Rechargeable Battery Questions

[Capt Caveman]

Need to replace about 24 AA 600mah NiCd rechargeable batteries that my solar patio lights use.

Can I use NiMh or Lithium batteries instead? Costco has 12 Energizer Lithium rechargeable batteries for $20 which appears to be a good deal.

The only place I've been able to find cheap NiCd AAs is here - Battery Junction

If not, any other good places to buy inexpensive NiCd AAs?

 

[Suspicious-Teach8788]

lithium AAs can't be recharged? Li-Ion can be, but those are not AAs. That's why the Lithium ones are so cheap. NiMh ones cost more.. but eneloops are always great

 

[Capt Caveman]

lithium AAs can't be recharged? Li-Ion can be, but those are not AAs. That's why the Lithium ones are so cheap. NiMh ones cost more.. but eneloops are always great

I'm an idiot. I guess the question is now - can I use NiMhs in place of NiCds?

 

[Aluvus]

Some NiCd chargers are fine for NiMH, others are not. Some look for a sharp spike in cell voltage as the cell reaches capacity, which is characteristic of NiCd but doesn't happen at all in NiMH (so they will happily keep trying to charge a NiMH cell until Bad Things happen). I don't know of an easy way to tell which type of charger you have.

 

[Eli]

Yes, you can replace them with NiMH batteries.

Some NiCd chargers are fine for NiMH, others are not. Some look for a sharp spike in cell voltage as the cell reaches capacity, which is characteristic of NiCd but doesn't happen at all in NiMH (so they will happily keep trying to charge a NiMH cell until Bad Things happen). I don't know of an easy way to tell which type of charger you have.

These are solar lights. They most likely do not have a charge controller. In most solar lights that I've played with, the solar cell itself is the limiting factor. It's just not possible to charge the batteries over ~1.4V.

 

[PottedMeat]

which kind tolerates the largest temperature swings and has the longest life?

 

[0roo0roo]

heat and weathering...so i dunno if nicd has advantage over nimh in that area, it might..who knows.

 

[mmntech]

NiCd are more tolerant to trickle charging, which is what these solar lights do. NiMH like to be fast charged, usually at 1C.

 

[Eli]

I use these guys for all my battery needs.

http://www.batteryspace.com/aasizeseriesnicdbatteriesandpacks.aspx

 

[Jeff7]

I would bet that they used Nicad because 1) You only really have to hold enough charge to light the light for one or two nights, and 2) Nicads are cheap.

Lithium batteries - no. Li-ion is the rechargeable variety, and they need a special charger to ensure that overcharging does not occur.

If you want to do a super-cheap replacement, there's always Wow-These-Suck! batteries.
Based on my experience with Powerizer, you might lose 25% of them within the first few months to severe capacity loss, though my usage was in applications more like a digital camera, which tend to be pretty dependent on stable discharge behavior.

If you're in the market for decent batteries, I'm a fan(boy?) of Eneloop low-self-discharge NiMH. The one problem I've got with them: They don't seem to have plans to sell LSD NiMH 9V, C, or D batteries in the US.


Edit: Well, Eli posted the BatterySpace link too.

Also, vB seems to screw up the percent sign.

%


...yeah, that was a percent sign right there.
Ampersand, pound sign, 37, semicolon.

 

[disappoint]

You're not an idiot.

24 AA= 24 x1.2 =28.8 V

which evenly divides into 3.6, 8 times.
28.8/3.6=8

Where did I get 3.6? Lithium ion rechargeable batteries are 3.6V

So you COULD use 8 Lithium ion batteries (3.6V) but they need a smart charger designed for Li-Ion or they will catch fire or burst if you overcharge them.

So yeah just replace with NIMH or NICD, NIMH likes to be slowly depleted, wheras NICD can take larger current draws ok. Which is why power tools for example usually use NiCD or Li-Ion and not NIMH. How much current do the light draw? A lot? then NiCD or Li-Ion would be better suited than NiMH.

 

[Eli]

Also realize that upping the battery capacity isn't going to do anything; their overall usable capacity depends on how much sun they get.

You're not an idiot.

24 AA= 24 x1.2 =28.8 V

which evenly divides into 3.6, 8 times.
28.8/3.6=8

Where did I get 3.6? Lithium ion rechargeable batteries are 3.6V

So you COULD use 8 Lithium ion batteries (3.6V) but they need a smart charger designed for Li-Ion or they will catch fire or burst if you overcharge them.

So yeah just replace with NIMH or NICD, NIMH likes to be slowly depleted, wheras NICD can take larger current draws ok. Which is why power tools for example usually use NiCD or Li-Ion and not NIMH. How much current do the light draw? A lot? then NiCD or Li-Ion would be better suited than NiMH.

He has twenty four solar lights, each one takes a single AA NiCd cell.

The draw from the lights is extremely low, but then again the feed from the solar cell is also extremely low.

