Which element determines the charging speed of a battery?

Which element makes the charging speed of a battery from 0% to 100% charged?

• Current (in A)?
• Voltage (in V)?
• Power (in watt), so the product of the two elements?
• Welcome to EE.SE! Is this homework? – winny Jun 17 at 12:20
• Non, I'm just curious – user33894 Jun 17 at 12:20
• Please be a little more clear when you ask a question. Are you asking what sets the charging speed or what device is used to charge a battery or what USB protocol charges a battery the fastest? – Prathik Prashanth Jun 17 at 12:27
• what sets the charging speed – user33894 Jun 17 at 12:27
• The charging current sets the charging speed. – Prathik Prashanth Jun 17 at 12:38

The "charging" speed.

It will be the current, as the charging is current regulated and voltage is pretty much set by the chemistry (it does vary during charging).

Most chemistry, besides NIMH will use the voltage to determine when to stop charging.

• Good question. Answer is immensely complex but there are guidelines that will get you closish. A good place to learn much about batteries is batteryuniversity.com – Russell McMahon Jun 19 at 8:29
• For interest - NiMH is fully charged at 1.45 V at 25 C at around C/10 rate.i had an application where cell potential was the only method possible. (Portable solar lights - sun varies or stops, temperature varies widely. – Russell McMahon Jun 19 at 8:33

I guess you want to make your battery charging faster and you want to know what quantity should be bigger in your next battery charger that you are going to purchase or build.

I guess you expect a clean single word answer - either "current", "voltage" or "power" with absolutely zero extra blahblah like "it's current, but the voltage has to be taken into the account, too, because blah blah...."

The capacity of batteries is measured in ampere-hours. (=Ah). If you happen to have a battery which has capacity say 3Ah and you charged it with current =1A the charging would take 3 hours from empty battery to fully charged. If you had only 0,5 amperes you'd need 6 hours.

Thus it may look like the right answer is "current". But most of us in this site are responsible persons who feel we must warn you. Modern batteries of electric tools, computers and phones need clever charging equipment which knows how much current a certain battery type stands without exploding to your eyes and when it's the right time to stop charging.

The allowed max. charging current is smaller for smaller capacity batteries and depends also on the chemical principle of the battery. Generally most batteries cannot be charged especially soon, charging from empty to full takes nearly always at least several hours.

Many modern batteries have inbuilt sensors that clever charger for a certain battery type can read.The sensors tell at least temperatures, but there can also be the voltages of the individual cells. Skipping that data by using some dumb charger is dangerous.

Making own customized connection wires to charge other batteries than the specific types is a dangerous gamble if one hasn't carefully studied the electrochemistry and properties of the batteries and charger.

The voltage between the poles of the battery is what the battery sets it to be. In theory you could charge a 12 volt battery by connecting it to say 15V DC voltage supply through a resistor. If the resistor was say 2 Ohm, the charging current would be 1,5 amperes as Ohm's law states. This kind of math is only approximately right because the voltage of the battery changes when the charging progresses and when the temperature changes. I recommend you to halt all attempts to construct or customize your own charger until you have studied how complex process charging is if it's done technically right and safely.

The battery chemistry/technology is the main thing. As a general rule, charging a battery faster makes it age faster. That is to say, you'll get fewer charge/discharge cycles before you have to replace it.

Sometimes people use the capital letter "C" to represent the amount of current that would (in theory) fully charge the battery in one hour. Recommended maximum charging current then is specified as a fraction of C. For example, for a 7 amp hour sealed lead acid battery, C=7 A. The manufacturer might recommend charging at a rate no greater than 0.2C (1.4A).* That means, it would take at least 5 hours. (In reality, longer than 5 hours if you use a "smart" charger that allows the charge current to taper off after the battery reaches a certain voltage.)

For a 20 amp hour battery of the same design, C=20 A, but the manufacturer still is going to recommend charging at no greater than 0.2C (4A), and at that rate, it's going to take the same five hours (or longer) as the smaller battery.

I don't know the typical charge rates for, say, LiPO batteries, but whatever it is, it will be roughly the same for all LiPO batteries, regardless of the battery size, *if* you express it as a fraction of "C."

For some battery chemistries, the physical limit overrules the "recommended" limit. You can't fully charge a "Nickel Iron" battery (a.k.a., "Edison battery") in anything less than about 20 hours (charge rate=0.05C), no matter how hard you try. The internal resistance of the battery prevents it.

* Limiting the charge rate of an SLA battery to 0.1C (takes at least 10 hours) will help it to last longer.

The internal resistance and battery chemistry voltage sets the charging speed, when charging batteries usually you run current through the battery, then once it reaches a certain voltage you trickle charge it with the max voltage of the battery. The internal series resistance of the battery limits how much current you can put through what and how much self-heating the battery generates

Main factor that affects the charging speed is the Charging Current. Increasing the charging current will make your battery to recharge faster.How fast charging is done, depends on Current. To charge a battery for 100%, we need potential greater than the battery voltage. So, I think Voltage.