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-   -   New NiMH Battery Storage/Initial charge/discharge methods? (https://forums.steves-digicams.com/batteries-power-packs/75205-new-nimh-battery-storage-initial-charge-discharge-methods.html)

coppertrail Dec 18, 2005 11:09 AM

Hello All -

I recently bought (8 )Powerex and ( 8 )Energizer 2500 mAh NiMH batteries. I'm using (4) of the Powerex batteries in my new Canon A620, and (4) of the energizers in my old sony and Kodak cameras. This leaves me with (4) powerex and (4) energizers that have never been charged.

Question 1: Can I storethe ones that haven't been charged without having to do a discharge/charge every month? I thought I read that there is a chemical reaction that takes place during the initial charge, so I'm hoping I can leave them be until I have a need for them.

Question 2: I've read that you should do 3-5 cycle charge/discharge with new NiMH batteries before they reach their full charging potential. I have the MH-C2-4W charger that has a conditioning feature. So, what would be best:

a. Charge them up, then drain them in a flashlight, and repeat 2x.

b. Use the conditioning feature in the charge to charge/discharge 3 times before initial use.

c. Charge them fully, then use them normally in the camera, and recharge them when the camera cuts out, and repeat 2x.

d. Any other methods not listed above . . .

Thanks in advance . . .

CT



blr Dec 19, 2005 5:43 AM

You can use your conditioning feture to cycle the cells 3-4 times before putting them to service. I wouldn't use a flashlight to discharge two or more cells fully since the light doesn't cut off when certain voltage has been reached. Insted it continues to drain, which may lead to cell reversal and damage.

Peva Dec 19, 2005 8:46 AM

I agree with blr's answer. I recently had a new cell in a set that I couldn't discharge using the camera because it was so weak even after being "charged" that the camera couldn't even turn on. The 204's discharge feature fixed it right up.

SilverFoxCPF Dec 19, 2005 3:55 PM

Hello CT,

Let me add...

Q1 - you can store new cells for about a year. It would be better if you did the discharge/charge cycle every month, but you can get by just fine without it.

Q2 - I start off new cells with a discharge, then I do a slow (low current) charge for a time limit. At the end of the time limit, I remove the cells from the charger. Sometimes new cells will fool the charger and it does not detect the end of charge signal. The cells get hot and that is not good for the cells. If you shut the charger off at the end of the time limit, you avoid this problem.

After you have your cells charged up, you can do some conditioning on the charger, or in your camera. As others have pointed out, don't expect peak performance if you condition your cells in your camera, but you should get decent use from them. I tend to condition in the charger. That way I know that I have peak performance when I go to use them.

Keep in mind that if your charger has a conditioning cycle, it is good to use that after 10-20 normal charge cycles. This will keep your cells at their peak capacity.

Tom

E.T Dec 20, 2005 5:10 AM

SilverFoxCPF wrote:
Quote:

Q1 - you can store new cells for about a year.* It would be better if you did the discharge/charge cycle every month, but you can get by just fine without it.
Actually NiMHs seems to require couple cycles to "wake up" fully after long storing.

SilverFoxCPF Dec 20, 2005 12:33 PM

Hello E.T,

That is correct, however I don't consider a year long term. It is always better to use fresh cells, but I have found that the cells remain pretty fresh for the first year. When you get much beyond that, you end up needing several refresh cycles to get the cells working to capacity.

Another thing to consider is the storage conditions. Cells that are displayed in the direct sun may be exposed to temperature extremes that can effect their performance.

Tom

coppertrail Dec 20, 2005 8:39 PM

Thanks all for your responses thus far, they've been very helpful.

A couple more questions to throw out there:

So, if I don't use the batteries for a month, should I simply charge them, then use the charger to discharge/charge, then store again? If so, great, that's simple enough.

Some FAQ's I've read suggest that you not use the charger's conditioning feature until after 10 charges, and to use them normally in your device. One mentioned that using it initially to condition batteries can put excessive strain on them and decrease life.

It's just that it's hard when you don't use your camera to take 100 pics a day, but the high powered disposable cells are just too expensive.

