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Topic: NiMH Batteries (~2000mah) (Read 3864 times) previous topic - next topic
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NiMH Batteries (~2000mah)

Guys / Gals,

  I am apart to part with some easy earned money for a new digital camera, and whilst the money is in the mood for departing from me, I have decided to buy some new AA batteries (here's where the subject comes in), of about 2000mah capacity.

  I have an old charger which was about when the largest capacity AA NiMH batteries were 1300 - 1500 odd mah.  I have some 1700mah AA's, which appear to outlast 1300mah ones, although I am only human, and deeply affected by placebo.

  Question: Will my charger continue to pump AA's full to their capacity, no matter what that may be?  Or will it bottle out and "say 'naaah', must be full by now, I'm powering down"?  How do chargers know when to stop?

  Cheers,

Markus

NiMH Batteries (~2000mah)

Reply #1 –
Many cheap chargers only have a timer stop. They are programmed to stop after the required time to charge the batteries provided with them.

As you may guess, it is then possible that if you use them with other batteries, the charging time can be wrong.

More evolved chargers are using other techniques:
http://www.gpbatteries.com.hk/Consumer/Pow...ge/pr_smart.htm

NiMH Batteries (~2000mah)

Reply #2 –
I don't know where you might be coming from, but I have a charger made by Rayovac.  It's a one-hour charger and will charge AAA and AA batteries in one hour.  Supposedly it works by measuring the temperature of the battery, and shutting off when it gets too hot 

Anyways, it works well for me, but I have no idea whether it will charge your battery to capacity.

NiMH Batteries (~2000mah)

Reply #3 –
I shall purchase and conduct experiments with my trusty wristwatch

NiMH Batteries (~2000mah)

Reply #4 –
If your charger is quite good charger and specially design for Ni-MH, it should be okay to charge bigger capacity batt. Because afaik. the good method to charge Ni-MH is to give the voltage slightly higher than the battery could generate. It's variable voltage. At the first when the battery is still empty the voltage which is given by charger is low then raise with the raise of battery charge level and stop at the certain voltage (1.2v) which indicates that the battery is fully charged.

To make sure that your battery is fully charged, try to compare with 1300 mAH battery. You can give the same load, for example a flashlight bulb. and count for how long the battery last.

FYI: Li-ion used constant voltage charge method.

NiMH Batteries (~2000mah)

Reply #6 –
I use the GP Powerbank rechargeable batteries... the store tech told me that higher capacity Ni-MH batteries just take longer to charge. I dunno how to check for full battery charge though, so if someone can provide me with a simple test I can test it for you people.

Regards

AgentMil
-=MusePack... Living Audio Compression=-

Honda - The Power of Dreams

NiMH Batteries (~2000mah)

Reply #7 –
not a simple matter. Check the fourth paragraph under "NiCD/NiMH Charging" "The negative delta V system relies..." http://www.angelfire.com/electronic/hayles...es/charge1.html
The guy in the store was correct, higher capacity NiMH cells can be charged by any NiMH charger, they'll just take longer to charge than lower capacity ones. If you're only going to be charging AA cells (and/or AAA cells) I can highly recommend the charger that I have here. It's a DynaCharge QuickCharger model CEF 12N. It seems to sense when the cells are fully charged, possibly the same way as that article describes. I have some Energizer NiMH cells here that are 1850mAH and some that are 2100mAH, and the 2100's do take longer to charge. The green LED on the charger flashes while it's charging, and comes on steady when they are fully charged. I don't know if you can get the charger on its own, or if it comes with cells. I didn't buy this one, it was inherited from my g/f's step-dad who never used it, heh. Great charger though, cells always come out cool, so they're not being overcharged or constantly subjected to the full charging current. Once they're fully charged they're only subjected to the low trickle charge current to keep them charged. It does only output 1800mA, so it's not going to recharge a pair of 2000+mAH cells in an hour, obviously. But for me it's fast enough, and the fact that I know it has a good charging methodology brings to mind "a bird in the hand..."



<edit> oh yeah, it's not a wall wart, there's an AC cord that plugs into the top of the charger so you can place it on a table, etc.

<edit> that GP Power Bank Smart looks pretty nice too, more than just the negative delta voltage detection, though it outputs slightly less current and so will take slightly longer to charge any given cell. One thing it has that mine doesn't is the ability to switch to a lower output current so you can safely charge older NiCd cells too, that's nice to have.

NiMH Batteries (~2000mah)

Reply #8 –
The GP Power Bank Smart also have individual sensors, which is a nice feature. It means that I do not have to fed it with identical batteries (or identically charged/discharged)

NiMH Batteries (~2000mah)

Reply #9 –
yeah, that one is particularly nice. I've no idea if this one does that, think I'll do a bit of experimenting to see

NiMH Batteries (~2000mah)

Reply #10 –
Quote
The GP Power Bank Smart also have individual sensors, which is a nice feature. It means that I do not have to fed it with identical batteries (or identically charged/discharged)

The Rayovac charger that I have can do that as well. I've lost the product literature, but reading these other posts leads me to believe that this can do the same as everything else listed here, since the product descriptions are so similar.

@Lev, short answer is that there are a number of different chargers that probably can charge up your 2000+mAh batteries.  Just pick whatever is the easiest to find in your area.  FYI, I paid about $30USD for my charger, and I suspect that others here paid around that price as well.
.....
Just checked out the Rayovac website.  Here's the page with my charger on it: http://www.rayovac.com/products/recharge/r.../recharge.shtml.
     
They've come up with a 15 minute recharging system.  There are charging controls on the battery itself which can cut down on charge time.

NiMH Batteries (~2000mah)

Reply #11 –
if I had to guess I'd say it's just a thermistor that gets monitored, so if the battery temp isn't too high they keep pouring on the juice.