Post by linegrab on Nov 25, 2005 16:33:41 GMT 8
Basic Battery Charging Instructions
Ni-CD Batteries
Standard Chargers:
1. You will need a charger that has a higher Voltage Output rating than the battery you plan to charge.
2. Most standard batteries are 8.4v, so anything higher will work.
3. mAH on the charger is the output of milliamp per hour. This is the amount of power that will flow into the battery given no resistance. This number does not have to be higher than the battery's mAH rating. The higher the rating on the charger, the faster it will charge the battery. However, for Ni-Cd batteries, you do not want to have an output higher than 2.5 times of the mAH capacity rating of the battery.
On a standard charger use the following:
X = Battery's mAH capacity rating. Y = Charger's mAH output
( X / ( Y*1.25) ) = Total Charge Time in Hours
On a Pulse-Charger: Amp setting must not exceed 2.75 times of the mAH capacity rating.
Ni-MH Batteries
Standard Chargers:
1. You will need a charger that has a higher voltage output rating than the battery you plan to charge.
2. Most standard batteries are 8.4v; we recommend the use of a 9.6v charger. We do not recommend anything higher.
3. mAH on the charger is the output of milliamp per hour. This is the amount of power that will flow into the battery given no resistance. This number does not have to be higher than the battery's mAH rating. The higher the rating on the charger, the faster it will charge the battery. However, for Ni-MH batteries, you do not want to have an output higher than 2 times of the mAH capacity rating of the battery.
On a Standard charger use the following:
X = Battery's mAH capacity rating.
Y = Charger's mAH output.
Z = Total Charge Time in Hours
Special note: Ni-MH batteries do not have a memory problem like the Ni-CD; however, they are more heat sensitive. Charging Ni-MH batteries should be done in segments of 15 minute intervals.
( X / ( Y*1.5) ) = Z
Z * 4 = # of charging intervals
Make sure to have a 5~10 minute cool-down time between charging intervals.
On a Pulse-Charger: Amp setting must not exceed 2 times of the mAH capacity rating.
Note: 1000mAH = 1Amp
MAKE SURE TO NOT OVER CHARGE YOUR BATTERY!
OVER CHARGING IS A FIRE HAZARD!
Add’l Info:
"Peaking" happens when rechargeable cells reach maximum charge/voltage. If/when the charging process continues, the voltage starts going down (called voltage depression) - thus voltage curve describing a slope going up to maximum, and then a slope going down as the batteries overcharge. The highest voltage value is the "peak". Most automatic chargers are designed to sense this drop in voltage and either cuts-off or switches to trickle charging.
Rechargeables tend to self-discharge at a rate from less than 1% to 3% per day, depending on condition. Damaged cells may discharge even faster. Thus, a battery pack charged a day before use would have lost some power by the time it is put to use. Some users resort to an additional or "topping off" charge, for a very brief period, to bring the charge up to maximum, before using the batteries. Be careful about doing this - it's very easy overcharge the cells this way.
1
It is not the voltage setting that is important, as long as the voltage setting is higher than the voltage of the battery to be charged, you'll be able to fully charge that battery.
What is more important is the milliAmpere rating of the charger. It is around a 1000mA or 1 Ampere charger based on the time it takes to fully charge your 1900mah battery. If you can set the voltage of the charger to about 10v, you'll still be okay but you may have to charge the battery longer than 2 hours.
2
Given in the formula is a very accurate way of measuring the amount of time needed to fully charge our AEG batteries. Why settle for just an estimate? Actually, if you come to think of it, it is really a very simple multiplication and division that you have to do just once. Just do the Math and maybe write down somewhere in the charger the time needed to charge this so and so mAH battery. If you want to avoid the hassle, get a linear charger with auto-cut off.
Regarding the number of bb/mah battery charged, it depends on a lot of different factors on the aeg like how heavy a spring it's pulling, what gears are used, what type of motor is installed, condition of the battery, capacity of the battery, voltage of the battery, etc.
it's really very hard to compute the battery usage based on a lot of variables. good thing we have friendly and accomodating tech gurus to spoon-feed us evry information we need from them. that's the reason why i re-posted this article, to take some of the burden off of them. besides wouldn't you wanna understand also how our aeg's work and at least how to trouble shoot any problem and not just run to the tech gurus everytime?
