Rechargeable battery charging

kiruthikar · 2010-12-02T20:03:18+00:00

Hi, What will the charging current do after the laptop battery is 100% charged? I do understand that the battery will no longer be charged. Conservation of energy states that energy cannot be destroyed. So what happens to the electric energy? Where will it go after 100%?

aj_onduty

@aj-onduty-BvuwMK • Dec 2, 2010

After 100% is reached, there is a switch inside the charger which shuts off the supply to the battery. The switch is electronic. When the battery charge comes below a certain limit, the switch turns on. When it comes above the limit, the switch turns off.

Hope I am clear enough.

Please correct me if I am wrong.
Thank you for asking.

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kiruthikar

@kiruthikar-l3prTT • Dec 2, 2010

Thank you. You are right. But my question is "what will happen to the current flowing from the wall socket?"
What happens to the current flowing from the wall socket? The electrical energy has to be converted to some other form right? Will heat energy be liberated? Will that degrade the battery life?

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aj_onduty

@aj-onduty-BvuwMK • Dec 2, 2010

kiruthikar
Thank you. You are right. But my question is "what will happen to the current flowing from the wall socket?"

Dear kiruthikar,
When the switch is turned off, where will the current flow? First, please understand the difference between current and voltage. When the switch is in off position, there will be no current, but there will be a voltage applied across the terminals of the switch. As you were speaking about energy,
Electrical energy=power *time=voltage*current*time. So, you need both voltage and current. When a switch is open(off), then there is no current flowing. This is the case when you are using a charger which is connected to a DC supply.

But in an AC supply, what we do is we step down the voltage to some 12V or 6V(as per requirements). So, we need a transformer. I hope you know the basics of the transformer. Now, there is a current flowing through the primary of the transformer which is due to the core losses of the transformer. That causes a small power wastage. As I know this, I remove the charger from my mobile whenever I hear the beep when it is fully charged.
Hope I have answered to your expectations.

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narayana murthy

@narayana-z4W16q • Dec 2, 2010

but aj mobile charges and lap chargers are dc devices they need dc not ac so we use the convertors there because they needed a storage we cant store ac so we store them in dc as a magnetic power anyway we use dc in mobiles and laps but i think ans to this question is when it charges completely no space to store there so it become opened and no current flows if current does flows there is no case of power flow then the current is get wasted almost your right aj but 1 thing laps and mobiles takes dc not ac

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aj_onduty

@aj-onduty-BvuwMK • Dec 2, 2010

I agree to the fact that laptops and mobiles-all battery operated devices require DC.
Open any old charger. You can see a board in it. If you are familiarized yourself to electronic circuits, you can see a small transformer, a few diodes, resistors and capacitors. The transformer brings down the voltage. Still, the power remains AC. Then there are a few diodes which rectifies the AC to form pulsating DC. This pulsating DC is smoothened to a perfect DC using capacitors. Thus we get a DC supply of the required voltage. The current value is altered using resistors.
Connect this with the question you have asked. Hope you will get the answer.

