# Tag Info

## Hot answers tagged charging

30

Phone chargers are indeed usually a 5 V regulated power supply. Here's an example of a simple circuit that is commonly used: Source. This is a flyback converter circuit. The output voltage is regulated even though it's not immediately obvious how that's done. But note the winding "Na" on the left, it is one of the transformer's windings. This ...

14

You could do the entire discharge at the lower rate but then it would take a lot more time. When discharging at a high rate the voltage may collapse prematurely so the battery seems discharged before it really is. By combining the two discharge rates you can discharge the battery in a reasonable time but be confident that it is fully discharged. The lead-...

13

It is correct. You normally see PMOS connected like this to act as a reverse-polarity "diode". simulate this circuit – Schematic created using CircuitLab It has much less voltage drop than an actual diode and will protect currents from flowing the wrong way when the voltage is connected between the battery terminals are connected in reverse. ...

11

Complementary to main answers: It is crucial to note that attempting to charge a Li-ion cell by simply applying 4.2 V (or whatever maximum voltage is required) is an extremely bad idea because: One normal charging method is to use CCCV (constant current / constant voltage) charging where a constant current is applied while Vbat is under 4.2 V and then a ...

10

simulate this circuit – Schematic created using CircuitLab The current is determined by the voltage across the resistor, which is V1-Vc. As the capacitor charges, Vc increases while V1 stays the same, so the current decreases. The rate at which a capacitor charges is directly proportional to the current, so the rate at which it charges decreases ...

10

The paper is about using the EV motor windings as a transformer or inductors as part of the charger when the vehicle is charging instead of using a separate component. A common problem of doing so is that the current flowing through the motor windings will cause it to produce unwanted rotation or vibration(torque) while the car is being charged. The study ...

8

A reason to do this would be to get a quicker assessment of the charge capacity at a constant 5A drain. Another may be because that more closely simulated the actual battery drain on the Llama farm 75 years ago. All batteries tend to have a characteristic open-circuit voltage to which they'll recover under no load. For some chemistries (NiCd, dry cells), ...

8

To answer one point ... Moreover, why can't we simply provide a 4.1 volts input to batteries instead of using 5 volts power supply with an overcharge protection circuit? Because to get current to flow you need a higher voltage than your target. With your approach the current would quickly fall to a very low value when the battery terminal voltage reached 4....

8

I have not yet been able to find a good visual representation of the saturation stage of the charging and how it is different from the constant current stage of charging. Does anyone have/know of a good visual representation of this? The 'saturation' stage isn't any different as far as the cell is concerned, it's just a result of the charger having to limit ...

7

I don't see any voltage regulator or a zener diode inside. In all of the phone chargers I have examined, there is a very small switching regulator chip. The chip often has an internal Zener diode to provide a bootstrap supply for the chip. The chip is a switchmode regulator and sends modulated width pulses through an inductor / flyback transformer to get a ...

6

The author is talking about charging an electric vehicle by re-using its drive train electronics (that is, the power electronics that drive the motor). This means that currents can flow through the motor's windings while charging, which would cause the motor to create mechanical torque. It therefore has to be locked in place to prevent it from spinning up. ...

5

I don't want to use a specific LiPo battery charging IC... If you think its possible can you guys give me some ideas? Yes, it's possible. All you need is a voltage regulator with current limiting. You could do this with a regulator IC (switching or linear) which has a current limit feature, a 3 terminal regulator with a transistor to provide current ...

5

When a series RC circuit is applied across a fixed DC voltage, the capacitor begins charging. It begins charging from 0 volts and, at that instant, the current that charges the capacitor is defined by the DC voltage and the value of the series resistor. That's simple ohm's law (if you are allowed to use that). As the capacitor charges, the voltage across it ...

4

Imagine a steel pressure vessel you are trying to charge with compressed air of constant pressure. This vessel will be your capacitor, the capacity -- amount of air mass it can store, being the capacitance. The compressor is the power source, outputting a constant air pressure -- the voltage. There is a restriction valve on the pipeline between your ...

4

I am somehow creating energy. For example for one cycle, It took 600 seconds to charge but it took 640 seconds to discharge, since the current is constant, that means the battery is somehow discharging more current than it was charged with! Charge is not energy - you have to consider the voltage of the battery as well as the current. When I charge at a ...