Sample computation 1:
daMan was asking for the charging time of a 12v 1700mah and a 9.6v 1700mah battery. here's a sample computation:
X = Battery's mAH capacity rating. Y = Charger's mAH output
( X / ( Y*1.25) ) = Total Charge Time in Hours
so:
X=1700mah Y=3amps or 3000mah, substituting for X and Y:
(1700 / (3000*1.25) ) = ___hours
(1700 / 3750) = 0.45 hours
converting to minutes:
1 hour = 60 minutes, then 60 x 0.45 = 27
0.45 hours = 27 minutes
the 12 volts 1700mah should be charged for 27 minutes
about the 9.6v 1700mah battery, you have to set the correct voltage to 9.6v.charging time should be the same. if it is a fixed voltage and there is no way of setting it below 12v, then charging time is still the same but the margin of error will be less, you may start overheating the battery before 27 minutes is up. the voltage setting is too high for the battery and the internal resistance of the battery will be easily overcome by the high voltage, thus producing a lot of heat very fast, near the end of full charge. when charging the 9.6v, monitor the temperature well near the 27 minute mark.
Some corrections:
After seeing this charging formula worked out in another thread.. I saw fit to go back to this one. I think there is a flaw in the given formula.
Using it to compute the charging time for a 2000mAh battery pack using a 550mAh charger:
X = Battery's mAH capacity rating. Y = Charger's mAH output
( X / ( Y*1.25) ) = Total Charge Time in Hours
= ( 2000mAh / ( 550mAh x 1.25 )
= ( 2000 / 687.5 ) = 2.90909090... hours
= 2 hours 54+ minutes
The thing is.. it doesn't quite work out that way. RadioShack's Model 23-333 Charger, specifically matched and packaged with their 7.2v 2000mAh battery, has an output of 550mAh, and automatic cutoff, takes 5 hours! Why is that?
550mAh for 5 hours is a total of 2750mAh. That equates to 2000mAh x 1.375, or 37% more. The charging process is not 100% efficient. There can be as much as 25%.. 30%.. or even 50% loss. In order to make up the difference, we have to increase somewhere. Since the charger output is (given) constant, we cannot increase that figure. BUT.. we can increase the length of time! We do this by multiplying the basic charge time by 1.375. Thus,
dividing battery capacity by charger output...
( 2000mAh / 550mAh ) we get
3.6363636363... hours, basic charging time
and multiplying this figure by 1.375, we get
3.636363.. x 1.375
= 5 hours!
It seems then that the correct formula is
( battery capacity / charger output ) x 1.25
Now.. revising grey man's formula to ( X / Y ) x 1.25, and applying it to daMan's example:
( 1700mAh / 3000mAh ) x 125
= 0.56666..7 hours x 1.25
= 0.708333... hours
= 42 minutes
Sample Computations 2:
How bout this one dude..
my batt is 9.6V 2000mah and my charger output voltage is
12V dc 350mah, how many hours ung charging nya?
using almighty's revisions:
(2000mah/350ma) x 1.25 = 7.15 hrs or 7 hours and 9 minutes
my advise is set your alarm clock 30 minutes before this calculated time and check your battery. if it's already hot enough, unplug it after 6 and a half hours. remember this charging time assumes that the battery is completely drained.
no no 1000 mAh = 1000 mA * Hr = 1 A * 1 Hr
1 A = coulomb / s
so x * A * Hr (ex. 3000 mAH or 3 * A * Hr) states the total charge (proportional to # of electrons) that can be stored by the battery.
the charge on a single electron is 1.602 × 10^-19 coul.
1 A * hr = 3600 coul or 2.27e22 electrons!!
Note: 1000mAH = 1Amp
keep a watchful eye when charging... nothing beats a well guarded instinct when doing it... it should be warm... not too hot... you might get the pack over charged...
when storing battery packs... keep it discharged at a safe level (specially nicads) based on the specifics in the postings
Additional Postings:
1. using a charger with a lower voltage rating on a battery (e.g. 7.2v charger on a 9.6v battery) is a NO NO..Tama ba ko? What will be the consequence? Sunog charger o sunog battery?
using a higher voltage will mean higher current flow from the high voltage charger to the low voltage-rated battery pack. this will work but the charging time will be very much shorter. if you don't have an auto cut-off function on the charger, you'll have to watch it very closely for increase in temperature. remember your battery doesn't like high temps
slow charge is the best
2. can I use a TLP 940E charger to quick charge a 3000 Nimh bat?
not really sure about the tlp940e charger but to quick/fast charge it, just crank the current setting way up to the max, the charger will automatically cut-off after end of charge is reached.
Hindi naman. It's just that the charger must be able to supply as much voltage as needed to fully charge the battery pack. A 9.6v battery pack has 8 cells.. and each cell, if in top condition, actually reaches 1.65v (instead of just 1.2v) when fully charged.. thus the 8-cell 9.6v pack actually needs as much as 13.2v to be fully charged! When in nominally discharged state of average 1v per cell, the 9.6v pack will show a reading of 8v.. just a little over 7.2v! In any case, a proper 7.2v pack charger has voltage output of 9.9v.. so it might be able to charge the 9.6v pack.. but just a little, and quite short of full. Repeated undercharging will eventually establish "memory" of the shortfall.
