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Author Topic: Eneloops and charger  (Read 2352 times)

simonbratt99

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Eneloops and charger
« on: March 25, 2013, 11:24:21 AM »
Hi

Just got 10 eneloops (3rd gen, AA 1900mAh) with a BL700 charger, couple of questions.

1. Does it matter if i part charge them before turning off the charger, (ie travelling before fully charged)?
2. Should the batteries be removed from a flashgun if not being used for x amount of days or weeks?

Surprised my eneloops only had 20mAh in them from new.
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Eneloops and charger
« on: March 25, 2013, 11:24:21 AM »

simonbratt99

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Re: Eneloops and charger
« Reply #1 on: March 26, 2013, 09:50:41 AM »
Additionally.

Does anyone know how to tell how much charge is in a battery?
The new charger BL700 give me readings for each battery etc etc. but i cant see that a battery that says FULL is reading anywhere near 1900mAh
I would assume if i put back in some newly charged batteries, the mAh should read near its capacity, but they read more like around 700mAh
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Re: Eneloops and charger
« Reply #2 on: March 26, 2013, 10:56:26 AM »
I have a PowerEx MH-C9000, the best charger you can get, IMHO and it charges by default at 1000MaH which for Eneloops is .5C (half of the rated 2000/1900) rating. When I charge a set of batteries the charger reports how much energy it stuffed into the cell - it has no means to determine how much energy is stored in the cell without performing a Refresh/Analyze or Break-in.

The Breakin cycle charges at .1C for 16 hours, discharges and reports what was stored in the cell and then charges again for 16 hours at .1C. This is recommended once a year or so. I always do this to new cells and routinely get the rated capacity reported or greater.

Here is a useful thread on charge rates for batteries:
http://www.candlepowerforums.com/vb/showthread.php?149804-Eneloop-Self-Discharge-study&p=2293058&viewfull=1#post2293058

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Re: Eneloops and charger
« Reply #3 on: March 26, 2013, 11:31:51 AM »
I've got the La Crosse BC-700, which looks like it's the same one as yours. I believe that's just displaying the current charging rate, not the current capacity of the battery. I don't know that it ever displays the actual current capacity of the battery, although I might be wrong.

Didn't the charger come with a manual? You know, those few pages of paper that we all throw away immediately because we already know how to use all of our devices since we're all so smart?
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simonbratt99

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Re: Eneloops and charger
« Reply #4 on: March 26, 2013, 11:33:21 AM »
Thanks for the reply.
Ah ok so the mAh reported for the AA is the enery its stuffed into the cell while charging, not the actual power of the cell. That makes sence.
I will probably run this breakin cycle later.

So if the cell charging stopped at reported full at 700mAh for a 1900mAh cell, then the cell probably had 1900-700=1200mAh in it when it started charging? is that the right way to look at it?

Im surprised the chargers cant tell how much energy is stored in the cells, as i also have a £2 analogue battery tester that tells me how much power a battery has in it.

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simonbratt99

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Re: Eneloops and charger
« Reply #5 on: March 26, 2013, 11:36:40 AM »
I've got the La Crosse BC-700, which looks like it's the same one as yours. I believe that's just displaying the current charging rate, not the current capacity of the battery. I don't know that it ever displays the actual current capacity of the battery, although I might be wrong.

Didn't the charger come with a manual? You know, those few pages of paper that we all throw away immediately because we already know how to use all of our devices since we're all so smart?

It shows the charging current, sure, i leave it on the default of 200mA as i was told slow is better.
The capacity is shown in mAh BUT, i think im being told thats only the power its stuffed into the cell during this charge cycle.
Yes ive read the paper manual. Its actually a little book!! but it only states the mAh is the capacity. So crazily i assumed this ment the capacity of the cell.

Just checked the manual again. It stated Capacity display while charging (mAh) is Accumulated Capacity. Slightly ambigious
« Last Edit: March 26, 2013, 11:40:15 AM by simonbratt99 »
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Re: Eneloops and charger
« Reply #6 on: March 26, 2013, 11:55:58 AM »
Thanks for the reply.
Ah ok so the mAh reported for the AA is the enery its stuffed into the cell while charging, not the actual power of the cell. That makes sence.
I will probably run this breakin cycle later.

So if the cell charging stopped at reported full at 700mAh for a 1900mAh cell, then the cell probably had 1900-700=1200mAh in it when it started charging? is that the right way to look at it?

Im surprised the chargers cant tell how much energy is stored in the cells, as i also have a £2 analogue battery tester that tells me how much power a battery has in it.

You cannot tell how much energy is in a cell, just measure the voltage.
 
However, your BC-700 charger will measure the energy that was in a cell when you do a discharge cycle.  Discharging a cell and measuring how much energy it was able to deliver is the only way to get a precise value.
 
Lots of inventors have been looking for a accurate way to tell.
 
Canon cameras measure the voltage of the cell very accurately, and that gives a reasonable indication of the charge remaining, say 50%, but it does not know what 50% is in terms of actual charge.   I think that they are also smart enough to track each battery's performance, and the charger writes some performance information to the battery as well.  The result is a fairly accurate estimate of charge remaining, and the three green bars indicate how much charge the battery is capable of holding (3 bars- high capacity, 1 bar, battery has a low capacity).  That's why the number of bars drop as a battery gets older and loses capacity.
 