Finally, my BC-900 should be here tomorrow. I also have a MH-C204W. Would one be better than the other for cell conditioning (new cells or used?)

Again, thanks for your responses . . .

Peva Dec 21, 2005 9:02 AM

coppertrail wrote:
Quote:

...charger's conditioning feature...One [FAQ] mentioned that using it initially to condition batteries can put excessive strain on them and decrease life...
I guess I don't know where they're coming from with that statement. The discharge mode pulls less current than most of our cameras, and is precisely what is needed to get a new NiMH running properly. Without knowing where they're coming from with that, I'd have to say they are FOS on that point.

SilverFoxCPF Dec 21, 2005 3:11 PM

Hello Coppertrail,

First let's take a look at the types of users there are.

Some are critical users. Law enforcement, emergency services, and search and rescue workers all fall into this category. If their battery operated equipment does not work, peoples lives can be effected. I would also group the RC people in this category. A fraction of a second is all that separates winning from second place.

The rest of us are casual users.

To get the best performance from your batteries, you need to form them, break them in by cycling them a few times, top them up frequently, test their performance in actual use, and do a monthly discharge/charge cycle to keep them in peak performance. In RC use, you want to top them off just before you use them and run them hot.

Casual use is not as critical. There is some self discharge associated with NiMh cells, but with the newer cells, it has been greatly reduced. If you charge your cells up and let them sit for 30 days, they will still have about 80% of their initial capacity left. If you let them sit for 90 days, you end up with about 50%. A lot of the time, 50% may be OK for what we are trying to do. If this is so, you need to cycle your cells every 90 days.

If your camera takes 150 pictures on a full battery, is it acceptable (to you) that after having the camera sit around for 3 months, you will only get around 75 pictures?

The BC-900 is a great charger. There are a few quirks that have been reported with it, but I still think it is worthy of a recommendation.

Let's take a look at how to treat brand new batteries. I think the first thing you should do is discharge them down to 1.0 volt per cell. Then they should be charged at a 0.1C rate for 16 hours. At the end of the 16 hours, the cells should be removed from the charger. It doesn't matter if the charger thinks they are done, just take them off. Now you have a set of fully charge batteries that have been formed. By the way, C refers to the capacity of the battery. A 2500 mAh cell has a C charging rate of 2500 mA. A 0.1C charging rate for the same cell would be 250 mA.

The BC-900 has a discharge function that does this for you. If you select the combination that gives you a 200 mA charge rate, you simply come back in 16 hours and shut the charger off. Your cells may not be "fully" charged, but will be close enough for the first charge. New cells often do not indicate the end of charge signal very well, and if you leave them on the charger until the charger thinks they are done, you may heat the cells up and could possibly do some damage to them. This is why I suggest setting a timer and pulling the cells at the end of the time.

The next step depends on whether we are using the batteries for critical use, or casual use. For casual use, we can install the batteries and go out and use them. Critical use requires discharge/charge cycling several times to get to the peak performance of the batteries. Keep in mind that batteries have limited life. You can spend cycles in the charger bringing them up the last 5-8% of capacity, or you can spend cycles taking pictures. The choice is yours.

The one thing you want to avoid is leaving the batteries on the charger all the time. With most chargers, this tends to cook them. The only charger I am aware of that you could possibly do this with is the new Maha 808M charger. It pulse trickle charges at 7 mA after it is done charging. That is probably low enough to just keep your cells topped off. There are other chargers that will only trickle charge for a certain time, then completely shut down. In spite of these advancements in chargers, I still do not recommend leaving the cells on the charger for extended periods of time. If you want to keep your cells topped off, put your charger on a timer and have it charge for a small amount of time every day.

The quality batteries that are currently available, seem to provide excellent use in spite of our best efforts to destroy them. If we take care of them, we end up with even better service from them. The other side of the coin is that the prices have come down. If we happen to ruin a set of batteries, it is not a major investment to replace them.

Tom

coppertrail Dec 21, 2005 9:42 PM

Again, thanks for your responses, very helpful.

BTW, does anyone have any US release date info on the new Sanyo Eneloop batteries?


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