Trying to find a 2600 mAh capacity 18650 sized LiFePO4 3.2 volt battery….anyone seen any (link?). Thanks,HB
LiFePO4 has a lower energy density than other chemistry in general. You’ll be hard pressed to find an 18650 with much over 1500 mAh actual capacity.
This 3-cell battery pack is 2600 mAh and 12 volts,so probably more like 3 18650 Li-ion cells,the charger has an output of 12.6 volts,1 amp. HB
A series three cell LiFePO4 pack is only going to produce a nominal 9.6V, NOT 12V. If you have a three cell pack that produces ‘12V’, those cells are either LiCo or LiMn. Of course, the voltage characteristics of a three cell LiMn/LiCo are going to be MUCH different from a four cell LiFePO4 pack. For 12V, LiFePO4 is MUCH, MUCH, MUCH better than LiCo or LiMn, particularly as a lead acid replacement.
As far as the largest capacity 18650 LiFePO4 battery, Fasttech sells an ‘1800 mAH’ protected (WHY!!!) cell and a ‘2200mAH’ cell. Keep in mind that these numbers are substantially higher than most any other cell I have seen, so I consider these numbers to be suspect. Like the other guy, I would consider anything much over 1500mAH to probably be unrealistic.
On the other hand, unlike LiCo, going from an 18650 to a 26650 gets you MUCH more capacity. Expect to get anything from around 2500mAH from a high current cell (like the A123 Systems 26650 ) to 3300mAH from a lower current cell. So if you CAN go with a 26650, this would be a better choice if you NEED more capacity.
For even more capacity, consider the 5000mAH Feilong 32650 . Tests have shown this to be an AWESOME battery. The voltage of that battery makes NiMH look downright unstable!
Man….too many battery types available…….now it could possibly be a LiCo 18650 sized pack,same voltages,buy much higher capacity,just what my pack says. I am thinking now that since the wall-wart charger has an output of 12.6 volts,that would rule out the pack being LiFePO4’s,so I guess the only real way to find out what batteries are in the pack is to remove the wrapper and see?! trying to get some info from my dealer where I bought my heated glove liners. Thanks,HB
DEFINITELY LiCo or LiMn. Both of these chemistries charge to 4.2V. So 12.6V = 3x4.2V. But 3 LiCo/LiMn charge to 12.6V and drop steadily to around 9V (depending on where you want to cut things off). Four LiFePO4, on the other hand, charge to 14.4V, quickly dropping down to 12.8V. The voltage stays more or less here until the pack is discharged. Because LiCo has a higher capacity, it is more often used where a voltage of around 12V is needed. But LiFePO4 is used when (1) a drop-in replacement for lead acid is needed, (2) greater safety is needed, and (3) a more constant discharge voltage is needed. This is typically not the case with heated gloves (although LiFePO4 would certainly work).
I received some information from my dealer regarding possibly what type of batteries make up these packs (2) and I was given this information: “The official cut off voltage is 8v. The indivudual cell cut off is 2.8v, so 2.8v x 3 = 8.4v. So, based on this information,what type of cells are in these packs? I wish there was some kind of info on the pack(s) other that just (12 volt 2600mAh lithium)
Thanks,HB
Go back and look at that discharge graph again. Like a LOT of manufacturer info a cut-off of 8v for a 3-cell pack is worthless and doesn’t tell you anything. Frankly I consider it to be a very bad recommendation, bad enough it puts the rest of their recommendations under suspicion.
Ultimately it doesn’t matter what ‘flavor’ they are. FAR more important is the REAL capacity, and if they are DECENT cells. The only way to get the real capacity is to do a discharge test with appropriate monitoring. Only way to tell what cells is open it up. They aren’t going to tell you, guaranteed. Even if they know this week, they may change suppliers next week.
It looks like some information went missing. Are you building a new power pack for your glove heaters? If so, could you drop 3 18650 cells into one of these
I already have two 12 volt battery packs that came with the gloves consisting of 3 cells each. They seem to be of the 18650 size,but not exactly sure which kind of lithium they are? I will probably open them up to see exactly what’s inside.
