battery rating

[mackeral]

what is the meaning of the 1,4 Ah on the side of my 12v cordless drill?

cheers

 

[andy]

its how much power the battery can hold. i.e a 20V battery at 20AH can supply 1A for 20 hours, 2A for 10 hours etc. note that they are normally rated at a 20hour discharge rate, so at 5A you may not get 4 hours.

dunno if a 20AH 20V battery exists, but its basically the same for all batteries

 

[swelec]

in theory, this will give 1.4 amps for 1 hour

or 0.7 amps for 2 hours etc

Ah = ampere hours

In practice, you will not get this

The higher the Ah rating, the longer the battery will last before needing a recharge ( doing the same task )

Must learn to type faster

 

[mackeral]

most informatives gents. And the higher the voltage, the more power then?

 

[breezer]

most informatives gents. And the higher the voltage, the more power then?

no.

voltage (v) is the potential difference between two points

submarines use batteries (cells actually) that are only 2 volts (or there abouts) but they can deliver astronomical amounts of current (dont know how much)

also the laws of physics must be taken into consideration.

in theory a 12v 7Ah battery can deliver 7amps for 1 hour
so it follows it can deliver:
14 amps for 30 mins
28 amps for 15 mins
56 amps for 7 1/2 mins

you see where this is going.

unfortunately due to the internal resistance of the battery etc this is not possible (but you can still get a lot of cuurent for a nano second)

also as nothing is 100% efficiant this also "upsets the reality"

 

[Panjandrum]

most informatives gents. And the higher the voltage, the more power then?

Not necessarily, rather than no.
Agree with Breezer - but I had the impression with battery-powered tools that those with more stamina and power are usually those with higher-voltage batteries too?
I assumed it was something to do with the internal resistance, size of conductors in motors, and so on - so that you get more efficient delivery of power to a less-weighty motor from a higher-voltage battery.
I may, of course, only be confused.

 

[swelec]

just to muddy the waters

a 12 volt 1 Ah battery has (theoretically) half the power capacity of a 12 volt 2 Ah battery

a 12 volt 1 Ah battery has (theoretically) half the power capacity of a 24 volt 1 Ah battery

watts ( power) = volts x amps

So a higher voltage battery of the same Ah capacity does have more "grunt"

 

[breezer]

sorry i forgot to mention.

the higher the voltage the less current is required to do the same work.

so a 9v drill will (in theory) last only half as long as an 18v drill

this assumes same Ah size of battery, same motor resistance, yak, yak, yak

that is why you can get more "higher voltage" drills etc they use less current, so the battery lasts longer

 

[Panjandrum]

So a higher voltage battery of the same Ah capacity does have more "grunt"

For any given load, the size of grunt depends only the voltage.
The Ah rating will determine how long it will grunt for rather than the size of the grunt - sort of an Ah, Ah, Ah, Ah, rather than just one short Ah

 

[swelec]

So a higher voltage battery of the same Ah capacity does have more "grunt"

For any given load, the size of grunt depends only the voltage.
The Ah rating will determine how long it will grunt for rather than the size of the grunt - sort of an Ah, Ah, Ah, Ah, rather than just one short Ah

I've spent 20 years in the battery industry

Thats the clearest explanation of battery capacity I have ever seen

Made me smile

I pictured that girl in the restaurant with Billy Crystal giving the explanation

 

[big-all]

think of the volts as the car engine and the ah as the fuel tank bigger the engine the more power bigger the a h [fuel tank ]longer it runs for

there are other factors like power lost in transmission so some are realy bad at converting the power into usefull drilling or cutting
others are realy good

also if you think you cant use the fuel at the very bottom of the tank say the bottom 10mm so on a oneah battery the last part is wasted as its not powerfull enough to do any work but on a two ah battery the first ah give full power and only the end of the second ah you run out of power

in other words two one ah batterys will give less drilling than one 2 amphour battery but only realy matters when in continouse use[over hours rather than days]

clear as mud ehh

 

[Careful_Bodger]

..... lost in transmission .....

was quite a good film with Bill Murray & Scarlet Johansson, as I recall (badly)



Oh well it IS Friday........

 

[ban-all-sheds]

what is the meaning of the 1,4 Ah on the side of my 12v cordless drill?

Let's stop with the silly analogies.

It means your tool is inadequate, and can't deliver enough grunt for long enough.