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Evaluating my Used Eneloops
Old 02-11-2015, 07:25 PM   #1
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Evaluating my Used Eneloops

I have a bunch of Eneloop batteries that I've bought over the years. It's impossible to rotate them effectively, so some don't work as well as others. I want to discard and replace the bad ones.

To solve this, I bought this charger/tester. I expected wide variation in the remaining capacity of the batteries, but so far all fall between 2,000 mAh and 2,200 mAh.

Do you think that discarding all those with a capacity under 2,100 mAh is a good strategy?
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Old 02-11-2015, 09:25 PM   #2
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Is there a refresh option on that charger/tester?

I got an older model BC-900 which does have a refresh function which over several discharge/recharge cycles can refresh a bad battery. The refresh process runs automated discharge/recharge cycles and can take up to a week but fixes bad batteries to their original capacities.

I believe the BC-900 has since been replaced by a model 1000.

http://www.amazon.com/Crosse-Technol...acrosse+bc1000
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Old 02-11-2015, 09:58 PM   #3
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I use the more traditional nimh and the way I cull is to charge a group (important to have a large charger where each battery is independent (not in series with its neighbor), then put the group into a device. When the device shows signs of low power, test each battery. If there's one that tests out lower than the rest, that one gets tossed.

I know your question had more to do with the supposed greener aspect of the eneloops, but I thought a similar strategy might work anyway.
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Old 02-12-2015, 01:56 AM   #4
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Quote:
Originally Posted by TromboneAl View Post
... so far all fall between 2,000 mAh and 2,200 mAh.

Do you think that discarding all those with a capacity under 2,100 mAh is a good strategy?
Do you throw away a car that drops its gas mileage to 20mpg from 22mpg when new? In normal use, I think one barely notices if a device's operating time is 10% shorter due to a weaker battery.

What may be more important is that the batteries are matched in an appliance, because it's the weakest battery that determines the running time of the entire group. RC enthusiasts routinely measure and match the cells of their battery packs for optimal performance.
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Old 02-12-2015, 02:56 AM   #5
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If you decide to get rid of them. I will pay for you to ship them to me.

Should have spent the $10 extra and got a charger with a refresh option.
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Old 02-12-2015, 08:34 AM   #6
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Do you throw away a car that drops its gas mileage to 20mpg from 22mpg when new? In normal use, I think one barely notices if a device's operating time is 10% shorter due to a weaker battery.

What may be more important is that the batteries are matched in an appliance, because it's the weakest battery that determines the running time of the entire group. RC enthusiasts routinely measure and match the cells of their battery packs for optimal performance.
+1 I don't understand why a 10% delta would be a reason to throw them out. I might expect near that much variation from new ones.

What was the original mA rating of these?

-ERD50
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Old 02-13-2015, 03:01 PM   #7
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Do you throw away a car that drops its gas mileage to 20mpg from 22mpg when new? In normal use, I think one barely notices if a device's operating time is 10% shorter due to a weaker battery.
I agree with your logic 100%, but here's my thinking.

Some of these batteries are lousy. When I put them in the camera I take a few shots and the camera wants new batteries. Others are okay.

I hoped that I'd get this charger/tester, and some batteries would test much worse than others. That wasn't the case. All are within 10%.

So, at that point my thinking is that I can use this 10% difference as an indicator as to which batteries, in real world situations, are worse.

IOW, 10% worse in the test might indicate 50% worse IRL.

Reasonable?

I know, I know. What I need to is to find a pair batteries that are definitely lousy IRL, and a pair that are definitely good, then compare the test results. Doing that would be easier if cameras used only one battery.
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Old 02-13-2015, 03:03 PM   #8
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I use the refresh cycle of the BC-900. I dump the ones with capacity 400 mAh or less. 2000 mAh are still very good.
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Old 02-13-2015, 03:18 PM   #9
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BTW, this:

http://www.amazon.com/Panasonic-Enel..._cd_ql_qh_dp_t

is only $23.99 at Costco. That's much cheaper than any on Amazon, even if you throw away the charger.
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Old 02-13-2015, 03:26 PM   #10
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I ...
IOW, 10% worse in the test might indicate 50% worse IRL.

Reasonable?
Doubtful. If they are showing LOW in the camera after a few shots, there is likely a parameter that is different between the good/bad that may not be very well correlated to this little 10% difference.

It sounds like that maH spec is a measure of current and time it took to charge the battery - that may or may not be a good measure of other things (and I suspect that it is not a good measure).

I assume the camera draws a fairly hefty current form the batteries (re-charging the flash will use a lot more - and it might re-charge to have it ready, whether you use it or not).

If I really wanted to sort good/bad, I'd fully charge them all, then do a load test. You'll have to determine the proper load, but some back of the Eneloop calculations (back of the 'Eneloop' - get it? ) say you want to draw something a bit more than the ~ 2000mA. Check the specs to see if they give a max "C" figure. That is a multiple of the nominal mAh rating, so a C of 3 means you can draw 2000 mA * 3 for a shorter time. That would be 6 Amps. But start with 2 Amps if you can't get the pspec. Load it and compare the battery voltages under load.

