How much power needed to charge a battery?

  • Thread starter niallniall
  • Start date
  • #1
Hello I am new here, Dont really know if I'm asking in the right place, but. Can anyone tell me how much power I would have to put into a 6v rechargeable battery to actually charge it. I am looking for the smallest ammount of power I can get away with to be able to Charge the 6v battery.

Thanks People. o:)
 

Answers and Replies

  • #2
30,031
6,425
You should be able to charge it with an arbitrarily small amount of power if you are willing to spend an arbitrarily long amount of time. In fact, the smaller the power you use the more efficient the charging will be because you will have less heat.

-Dale
 
  • #3
Thanks Dale, How small is arbitrary?:blushing: less than 1 v?
 
  • #4
Pengwuino
Gold Member
4,989
15
Depends on what kind of battery you have (capacity wise). Volts is not a unit of power either. You will need to give it 6V i believe and how much power you need is completely dependant on what the capacity of the battery is.

I've never heard of a 6V rechargable battery (I've seen 4 1.5's in series....) so I wouldn't have a clue how much power you would need.

I believe a AA battery can supply roughly 3Watt-hours of electricity at normal draw which is about 1100 Joules of energy....
 
Last edited:
  • #5
Danger
Gold Member
9,607
246
Pengwuino said:
I've never heard of a 6V rechargable battery (I've seen 4 1.5's in series....) so I wouldn't have a clue how much power you would need.
Since most 6V batteries are the spring terminal or screw terminal types, I have also never seen a rechargable version of them. The type that are available here will recharge AAA, AA, C, D or 9V. Anything else pretty much has to be bought new.
 
  • #6
Pengwuino
Gold Member
4,989
15
ohhhhhhhhhh yah, those kinds of batteries. What are those things called with the spring terminals... lantern batteries?
 
  • #7
Danger
Gold Member
9,607
246
Correctomundo, oh flippered one. Both types are. The spring terminal type fit inside a lantern housing. The screw terminal type actually becomes the main body of the lantern, because the lamp holder part screws onto the top of it.
 
  • #8
berkeman
Mentor
58,025
8,084
niallniall said:
Thanks Dale, How small is arbitrary?:blushing: less than 1 v?
Welcome to PF, niallnaill. Do you know the relationship between power and energy? Are you familiar with the energy content of the batteries that you want to recharge? A volt is not a measure of either power or energy -- what exactly are you trying to optimize?
 
  • #9
30,031
6,425
niallniall said:
Thanks Dale, How small is arbitrary?:blushing: less than 1 v?
Well, your battery is 6V so you will need at least 6V as indicated by others here. You can use an arbitrarily small current, meaning as small as you want, 1 mA or even less if you wanted. Power is voltage times current, so that could be as small as you want. (e.g. 6V * 1mA = 6 mW)

-Dale
 
  • #10
rcgldr
Homework Helper
8,708
534
The voltage just has to some amount over 6 volts, or since a typical 3 cell battery is really 6.6 volts, you'd need 6.6 volts to top off the battery. The initial voltage on a drained battery would be less, so you'd need less voltage, but as it approached full charge, you'd have to keep increasing voltage to just exceed that of the battery.

Most batteries include an capacity rating, but the actual capacity varies with the load (or charge rate). AA nicads for radio control models typically have about 1.1AmpHour capacity. AA nimh batteries hold about 1.7 AmpHours. LiPoly batteries are even better in terms of capacity versus weight, but usually come in flat packs, and are combined both in series and/or in parallel in a pack to increase current output (parallel) and voltage ouptut (series). Nicads, Nimh, LiPoly, and typical dry cell batteries work best when cold. Lead-acid batteries work best when fairly warm.
 
  • #11
Thanks for all the help guys and girls. I actually no nothing at all or very little about physics. Just what I learned in school basically, and the stuff I have read here.

So am I right in thinking that if I have the right battery, lets say 6v I can fully recharge it using a 6v supply?

Also how many watts is equal to 6v?

Thanks in advance for answers :)
 
  • #12
Pengwuino
Gold Member
4,989
15
Volts and watts aren't the same unit so theres no way of saying what it's equal to. Since we're dealing with a battery, we say it's DC current.Watt is a unit of power. It is Joules/Second. Joules is energy, it's the water in the cup, it's the coal on the train, it is the main thing here. You can determine how many watts are being produced when you know the current being generated by multiplying the Volts * Amps (current). When you're looking at how many Joules can be stored in a battery... it's more meaningful to talk about WH (watt-hours). If your battery has 500Watt-hours in it, that means it can produce 500 watts for 1 hour or 250 watts for 2 hours etc etc. That means it can produce 500 Joules per second for 1 hour which tells you it has a capacity of 500wh's.

The problem is, in your situation, is that the battery is already empty. You will simply have to hook it up and let it charge because unless you know anything else about the battery, theres no way of telling it's capacity.
 
  • #13
rcgldr
Homework Helper
8,708
534
niallniall said:
So am I right in thinking that if I have the right battery, lets say 6v I can fully recharge it using a 6v supply?
A typical 6 volt battery is really 7.2 volts, and charging voltage is a bit higher than this to top off the battery.
 

Related Threads on How much power needed to charge a battery?

Replies
14
Views
7K
  • Last Post
Replies
5
Views
2K
Replies
2
Views
903
Replies
4
Views
2K
Replies
2
Views
9K
Replies
13
Views
27K
Replies
7
Views
5K
Replies
6
Views
835
  • Last Post
Replies
1
Views
2K
Replies
0
Views
1K
Top