OptimusPrime
10 W
Going a little crazy trying to sort this out. LiFePO4 looks to be safer and for a little more money they last a lot longer. So why are the 18650's seemingly so popular? What am I missing?
Trying to make the decision between 18650's and LiFePO4
- Thread starter OptimusPrime
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chvidgov.bc.ca
10 kW
Energy density (weight of pack/volume of pack for a given energy content), and/or power density - sustainable power level for a given weight/volume of pack. I've used Headways and Pings and prefer the newer 18650 packs in general. The only advantage of LiFe types (with Headways/not pings) is easy replacement if you need to put in a new BMS or change out cells due to the simpler interconnects, unless you can spot weld. The 18650 packs are probably also safer. It makes a big difference shaving off a whole pile of pack weight and pack volume, for the same range.
Drunkskunk
100 GW
There are many types of 18650 cells. IMR, INR (NMC), and NCA ( source) are what we usually refer to as "18650", but in reality, 18650 is a size, not a type. It's like saying AA, or C, or D. it's a cell that is 18mm wide and 65mm long. LiFePO4 can be found in a 18650 cell as well, like the often mentioned A123 cells. Lipo can come in 18650 cells as well, like many old laptop batteries.
The advantage of the cells we on this forum often call "18650", such as the Samsung INR 18650-25R, is that they split the difference between the psychotically unstable but amazingly power dense Lipo cells, and the reasonably safe but low density LiFePO4. With a IMR, INR, or NCA cell you get reasonable safety with good power and good cycle life.
The advantage of the cells we on this forum often call "18650", such as the Samsung INR 18650-25R, is that they split the difference between the psychotically unstable but amazingly power dense Lipo cells, and the reasonably safe but low density LiFePO4. With a IMR, INR, or NCA cell you get reasonable safety with good power and good cycle life.
Cephalotus
10 kW
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LFP (or LiFePO4) is overhyped.
http://batteryuniversity.com/learn/article/types_of_lithium_ion/1
I see one advantage:
You can replace 12V lead systems with a 4s LFP battery and the voltage range will "fit".
and one differentiator:
discharge voltage curve is quite flat (can be an advantage, but also a disadvantage, depends what you want)
There is neither a price nor a longitivity nor security advantage on LFP cells if you design a battery based on its maximum weight / volume. But there is a very significant disadvantage in capacity.
http://batteryuniversity.com/learn/article/types_of_lithium_ion/1
I see one advantage:
You can replace 12V lead systems with a 4s LFP battery and the voltage range will "fit".
and one differentiator:
discharge voltage curve is quite flat (can be an advantage, but also a disadvantage, depends what you want)
There is neither a price nor a longitivity nor security advantage on LFP cells if you design a battery based on its maximum weight / volume. But there is a very significant disadvantage in capacity.
Ping makes LiFePO4 in a block form, there are triangle packs available in at least 5 different sizes.
There are other reasons, some stated above...
There are other reasons, some stated above...
wesnewell
100 GW
lifepo4 is safer, but that's about where the advantages end imo. If you check the specs, life expectancy is based on <1C discharge rates, And that's usually at 0.2C. Start pulling >2C and life decreases dramatically. It also sags like teats on a boar hog, but then so does a lot of 18650's. That's why I've never used either. I've got close to 4 years and 15K miles on my 20C 10ah 24s rc lipo pack. I bought a new one for $180 not long ago when they were on sale. I'll switch over to them in June, maybe.
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