Storing solar light Ni-Cd for the winter

Black Rose

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Mar 8, 2008
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Ottawa, ON, Canada
I could've sworn I recently saw a post about storing Ni-Cd cells but now can't find it.

Anyway, this weekend I will be taking all the batteries out of my solar garden lights.

I am going to run conditioning cycles on them all since the amount of light they've been getting lately hasn't been that great and they're lucky if they last 2 hours now.

After I've conditioned them, how should I store them for the winter?
They will be stored indoors, but should they be fully or partially charged, or completely drained to store them?
 

Black Rose

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Mar 8, 2008
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Location
Ottawa, ON, Canada
I removed all of the AA and AAA NiCd cells from my solar lights.

The plan was to condition and discharge them before storage.

Yeah, well....

Of the 20 AA NiCds, 16 of them will not charge on my MH-C800S or MH-C9000. Some of them started to charge on the C800S and then stopped prematurely.

They are failing the impedence check on the C9000 (reporting HIGH). The C9000 manual basically says to discard them.

All of my other smart and dumb chargers (Rayovac PS13 and PS16, Sanyo NC-MDR02NU2) can only take Ni-Mh cells and I have no idea if my old Sanyo Cadnica charger from the late 80s even works anymore.

I may try the trick of putting a good cell into each slot of the C9000 so that it passes the impedence check and then swap in the NiCd to see if I can get them to charge.

Otherewise, it looks like I'll need to buy some AA NiCds for the spring:mecry:
 

Turak

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Jul 24, 2007
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Hi Black Rose,

I have a dozen of the solar lights in my yard. They are the Hampton Bay brand lights that come with the cheap 600mA or 800mA Wintonic NiCd's.

I leave the batteries in them year round...live in Michigan, so in the winter it definitely gets down to 0 and below sometimes. In the spring, I will typically bring them in and run them through typically 3 R/A cycles on the MH-C9000 or a Discharge Refresh cycle on the BC-900 to help revive them to full capacity.

So far out of the 24 batteries that power the lights, I have only had 3 fail in 3-5 years. Meaning that some of the batteries are 5 years old (when I bought the first set of lights) and some are about 3 1/2 years old (when I bought a 2nd set of lights). For replacement batteries, I went and bought some cheapie Harbor Freight NiCd's (on sale) to test and see how they perform over time, compared to the cheap Wintonics that came with the lights.

During the Winter months on a good day, they will put out about 2-4 hours of light, where in the summer, they will put out about 4-6 hours of useable light. It really has more to do with the amount of sunlight the little solar cells get for charging them than the capacity of the batteries.

I have found that the NiCd's (even the cheap ones) tolerate the cold MI winter temperatures just fine, although with half the amount of typical runtime as the summer time.

Heck there are times that the solar cells are buried under 2 feet of snow. I just scrape the snow and ice off the top of the solar cells so they get some light, kinda neat how it makes the snow glow when they come on at night, albeit only for a few hours.

Keep in mind.... One of the recommended places to store batteries is in a cold environment. It helps reduce the self discharge rate. I kind of look at it like, even though they are getting much less runtime, at least they are getting some exercise. So far I have had pretty good results it seems.

As for your batteries failing the impedence check on the MH-C9000....

Try running them through a discharge cycle set at 100mAh first. This will work, since there is no impedence test on a discharge cycle. This will lower the internal resistance as far as it can go. Then try running a B/I or a R/A cycle on them. If they still fail the impedence check, then you will need to either charge them on a different charger that is not so picky or pitch them and get some new NiCd's.

p.s. Stick with the low capacity (600-1000mA) NiCd's for the solar lights.....IMO
 
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Black Rose

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Location
Ottawa, ON, Canada
I'll try discharging them at 100 mA and see how that goes. Hopefully it will work, since all of these lights were new this year.

I tried 300 mA and they immediately shows DONE.

I'd like to leave them out for the winter as the glow in the snow is cool to see, but due to the angle of the sun now, only a few of the lights were getting any useful sunshine.
 
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