1.5V at 2A means a 0.75 ohm Resistor, 3 watts total (cheap at a place like Digi-Key). I'd probably just buy 10 7.5 ohm 1/2 W resistors and connect in parallel (5 watts, so you have some leeway). Compare voltage drops with the load - I bet that shows up good/bad. You might find a suitable flash light bulb that would load it down.

-ERD50
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Old 02-13-2015, 03:41 PM   #11
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I use the refresh cycle of the BC-900. I dump the ones with capacity 400 mAh or less. 2000 mAh are still very good.
That is what I'd do also. When encountering a possible bad battery, just let the BC-900 work on refreshing that, even if it takes several days.
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Old 02-13-2015, 04:29 PM   #12
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I look at the specs of T'Al's charger, the BC500, and see that it can test the capacity of a battery by discharging it and counting the coulomb. Assuming that's how T'Al got the 10% difference between the "good" and "bad" batteries, then how could the batteries' performance differ so much when used in a digital camera?

The only thing that comes to my mind is that a weak battery may have a higher internal resistance, causing its voltage to sag more when under a heavy load and the camera to trigger the low-battery indication. However, I have not seen a weak battery that does not have a reduced capacity along with a higher internal resistance. This is a conundrum.

I believe that the BC500 uses a discharge current of 200mA as default. I do not know if this current can be programmed to a higher value to test for voltage drop, in order to do the same load test as ERD50 suggested.

I have a hobbyist charger that has fully programmable charging/discharging current. It can charge single cells as well as multiple cells up to 10 in series. You will need a DC power supply to power it. It has programmable criteria to properly terminate the charging of NiCad, NiMH, LiIon, and lead acid batteries.

I bought it many years ago, and paid $120 for it. Just now, I look on eBay and see a few equivalent chargers offered at $50. These are meant for RC hobbyists who build their own battery packs, hence come with alligator clips. You will need to buy your own battery holders to use it with consumer AA or AAA batteries.
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Old 02-13-2015, 05:24 PM   #13
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The 'low battery' warning in many devices that use standard cells is triggered by low voltage from the battery, rather than total power consumed. (There's too much variability between batteries to use total power, as well as problems with used batteries being removed and re-installed over storage intervals.)

Conventional alkaline cells develop about 1.5 volts when fresh (unloaded, may be 1.5-1.65V). They'll develop about 1.3 volts under moderate load of 0.5 amps. They're considered fully discharged at about 1 volt.

Eneloop and other NiMH batteries develop about 1.2 volts under moderate load of 0.5 amps, and about 1.4 volts immediately after charging. They're considered discharged at 1.0-1.1 volts.

The Eneloop battery might be drooping below the camera's 'low battery' threshold before it is anywhere near fully discharged.
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Old 02-13-2015, 05:54 PM   #14
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Late to this thread, but dang, Al, 'recharging' used envelopes? I knew you were cheap frugal, but come on man, live a little!
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Old 02-13-2015, 08:50 PM   #15
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The 'low battery' warning in many devices that use standard cells is triggered by low voltage from the battery, rather than total power consumed. (There's too much variability between batteries to use total power, as well as problems with used batteries being removed and re-installed over storage intervals.)

Conventional alkaline cells develop about 1.5 volts when fresh (unloaded, may be 1.5-1.65V). They'll develop about 1.3 volts under moderate load of 0.5 amps. They're considered fully discharged at about 1 volt.

Eneloop and other NiMH batteries develop about 1.2 volts under moderate load of 0.5 amps, and about 1.4 volts immediately after charging. They're considered discharged at 1.0-1.1 volts.

The Eneloop battery might be drooping below the camera's 'low battery' threshold before it is anywhere near fully discharged.
+1
The camera is fibbing, the cells are most likely fine, but the camera is programmed for alkaline cell parameters. Some cameras have a setting in the menu to select either alkaline or rechargeable cells. AA Lithium cells are a decent choice for cameras.
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Old 02-15-2015, 05:07 PM   #16
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Is there a refresh option on that charger/tester?
Yes, and I'm testing now to see if I can bring the 2,000 mAh batteries back to 2,200 (the rated capacity).
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Old 02-19-2015, 08:06 PM   #17
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Yes, and I'm testing now to see if I can bring the 2,000 mAh batteries back to 2,200 (the rated capacity).
Al,

Any luck with bringing the batteries back to 2,200? Or is the refresh still in progress?
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Old 02-20-2015, 07:31 PM   #18
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Al,

Any luck with bringing the batteries back to 2,200? Or is the refresh still in progress?
No. Four cycles and no change.

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Old 02-20-2015, 07:49 PM   #19
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Anyway to have the camera tested for excess current draw ? Back when I was working , we last had canon cameras for work use. Some became battery eaters for no apparent reason.
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Old 02-20-2015, 07:52 PM   #20
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Anyway to have the camera tested for excess current draw ? Back when I was working , we last had canon cameras for work use. Some became battery eaters for no apparent reason.
And is this one of the cameras found by the side of the road?

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