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freak16

@freak16-XgiLj6 • Dec 24, 2010

Following types of batteries are charged using some type of charger.But Efforts have been made to reduce the size , weight and charging time of a charger. atmel battery charger is good one and can be used for all typre of battery charging.
• Sealed Lead Acid (SLA)
• Nickel Cadmium (NiCd)
• Nickel Metal Hydride (NiMH)
• Lithium-Ion (Li-Ion)
As you can see each battery involves chemical reactions. therefore after complete charging..It gets auto discharge as in ions start breaking itelf in reverse direction.
so answer to your question where is electric energy going has been cleared.It is converting back into chemical energy and some losses and all other buddies said. now what happens to current when it is fully charged. first of all i appreciate you it is really a nice question now see.
There are four stages of battery charging:
(i) trickle charge, (ii) bulk charge, (iii) over
charge and (iv) float charge
A. 1º Stage (from T0 to T1) – Trickle Charge
This first stage appears when the battery voltage is below the
value VCHGENB, This voltage value, specified for the
manufacturers, shows that the battery arrives at its critical
discharge capacity. In this condition the battery should receive
a small charge current defined by ITC that has a typical value of
C/100 where C is the normal battery capacity with a 10 hours
charging process. This small current ITC is applied until the
battery voltage reaches the value of VCHGENB. This stage also
avoids that some accident could happens in the case of the one
battery element is in curt circuit, therefore if this really
happens the battery voltage will not grow and then the battery
charging process does not pass for the next stage.
B. 2º Stage (from T1 to T2) – Bulk Charge
After the battery voltage reaches the value VCHGENB will be
delivered to the battery a constant current IBULK. The IBULK is
the maximum charge current that battery supports with out a
big water losing, and its value is specified by the
manufacturers. This current is applied until the battery voltage
reaches the maximum value of over charge voltage, defined by
VOC, and specified by the manufacturers.
C. 3º Stage (from T2 to T3) – Over Charge
During this stage the control algorithm should regulate the
battery voltage in the VOC for the complete charge has been
reached. When the charging current fall down to a pre-
established value IOTC and the voltage stays in the value VOC,
the next stage will be executed. The value of IOCT is around
10% of the IBULK.
D. 4º Stage (from T3 until the end) –Float Charge
In this stage the control algorithm will apply in the battery a
constant voltage VFLOAT which is a specified value by the
battery manufacturers. This voltage is applied to the battery
with the objective of avoid its auto-discharge. During the
discharging process the battery voltage will fall down and
when it achieves 0.9 VFLOAT the control algorithm will execute
again the 2º stage providing the IBULK current. The control
algorithm only returns to the 2º stage if the PV panel is
producing energy, if not the battery will continue the discharge
process that could reach a voltage below to the value
VCHGENB, in this situation the control algorithm should
restart the charging process in 1º stage when the PV panel will
have energy again.
I hope it has been clear now..
if you still have doubts ..PLz ask..

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narayana murthy

@narayana-z4W16q • Dec 24, 2010

nice post freak this may be helpful

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Sachin Jain

@sachin-0wuUmc • Dec 24, 2010

Good info freak16.....Its very helpful

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sarathwnoe

@sarathwnoe-SmLimu • Jul 20, 2011

i want make charger to charge mobiles using small battery what kind of battery i want to use >>>>>>>

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narayana murthy

@narayana-z4W16q • Jul 20, 2011

hey in this case i want to make it add this now a days we are trying to give solar charging battery then why we still trying on this stuff

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ShrinkDWorld

@shrinkdworld-WWdBBc • Jul 20, 2011

I am not clear but i heard somewhere that current is continuously passed from battery in case of laptop & Mobile even its charging is 100%
I may be wrong. But i think i am right because we can not start laptop or Mobile without battery.

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narayana murthy

@narayana-z4W16q • Jul 20, 2011

yes it you are right even it is totally charged some current will flow but magnitude will be less and i have add a point here
system and laptops more energy while starting

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praba230890

@praba230890-vPFAoQ • Jul 24, 2011

The switch doesn't turns off when the battery is full. It just switches the supply directly to laptop and disconnect it from battery.

aj_onduty
After 100% is reached, there is a switch inside the charger which shuts off the supply to the battery. The switch is electronic. When the battery charge comes below a certain limit, the switch turns on. When it comes above the limit, the switch turns off.

Hope I am clear enough.

Please correct me if I am wrong.
Thank you for asking.

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praba230890

@praba230890-vPFAoQ • Jul 24, 2011

I believe that none of the charger manufacturers using transformer in chargers after the advent of power electronics.

aj_onduty
I agree to the fact that laptops and mobiles-all battery operated devices require DC.
Open any old charger. You can see a board in it. If you are familiarized yourself to electronic circuits, you can see a small transformer, a few diodes, resistors and capacitors. The transformer brings down the voltage. Still, the power remains AC. Then there are a few diodes which rectifies the AC to form pulsating DC. This pulsating DC is smoothened to a perfect DC using capacitors. Thus we get a DC supply of the required voltage. The current value is altered using resistors.
Connect this with the question you have asked. Hope you will get the answer.

