14500 LiFePo at Wal-mart

[wingate]

While looking at solar landscape lighting, I noticed that they are selling GE branded 14500/AA sized LiFePo (4/pk for ~$10). They are stated as 3.2V, 400mAH which I guess is about right if a 16340 LiFePo is getting around 500mAH. They are also selling chargers - the only caveat is that they are solar and shaped like a rock

Robert

 

[Rocketfish]

I'm a bit confused by the whole Lithium thing, I thought lithium rechargeables had a higher capacity then NiMH?
a rock charger may not be a bad idea for a super secret bug out shelter.:twothumbs

 

[LuxLuthor]

Seeing these sold at Walmart is what I was expecting, now that the safe chemistry Lithium Ion cells are coming more online.

Rocketfish, the confusion comes about in part with the various categories of Lithium cells....each with different features which I tried to organize here.

The original Lithium Cobalt has the highest capacity....but it has the fire/explosion risk and hundreds of millions of dollars have been lost on laptop and other recalls, so the industry is moving to safer Lithium chemistries which have lower capacities.

 

[Bushman5]

i saw those too, but was put off by the weak 400 mah........ my energizers (AA) are 2500 mah... and about the same price....


why so little capacity in the lifepo AA's??

 

[evenchaos]

I'm a bit confused by the whole Lithium thing, I thought lithium rechargeables had a higher capacity then NiMH?
a rock charger may not be a bad idea for a super secret bug out shelter.:twothumbs

They do - remember that NiMH voltage is 1/3 that of Li-ion which means that you need 3x the mAh rating to have the same capacity as that of a Li-ion. Don't confuse (m)Ah with (m)Wh

 

[LuxLuthor]

i saw those too, but was put off by the weak 400 mah........ my energizers (AA) are 2500 mah... and about the same price....


why so little capacity in the lifepo AA's??

It's a whole different chemistry. It has mega high current output and fast charging, but is pretty worthless compared to NiMH in that size. It becomes more useful in 18650 and 26700 size cells.

 

[Bushman5]

AH! sorry Lux, i brainfarted......completely missed that there was two different chemistries.... my bad..

thanks for the reply Lux, both you and EvenChaos!

 

[Benson]

It's a whole different chemistry. It has mega high current output and fast charging, but is pretty worthless compared to NiMH in that size. It becomes more useful in 18650 and 26700 size cells.

Worthless?! Maybe, but that depends what you want -- 10A, 6.4V could make that Minimag worth buying. :devil: Granted, AA hosts have so little room to work with, there's some difficulties in modding them -- but it could be worth it.

It's surprising, to me, that Li-ions mechanically compatible with existing KOH cells are being sold in a standalone package, but it certainly makes for modding fun! Anyone know if these are flat-top or something to prevent idiots from using them in AA applications?

 

[LuxLuthor]

Well I mean "worthless" in a relativistic manner, only because of the low 400mAh capacity.

While true you start with a higher voltage equal to 2-3 NiMH cells, these get drained before Bushman5 has time to brainfart.

Stop and calculate how long they will last with a 10A drain application....depending on how well they actually hold voltage at high drain rates, which might suck since they will be less than 18650 A123 performance. Even if you got every last of the 400mAh out of it (which won't happen) the run time would decrease accordingly:

400 mA for an hour
800 mA for 30 min
1000mA for 24 min
1.2A for 15 mins
5A for 5mins
8A for 3 mins
10A for 2.4 mins

Realistically, you would be lucky if they lasted 1 min at 10A.

 

[Benson]

Well I mean "worthless" in a relativistic manner, only because of the low 400mAh capacity.

While true you start with a higher voltage equal to 2-3 NiMH cells, these get drained before Bushman5 has time to brainfart.

Stop and calculate how long they will last with a 10A drain application....depending on how well they actually hold voltage at high drain rates, which might suck since they will be less than 18650 A123 performance. Even if you got every last of the 400mAh out of it (which won't happen) the run time would decrease accordingly:

400 mA for an hour
800 mA for 30 min
1000mA for 24 min
1.2A for 15 mins
5A for 5mins
8A for 3 mins
10A for 2.4 mins

Realistically, you would be lucky if they lasted 1 min at 10A.

Sure; I knew what you meant, and realize the limitations. But the pure fun one can get from a half-minute-runtime toy must not be underestimated.

