Can we charge a battery using a power supply?

[FlorianB]

Hi!

Is there any difference between the 2 following scenarios:

A: I charge a battery using a basic electronically controlled charger that will stop when it judges necessary.
B: I power the battery with a lab power supply to a voltage slightly above the battery voltage, and I stop once the current is getting close to zero.

And that leads us to a curiosity question: how does an electronically controlled charger work exactly?

Thank you!

 

[martin the warrior]

they measure voltage of the battery once it reaches full it stops. it knows its charged because of voltage/amp readings. here is a link i found by google it: http://www.batterychargers.com/faqs/

 

[ADRT]

Depends on what kind of battery. You cannot charge an NiMh battery the same way you charge a lead acid battery.

 

[davenn]

B: I power the battery with a lab power supply to a voltage slightly above the battery voltage, and I stop once the current is getting close to zero

as ARDT said, batteries are different and as such all have different charging methods

so, with that in mind, did you have a particular type of battery in mind ?

Dave

 

[FlorianB]

Thanks for your replies.
Yes, Acid battery (12V 7Ah).
What I'm wondering then is how do they measure the voltage... that means they have to stop charging for a while I guess?

 

[ADRT]

Not sure how they do it, but I have done it with an Arduino. Using a voltage divider circuit to cut the voltage down to a safe voltage range for an analog input on the arduino and then calibrating with a bench top PSU to stop charging at about 14.8 vdc. Use a relay to open the circuit to the battery. Automotive relay works great for this. I can give more details if interested.

 

[Alec_t]

Lots of info on safe charging to be found by visiting www.batteryuniversity.com .

 

[AnalogKid]

What I'm wondering then is how do they measure the voltage... that means they have to stop charging for a while I guess?

Nope. You can measure the battery terminal voltage while it is being charged by connecting the battery terminals to a voltage monitor circuit. Also, if you put a small resistor in series with the battery, you can measure the voltage across the resistor and determine the charge current. Generally speaking, a battery charge circuit does not know what it is attached to. You program it, either digitally for some controllers or with resistors for analog controllers, to tell it at what voltage to shift from full power charging to float, and at what currents to hold at for charging or decrease to for float, or signal an alarm for a damaged cell.

Linear Technology, maxim, and Unitrode (now TI) make battery charger controllers. Their datasheets and app notes are full of information.

ak

 

[BGB]

Thanks for your replies.
Yes, Acid battery (12V 7Ah).
What I'm wondering then is how do they measure the voltage... that means they have to stop charging for a while I guess?

as others have noted: no.

rather, you limit charging current to a certain amount (say, 1A). if the battery wants more than this, then the voltage to the battery drops. when the battery nears being fully charged, then the voltage rises to match the charger voltage, and current drops off. depending on the specific charger, it will then switch to a mode where it supplies a fixed voltage (say, 13.6 or 14v), and just sits there (the remainder of the charging happens gradually, with the current dropping to "pretty much nothing" when the battery is done charging).

the ideal charge current limit depends some on battery capacity and other things. it is typically around 0.3C (say, 2.1A for a 7Ah battery), and is sometimes stated on the battery.

 

[Colin Mitchell]

There are 3 completely different types of Lead Acid Batteries. Which one do you have?

 

[FlorianB]

Thanks again.
This is the battery:
http://www.amazon.com/gp/product/B00AAZJ9Y8?psc=1&redirect=true&ref_=oh_aui_detailpage_o09_s00

Basically, I was wondering if I can save by using a power supply to charge those as I have really many to charge. But I'll just buy 20 chargers because I found a pretty cheap one that works fine:
http://www.amazon.com/gp/product/B000BQSIWK?psc=1&redirect=true&ref_=oh_aui_detailpage_o07_s01

 

[HellasTechn]

Thanks for your replies.
Yes, Acid battery (12V 7Ah).
What I'm wondering then is how do they measure the voltage... that means they have to stop charging for a while I guess?

Here is an interesting and easy circuit you You may like to build for charging 12V SLA.
http://www.talkingelectronics.com/projects/BatteryCharger-12vSLA/BatteryCharger-12vSLA.html
I have used it and works really good !