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aj_onduty

@aj-onduty-BvuwMK • Jul 29, 2011

praba230890
I believe that none of the charger manufacturers using transformer in chargers after the advent of power electronics.

(Scratching my head)
I strongly believe that mobile and laptop chargers still have transformers in them. And I hope that is why the charger gets super hot when we charge our laptop, mobiles or any other electronic device, whichever it is meant for. And I believe that for a 230V supply, a transformer can be the most viable option, it being low cost and, sometimes, more efficient compared to power electronic devices. And please do not misunderstand me, I am never saying that electronics cannot replace a transformer, but right now, we commonly use transformers(if I am not wrong.) Please correct me if I am wrong.

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aj_onduty

@aj-onduty-BvuwMK • Jul 29, 2011

praba230890
The switch doesn't turns off when the battery is full. It just switches the supply directly to laptop and disconnect it from battery.

Thats better. Thanks for the answer.

I got to ask one small question. The vendors usually say you should never do overnight charging. What they mean to say is that once the device is fully charged, you must remove the charger, stop charging. If you perform overnight charging, what happens is that the battery gets degraded, its quality decreases (coarse language, I just translated what they said, please excuse).
But, if the supply is diverted from the battery to the mainstream, how can it possibly affect the battery? I am really curious about this. Fellow CEans, please do answer.

Thanks in advance.

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praba230890

@praba230890-vPFAoQ • Jul 29, 2011

I am not sure about laptop chargers as i didn't got a chance to open them. In case of mobile chargers i'm pretty sure about it, even the weight of the chargers now prove that they don't have a transformer.

aj_onduty
(Scratching my head)
I strongly believe that mobile and laptop chargers still have transformers in them. And I hope that is why the charger gets super hot when we charge our laptop, mobiles or any other electronic device, whichever it is meant for. And I believe that for a 230V supply, a transformer can be the most viable option, it being low cost and, sometimes, more efficient compared to power electronic devices. And please do not misunderstand me, I am never saying that electronics cannot replace a transformer, but right now, we commonly use transformers(if I am not wrong.) Please correct me if I am wrong.

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praba230890

@praba230890-vPFAoQ • Jul 29, 2011

The main reason for advising to avoid the overcharging is the overheating of the power circuit and the chances for burning out of power circuit. Also as we know while the charger is plugged in both the charging and discharging takes place in parallel and this is why the battery life and quality degrades as aj asked. But the battery quality isn't a problem anymore as the laptops are manufactured to switch the charger power from battery to directly laptop power input if battery is fully charged. All we got to concern about is the power circuit.

aj_onduty
Thats better. Thanks for the answer.

I got to ask one small question. The vendors usually say you should never do overnight charging. What they mean to say is that once the device is fully charged, you must remove the charger, stop charging. If you perform overnight charging, what happens is that the battery gets degraded, its quality decreases (coarse language, I just translated what they said, please excuse).
But, if the supply is diverted from the battery to the mainstream, how can it possibly affect the battery? I am really curious about this. Fellow CEans, please do answer.

Thanks in advance.

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aj_onduty

@aj-onduty-BvuwMK • Jul 29, 2011

praba230890
I am not sure about laptop chargers as i didn't got a chance to open them. In case of mobile chargers i'm pretty sure about it, even the weight of the chargers now prove that they don't have a transformer.

I will gladly buy you one charger each, laptop and mobile, to open it up. You can see a transformer in it. Both these types of chargers are heavy, at least heavier than a box containing just a PCB with a few electronic components.
Even now, if you are saying that there is no transformer in the chargers, kindly let me know how they bring down the voltage from 230V to 6 or 12V.
Thanks for the answer.

