Hello.can please someone help me with this problem
Lets say we have a 2100 mAh capacity NiMh battery with 1.2 v.
In order to charge it in 14 hours mode you select 200mA charging current and 1.2 V right?
When you want to charge the battery in fast mode 52 minutes then the battery is charged with the same current as in normal mode? 200mA?
or is there maybe another kind of higher charge current generated to supply the battery?
because if you think about it 52 minutes of 200 mA charging current then the battery will be 1/10 charged and thats so low!
thank you
Faster charging = using a higher current. So at fast charge in about one hour for a completely empty battery, you need quite some current: for your 2100 mAh this would be a current of about 3 amps, which is dangerous with this simple kind of charger. Using such high charging currents needs to be done under control of a special charging IC which measures several parameters and temperature.
So if i get this right you mean that :
A)14h charging mode : charging current = capacity of the battery/10
52 minutes charging mode: charging current = equals to capacity of the battery or even more?
B) when it comes to fast charging in 52 minutes there is NO such thing as a standard charging current like in 14 hours (capacity/10 ) right?
i mean, i get to choose what charging current i should supply in order to have a decent amount of charging along with safety( no overpressure on the battery,no overheating etc) right ?
and
c) so lets say i have an 750 mAh battery in order to charge it in 14 hours i shunt the 75 mA charging current (that will supply the battery with 75 mA X 14 hours=1050 mA in total and 100% charged) whereas if i want to charge the battery in 52 mins i should shunt the 750 mA charging current and after 52 mins the battery would receive in total 650 mA so it would be like 85% charged ?
looking forward for your help
thank you
First part of A is correct!
At 52 minutes the charging current is always higher than battery current so dangerous.
B: there is NEVER a standard charging current for an amount of time! These calculations assume a completely empty battery which almost never happens. For charging at 1/10th or less, overcharging is not a very big problem but with higher currents, you should stop earlier or you are shorting the life span of the batteries. Time depends on temperature, current and how much capacity there is still in the battery.
C: first is correct. But second not: after charging a COMPLETELY empty battery with 750 mA during 52 minutes, THEORETICALLY, you end up with a battery that is charged for 464 mA = 62%. You have always a “loss” of factor 1.4.
““At 52 minutes the charging current is always higher than battery current so dangerous.””
what do you mean always?I am the one who chooses what charging current i want right?,i mean i can choose 75 mA or 200 mA or 750 mA ,in the end the only change is how charged my battery is gonna be after 52 minutes.higher current =increased danger but more efficient charging///// lower current=decreased danger but less efficient charging
can you please tell me the mathematical equotation that contains the loss factor inside (1.4) so i can calculate on my own the different results on every different current selection?
thank you
If you want your battery charged in 52 minutes, you need a current that is higher than the battery current.
Higher current = more heat and a hot battery has lower efficiency.
As a rule of thumb, always calculate the 1.4 everywhere: in charging and in discharging.
yeah but what is the mathematical equotation that contains the loss factor of 1.4 ?
you said two posts before “”" after charging a COMPLETELY empty battery with 750 mA during 52 minutes, THEORETICALLY, you end up with a battery that is charged for 464 mA = 62%. You have always a “loss” of factor 1.4."""
i mean what is the mathematical process,the calculations you do to find out this result ??
750 mA during 52 minutes is a capacity of 650 mAh but due to losses: 650/1.4 = 464 mAh
thaaaank you so much 
you’re welcooooome