More realistically than 10A, I was actually thinking of things like a MiniROP/MiniMag11 (up to 5A draw), or a full-bore (3A+ at the emitter) P7 or MC-E (~2A draw), would mean runtimes between 2 and 10 minutes, and the LEDs could actually give decent runtimes on low output (comparable to AAA/10440 lights). (Hotwires, of course, could also get somewhat improved runtimes on low, orange output, but this would be better served by a neon indicator light... :laughing

 

[kz1000s1]

Sure; I knew what you meant, and realize the limitations. But the pure fun one can get from a half-minute-runtime toy must not be underestimated.

More realistically than 10A, I was actually thinking of things like a MiniROP/MiniMag11 (up to 5A draw), or a full-bore (3A+ at the emitter) P7 or MC-E (~2A draw), would mean runtimes between 2 and 10 minutes, and the LEDs could actually give decent runtimes on low output (comparable to AAA/10440 lights). (Hotwires, of course, could also get somewhat improved runtimes on low, orange output, but this would be better served by a neon indicator light... :laughing

I finally found some of these at a different store and your estimate for an
MC-E is about right. No actual runtime test yet, but in an Energizer 1xAA with an MC-E, it's probably 10 min. or slightly less.

 

[PhantomPhoton]

Hmmm interesting indeed. Too bad they don't come with a plug in charger, but I should be able to dissect the solar "rock" and make it work from a wall small wall wart.
400mAh sounds a bit on the low end, I've generally found 14500s to have just a bit more capacity than RCR123s. Could be cheap cells, could be the chemistry, or I could just be wrong.

Regardless, I'm interested in how much current these can hold. The cheap LiFePo4s form Kaidomain die at around an amp, so I haven't been able to so much with them so far.

 

[SemiMan]

The other advantage of the 14500 LiFePo other than high power density is life. It should last many more charge cycles than NiMh and its shelf life is much longer than regular cobalt based lithium ions. You can leave these charged without them self degrading much. Cobalt based lithiums are good for 3-5 years max if kept in a charge state most of the time. LiFePo can be good for 10+ years.

Semiman

 

[Chrontius]

I'm going to grab some of these things, an Everready industrial 2xAA, and my spare ROP bulbs...

Even if I'm horribly underdriving it, what the hell, it's still 20ish watts of incandescent surprise and it should preserve the poor reflector.

Edit: on second thought, this would be a perfect host for the Mag 6D bulbs I've got kicking around, with reasonable runtime and reflector life.

 

[Benson]

I'm going to grab some of these things, an Everready industrial 2xAA, and my spare ROP bulbs...

Even if I'm horribly underdriving it, what the hell, it's still 20ish watts of incandescent surprise and it should preserve the poor reflector.

You know that light just has 4 ribs supporting the AA cells, and can be easily "bored" with a chisel or knife to accept 17mm (keeping the two ribs next to the brass conductor), or even 18mm if you trust your cells' insulation (removing all 4 ribs), so 2x LiFePO4 rcr123 and a spacer would be better capacity-wise.

 

[Chrontius]

This is nicer because a charger is available. I find myself really frustrated when trying to source a nice li-ion charger, and can't really afford to throw money at the problem.

Why hasn't anybody made a second run of AuroraLight conversion kits? Fivemega, are you listening?

 

[kz1000s1]

I'm going to grab some of these things, an Everready industrial 2xAA, and my spare ROP bulbs...

Even if I'm horribly underdriving it, what the hell, it's still 20ish watts of incandescent surprise and it should preserve the poor reflector.

Edit: on second thought, this would be a perfect host for the Mag 6D bulbs I've got kicking around, with reasonable runtime and reflector life.

If it's this light, you're going to have a problem if they still have plastic reflectors.

I invented a mod for this light with 3xCR123 and a KPR112 bulb years ago. If you leave it on more than 2 minutes, the reflector will warp from the heat and shut off the light. That combo worked much better in a 2C Mag. Even if you got much light from a 20W bulb with only 6.4V, it wouldn't last long.
What works better is installing a P91 Surefire bulb. Like this:

http://www.candlepowerforums.com/vb/showthread.php?t=18833

 

[Chrontius]

Yeah, that's the one, plastic and all.

Would 6.4v eat a P60 for lunch? Does anybody make a similar, metal light? I really would like to make a 2xAA shocker to wow the unenlightened.

 

[kz1000s1]

Yeah, that's the one, plastic and all.

Would 6.4v eat a P60 for lunch? Does anybody make a similar, metal light? I really would like to make a 2xAA shocker to wow the unenlightened.

The answer is no. I just tried it for a minute and it works with a P60 and 2 Lifepo in the Energizer. I'm not sure if it's as bright as it should be though, but I've been getting spoiled by P7's and MC-E's lately.

 

[kz1000s1]

I had another idea for these batteries, but it didn't work.
Putting them in a minimag with a streamlight scorpion bulb.