Battery Charger Calculator

[M4SK13]

Since i am new i wanted to know how long to charge my battery or how long it should take

i found this brilliant link

http://www.battery-force.co.uk/chargetime.html

That has a calculator 20% loss is enough conversion loss of any charger/rate at this level.
I have a 48v10a LifePO4 battery from BMSBattery 6 Hours.

I thought'd post this as it took me ages to find it so it may help others...

Simon

 

[dogman dan]

Man, that's a cool tool, especially for the math challenged like myself.

 

[ian.mich]

huh? it's pretty straightforward to take Ah and divide by charger A and add a little bit of time for inefficiencies

 

[SamTexas]

i found this brilliant link

http://www.battery-force.co.uk/chargetime.html

It's not that brilliant. So simplistic that it's almost useless (other than doing a simple division).

Its calculation is based on an imaginary battery characteristic: ZERO internal resistance. All batteries have internal resistance and all batteries have a ceiling voltage that should not be exceeded. Because of these two, charge time is NEVER equal to capacity (Ah) divided by charger current (A). Charge time is always more. This is true even for the most sophisticated CC/CV charger. How much more depends on
1) The quality of the charger (CC/CV is best)
2) The internal resistance of the battery (the higher the resistance, the longer it takes to reach full charge)

 

[dogman dan]

Still likely comes out closer than me doing simple math.

I'm sure you others just can't imagine being that math stupid. I'm just great at three dimensional visualization, take it apart, reassemble it properly, or assemble without looking once at directions, stuff like that.

But for me, getting the decimal point in the right place can be really hard. If nothing else, it gives you a quick ball park estimate. It should be pretty close for the first 90% of the charge. The last 10% is hard to estimate time for, since the amps draw begins to vary.

 

[dnmun]

the assumption that the charge rate is linear is simplistic. charging current changes as the voltage of the battery increases. not all chargers have the same efficiency so the output power will vary also.

 

[SamTexas]

In theory the charge current for CC/CV charger is constant until terminal voltage is reached. In practice, well that's a different story.

 

[M4SK13]

lol I take it into account what some of the comments on here state; but this is a layman’s calculator.

I have to say google it and see how simple the maths is! The simple equations that some people have put above are not by comparison to that of the actual complicated answer. It is and the theories and use of equation laws associated with the inaccuracies’ of battery technologies and the efficiencies or in-efficiencies with the different variable factors that have to be considered.

See how complex the above is? Now my calculator link puts a simple view on it with a simple answer, with the person inputting it knowing it’s a just a good guide.
ian.mich says it spot on but i could not find that answer anywhere easily.

Simon

 

[ian.mich]

lol I take it into account what some of the comments on here state; but this is a layman’s calculator.

I have to say google it and see how simple the maths is! The simple equations that some people have put above are not by comparison to that of the actual complicated answer. It is and the theories and use of equation laws associated with the inaccuracies’ of battery technologies and the efficiencies or in-efficiencies with the different variable factors that have to be considered.

See how complex the above is? Now my calculator link puts a simple view on it with a simple answer, with the person inputting it knowing it’s a just a good guide.
ian.mich says it spot on but i could not find that answer anywhere easily.

Simon

Huh? I said that you had to add a bit of time for inefficiencies and CC/CV of course, I too believe that Ah/A is merely a guide.