Ni-CD Batteries
Standard Chargers:
1. You will need a charger that has a higher Voltage Output rating than the battery you plan to charge.
2. Most standard batteries are 8.4v, so anything higher will work.
3. mAH on the charger is the output of milliamp per hour. This is the amount of power that will flow into the battery given no resistance. This number does not have to be higher than the battery's mAH rating. The higher the rating on the charger, the faster it will charge the battery. However, for Ni-Cd batteries, you do not want to have an output higher than 2.5 times of the mAH capacity rating of the battery.
On a standard charger use the following:
X = Battery's mAH capacity rating. Y = Charger's mAH output
( X / ( Y*1.25) ) = Total Charge Time in Hours
On a Pulse-Charger: Amp setting must not exceed 2.75 times of the mAH capacity rating.
Ni-MH Batteries
Standard Chargers:
1. You will need a charger that has a higher voltage output rating than the battery you plan to charge.
2. Most standard batteries are 8.4v; we recommend the use of a 9.6v charger. We do not recommend anything higher.
3. mAH on the charger is the output of milliamp per hour. This is the amount of power that will flow into the battery given no resistance. This number does not have to be higher than the battery's mAH rating. The higher the rating on the charger, the faster it will charge the battery. However, for Ni-MH batteries, you do not want to have an output higher than 2 times of the mAH capacity rating of the battery.
On a Standard charger use the following:
X = Battery's mAH capacity rating.
Y = Charger's mAH output.
Z = Total Charge Time in Hours
Special note: Ni-MH batteries do not have a memory problem like the Ni-CD; however, they are more heat sensitive. Charging Ni-MH batteries should be done in segments of 15 minute intervals.
( X / ( Y*1.5) ) = Z
Z * 4 = # of charging intervals
Make sure to have a 5~10 minute cool-down time between charging intervals.
On a Pulse-Charger: Amp setting must not exceed 2 times of the mAH capacity rating.
Note: 1000mAH = 1Amp
MAKE SURE TO NOT OVER CHARGE YOUR BATTERY!
OVER CHARGING IS A FIRE HAZARD!
Add’l Info:
"Peaking" happens when rechargeable cells reach maximum charge/voltage. If/when the charging process continues, the voltage starts going down (called voltage depression) - thus voltage curve describing a slope going up to maximum, and then a slope going down as the batteries overcharge. The highest voltage value is the "peak". Most automatic chargers are designed to sense this drop in voltage and either cuts-off or switches to trickle charging.
Rechargeables tend to self-discharge at a rate from less than 1% to 3% per day, depending on condition. Damaged cells may discharge even faster. Thus, a battery pack charged a day before use would have lost some power by the time it is put to use. Some users resort to an additional or "topping off" charge, for a very brief period, to bring the charge up to maximum, before using the batteries. Be careful about doing this - it's very easy overcharge the cells this way.
1
It is not the voltage setting that is important, as long as the voltage setting is higher than the voltage of the battery to be charged, you'll be able to fully charge that battery.
What is more important is the milliAmpere rating of the charger. It is around a 1000mA or 1 Ampere charger based on the time it takes to fully charge your 1900mah battery. If you can set the voltage of the charger to about 10v, you'll still be okay but you may have to charge the battery longer than 2 hours.
2
Given in the formula is a very accurate way of measuring the amount of time needed to fully charge our AEG batteries. Why settle for just an estimate? Actually, if you come to think of it, it is really a very simple multiplication and division that you have to do just once. Just do the Math and maybe write down somewhere in the charger the time needed to charge this so and so mAH battery. If you want to avoid the hassle, get a linear charger with auto-cut off.
Regarding the number of bb/mah battery charged, it depends on a lot of different factors on the aeg like how heavy a spring it's pulling, what gears are used, what type of motor is installed, condition of the battery, capacity of the battery, voltage of the battery, etc.
it's really very hard to compute the battery usage based on a lot of variables. good thing we have friendly and accomodating tech gurus to spoon-feed us evry information we need from them. that's the reason why i re-posted this article, to take some of the burden off of them. besides wouldn't you wanna understand also how our aeg's work and at least how to trouble shoot any problem and not just run to the tech gurus everytime?
