The Capacity of New Rechargable batteries

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Zebretta
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The Capacity of New Rechargable batteries

When you go hunting for new batteries and they are advertised as So & So capacity or they have their capacity listed on the package……

Is that the Charge Capacity or Discharge Capacity they are advertising?

BlueSwordM
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If you see 3000 mAh, that is the capacity.

If it says something like 20A, that that is the max discharge specification.

mAh = capacity

A/mA = discharge capacity

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

Zebretta
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Not sure that answered the question….or at least I’m still not sure.
Let’s just focus on NiMh for the sake of this discussion. Forget all others.

I have an SkyRC MC3000 and an AccuPower IQ338XL

EVERY NiMh battery I’ve ever bought has a mAh rating on it.
But…all my NiMh chargers show two distinct capacities after a refresh cycle…..
One when discharging from Full charge to minimum voltage (Discharge Capacity) and….
One when charging from minimum voltage back to full charge (Charge Capacity).

So you’re saying the one normally stated and advertised is the capacity going from an empty battery to a fully charged battery.

Lightbringer
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You can trickle-charge a NiMH forever, and it’ll just constantly run up the “charge capacity” higher and higher, forever, albeit slooooowly.

Discharge it, and it’ll only reflect the true capacity.

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tatasal
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About niMh chemistry:

First of all, the discharge and charge figures will always be different…during charging some of the figures can be accounted to heat, that’s why we always use the Discharge Mode (regardless of chemistry) to get the truer Capacity.

Secondly, niMh benefit from Break-In, Refresh modes of some of the better charger/analyzers in the market. That is why the figures will actually become higher as more of the these two modes are used, and that is especially beneficial to niMh cells that are hardly subjected to high loads (ie: remote controls, etc) and long cycles between re-charges.

Pablo de Llama
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Thirdly ( LOL ), trickle charging is harmful for low-self-discharge (LSD) batteries, like eneloops. Trickle charging is a holdover from when batteries lost their charge sitting on a shelf very fast, and should only be used for high-self-discharge batteries. Beware if your charger trickle charges.

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The capacity figures for NiMh and NiCd batteries are likely to be more accurate than they will be for Li-Ion cells. The discharge voltage curve is pretty flat for NiCd and NiMh batteries, and then suddenly collapses as full discharge approaches. By contrast with Li-Ion the capacity is sensitive to both the beginning point (while most are 4.2 volt, there are some 4.35 batteries out there), and the end point, which varies from charger to charger, typically between 2.5 and 2.8 volts. While there is not a lot of capacity between 2.5 and 2.8 volts, there is some. Consequently unless you know the intended beginning and ending point for the charger as well as the beginning and ending points the battery was designed for, and they match up, there will always be differences between the labeled capacity and the measured capacity. As others have pointed out, the charging process is not 100% efficient, more energy will go into the battery in the charging process, than will actually be stored in the battery. This is typically on the order of 10% and also depends upon the starting point with cell in question. If you have a cell designed for 2.5 volts that is only discharged to 2.8 volts, then both capacities will likely be less than quoted because of available energy left in the cell between 2.5 and 2.8 volts,

Zebretta
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The answer to the OP is still out there.......

So...... When you buy a brand new NiMh battery......what is listed on the package?

 

Charge Capacity or Discharge Capacity ? 

Pete7874
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Zebretta wrote:

The answer to the OP is still out there…….


So…… When you buy a brand new NiMh battery……what is listed on the package?


 


Charge Capacity or Discharge Capacity ? 


Discharge capacity.

But to fully understand how they measured it, you would also need to know what discharge current and termination voltage they used when measuring it.

Zebretta
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Thanks Pete.
Yeah, I know there’s a lot of factors that can go into it and it’s not plain vanilla.
But at least knowing that gives me a starting point.

Cheers

PS
I’m surprised sneaky battery packaging doesn’t list the Charge Capacity because it’s usually higher and few would know the difference.

Pete7874
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Zebretta wrote:
PS
I’m surprised sneaky battery packaging doesn’t list the Charge Capacity because it’s usually higher and few would know the difference.
Charge capacity cannot be accurately measured, or at least not as accurately as discharge capacity.

The reputable battery manufacturers stick to testing methods that are verifiable/reproducible (is that a word?), hence discharge capacity.

The other battery manufacturers typically give some inflated bogus capacity numbers that are so far off that it really doesn’t matter if you are talking about charge or discharge capacity.

Zebretta
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lol.

You mean like ebay UltraFire 8000mAh 18650’s……..for $2.00 ea? haha!!

Lightbringer
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Pete7874 wrote:
The reputable battery manufacturers stick to testing methods that are verifiable/reproducible (is that a word?), hence discharge capacity.

They’re perfectly cromulent words.

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Lightbringer
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Zebretta wrote:
You mean like ebay UltraFire 8000mAh 18650’s……..for $2.00 ea? haha!!

Well, how else you gonna power those 300,000lm XP-E clone zoomies?

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Pete7874
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Lightbringer wrote:
They’re perfectly cromulent words.
Big Smile
Love the Simpsons.
WalkIntoTheLight
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Pete7874 wrote:
Zebretta wrote:

The answer to the OP is still out there…….


So…… When you buy a brand new NiMh battery……what is listed on the package?


 


Charge Capacity or Discharge Capacity ? 


Discharge capacity.

But to fully understand how they measured it, you would also need to know what discharge current and termination voltage they used when measuring it.

IIRC, I think the ANSI standard is something like 0.2 C, when doing discharge tests. As for termination voltage, I think it’s usually somewhere around 0.8v for complete discharge tests. But anything below 1.0v is basically empty, so it doesn’t really matter below that.

Of course, manufacturers can put whatever capacity they want on the label. Most consumers wouldn’t know the difference.

flydiver
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In reputable manufacturers I believe there is a ‘discharge standard’ for NiMh; something like 0.2 x C. I could not verify that with a modest search, so take that FWIW.

Generally, higher discharge rate you get less capacity, lower you get more. That’s very evident in discharge graphs.

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Zebretta
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WalkIntoTheLight][quote=Pete7874 wrote:
Of course, manufacturers can put whatever capacity they want on the label. Most consumers wouldn’t know the difference.

So true.
Just look at the number of people who buy those ultra high capacity , ultra cheep batteries. Sad. And then they leave feedback of how pleased they are Facepalm

Angler
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Zebretta wrote:

The answer to the OP is still out there…….


So…… When you buy a brand new NiMh battery……what is listed on the package?


 


Charge Capacity or Discharge Capacity ? 

Big Smile LOL Big Smile
Zebretta
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Angler wrote:
Zebretta wrote:

The answer to the OP is still out there…….


So…… When you buy a brand new NiMh battery……what is listed on the package?


 


Charge Capacity or Discharge Capacity ? 

Big Smile LOL Big Smile

LOL!