designed 12V, so the current probably be close to 0.18A, maybe less maybe, even more, it depends on the fan, the fan is not a resistor it is hard to predict what current will be, but it will be safe for the fan for sure. Just make sure you connected the fan correctly: plus of the fan should be connected to the plus of the power supply. I am happy that you are trying to understand :) This circuit looks simple but it is a bit tricky, it is not the best example for beginners.
@@ElectricalPro Since 0.18A (if using a fan as replacement for a 12V light bulb) will be the ampere going into the battery, does this also means that it will take longer time to charge the battery as compared to using a 12V light bulb ? Thank you for spending your time answering.
Yes, it will take a long time to charge the battery, especially if it is a big battery. You can also connect two fans in parallel to double the charging current. But with a proper lightbulb the charging current will be much higher and charging will be much faster. Usually, people in such cases limit current with a resistor, but in our case it will be a very powerful resistor, and it is not easy to find. For example, if the battery deeply discharged and has 10V then the difference in voltage 19V-10V=9V. Now let's say you want a 2A current... what resistor should you use? let's calculate: 9V/2A=4.5Ohms, but let's calculate how powerful the resistor should be 9V*2A=18W. Finding 18W resistor is not easy, but finding a 21W or 48W bulb is easy, that is why I used a light bulb. Also the voltage of the battery changes during charging, from 10V to 14.2V, which means the current will change as well. Happy to help.
@@ElectricalPro Thank you for detailed explanation. I think I'll give up the idea of using a CPU fan to replace the light bulb. I thought a CPU fan uses less current (waste less energy) will make the remaining current from the power supply goes into the battery, but that is not the case.
Its work! Thanks a lot for this video. I already charge 3 car baterry and all good.. and right now im charging 1 more battery but this time the light are different not like before this.. when i on the plug the bulb not working have no light at all then i leave it for 5minute the bulb start to lighting slowly. Now it dim light is it okay?
Help me! So the laptop charger can charge batteries directly!? I have three 6 volt batteries that I will connect them series to produce 18 volts, that laptop charger which is about 18 volt itself will charge them from end-to-end correct? Also if I added 1/4 battery to get 24 volts will the charger be sufficient and work properly? Thanks
To fully charge a 12V battery you'll need 14.2V, therefore for a 6V battery, you will need 7.1V, but since you have 3 of them connected sequentially you will need 21.3V for a full charge. So 19V Power supply will not be enough. Moreover, to charge a battery you will need some kind of current limiter, in the video, I've used a light bulb for such purpose.
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