 

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Re: Eneloops and charger
« Reply #6 on: March 26, 2013, 11:55:58 AM »

simonbratt99

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Re: Eneloops and charger
« Reply #7 on: March 26, 2013, 12:10:03 PM »
Im surprised the chargers cant tell how much energy is stored in the cells, as i also have a £2 analogue battery tester that tells me how much power a battery has in it.

no it does not. :)

Ok er, its telling me the voltage in the battery? which in turn is (on the same scale) telling me if the battery is good or needs replacing. For £2 this better be highly accurate!
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Re: Eneloops and charger
« Reply #8 on: March 26, 2013, 12:20:47 PM »
Alkaline's typically have 1.5v of voltage and rechargeable's have 1.2v. Voltage on its own does not tell you how much charge (Juice or mAh) remain in a cell - the only way to accurately determine this today is to discharge the cell, like the MAHA C-9000 does in the Refresh/Analyze or Breakin cycles.

Alkalines tend to hold voltage near 1.5v and then suddenly drop off whereas rechargeables will drop-off gradually.

BTW, you should always keep your cells together in sets of two or four, depending on your use and make sure whatever charger you use, it is capable of doing single cell charges.



simonbratt99

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Re: Eneloops and charger
« Reply #9 on: March 26, 2013, 12:36:27 PM »
Alkaline's typically have 1.5v of voltage and rechargeable's have 1.2v. Voltage on its own does not tell you how much charge (Juice or mAh) remain in a cell - the only way to accurately determine this today is to discharge the cell, like the MAHA C-9000 does in the Refresh/Analyze or Breakin cycles.

Alkalines tend to hold voltage near 1.5v and then suddenly drop off whereas rechargeables will drop-off gradually.


BTW, you should always keep your cells together in sets of two or four, depending on your use and make sure whatever charger you use, it is capable of doing single cell charges.

hmm i could have sworn it was the otherway round, rechargeables keep the power then suddenly drop and alkies start dropping power as they are used, straight away.

Also my eneloops are showing 1.4v and 1.47v instantaneous battery voltage

I would keep cells together, but i have devices that need 1, 2, 3 and 4 batteries.
« Last Edit: March 26, 2013, 12:43:07 PM by simonbratt99 »
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Re: Eneloops and charger
« Reply #10 on: March 26, 2013, 12:51:52 PM »
Alkaline's typically have 1.5v of voltage and rechargeable's have 1.2v. Voltage on its own does not tell you how much charge (Juice or mAh) remain in a cell - the only way to accurately determine this today is to discharge the cell, like the MAHA C-9000 does in the Refresh/Analyze or Breakin cycles.

Alkalines tend to hold voltage near 1.5v and then suddenly drop off whereas rechargeables will drop-off gradually.


BTW, you should always keep your cells together in sets of two or four, depending on your use and make sure whatever charger you use, it is capable of doing single cell charges.

hmm i could have sworn it was the otherway round, rechargeables keep the power then suddenly drop and alkies start dropping power as they are used, straight away.

Also my eneloops are showing 1.4v and 1.47v instantaneous battery voltage

I would keep cells together, but i have devices that need 1, 2, 3 and 4 batteries.

I was basing my thoughts on this post by Flash Havoc on the YN-622-c's which I mis-interupted voltage drop for starting voltage levels:
http://flashhavoc.com/yn622c_review/ (near the end):
"...like many TTL triggers the YN-622C are sensitive to battery voltage, that is why we use good alkaline when possible (Energizer/Duracell) and not rechargeable. That is because alkaline have a considerably higher voltage to start with, the rechargeable NiMH are already close to the YN-622 cut off voltage when fully charged."

All my Eneloops are routinely in the 1.4 to 1.147 range - this is normal.

Most of my sets runs flashes or triggers is sets of two or four. For single cell use like mice and remotes I tend to use different sets of Eneloops or Duraloops and this is where a charger such as the MAHA C-9000 charges single cells. Cheaper chargers will charge in pairs or worst four cells at the same time - all the cells will get the same amount of charge whether they are full or not.

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Re: Eneloops and charger
« Reply #11 on: March 26, 2013, 01:10:49 PM »

Ok er, its telling me the voltage in the battery? which in turn is (on the same scale) telling me if the battery is good or needs replacing. For £2 this better be highly accurate!

Most of the traditional battery testers drain current from a battery and measure the voltage under load.  For Alkaline batteries, this is a indication of remaining battery life.  However, its going to be different for ni-cad, and nimh batteries, so unless the battery tester has a battery type selector switch, or specifically tests a particularly type of battery, then assume its only accurate for alkaline or conventional batteries, and then, only for a particular cell type.
I have one that provides 4 different loads so I can use high loads for "D" cells and light loads for AAA cells.  The green, yellow, and red bars are only accurate for conventional batteries, but it will read volts as well.
Its only useful to tell battery condition in very broad terms, and I'd never use it on a rechargeable battery.

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Re: Eneloops and charger
« Reply #11 on: March 26, 2013, 01:10:49 PM »