battery charge after charge...

[rat]

hey,

basically i have a 9.6v 1700mah NiCD battery and an overated TLP 4000C cahrger. now the following question can apply to all batteries.

basically, i want to know how come after my charger beeps telling me that it has fully charged after i fast charge it, i can then charge it again for a while. i mean, if it is charged shouldnt it beep again telling me the battery has reached its full charge just a short while after recharging it?

[Zyre]

As a Ni-Cad battery is charged its voltage increases.

alot of nicd chargers detect a full state by watching for the point where the voltage levels off, or peaks. Some chargers go into a trickle charge state after it detects a full state, that might be what its doing.

Its also harder to tell if a nicad is full after the peak is hit (a kind of...if you blink you'll miss it kind of deal), because its not looking for a certain voltage, its looking for a change in the rate of voltage change. Li-ion batteries and their associated circuitry are alot more intelligent.

[odp]

Yeah, most chargers will try to charge about 100 mah or so, to help it figure out the state, regardless of the state. If I was you, I would time it, to see how long this period is, so you know if a battery really is charged or not.

[rat]

Originally Posted by odp

Yeah, most chargers will try to charge about 100 mah or so, to help it figure out the state, regardless of the state. If I was you, I would time it, to see how long this period is, so you know if a battery really is charged or not.

well like Zyre pointed out, my charger does the trickle charge after it peaks...

[Haggis]

hey Rat,
I use one of those fussy logic chargers and after i give it the full charge...if i disconnect and reconnect...it tries to charge for like 3 secs then beeps to tell me its full....dont know if its a help but its kinda relevent...didnt stop my friggen batt running out at 10:30 last night...i was a trigger happy pappy
nice meeting you

[Gryphon]

What you're getting is known as a false peak. Some modern chargers will allow you to set the peak detection anywhere from as low as 3 mV/cell to 25 mV/cell or so, depending on the cell chemistry you're charging. NiCds have a higher peak than NiMHs do and are more tolerant to overcharging.

This could also be the result from fast charging at too high a current. How many amps are you charging at?

[rat]

charging usually at 2 amps, but also tested at 2.5 with same result.

once again, the batt is a 9.6v 1700mah NiCD

[Gryphon]

Hmm, hard to tell what the charger's thinking since there's no readout. Maybe try charging at 1 amp and see if that helps?

[rat]

will give it a shot...cant hurt...

[freeman]

Originally Posted by rat

will give it a shot...cant hurt...

Does that work?Have you got any solution for this.

I have exactly the same charger.This is what i usually do.
When the charger beeps telling me that it has fully charged after i fast charge it,i will usually fast charge it again for a while (30-45 minutes using 110mAh)to make sure it is fully charged.Since there is no readout in this charger,I am not sure if i over charged the battery or not.
I find out that the battery would last longer if i do this additional step after the charger telling me the battery is fully charged.

Am i doing something wrong here?Is overcharging really bad for batteries.

ps:all of my batteries are nicd.

[rat]

i charge it a couple of times...each time the beeps getting sooner and sooner...usually charge it 3 times, each time lowering the setting. i also feel when the batt gets warm. anyway when i play i rarely just run around spraying and praying. i am not even close to ever using up the whole battery charge imo.