# Calculate Charging Current of Generator & Battery

• nemesis24
In summary, this conversation is about how to calculate the charging current needed for a 30V generator to charge a 24V battery. The equation used is 30-24 = 2I + I, and using the internal resistance of the generator and battery, the charging current can be calculated.
nemesis24
Charging current??

i have a question that says a generator is charging a normal battery the internal resistance of the generator and battery are given, and i must calculate the charging current how might this be done?

generator is 30v with 4 ohm internal resistance.
battery is 24v with a internal resistance of 2 ohms.

This, at it's most simple, is just ohm's law.
You know the potential difference in the circuit and the resistance in the circuit therefore you can calculate the current flow.

Redraw the circuit lumping all the voltage sources together and resistances together and you should see how to work it out.

Or were you wanting it a chemical level?

no chemical level, its just a generator pointing up with a resistance on top of it, and on the right side a resistor on top and a battery at the bottom (with the positive side facing up) and its all connected in series. and its asking 4 the charging current so i thought it may be asking the exact current needed for a 30v generator to charge a 24v battery. i was thinking of using kirchhoffs 2nd law and i got the equation 30-24 = 2I + I (not sure if its right). can i use this or if your method best?

You're making this too complicated, nemesis24. Draw a picture. It'll contain two voltage sources (one 30V, one 24V), with a total of six ohms of resistance between them.

That's six volts dropped across six ohms... use Ohm's law to find the current.

- Warren

so i take it that the two voltages would be substracked as it is the charging current. or would it add to give the total voltage?

You're thinking about it too much, still.

One one side of this combined six ohm resistor, you have 30V. On the other side, you have 24V. There is, thus, 6V across the resistor. 6V across a 6 ohm resistor gives...

- Warren

nemesis24 said:
... its just a generator pointing up with a resistance on top of it, and on the right side a resistor on top and a battery at the bottom (with the positive side facing up) and its all connected in series. and its asking 4 the charging current so i thought it may be asking the exact current needed for a 30v generator to charge a 24v battery. i was thinking of using kirchhoffs 2nd law and i got the equation 30-24 = 2I + I

Actually you are on the right track here, using http://www.physics.uoguelph.ca/tutorials/ohm/Q.ohm.KVL.html (The total voltage around a closed path equals zero). Except you have an error in your equation 30-24 = 2I + I [hint: What did you say was the internal resistance (Rs) on the generator? ]

## 1. How do you calculate the charging current of a generator?

The charging current of a generator can be calculated by dividing the generator's rated power output (in watts) by the battery's charging voltage (in volts). This will give you the maximum charging current that the generator can provide to the battery. However, the actual charging current may vary depending on the condition of the battery and other factors such as resistance in the charging circuit.

## 2. What is the relationship between charging current and battery capacity?

The charging current and battery capacity have an inverse relationship. This means that as the charging current increases, the battery will charge faster, but the battery's overall capacity will decrease. On the other hand, a lower charging current will result in a longer charging time, but the battery will have a higher capacity.

## 3. How do you determine the charging voltage for a battery?

The charging voltage for a battery can be determined by checking the manufacturer's specifications or by using a multimeter to measure the voltage of the battery when it is fully charged. It is important to use the correct charging voltage to prevent overcharging or undercharging, which can damage the battery.

## 4. Can a generator overcharge a battery?

Yes, a generator can overcharge a battery if the charging voltage is too high or if the battery is left connected to the generator for an extended period of time. Overcharging can damage the battery and reduce its lifespan. It is important to monitor the charging process and disconnect the battery once it is fully charged.

## 5. What is the ideal charging current for a battery?

The ideal charging current for a battery will depend on its capacity and the type of battery. In general, the charging current should be around 10-20% of the battery's capacity. For example, a 100Ah battery should be charged at a rate of 10-20A. It is important not to exceed the recommended charging current to avoid damaging the battery.

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