Enloop vs NIMH initial discharge & use on Wii

[Phlack]

Hello.

I'm curious about the initial discharge of the normal NIMHs works, and what would be better in my situation.

I use mostly Energizer 2500mah NIMHs. I charge the with the Maha MH-C808M charger.

From what I understand, the NIMHs will self-discharge ~20% or so in the first 24hrs. That puts those batteries at around 2000mah. Which is the same as the Enloops start out at, with very little discharge on their end.

Questions:
1) If the NIMH batteries are used immediately (in my case, usually in Nintendo Wii Remotes) will it essentially discharge to 80% of the 2500 (considering it will be used for a while)?
2) Am I better off using enloop (or other hybrid batteries) instead, in the Wii remote?

These Wii remotes drain batteries like crazy!

Thanks
-Mike

 

[mdocod]

The Wii remote probably doesn't drain batteries like "crazy," more than likely you are experiencing the massive self-discharge problems common to the 2500mAH Energizer cells. My Energizer 2500s got to the point that they would discharge from fresh off the charger to completely dead in 3 days give or take. My gut tells me that your cells are suffering a similar problem. I think a set of eneloops would be well worth a try.

 

[Marduke]

I use Duracell 2650's in the Wii remote I personally use quite a bit (charge cycle every 2-3 weeks), and Rayovac Hybrids in my two other Wii remotes, which are used much less, and usually by guests.

 

[Phlack]

The Wii remote probably doesn't drain batteries like "crazy," more than likely you are experiencing the massive self-discharge problems common to the 2500mAH Energizer cells. My Energizer 2500s got to the point that they would discharge from fresh off the charger to completely dead in 3 days give or take. My gut tells me that your cells are suffering a similar problem. I think a set of eneloops would be well worth a try.

Well, the batteries seem to work well in other situations fine. I say that about the Wii remote only because it handles not only signals, but powers a speaker, and has some force-feedback...all from two AA batteries. That's a lot of drain.

I doubt my kids would use it more than the 20% initial drain in one day (thus my question about the initial 20% drain and how it occurs). I think I'll pick up a pack of enloops next time I'm in Target (my walmart doesn't have them for some reason)

-Mike

 

[SilverFox]

Hello Mike,

A point of clarification...

20% is a high figure. Usually it is closer to around 10%, with most of the loss occuring during the first 30 minutes while the cell cools down.

With that in mind, you need to understand that this loss applies to all NiMh cells, even the Eneloop cells.

Tom

 

[FlaGator]

.........I think I'll pick up a pack of enloops next time I'm in Target (my walmart doesn't have them for some reason)

-Mike

At Target, I have found Duracell "Precharged" for about $12.50 for a 4-pack, either AA or AAA. I have seen two different versions of the Duracells - one has construction that appears identical to the Eneloops (a white band around the "+" terminal) and one that looks like a Rayovac Hybrid (black band). They also have the Hybrids at about $10/4. I've yet to see Eneloops at Target stores in my area, though Costco is carrying them.

The Walmarts in my area are carrying ROV Hybrids for about $10 for a 4-pack of AA. Similar technology to the Eneloops, but they are slightly larger diameter. They are also stocking the white-banded Duracell Precharged at prices similar to Target.

There was a recent thread comparing Eneloops and Hybrids, and IIRC, performance of the two was very similar. I'm using all three of these brands at present and haven't noticed any practical difference.

 

[Phlack]

With that in mind, you need to understand that this loss applies to all NiMh cells, even the Eneloop cells.Tom

Wow. I must have read all the threads wrong, then. I thought the enloops (or other hybrid-types) didn't have the initial large self-discharge...or if it did, it wasn't as significant as a normal NiMh. At least the ads show 90% capacity after 6 months. Yeah, those are ads, I agree, but still seems like a lot.

Though I trust your testing vs any advertisement! Is it really that much?

-Mike

 

[SilverFox]

Hello Mike,

You are confusing long term self discharge with short term self discharge.

The Eneloop cells, as they cool down from charging, seem to develop a pacification layer that greatly limits the self discharge rate. The 90% figure is actually pretty close, but it is based on standard charging and standard discharging. The cell is rested, after charging, for 1 - 4 hours prior to discharging in the standard discharging protocol.

"Hot off the charger," you may see capacies of 2000 mAh, or a little higher, with the Eneloop cells, but if you let them rest, the capacity drops down to a little over 1900 mAh. So, starting with 1900 mAh, in six months of room temperature storage we expect to see a minimum of 1710 mAh if we are talking about 90% charge retention over that time.

There is a thread where I showed the test results of Eneloop and Hybrid cells over long term storage. You should search for it and check it out.

Notice that the self discharge rate changes over time. It starts out steeper then finally levels out.

The RC people have demonstrated that a NiMh or NiCd battery pack performs best when it is used "hot off the charger." If you let it cool down and sit for awhile, it seems to loose its "punch." This is about the best example of the initial self discharge that I can think of. The loss of "punch" is caused by a loss in capacity, a loss in voltage, and a loss in the temperature of the chemistry.

On a side note, all batteries will exhibit higher rates of self discharge under higher temperatures. This includes the low self discharge rate batteries as well. At somewhere around 100 F, Eneloop and normal NiMh cells will self discahrge at about the same rate.

Tom

 

[Phlack]

Tom,
Thanks for the reply. I'll check out the thread (couldn't find it initially, but I'll keep looking). Didn't know about the temperature affecting the enloops that drastically, but then again, I don't intend to be in 100 F .

-Mike

 

[SilverFox]

Hello Mike,

Here you go.

Tom

 

[roymail]

SilverFox, so cutting through the tech stuff for us "challenged" folks, which would be the best to use in a 1 or 2 AA light that is used some, but not a lot, each day? I've got several 2AA and will soon purchase a 1A light. I've been using standard alkaline batteries and they work OK for what they are. Thanks.

 

[SilverFox]

Hello Roymail,

If you go through a set of batteries every week or two, rechargeable cells make a lot of sense. If it takes you several months to go through a set of batteries, the advantage of rechargeable cells is minimal.

Now, if you get some rechargeable cells and plan on letting them just sit around hoping some day to use them, go for the low self discharge cells. However, if you find yourself "playing" in the dark more, you may end up going through a set of cells more quickly. Now you are in an area where you may be able to take advantage of a higher capacity cell.

It all comes down to how you use them...

Tom

 

[brightnorm]

... At somewhere around 100 F, Eneloop and normal NiMh cells will self discahrge at about the same rate.

I didn't realize that. Makes me wonder whether higher capacity regular NiMH's are better for Summer use, especially if the self-discharge rates start equalizing at lower temps.

Brightnorm

 

[cannesahs]

If you go through a set of batteries every week or two, rechargeable cells make a lot of sense. If it takes you several months to go through a set of batteries, the advantage of rechargeable cells is minimal.

Most of time I fall to that category, where batteries sitt month(s) in light. For me the biggest advantage of rechargeables comes from that I can keep them always atleast half-full.

So no need to worry about runtime or backupbatteries in normal use. I just have to recharge them after heavy use or once in the while.