3

Perpetual motion machines are impossible no matter how clever you think you are and how complex you can build them. In your case, the dynamo will impose an additional load to the motorcycle motor and additional consumption from the battery. And, because you lose some energy as heat at any conversion stage, you will in fact get LESS mileage. Sorry, that's how ...

3

It looks like there is a plug overheat detection system, with something like a thermistor between the red and white wires. That will be buried inside the plug somewhere. If you don't connect the wires, then the charging unit will probably refuse to work. You also have the problem that a standard 13A plug isn't designed to take 2.5mm² cables. While it may ...

3

If you design the hair dryer so that air is pulled past the batteries first, then blown through the heating wire, you will be able to extract all the heat from the process of discharging the batteries, including what would otherwise be considered waste heat. The relevant spec will then be Watt-hours (Wh). Doing the math from this is easy: Your 4.8 Ah 3.7 V ...

3

Yuck, Apple charging. The configuration of resistors on the data lines you need for this is proprietary (a polite way of saying "customer lock-in") Apple and will not only depend on the type of Apple device (IPhone, IPad, IPod), but also on its generation, and possibly on the phase of the moon at the time of manufacture. What you want is doable, ...

3

Yes, you do have a problem. Series-connected batteries should be balanced, otherwise you always overcharge one of them and over-discharge the other. Neither is good for the battery life and you also get less cycle capacity. Ways to solve it: A balancing device. A search for "24v battery equalizer" will get you some ideas. Charge the batteries in ...

3

No, you can't use the module to charge batteries in a same pack simultaneously with the same power supply. That will short out the batteries via the modules together. The modules are meant to chage one cell only. Connecting them in parallel means shorting the battery cells as they are connected in series inside the pack but parallel at the poer supply side. ...

3

what does PMID actually stands for? It stands for "power-middle" as per this explanation from TI: -

3

Since you do not know how much charge is already in each battery you cant actually find the state of charge, how do you overcome this problem? Fully charge the battery, then 'count coulombs' until voltage shows it is nearly empty. This can be used as a reference for future partial charge and discharge, but may have to be repeated occasionally if the battery ...

3

They self-balance based on voltage. Not charge. Because things in parallel want to have the same voltage. Your example of 50% and 100% balancing out to 75% doesn't work like that as a result. Because battery voltage vs remaining capacity is not linear, and even if it were linear the 50%||100% = 75% would only happen for batteries with identical capacities. ...

2

The USB C standard has a Power Delivery Protocol. Basically what happens is the device that you want to charge in question will ask the power supply (power bank, wall outlet, car charger, etc) for a certain voltage. The power supply will respond by either giving the device the requested voltage, or give the device the next lowest available voltage since it ...

2

Guess it would require one charger to be a master (comunicating with the car) and one or more slave chargers which need to be perfectly syncronized with the master. Thus the slaves need to messure the masters voltage and phase at the plug und control their own output to a very tight match, as already minimal differences in voltage and or phase will cause ...

2

The calcium is used as a hardener like antimony was used, a benefit of calcium over antimony is it creates less gassing and that's why batteries can be truly be sealed and maintenance free. The calcium does create higher internal resistance which has to be overcome with higher amperage. The voltage must remain consistently at 12.66 volts to protect vital ...

2

You don't want to charge lead-acid from a constant voltage, and if you do, you need to change the voltage depending on the state of charge of the battery (switching from constant voltage "second stage" charging to trickle charge). Google "lead acid charging algorithm".

2

When connection is made using long wires (more than a few cm) the inductance of the wiring becomes important to consider. There is significant inrush into a power supply when power is first connected and caps are uncharged, this high current pulse through the wiring inductance, coupled with a very good (low ESR, high Q) capacitor forms a series resonant tank ...

2

I know that there are modules like the TP4056 for Lipo batteries and 18650 cells, but I don't know that there is something similar for an AA battery. it's not about the form factor (AA), but about the chemistry (NiMH/NiCd?). Yes, charge ICs for such batteries are available. You'd want to check the offerings of the major power IC manufacturers (Maxim, Texas ...

Only top voted, non community-wiki answers of a minimum length are eligible