My dealer said the pack has a low voltage cut-off of 2.8 volts,so that makes 8.4 volts for the whole pack,which seems kind of low and from what I have been told, they are near dead at that voltage……so I dunno.Thanks,HB
I got the impression from some other threads those heater elements are just resistive and have a range of voltage, resulting in different levels of heating. If that’s so, why not just experiment a little and connect 3 18650’s of you choice and see how it goes. You could probably use any chemistry you wanted depending on how hot you want them. There’s another thread in here that goes into the properties of those heating elements in more detail. The ones I’ve been waiting for for the last 2 months (from ALi Express) are rated at 5-6V 2A, so I’m planning to use a USB power pack and see how that goes.
These glove liners have three heat settings. Thanks,HB
It would be interesting if you could measure what power is used for each setting. Is it controlling the heat by limiting the voltage? As my tracking software is telling me that my foot warmer elements are finally waiting for pickup at the post office after a wait of almost 2 months, I guess this will be something I’ll be looking at this afternoon myself.
Hope you enjoy your heated in-soles….I love the heated glove liners,as my fingers were always the first to freeze no matter what I bought or how much I spent on gloves/mitts!! I can just put a cheapy pair of gloves or mitts over the liners and I am good.
I think it said that they use kevlar fibres instead of actual wires……I dunno about that!? HB
Kevlar is a non-conductor, wouldn’t work.
Well, I have been experimenting with those heater elements since last night, I even took them to bed and made my spouse lay on them for a second opinion. That was a mistake, she kicked my out and said they performed better…. (I know, too much information….)
So back onto the germain topic. What I’m finding interesting is they really seem to challenge the Power Packs that I am using. (These warmers are supposed to be for USB power, as they come with USB cords pre attached). So far I have been trying them with 2 power packs from FT ( I seem to recall that the foot warmer elements require an output of 2A). I bought this pack specifically for the foot warmers because it had been reviewed by HKJ and found to support 2A. For some reason the warmers didn’t seem to get very warm. I had previously found that this 3 cell ENB pack would charge my Lenovo Tablet in spite of the 1A rating, so I gave it a shot. It seemed to make them heat up OK for about 20 minutes, then shut down. So it seems to come down to finding an appropriate battery pack. I’m wondering if perhaps I’d be better off using the NCR18650PD cells in that pack instead of the 2200mAh cells that are in there now.
In a few minutes I’m going to put one of them into one of my ski boots, then put one of the wireless thermometer sensors in the boot, plug the boot top with insulation, and then set the boot outside and do some with/without temperature comparisons. As these boot warmers with the USB cables already attached were just $9.00 from a seller on Ali Express, I’ve got my fingers crossed they will perform well, then they would be a good find.
Sorry… I made a mistake…it’s carbon fibre not Kevlar. He shows it at around 1:10 on the video here:http://www.youtube.com/watch?v=w3E4Rig4yuc
Thanks,HB
I have no idea how this test will translate to real world, but this is what I did last night:
Air temp was –5C. I took one of my insulated ski boots and placed the warmer under the footbed, and a wireless sensor in the cavity. I plugged the boot top with a wool T-Shirt, wrapped it in a plastic bag, and buried it in the snow. I waited until the boot was reading –5, then I plugged it into the power pack. By the time we went to bed a few hours later, the outside air temperature had gone to about –7C, and the boot was reading +11C. Obviously the presence of a foot in the boot on a pair of touring skis would change the results a lot, at this point about all I can gather from the above test is it’s doing something.
The other thing that is already apparent. The CHinese did not really consider that downhill and touring ski boots have a higher cuff on them than your average shoe, so their socket where you connect the wires is going to be in your boot. There may be enough of a cavity in the touring boot to get by, but I’m sceptical about the downhill boot. It’s a minor problem to lengthen it by soldering a longer piece of wire into the lower section, but would obviously be better if they could just make the socket at least 4” further up, as even the solder joint could have just enough extra material to give you a rub point in your boot.
It is hard to find beyond 1500mAh, for qualified lifepo4 cells, you can find on http://www.ultrablecell.com/en/Products/LiFePO4-Battery/23.html