What is Battery charger: Definition and 38 Discussions

A battery charger, or recharger, is a device used to put energy into a secondary cell or rechargeable battery by forcing an electric current through it.
The charging protocol (how much voltage or current for how long, and what to do when charging is complete, for instance) depends on the size and type of the battery being charged. Some battery types have high tolerance for overcharging (i.e., continued charging after the battery has been fully charged) and can be recharged by connection to a constant voltage source or a constant current source, depending on battery type. Simple chargers of this type must be manually disconnected at the end of the charge cycle, and some battery types absolutely require, or may use, a timer to cut off charging current at some fixed time, approximately when charging is complete. Other battery types cannot withstand over-charging, becoming damaged (reduced capacity, reduced lifetime), over heating or even exploding.
The charger may have temperature or voltage sensing circuits and a microprocessor controller to safely adjust the charging current and voltage, determine the state of charge, and cut off at the end of charge.
A trickle charger provides a relatively small amount of current, only enough to counteract self-discharge of a battery that is idle for a long time. Some battery types cannot tolerate trickle charging of any kind; attempts to do so may result in damage. Lithium ion battery cells use a chemistry system which does not permit indefinite trickle charging.Slow battery chargers may take several hours to complete a charge. High-rate chargers may restore most capacity much faster, but high rate chargers can be more than some battery types can tolerate. Such batteries require active monitoring of the battery to protect it from overcharging. Electric vehicles ideally need high-rate chargers. For public access, installation of such chargers and the distribution support for them is an issue in the proposed adoption of electric cars.

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  1. Juanda

    Manually charging batteries

    I want to buy a car/motorcycle battery charger because it's a very convenient thing to have. Also, for a while, I have wanted to have a simple power source like shown. How safe is it to use it to charge lead-acid batteries from cars or motorcycles? I know the simplest option is to buy the...
  2. K

    Could a battery charger be damaged more easily than the battery / device?

    I've got an electric toothbrush which is rechargeable, it had been regularly used and charged for years until one day it didn't charge. I immediately thought that the toothbrush was failing but at the end of the day I found that it was the charging stand failing, the toothbrush was fine. But I...
  3. F

    Battery Powered Electric Motor and Charging Requirements

    I need to build a battery system to drive a 10 HP pump motor. The actual BHP varies as the pressure in the system rises, but for the most part we are operating at a 10.1 brake horsepower. Run time requirements will vary from a few hours to many hours. I settled on 8 hrs as a basis. Motor...
  4. DaveC426913

    Appliances Faulty DeWalt Battery charger for power tools

    I've replaced the charger for my DeWalt tools several times, and now I may have to go out and get a fourth one. One of them flashes a fault warning (steady slow flash), the other two do not light up at all. Now, I do not take care of my tools. All three of these chargers may have been exposed...
  5. J

    Using 6 Diodes for a 30 Amp Battery Charger

    I was told once that two 1 amp tv type diodes parallel will not work because one will always carry the load, but I am working on a car 30 amp battery charger and it has 6 diodes 1/2" press in type all parallel same as from a 10DN series Delco alternator from the 60's where they used three...
  6. G

    Battery charger circuit fault(s)

    My cheapish 12V battery charger suffered an overcurrent, and now is not working properly. Below is a schematic of the main power side: The MOSFET M1 will not turn on, which I'll tackle later, but even with the drain bridged to source the voltages are wrong. The black, slow charge (rail at...
  7. E

    Battery charging: Minimum voltage differential?

    I have a question that I believe requires knowledge on the graduate level, but I can't necessarily express it in terms more complicated than plain English. If this is not so, moderator, please adjust to your taste, and thank you! If it helps to know this, I'm an audio/video systems designer and...
  8. Mike9119

    How can I put deep cycle batteries in a semi tractor-trailer?

