2300mAh one hour quick charger

[Stream]

I'm thinking about buying a one hour quick charger with automatic shut-off. It comes with 2300mAh Ni-mh batteries. My question is probably a dumb one: can I charge 2700mAh Ni-mh batteries in this charger? I haven't looked closely at the charging amperage but my understanding is that a charger designed for 2300mAh (for example) can charge most common mAh ratings but that the charging time will vary. So it may take a little more than one hour if I want to charge 2700mAh Ni-mh batteries in it. Am I completely off here? Will 2700mAh cells never achieve a full charge in a 2300mAh charger?

Any advice would be appreciated.
Thanks in advance

 

[JamesWong]

It depends on the design of the charger. For 1 hour charger for 2300mAh, the charging current will be around 2.5A. And for safety the charger will also has timer for maximum charging time, but it should not be exactly 1 hour, may be 1.5hour if fully-charged signal cannot be detected.

In short, it should be 80% possible to fully charge a 2700mAh Ni-MH. Just a bit longer than 1 hour.

Just try. If it charges around 20% longer, it works.

 

[Stream]

It depends on the design of the charger. For 1 hour charger for 2300mAh, the charging current will be around 2.5A. And for safety the charger will also has timer for maximum charging time, but it should not be exactly 1 hour, may be 1.5hour if fully-charged signal cannot be detected.

In short, it should be 80% possible to fully charge a 2700mAh Ni-MH. Just a bit longer than 1 hour.

Just try. If it charges around 20% longer, it works.

Ok here's the charger I was looking at: http://www.jula.se/Butik/default.as...cs/produkt.asp?pf_id=SE-937065&dept_id=SE-937

Upon closer inspection I see that it states that it will charge 800 mAh in 1 hour and 1700 mAh in 1,9 hour. But it includes 4 AA- 2300 mAh batteries. I've looked at this charger in the store but haven't read the specs online before. So what's your opinion from what you can see in the link? And by the way, what should the voltage read on 80% full?

Thanks again

 

[johnny13oi]

Most likely, the charger will charge 2700mah batteries. And I don't think that there is a certain voltage that the battery will be at 80% full. It's not like li-ions where you can get an idea with voltage values.

 

[Stream]

Most likely, the charger will charge 2700mah batteries. And I don't think that there is a certain voltage that the battery will be at 80% full. It's not like li-ions where you can get an idea with voltage values.

Ok, so what do have to do to measure the charge of a Ni-mh cell? Does it have to be under load?

Thanks,
Stream

 

[Handlobraesing]

The charger is designed with some latitude. If it was designed around say a 2000mAh and using the latitude to the max to charge 2,300mAh, you won't fully charge 2,700mAhs.

My Duracell 30 min charger came with 2050mAh batteries. It charges at 3.8A and it actually charges for up to 40 minutes before forced shut down and tops off after the shut down.

It won't fully charge 2500 or 2700mAh batteries without running two cycles... I have tested this.

 

[Curious_character]

Ok, so what do have to do to measure the charge of a Ni-mh cell? Does it have to be under load?

Thanks,
Stream

The only reliable way is to discharge it and see how much charge it contained.

Some clever devices like my Garmin 60CSx GPS receiver have a battery gauge which functions with NiMH cells. It seems to measure not only the voltage, but also the rate of voltage drop at turn-on -- and perhaps the temperature also -- then uses some sort of algorithm to arrive at an approximation of the charge state. It's not very accurate, though.

The ZTS tester purports to show the charge state in 20% increments based on a voltage test under a pulsed load. Has anyone checked its results against a discharge-based test for cells in various charge states?

c_c