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aj_onduty

@aj-onduty-BvuwMK • Jul 29, 2011

praba230890
The main reason for advising to avoid the overcharging is the overheating of the power circuit and the chances for burning out of power circuit. Also as we know while the charger is plugged in both the charging and discharging takes place in parallel and this is why the battery life and quality degrades as aj asked. But the battery quality isn't a problem anymore as the laptops are manufactured to switch the charger power from battery to directly laptop power input if battery is fully charged. All we got to concern about is the power circuit.

I believe that the power circuit is designed to handle some power through it, and the charger, battery or any such source is designed such that the power circuit is provided only that much amount of power which it can handle without any hassles. It is because I believe in this logic, that I fail to understand the above quoted paragraph. Please do explain.
Also, please do verify if mobile phones and almost all the battery operated devices switch the charger power from battery to the power circuitry(I got an almost affirmative result when I observed a few new mobiles). I am not sure of it, but let me know if you find that the statement is true.

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praba230890

@praba230890-vPFAoQ • Jul 29, 2011

In labs you may have noticed that some IC's keep on heating up with increased usage time. This is what the Electronic devices does, they release the heat when used for a long time. Because they are not made up of conductors. Also the power circuit elements were mostly linear electronic devices which works in linear mode while the computation/processing circuit works in switching mode(alternatively between cut-off and saturation region). This leads to more losses in power circuit elements. These losses were released in the form of head. According to your question if every device in my laptop is designed for a particular power to work with and also they were supplied with the rated power, then why it stats burning my lap if i using for long hours?

aj_onduty
I believe that the power circuit is designed to handle some power through it, and the charger, battery or any such source is designed such that the power circuit is provided only that much amount of power which it can handle without any hassles. It is because I believe in this logic, that I fail to understand the above quoted paragraph. Please do explain.
Also, please do verify if mobile phones and almost all the battery operated devices switch the charger power from battery to the power circuitry(I got an almost affirmative result when I observed a few new mobiles). I am not sure of it, but let me know if you find that the statement is true.

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praba230890

@praba230890-vPFAoQ • Jul 29, 2011

Talking about the switching of power during fully charged battery condition, i'm sure bout it. For me all devices i've encountered were well fitted with this condition. Can i know which company(brand) doesn't have this feature.

aj_onduty
I believe that the power circuit is designed to handle some power through it, and the charger, battery or any such source is designed such that the power circuit is provided only that much amount of power which it can handle without any hassles. It is because I believe in this logic, that I fail to understand the above quoted paragraph. Please do explain.
Also, please do verify if mobile phones and almost all the battery operated devices switch the charger power from battery to the power circuitry(I got an almost affirmative result when I observed a few new mobiles). I am not sure of it, but let me know if you find that the statement is true.

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aj_onduty

@aj-onduty-BvuwMK • Aug 2, 2011

aj_onduty
I believe that the power circuit is designed to handle some power through it, and the charger, battery or any such source is designed such that the power circuit is provided only that much amount of power which it can handle without any hassles. It is because I believe in this logic, that I fail to understand the above quoted paragraph. Please do explain.

For your reference, praba, I used the above sentence because you used the following

praba230890
The main reason for advising to avoid the overcharging is the overheating of the power circuit and the chances for burning out of power circuit.

Please note that all circuits are designed according to some specifications, for some rated power. I hope I am still right about it.

The base of your laptop heats up because the circuits inside heat up due to the current which flows through them.
Also, I just picked up my laptop charger, and i just looked at the specs. i saw a symbol. i think that symbol represents that there is a transformer in it.
I didn't take a picture of it, as I got a ready-made in the net.(Google is so good).
Here it is. Please see the pic below. The symbol is marked in yellow below.
Please let me know what it is.
Thanks in advance.
[IMG]

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Rechargeable battery charging

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