I would just go with some of the 700mAh NiCd's in my link. They're dirt cheap.

 

[Capt Caveman]

Also realize that upping the battery capacity isn't going to do anything; their overall usable capacity depends on how much sun they get.




He has twenty four solar lights, each one takes a single AA NiCd cell.

The draw from the lights is extremely low, but then again the feed from the solar cell is also extremely low.

I would just go with some of the 700mAh NiCd's in my link. They're dirt cheap.

Thanks for all of the info guys! Actually, these lights take two AA NiCd at 600mah. I appreciate the help.

 

[disappoint]

he has twenty four solar lights, each one takes a single aa nicd cell.

There are 4 lights!

 

[EagleKeeper]

How long did the lights last from when you first installed them?

 

[Eli]

There are 4 lights!

Oops, my bad. I just assumed they were single battery units. So he has 12 solar lights.

 

[Jeff7]

Oops, my bad. I just assumed they were single battery units. So he has 12 solar lights.

I don't know....I see 5 lights.

 

[Capt Caveman]

How long did the lights last from when you first installed them?

After a day's worth of charging the lights last about ten hours, a few of them are still going after 3 years.

 

[Eli]

After a day's worth of charging the lights last about ten hours, a few of them are still going after 3 years.

Theoretically, they could last as long as 25 years. Though, I would assume the environmental conditions are pretty harsh. 10 years shouldn't be out of the question though...

Then again, the cells probably aren't of the highest quality, but in theory, yeah.

We've been kinda on a solar light rampage lately, lol..

We picked up ten of these cheezy 4th of July themed solar lights they had at Wal-Mart. They were 2 for 3$. They use a single 2/3rd AA NiCd cell rated at 250mAh. They light all night.. but are quite dim overall. We took them camping with us, which was kinda fun.

The other day, we went into Big Lots because their solar lights were 30 percent off. The isle was a mess, with solar light pieces everywhere. We loaded up a box, took it to the counter and asked how much it would be. They gave it to us for $5. Ended up getting 8 solar light tops out of it. Pretty good deal.. they're the more expensive kind that actually have an on/off switch. They should make fun projects and such...

 

[Capt Caveman]

Theoretically, they could last as long as 25 years. Though, I would assume the environmental conditions are pretty harsh. 10 years shouldn't be out of the question though...

Then again, the cells probably aren't of the highest quality, but in theory, yeah.

Yeah, when some of the lights were dying, I wasn't sure if the lights were just cheap, the charger was dead or it was the batteries. I believe the batteries are good for 1000 cycles = 3 years. I dropped the batteries that were still working in the lights that had died and they've been working for about a week.

I'm guessing that the lights that were in the sun all day may have gone thru more full cycles than the one's that only got sun for a part of the day.

 

[EagleKeeper]

After a day's worth of charging the lights last about ten hours, a few of them are still going after 3 years.

thanks

This Spring the wife found some onsale at WalMart and picked up 3 boxes.

2 sets in the front and one set along the rear walkway.

Biggest problem I have had with the ones that have a square base is the riser has snapped for a couple and darn lawn service weed whacked a couple more.

Company will not sell me replacement stems.

They will send replacements if I can send a copy of the receipt. Of course, the receipts from April is not around

Maybe if I purchase another set and send a copy of that receipt....^_^

 

[Eli]

Yeah, when some of the lights were dying, I wasn't sure if the lights were just cheap, the charger was dead or it was the batteries. I believe the batteries are good for 1000 cycles = 3 years. I dropped the batteries that were still working in the lights that had died and they've been working for about a week.

I'm guessing that the lights that were in the sun all day may have gone thru more full cycles than the one's that only got sun for a part of the day.

NiCd should be good for 2,000 cycles. So 6 years.. But the cycle count is usually to something like 80 percent of capacity. So the lights could still be operating, just with diminished performance.

Also, having two cells is tricky. If one cell is weak, this will become very apparent as time goes on. You should test all the cells and re-match them.

 

[Dubb]

in a sorta similar vein, anyone know where I can find one of these in the US?

http://www.ctsbayswater.com.au/batt...-19_23/bh-425a-aaa-cell-2-battery-holder-p-75

no luck on digi-key, battery space, ratshack, etc.

 

[Jeff7]

in a sorta similar vein, anyone know where I can find one of these in the US?

http://www.ctsbayswater.com.au/batt...-19_23/bh-425a-aaa-cell-2-battery-holder-p-75

no luck on digi-key, battery space, ratshack, etc.

Mouser: 12BH325A-GR
(Can't post the link, the latest vB update screws up percent signs in everything, including links. This is what it looks like now: % )

And your Digi-key-fu skills are weak, young grasshopper.

(Also, get the Digikey Sort By Price Greasemonkey script, while you're at it. )

 

[theflyingpig]

It doesn't really matter what your question is. The answer is the new Apple rechargeable batteries. Really, what other brand would you even consider, if given a choice?