Maximum charging voltage for batterier

[Reynard]

Hi

i got a GP battery and its data sheet stated that the maximum charging voltage is at 1.5V, 100mA. If i charge the battery using more than 1.5V say about 5V but i used 50ohm resistor to provide a current of 100mA, will i burst the battery?

Am i right to say that if the charging current never exceeds 100mA, the battery will be safe?

Thank You

 

[poopeater]

If you put a 50ohm resistor in series like you want to, you'd basically be putting a 3.5V drop across the resistor, which would provide the battery with 70mA charge current. I think you should be alright.

 

[audioguru]

The max charging voltage is probably stated as 1.5V because when the battery becomes fully charged its voltage reaches 1.5V and therefore the current automatically becomes less. With a 5V supply and a resistor to limit the current then the battery can easily become overcharged.

The battery is not safe when you overcharge it. It gets hot which can melt the plastic parts inside and overcharging builds pressure from gasses that are created inside.

 

[Thunderchild]

perhaps use a time control by working out what current is needed for how many hours and set the timmer (555 circuit)

 

[oldtimer]

put a 1.5V zener diode after the resitor to ground this should do the trick. If you can't find one remember a transistor base to emitter gives 0.6 V leave the collector open.

 

[audioguru]

perhaps use a time control

A timer is useful to eliminate overcharging, but doesn't prevent overcharging a battery that is already charged.
Maybe a discharge circuit followed by a timed charging circuit is best.

 

[Hero999]

How many 1.5V zeners have you seen recently.

Reynard, you haven't said what capacity the battery is, a 2200mAh unit probably won't be harmed if you overcharge it for a few hours but a 100mAh unit would die for sure.

 

[Oznog]

The max charging voltage is probably stated as 1.5V because when the battery becomes fully charged its voltage reaches 1.5V and therefore the current automatically becomes less. With a 5V supply and a resistor to limit the current then the battery can easily become overcharged.

The battery is not safe when you overcharge it. It gets hot which can melt the plastic parts inside and overcharging builds pressure from gasses that are created inside.

Well since the voltage listed indicates a NiCd/NiMH battery, this is not the case even with good voltage control. The voltage will not rise much at the end of charge, the current will not slow much and the battery will absorb an overcharge.

Actually max voltage on the battery does not mean much at all. You need to design the circuit for max current. What 1.5v generally means is this is the voltage produced by a good charging current, you use this to calculate the source voltage and series resistance for a simple charging circuit.

 

[mpj111]

use a bulb in series insted of resistor.