Hi everybody,
I recently bought a small chaep charger for 300 bucks, its a Godrej GP S350 NiMh charger for AA cells.
(http://cdn-img-a-tata.infibeam.net/img/2acf123a/Godrej/GP-Powerbank-S350/upload/front/Godrej-GP-Powerbank-S350_89291.jpg?hei=270&wid=250&op_sharpen=1)
Link to manufacturer's site
http://www.gpbatteries.com/html/products/powerbank_standard.html#pb350
http://www.gpbatteries.com/html/pdf/S350-manual.pdf
My question is that,i plugged 4 x 2800mAh batteries into it and it has been over 24hrs of charging but the LED on it still glows red. The cell are slight warm.
I am really confused whether this charger has auto cutoff or not since the led are not turning green or infact,any other color.
I used a multimeter to check the cell voltage and it was around 1.48V for Nimh cells but the charger is still charging them..!!
Pls help.
The charger does not have auto cut off
read the manual - it charges AA cells @ 200 mah
and nowhere does it say that the led will change color
you have to time your charge - usually overnight charging
will give you fully charged cells.
Don't over analyse this - its not rocket science.
1.48 is the max capacity. You are abusing those batteries. :)
Do you mean max voltage?
And i guess there is no simple way to check the mA in the battery with a multimeter right?
You mean mAH ? if yes then you can't measure mah with multimeter.
max voltage of nimh is around 1.40 .. . 1.48 is a bit more but i Think its nothing alarming as nimh can handle a lot of abuse.
Read the note on your battery for how long to charge
yes,i maent mAh...sorry about my poor knowledge, i am actually way off from this field (i am from medicine).
Quote from: srivatsa on August 12, 2012, 05:51:01 PM
max voltage of nimh is around 1.40 .. . 1.48 is a bit more but i Think its nothing alarming as nimh can handle a lot of abuse.
Definitely Nimh are not as bad as Lipo when it comes to overcharging. But I remember reading that they are not as robust as NICD. Overcharing Nimh can lead to premature failure of battery / Reduce batter capacity. Hence most of the NiMh chargers out there have auto cutoff.
I did not read the manual, but from the above post if the charger has a charging current of 200 ma per battery and the if the batteries are 2800 mah.
Let us consider(to be on the safer side) that the batteries are over rated and their actual capacity is 2600 mah. So charging would Ideally take 2600/200 = 13 hours. Now that since the charging is done at a slower rate, you need to charge them for slightly longer than 13 hours.
Use the calculator below.
http://convert-to.com/491/recharging-rechargeable-nimh-nicd-batteries.html
It says 15.6 Hours. So charge your batteries for 15 hours and that should be enough. Also remember that this time is for a fully weak battery :)
Hope this helps.
Thanks, that is very helpful.
I did read the manual now, it says divide capacity by charging rate and then multiply by 1.2 for compensation of energy lost.
So (2800/200)x1.2= 16.8 hours
Lol..i overcharged them so badly
An auto cutoff charger is always ideal. since you can put a half weak battery and it would know when to stop charging. :)
I never knew there are chargers without auto cutoff...!
Every charger that i had bought till date had a cut off.