Maximum current from a battery

In summary, batteries cannot be reduced to a simple series ohmic resistance and their maximum current cannot be determined solely based on their internal resistance. The temperature and chemical process inside the battery can affect the voltage and thus the maximum current. However, PV cells are usually characterized in terms of open circuit volts, short circuit current and maximum power output. Careful temperature control can result in high currents from small cells. Additionally, the Nernst equation explains the direct relationship between voltage and temperature in batteries.
  • #1
abdo799
169
4
If we had a battery with internal resistance 1 ohm and 9 V.
If we connected to just wires ( resistance 0) i will produce a 9 amps current. Is this the maximum current? If we connect to this battery a 0.5 ohm resistor (in parallel ) the total resistance will be lower than one, will the current produced be greater than 9 amps?
 
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  • #2
You can't connect a resistor so that it's in parallel with internal resistance of battery with respect to the voltage drop of the battery. So yeah, you get maximum current if you just short the battery out.
 
  • #3
So basically maximum current = voltage/internal resistance and i can never surpass it
 
  • #4
Yep.
 
  • #5
If we connected to just wires ( resistance 0) i will produce a 9 amps current. Is this the maximum current? If we connect to this battery a 0.5 ohm resistor (in parallel ) the total resistance will be lower than one...

The total resistance will be higher than one.
 
  • #6
Yup...i got it
 
  • #7
abdo799 said:
If we had a battery with internal resistance 1 ohm and 9 V.
If we connected to just wires ( resistance 0) i will produce a 9 amps current. Is this the maximum current? If we connect to this battery a 0.5 ohm resistor (in parallel ) the total resistance will be lower than one, will the current produced be greater than 9 amps?

The idea of 'internal resistance' is not that simple. What actually happens inside batteries cannot necessarily be reduced to a simple series ohmic resistance when the load gets higher and higher. Any power dissipated inside the case will raise its temperature and this can alter the emf produced by the chemical process. Batteries are sometimes rated by their short circuit current (for a brief, specified, time) but they are not designed with a short circuit in mind.
Otoh, interestingly, PV cells are usually characterised in terms of open circuit volts, short circuit current and maximum power output (at specified temperatures). Continuously taking near-short circuit current is not too harmful for PV cells I believe.
 
  • #8
Very true. Model aircraft and car racing competitors carefully control the temperature of their battery packs to get the best out of them. It's possible to get very high currents out of some quite small cells if you know what you are doing.
 
  • #9
sophiecentaur said:
Any power dissipated inside the case will raise its temperature and this can alter the emf produced by the chemical process.

http://en.wikipedia.org/wiki/Nernst_equation

Basically voltage is directly proportional to the temperature.
 

1. What is the maximum current that can be drawn from a battery?

The maximum current that can be drawn from a battery is determined by the battery's internal resistance and its capacity. Generally, the higher the battery's capacity, the higher the maximum current it can provide. However, drawing a high current from a battery for an extended period of time can significantly reduce its overall capacity.

2. How is the maximum current of a battery calculated?

The maximum current of a battery can be calculated by dividing the battery's voltage by its internal resistance. This value is known as the short-circuit current, and it represents the maximum current that the battery can deliver without damaging itself.

3. Can the maximum current of a battery be exceeded?

Yes, the maximum current of a battery can be exceeded, but it is not recommended. Drawing a higher current than the battery's maximum can cause overheating and damage to the battery. It is important to use a battery with a maximum current rating that is appropriate for the device it is powering.

4. How does temperature affect the maximum current of a battery?

Temperature can have a significant impact on the maximum current of a battery. In general, high temperatures can increase the maximum current that a battery can provide, while low temperatures can decrease it. It is important to consider the operating temperature range of a battery when selecting one for a specific application.

5. How can I increase the maximum current of a battery?

The maximum current of a battery is primarily determined by its internal resistance. To increase the maximum current, you can use a battery with a lower internal resistance or connect multiple batteries in parallel to decrease the overall resistance. However, it is important to note that drawing a high current from a battery can also decrease its overall capacity and lifespan.

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