Sample computation 1:
daMan was asking for the charging time of a 12v 1700mah and a 9.6v 1700mah battery. here's a sample computation:
X = Battery's mAH capacity rating. Y = Charger's mAH output
( X / ( Y*1.25) ) = Total Charge Time in Hours
so:
X=1700mah Y=3amps or 3000mah, substituting for X and Y:
(1700 / (3000*1.25) ) = ___hours
(1700 / 3750) = 0.45 hours
converting to minutes:
1 hour = 60 minutes, then 60 x 0.45 = 27
0.45 hours = 27 minutes
the 12 volts 1700mah should be charged for 27 minutes
about the 9.6v 1700mah battery, you have to set the correct voltage to 9.6v.charging time should be the same. if it is a fixed voltage and there is no way of setting it below 12v, then charging time is still the same but the margin of error will be less, you may start overheating the battery before 27 minutes is up. the voltage setting is too high for the battery and the internal resistance of the battery will be easily overcome by the high voltage, thus producing a lot of heat very fast, near the end of full charge. when charging the 9.6v, monitor the temperature well near the 27 minute mark.
Some corrections:
After seeing this charging formula worked out in another thread.. I saw fit to go back to this one. I think there is a flaw in the given formula.
Using it to compute the charging time for a 2000mAh battery pack using a 550mAh charger:
X = Battery's mAH capacity rating. Y = Charger's mAH output
( X / ( Y*1.25) ) = Total Charge Time in Hours
= ( 2000mAh / ( 550mAh x 1.25 )
= ( 2000 / 687.5 ) = 2.90909090... hours
= 2 hours 54+ minutes
The thing is.. it doesn't quite work out that way. RadioShack's Model 23-333 Charger, specifically matched and packaged with their 7.2v 2000mAh battery, has an output of 550mAh, and automatic cutoff, takes 5 hours! Why is that?
550mAh for 5 hours is a total of 2750mAh. That equates to 2000mAh x 1.375, or 37% more. The charging process is not 100% efficient. There can be as much as 25%.. 30%.. or even 50% loss. In order to make up the difference, we have to increase somewhere. Since the charger output is (given) constant, we cannot increase that figure. BUT.. we can increase the length of time! We do this by multiplying the basic charge time by 1.375. Thus,
dividing battery capacity by charger output...
( 2000mAh / 550mAh ) we get
3.6363636363... hours, basic charging time
and multiplying this figure by 1.375, we get
3.636363.. x 1.375
= 5 hours!
It seems then that the correct formula is
( battery capacity / charger output ) x 1.25
Now.. revising grey man's formula to ( X / Y ) x 1.25, and applying it to daMan's example:
( 1700mAh / 3000mAh ) x 125
= 0.56666..7 hours x 1.25
= 0.708333... hours
= 42 minutes
Sample Computations 2:
How bout this one dude..
my batt is 9.6V 2000mah and my charger output voltage is
12V dc 350mah, how many hours ung charging nya?
using almighty's revisions:
(2000mah/350ma) x 1.25 = 7.15 hrs or 7 hours and 9 minutes
my advise is set your alarm clock 30 minutes before this calculated time and check your battery. if it's already hot enough, unplug it after 6 and a half hours. remember this charging time assumes that the battery is completely drained.
no no 1000 mAh = 1000 mA * Hr = 1 A * 1 Hr
1 A = coulomb / s
so x * A * Hr (ex. 3000 mAH or 3 * A * Hr) states the total charge (proportional to # of electrons) that can be stored by the battery.
the charge on a single electron is 1.602 × 10^-19 coul.
1 A * hr = 3600 coul or 2.27e22 electrons!!
Note: 1000mAH = 1Amp
keep a watchful eye when charging... nothing beats a well guarded instinct when doing it... it should be warm... not too hot... you might get the pack over charged...
when storing battery packs... keep it discharged at a safe level (specially nicads) based on the specifics in the postings
Additional Postings:
1. using a charger with a lower voltage rating on a battery (e.g. 7.2v charger on a 9.6v battery) is a NO NO..Tama ba ko? What will be the consequence? Sunog charger o sunog battery?
using a higher voltage will mean higher current flow from the high voltage charger to the low voltage-rated battery pack. this will work but the charging time will be very much shorter. if you don't have an auto cut-off function on the charger, you'll have to watch it very closely for increase in temperature. remember your battery doesn't like high temps
slow charge is the best
2. can I use a TLP 940E charger to quick charge a 3000 Nimh bat?
not really sure about the tlp940e charger but to quick/fast charge it, just crank the current setting way up to the max, the charger will automatically cut-off after end of charge is reached.
Hindi naman. It's just that the charger must be able to supply as much voltage as needed to fully charge the battery pack. A 9.6v battery pack has 8 cells.. and each cell, if in top condition, actually reaches 1.65v (instead of just 1.2v) when fully charged.. thus the 8-cell 9.6v pack actually needs as much as 13.2v to be fully charged! When in nominally discharged state of average 1v per cell, the 9.6v pack will show a reading of 8v.. just a little over 7.2v! In any case, a proper 7.2v pack charger has voltage output of 9.9v.. so it might be able to charge the 9.6v pack.. but just a little, and quite short of full. Repeated undercharging will eventually establish "memory" of the shortfall.
