How to preserve rechargeable batteries?

[Scott R]

I have a touchpanel system in my house, it controls most everything in the house. The problem I have is the batteries for the panels are now discontinued by Crestron. The solution from Crestron is to upgrade to a new panel, this however takes a huge effort to get a programmer out and change equipment and software.

What I did was buy up a few of these custom battery packs and I want to store them. They last about a year if you maintenance them correctly, so I purchased three more and I want to store them to be used in the next few years. Here are the specs:

Type
Removable, rechargeable NiCad
Dimensions
1.16" / 2.94cm (H) x
4.25" / 10.78cm (W) x
2.28" / 5.79cm (D)
Weight
0.79lbs / 0.36kg

Do I freeze them? Keep them in a drawer? Refrigerate them? Put them in sealed containers? How can I keep these for future use?

[red-beard]

NiCd Battery Care and Storage

The Care and Feeding of NiCd Batteries
I have in front of me a NASA publication on the care and feeding of NiCd batteries, as learned from 30 years in space satellite operations. What follows here are some excerpts from this text organized in some potentially useful manner.

This is not an exhaustive dissertation and comes entirely from the experiences of NASA scientists and engineers and what they have decided are the important points to discuss in their publication. This doesn't even touch on all of what they did, its only the parts that I thought would be interesting to those of us in the RC hobbies. For more information see my reference to the publication at the end of this page.

I am not an expert in NiCd batteries and I am stating right now that I am not even trying to pretend that I am one. I am just regurgitating information that I have found in a NASA publication on the care and storage of NiCd batteries.

A common term you will see in this C something. Just substitute your packs' rating for the C, for instance: C/100 for a 1700 pack would be 1.7ma or C2 would be 3.4Amps (3400ma).

Storage of NiCd Batteries
Guideline No. 2 Flight batteries should be maintained in a discharged and shorted condition and stored at cold temperatures when not required for "critical" spacecraft testing. Optimal temperature is around 0 degrees C. NASA does it this way:

Discharge at C/2 constant current rate to first cell at 1.0 Volts
Drain each cell with a 1 ohm resistor to less than 0.03V
Short each cell with a bar
Place batteries in a sealed bag with dessicant (stops condensation)
Store in cold temperature (about 0 deg C)
To re-charge such a stored battery Guideline No. 7 A battery stored discharged and shorted for a period greater than 14 days should be activated with a "conditioning cycle" prior to placing it in use. The conditioning cycle (20 deg C) is defined as follows:

Remove from cold and allow to come to room temperature
Charge at C/20 for 40 hours +/- 4 hours (Deliberate over-charge)
C/2 discharge until first cell reaches 1.0V
Drain each cell with a 1 ohm resistor to less than 0.03V
Short each cell with a bar for 4 hours
C/10 charge for 16 hours +/- 1 hour
Do steps 3 and 4 again
C/10 charge for 16 hours again ***
*** Steps 4,5,7 and 8 are not needed if the batteries haven't been stored for an extended period of time. See note in Guideline 9 below.

[red-beard]

BTW, there are a lot of places which rebuild old battery packs with new Ni-Cad cells, just for your sort of problem.

[GH85Carrera]

If you still have one of the old packs try to take it apart. Most likely it is full of standard size ni-cad cells. Local battery stores usually have a guy to replace those cells. There is a local Interstate battery store that has rebuilt several of my cordless drill battery packs.

It is worth a try.

[Scott R]

Originally Posted by red-beard

BTW, there are a lot of places which rebuild old battery packs with new Ni-Cad cells, just for your sort of problem.

Jim, that's exactly what I'm looking for, thank you! Also I will start looking for a re builder, I had no idea these things could be opened up, they look like a solid sealed brick.

[Joeaksa]

Have you tried at batteries plus to get them remade? They can usually put new cells in most battery packs.

[Scott R]

Originally Posted by Joeaksa

Have you tried at batteries plus to get them remade? They can usually put new cells in most battery packs.

No, I never even considered it. I'm going to now. I've been shelling out a good amount of money for these things each year. I need two per year, and I do everything they say to do right down to the discharge process.

[dad911]

Di-sect one of the old ones, let's see what's inside.

I'd bet on standard size cells.

[Eric Coffey]

Yeah, what James/Joe said. Check out a "Batteries Plus" type place, and see if they can make one up. Ni-Cds are pretty old tech these days as well, so you might see if they could retro a Li-Ion (or similar) pack. At the very least I'd upgrade to better/higher capacity Ni-Cds. If you are handy with a multi-meter, soldering iron, and shrink tubing, it shouldn't be that hard to DIY it either.

[Scott R]

OK, I got home tonight and decided to get crazy with this. I used a knife to open the case, it took about 30 mins of careful cutting. Below is what was inside:





So from the sticker on the side of the battery they are "Metal hydride Rechargeable." And I think I get the batteries I need from the store and build a new pack. However... what is the raised diode looking item?

I'm asking because when these fail, they die quick. So I'm wondering if this has something to do with it.

[Scott R]

And I found the batteries:


http://www.batteryspace.com/nimhrechargeablecellcsize12v5000mahflattop15arate1 pc.aspx

$5

I want to kick myself.

[Eric Coffey]

Originally Posted by Scott R

So from the sticker on the side of the battery they are "Metal hydride Rechargeable." And I think I get the batteries I need from the store and build a new pack. However... what is the raised diode looking item?

I'm asking because when these fail, they die quick. So I'm wondering if this has something to do with it.

Nice!

Not 100% sure, but I am guessing the "raised diode looking item" is a thermistor to control the temp while charging, hence the 3rd (white) wire. If not, it may be a diode to regulate voltage going to the device/panel.

[krystar]

NiMH are similiar to NiCad's. chemical difference. and voltage dropoff difference, but effectively same rechargeable 1.2V cell.

can't really tell from the picture w/o reference, but looks like a subC cell. there's some print on the middle of the cell. that'll prob show the size.

BATTERIES AMERICA