Batteries

charlie b

Moderator
Staff member
Location
Seattle, WA
When it is connected to its maximum load. Or perhaps I don't understand the question. What type of battery (flashlight, emergency light, car, boat, UPS storage, etc.)?
 

just the cowboy

Inactive, Email Never Verified
Location
newburgh,ny
I was told temperture

I was told temperture

In car batteries I was told the produce their most power in the summer when it's hot and you don't need that cranking power. And they produce the least power when it is cold and you do need it to turn over a cold engine.:lol:
 

winnie

Senior Member
In general chemical reactions happen faster when things are warmer. So an electrochemical cell (in a battery) will have lower internal resistance, and can deliver higher current when warm.

There are second order changes in battery voltage versus temperature, but the big one is the change in rate that current can be delivered.

The maximum power that a battery can deliver is when it is connected to a load that has the same resistance as the internal resistance. The output voltage is half the open circuit voltage, and the product of voltage and current is maximum.

-Jon
 

gar

Senior Member
150624-2343 EDT

preenee1:

Exactly what winnie said.

If you do not have knowledge of calculus, then a way to see how power in the load varies as load resistance varies with constant source voltage and constant source internal resistance is to perform calcultations for incremental load resistance changes and calculate the load power. You will find that this maximum power transfer occurs at Rload = Rinternal.

Edison understood that a practical power distribution system could not be based on maximum power transfer as many others thought in 1879. Rather Edison understood that a low source impedance and moderately constant voltage distribution system was required.

.
 

GoldDigger

Moderator
Staff member
150624-2343 EDT

preenee1:

Exactly what winnie said.

If you do not have knowledge of calculus, then a way to see how power in the load varies as load resistance varies with constant source voltage and constant source internal resistance is to perform calcultations for incremental load resistance changes and calculate the load power. You will find that this maximum power transfer occurs at Rload = Rinternal.

Edison understood that a practical power distribution system could not be based on maximum power transfer as many others thought in 1879. Rather Edison understood that a low source impedance and moderately constant voltage distribution system was required.

.
:thumbsup:

For practical distribution, the goal has to be not to transfer the highest possible amount of power, regardless of the fact that it wastes half of the available energy, but instead to go for a combination of high efficiency and reasonable power.
 
Top