    Hello I drive for a truck company and am getting tired of being charged for idling my truck to keep my batteries from depleting. I have a 2000w inverter now that's hooked to the truck. I had the idea of putting a few deep cycle batteries and charging them somehow with truck inverter or outlets...
  9. P

    Charging Lipos @ 5C with Digital Power Supply

    I have a ton of 3.7 volt lipo's at my house, each of which can be charged @ 5C, and since each have a capacity of 270 mAH, than I should easily be able to charge them @ 1amp. I put 8 in parralel with each other so it is a 1s, 8p battery pack. each of the lipos is the same (in tems of specs, ik...
  10. S

    Pedal-Powered Home Office: Charging a Battery & More

    So I want to charge a battery from a pedal-powered dynamo, and use that to power my PC, my screen, and pretty much everything else in my home office. This whole thing is a little project to improve my own health while I'm working; I'm not here expecting to make major miracle savings on the...
  11. P

    Shopping advice: Solar battery charger and power supply

    I'm sorry if this isn't the right place for a shopping question, but I'm not sure where else to go for advice. I got a https://www.amazon.com/dp/B0094KM4VK/?tag=pfamazon01-20 on sale and the unit is great, but the batteries don't hold a charge very well, especially when using rechargeables - it...
  12. Semiavas

    Class 2 battery charger as a LED power supply?

    Hello, I'm planning to light up a tile chess board with 64 LEDs (blue and white) set between the tile squares, and I was wondering if this Class 2 Battery charger output: 12VDC 900mA, would work to power 16 parallel sets of 4 LEDs + 1 ohm 1/8W resistor and a SPST toggle switch? The current...
  13. M

    Would this Battery charger work as a direct power source?

    Hello I need a source to power ADSL router when the electric power would be cut for any reason because i need to keep my laptop that i use for work connected to the internet. I found this "Anker® 2nd Gen Astro Pro2 20000mAh 4-Port Aluminum Portable External Battery Charger with 9V/12V...
  14. T

    Charge 4 AA Lithium Ion Batteries at 5V in 2 Quarters

    Hi I need a circuit to charge 4 aa lithium ion batteries. I need it to charge at 5 volts and when the batteries are done charging, the circuit cuts off. It would help a lot if I could get this in a small space around 2 quarter's. Thank You.
  15. S

    Mylar to increase efficiency of solar battery charger?

    I just got my hands on a solar battery charger with a set of usage specifications that makes me believe it will only be useful some four days a month and will take more or less such time to charge a single set of batteries, despite promises on the contrary in the instructions. Since the case is...
  16. V

    Need help making a solar panel AA battery charger

    Hi, I'm working on a project to build a solar powered AA battery charger. This is definitely not my profession, I only have a small understanding of electrical engineering. Mostly from what I learned in high school electrical class. Here is what I'm looking to do: I want to charge 16 AA...
  17. D

    Battery Charger Considerations?

    A friend of mine lost his battery charger for his airsoft gun and he naturally comes to me for electrical help. Problem is, I'm freshmen level right now. I looked up how to hack and build a basic battery charger, my question is do the internal resistance/impedance of the batteries matter when...
  18. F

    Build Solar USB Charger: Voltage & Current for Rechargeable Batteries

    I want to build a usb charger that works with solar power (and later add a crank dynamo too). The photovoltaic cell will charge rechargeable batteries and they will charge the usb device, like my smartphone. The smartphone charges with 5V and 1500mAh. I'm planning to use 2 AA batteries 3.4V...
  19. M

    How Does a Battery Charger Work and What Causes Overcharging?

    I'm thinking about all types of charging (LiIon, lead acid, etc.). I get the basics...but would really enjoy more info on the subject. Also...one thing that confuses me is how you can "overcharge" a battery...and how you can supply too much current (amps) to the battery. Since its generally...
  20. M

    Hand crank generator battery charger circuit

    Hello, I want to use a DC permanent motor as a generator in order to use it to charge a battery. This generator will be rotated by hand. The speed is varying as it rotates by hand. I would like to know what is the circuit that I could use it to charge 12 V chargeable batter? Best wishes,
  21. G

    How can I create a continuous UPS using a 12V 7Ah battery and an adapter?

    12 v 7 ah battery charger urgent hello everyone i am getting stuck with 12 v 1 amp adapter and with 12 7ah smf leada acid battery . i give supply from adapter to battery through 1n4007 and then from this batttery to my microcontroller kit. by this my batteyr get charged and kit gets supply...
  22. L

    Creating a battery charger indicator

    I have built a battery charger for a cordless drill. It works fine, however, I would like to add an LED indicator to let me know when the battery is fully charged. I'm getting tired of checking the voltage across the battery all the time to see if the thing is charged. I'm not picky on how...
  23. F

    Hybrid Battery Charger Question/Idea

    I have a Ford Escape Hybrid. it is a 330v battery with about 1.4kw of capacity. Currently there is no cost effective after market charger. Also my location in NYC does not allow me a "plug in" option. I had an idea on how to access the battery pack to charge it, but I wanted to know if...
  24. E

