Instructables

The Simplest Rechargeable Battery Circuit (and save the planet too)!!!

Picture of The Simplest Rechargeable Battery Circuit (and save the planet too)!!!
Hallo to all.....

The idea came to me when i was ready to replace a battery cell in my alarm clock next to my bed. Even i am using the last 5 years only rechargeable batteries of the most types i considered how many battery cells people around the world throw away in a simple move like that i did now.....How meny disposed battery cells thrown away in each household? Who knows? But what if we had a rechargeable system to recharge batteries when the device is connected to an outlet and when we will need the battery (In a black out) this will continue working the device.So first we will have power continuity, second we will save money buying and dispose all the dead batteries, and third under normal conditions we can rechargeable any type of battery we like. My next question to my self was that this kind of circuit must be simple, cheap, realible, and easy convertible to recharge any battery cell and giving power to a device at the same time. SimpleEhhh????

So i tried to recall my studies from university and i reminded a very simple circuit which actually recalls all the science of electricity and every 1st year stuedent knows well.

Materials..... Cheap and Easy

>>4 diodes of 1N 4001 type for making the bridge which conncects to the transformer
>>a transformer 2x6 if you want to recharge batteries from1-6VDC or 2x12 for devices up to 12VDC (input 220VAC europe output 2x3,2x6,2x12 choose your one)
>>a 1000uF Capacitor, using it as a filter and elevator of the power
>>a Relay (6VDC if you will give power from 1-6VDC or a 12VDC if you like to recharge a 12VDC battery)
>>a resistor of 33 or 39 Ohm /5W (5W is ideal because the resistor cool down faster)
>>a diode of BY251
>>2 rca female for chassis
>>2 rca male
>>a prototype card or a perforated card, no PCB needed
>>a nice box for the battery recharging docking station appx12cm X 5cm X 3 cm ( in this box you will try to fit a transformer, the basic circuit , cables, the battery nest and your spirit! :D

All materials costed to me 12euro (15USD) The most expensive is the transformer.
Lets go now at the circuit design and i will explain to you....

 
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Nice. I will try this on next week. Thanks for sharing. I have a battery charger circuit which can be designed using LM311 and SCR.

Estela Alano10 months ago
Hey there. Can i simply replace a supercapacitor with a rechargeable battery? Or i must make some modifications? Thanks
This is a very 'nice' simple circuit. It would have been even better if there was some sort of connection between the bridge and the battery! But hey ho! we can't have everything.
agis68 (author)  Mark Mercer1 year ago
oups sorry you got right man! The real battery you charging is incuded in doted lines. The NC of reley gives + and NO gives - so them are going to battery you want to charge. The outlined battery is a dummy battery which you take the - from ground (charging battery) and + from relay
Actually that was my first attempt in electronics. Thanks for your humorous view
agis68 (author) 3 years ago
I build a better circuit for charging batteries Problem is that charges only 100mA batteries (like the wireless phones use) I charged also bigger Ni batteries of 300mA but it takes more time. 

You will need also Pack 100mA Wall transformer,  LED , 10K resister, 1N4001 Diode ,1000uF capacitor

Please before plug it to 220 or 110 V AC double check for any short circuit.
Batterycharger.gif
phillipewu4 years ago
I have a question about the circuit - what is the purpose of the diode and the resistor in series? Is this to reduce the voltage from 12v to what is required by the battery?

I want to charge a NiCd power pack from a radio control toy and I think the voltage is 7.2V. I also have a power supply from a junked computer which I think can supply 12V. What type of diode and resistor is required?

With this type of circuit can the battery become overcharged? If so what what is the safe charging time?

Thanks for any help.
You need that diode to prevent a switching power supply from tripping to 'off' when charging batteries and the resistor current limiter for charging to take place safely.
agis68 (author)  phillipewu4 years ago
 you answered correct in your fist question. The resistors reduces the Voltages not the Amperes to do so you need any diode. For your 7,2 i will use a 6,1 diode (i am not sure if you can find in the market 7,2 exact and then using the Ohm's Law you have to calculate the available mA you need for your toy. Usually the NiCd batteries are in class of 800mA so 12V/0.8=15Ohms
I ve made this circuit to charge the batteries and protecting them for overcharging. Safe time is about maximum 120-140 min
Dr.Bill3 years ago
Charging happens when the relay is energized and the power comes in from the right side surrounded in Purple. Probably a switching power supply or other regulated (or not) DC supply. If you put a tap in there, when the power went off the batteries would supply the load making a slow UPS.
This circuit needs work though to do that.
A circuit very much like this one was written up in QST Magazine and it is used to provideemergency power to Ham Radios when the lights go out.
73's
profpat3 years ago
HI Agis, sorry for the late comment, just read this today, question, what is the purpose of the relay? how does the battery charge? i dont see any connection from the bridge rectifier going to the batteries? i guess i am missing something!
agis68 (author)  profpat3 years ago
the relay supports the battery charging. when is charged (the Batt) then the rellay released and stoping the charging.....This cisruit is just a part of another circuit (to charge the battery for an alarm for example so also the relay can be connected to the missed cisrcuit....
profpat agis683 years ago
Thanks for the reply! will figure it out somehow!
chefbrian5 years ago
i have a 120vAC-9vDC adapter, how could i use this to charge a rechargable 9v battery? would a simply attach the positive lead on the charger to the positive lead on the battery? that's what the diagram seems to do.while charging, will it continue to power the battery operated device? also (stupid question probably) does an LED work like a regular diode, as a "one way valve" for current?
agis68 (author)  chefbrian5 years ago
Not a LED but a regulate real diode like 5v1, or 6v1.and 9v1. It depends from the final power u want to have. For example if you want to have 9 volt then put a 9v1 Diode. U have to place always with in parallel with an apropriate resistor. For 9V u have to get a 220-360Ohm resistor. Of course u can place also a Led as indicator. The answer in the other question is what u suggested.
Colonel885 years ago
...(uh, what is this?) I just hooked up a power supply with a battery and boom let there be light.(or more correctly, electrons!!!
You mean photons.
told...
agis68 (author)  Colonel885 years ago
u have right but the circuit is not completed yet...firts of all in fron of the diode bridge u need a transformer of 12V (from 220V AC to 12V DC) The Realy kit gives u an exit of the circuit to give power in a device of 1,5 V DC The circuit just gives u an idea and NOT a really method .....
dbunting5 years ago
how do you prevent the battery (NiCad, NiMh for the most part) from lossing its Zero Point due to "over charging". You know, that irritating point where you left the battery in the charger for so long it no longer holds a charge. Did you do anything to combat that?
tech-king6 years ago
your linear power supply is not that good. i lacks any form of regulation, a serious problem with dc devices and chargers. a 12 volt and 6 volt zener diode would work well. also, most linear power supplys use 3000 uf filter caps to power dc devices.
agis68 (author)  tech-king6 years ago
maybe u have right about the capacitor, 1000uf is small but it works fine with small battery cells (like 1,5v). But of course u have to change it to 3000uf for covering bigger voltage.... thanks for the recommendation