will MH-C9000 shows the mAH capacity??

[Sanyo.Eneloop]

i'm thinking of buying MH-C9000 charger my question is that if i put any good nimh cell in it and i wanna know how many mAH are left in there will that charger tell me????


for example i put eneloop in it and i want to know its remaining capacity in mAH will it display the capacity ??????? just like volt meter

 

[russthetoolman]

It does not display what is left, only what is put into it during the charging cycle.
I use a ZTS battery tester to get readings of my batterys capacity, maybe that's what you are asking for?
Russ

 

[Black Rose]

The C9000 can display what the remaining capacity of a cell is, but you have to actually discharge the cell in order to find out what the remaining capacity of the cell was.

 

[Sanyo.Eneloop]

It does not display what is left, only what is put into it during the charging cycle.
I use a ZTS battery tester to get readings of my batterys capacity, maybe that's what you are asking for?
Russ

but that ZTS tester is expensive than MAHA chager and also it shows results on LED'S i want a device that shows me correct mAH readings anytime i want on LCD display i'm ready to pay any price for it!

 

[wapkil]

but that ZTS tester is expensive than MAHA chager and also it shows results on LED'S i want a device that shows me correct mAH readings anytime i want on LCD display i'm ready to pay any price for it!

Sure, no problem. I would start from a scanning device to non-destructively determine the precise state of the electrolyte inside the battery. Then add some modeling and it should be pretty accurate. I would only need a small grant to start this project - how about $500k? I'm not sure what exactly will be the overall cost but I don't think more than $5M. Shouldn't take more that 3 years. Please excuse my question, but could you confirm that you are indeed ready to pay any price? :devil:

Seriously though, the devices that try to measure the remaining capacity of NiMH batteries do it by measuring the voltage at different loads, maybe also internal resistance in different conditions. They are only guessing what's inside. The mAh figure also depends on what the discharge current will be. The chemistry behaves differently if you try to draw 2A than when you take only 50mA. If you want to know the exact charge, you have to discharge the battery. At least, if you can't afford to finance the project I proposed above :nana:

 

[SilverFox]

Hello Sanyo.Eneloop,

You will first have to develop a way to do this...

The ZTS comes close, but it is not precise.

The best you can do is to conduct a series of tests with your cells, discharging them after storage for various amounts of time, then compile a chart that applies to your cells. When you replace your cells, you will have to do the testing again and adjust your charts for the new cell performance.

Having done all of this, I have found that it is easier to store cells discharged and have a charger capable of quickly charging them. This way I know what condition they are in without having to factor in a lot of data from my charts.

Tom

 

[Sanyo.Eneloop]

but why precise mAH meters are not invented?????? yah i know MH-c9000 will show mAH when charging and discharging which will take time,

to make an mAH meter we need technology from outer space????

 

[wapkil]

to make an mAH meter we need technology from outer space????

We probably already have the technology. The problem is, as I wrote, that it may be rather expensive to use it for unknown cells.

I think the easiest and cheapest way it can be done (and usually is done) automatically is to keep the records for every battery. It can be achieved by attaching a dedicated IC to them. The IC will measure the current drawn from the battery. Using historical capacity data and self discharge rate estimation it will estimate for you the amount of the charge left. These ICs are usually called battery fuel or gas gauges. They will essentially do the task proposed above by SilverFox but automatically instead of manually.

One inconvenience of fuel gauges is that they will "learn" only the battery behavior that you let them see. AFAIR it's recommended to completely discharge batteries with fuel gauges from time to time so the ICs can recalibrate.

 

[Hitthespot]

yah i know MH-c9000 will show mAH when charging and discharging which will take time,

As I believe was said above. Make sure you understand ( and maybe you do ) that the Mah shown when charging the cell is not the discharge capacity available. When charging the battery the amount of energy required to charge the cell (Mah) is always higher than the discharge capacity available (Mah). Some of the charge energy is losses. For example the heat that is generated during charging is lost energy.

If you need to know the discharge capacity of your batteries, charge them and dis-charge them on a charger which will give you the total discharge capacity, ( like the C9000). This should be close enough for any application. However even batteries of the same brand and type will give you different discharge capacities, so as Tom said, you would need to run the test on each and every battery. Also the discharge capacity can be different based on the voltage and current drain of the discharge. So you would need to know the exact voltage and current your application uses throughout the the discharge curve. Batteries will also age and the capacities will change, so you will need to run the test every 6 months to a year to keep your figures accurate. Frankly I'm not sure why such accurate discharge numbers would need to be known. Buy good batteries like Enelooops and carry some spares.

Bill