    Li+ battery charger chip without buck

    hi I want to design a 4 cell (16.8V) lithium ion battery charger. The normal chips available have built in buck (reall buck or synchronous buck) or at least control circuitry for buck with external mosfets. This is necessary as wall adapter/source input voltage are higher and unregulated...
  25. K

    Battery Charger using LM317

    I'm designing a battery charger consisting of an LM317. The regulator will charge three batteries successively, for example, when battery 1 reaches a terminal voltage of 13.8, a voltage comparator will activate a relay that will switch on the second battery while switching off the switch for...
  26. M

    Too Long on the Battery Charger

    What happens if re-chargable batteries are left too long on their chargers? is there a fire risk? do some of them such as the ones used for moble phones and chordless power tools have some sort of cut-off safety mechanism?
  27. S

    Why Does My Battery Keep Running Down in a Closed Loop Charging System?

    Hi i embarked on a project to design a battery charging system using an alternator, an electric motor and a battery all connected in a closed loop. The battery powers the electric motor and in turn the electric motor powers the alternator and finally the alternator charges the battery. My...
  28. A

    Work done by a battery charger

    Homework Statement To recharge a 5V battery, a battery charger must move 7x10^6 C of charge from the neg. to pos. terminal. How much work is done by the charger in joules? Homework Equations QV=U The Attempt at a Solution If the battery needs to be recharged, isn't the potential...
  29. R

    How does a battery charger know when to stop charging?

    Dear Experts, I am fascinated how a cell phone battery charger knows when the battery is fully charged such that it cuts off the power to prevent further charging. If its based on sensing a particular voltage has been reached, i wonder how is that achieved? Or is it achieved by measuring...
  30. G

    Electrical How difficult to build a DIY Lithium Ion Battery Charger?

    Not asking for a schematic, more a notion of roughly how challenging this will be.
  31. K

    How does a battery charger work?

    I have little idea on how a battery charger works but i'll just state here what I think is the case and then state my queries. When you receive an AC input from the mains there is first a step down transformer which lowers the voltage - then there is some regulation and it is converted to DC...
  32. B

    How Do NIMH Chargers Detect End of Charge?

    i am intersted in the end of charge detection(-deltaV) on some NIMH chargers, i would like to test that effect on some chargers. I got some chargers(like GP Smart power bank, GP H500,etc...),all the chargers i have use the drop of voltage as end of charge detection, so what i did is, I...
  33. D

    What are the best settings for charging a 24v 12ah Lead Acid Battery?

    Hi, can someone tell me what are the optimum settings for a charger to charge a 24v 12ah Lead Acid Battery? I know that the voltage stays the same. I just need to know what current will cause the faster charging and, at the same time, won't destroy the battery.
  34. M

    Old Battery Charger for RC Car in Wichita KS - Can it Charge Ni-H Batteries?

    moe in wichita ks i have a old battery charger, about 15 years. it is for charging 2 or 4 ni-cad AAs, 500 ah, for a radio control car. input 120/60 9w. out put 5.8 volts 500ma dc, charge time 1 hr. my Q is can this charger work on ni-h batterys? thanks
  35. J

    How Do You Calculate the Variable Resistance for Optimal Battery Charging?

    Homework Statement http://img2.freeimagehosting.net/uploads/bf073a5eb1.png http://img2.freeimagehosting.net/uploads/bf073a5eb1.png Determine the variable resistance R if the 25 Watts to be absorbed by the battery (0.035 ohm resistor and the 10.5 V element). Homework Equations V = IR P =...
  36. ranger

    Can a wireless charger eliminate the hassle of tangled cords?

    There have been a few posts about wireless power transfer here on PF, so some of you may find this useful. I came across this post in another forum about designing a wireless battery charger. The author gives a rather through description of what's going on and why he's doing certain things...
  37. M

    Testing a Car Battery Charger for 6-12V Batteries

    I have a car battery charger (for 6 or 12 volt batteries), that I don't know for sure if it works or not. I want to use it for a power supply in an electrolytic cell, so I decided to test it out to see if it worked. When I hook it up and plug it in, nothing happens, the needed doesn't jump on...
  38. R

    Building a Battery Charger with Car Alternator

    hi i wish to build a battery charger using a 3/4hp240voltac motor driving a 55amp car alternator will this work has anyone done this before and will my caravan batteries be oka i have a gen set to drive the electric motor all these questions i hope to be reveled rolly