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#31
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a Li-Ion in a lead acid world.
I just wanted to repeat something bildan stated:
THERE ARE MANY TYPES OF LITHIUM BATTERIES. The term "Li-Ion" gets tossed around a lot, but it is incorrect to call all Lithium batteries "Li-Ion", just like its incorrect to call all sealed lead-acid batteries "Gel Cells" (ignoring the differences between Gel, VRLA, and AGM). There's the Li-Ion system/chemistry that is used in a lot of consumer devices (such as what Brian tested). These tend to have a much better track-record than many of the "Lithium Polymer" batteries (but at a lower energy density). Some people use "Li-Po" and "Lithium Polymer" interchangeably; while other groups use "Li-Po" to designate Lithium Phosphate formulations. And to make matters worse, "Li-Po" and "Lithium Polymer" batteries themselves are now coming in different formulations. The earlier "flat rectangle" cells from makers like Kokam were cutting edge for awhile and used by many in the R/C modeling world; but have proven to be highly flammable under high charge/discharge loads. One of the telltale signs for these cells is that they provide 3.7 volts per cell (a slightly awkward voltage for many applications). Different Lithium formulations tend to provide slightly different voltage on a per-cell basis. No particular per-cell voltage equates to safety - but its a handy way to check what kind of cells you're getting if the manufacturer isn't really specific about which brand or formulation is being used inside the battery pack. The LiFePo4 that is discussed in the Soaring magazine article is one particular formulation. I haven't had a chance to research it in detail, but it does look safer than some other "Li-Po" systems. If the price comes down I'd certainly consider buying the new cells; but as Brian pointed out the newer high-density SLA cells are pretty nice for the price! --Noel |
#32
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a Li-Ion in a lead acid world.
On Nov 15, 2:49*pm, "noel.wade" wrote:
I just wanted to repeat something bildan stated: THERE ARE MANY TYPES OF LITHIUM BATTERIES. The term "Li-Ion" gets tossed around a lot, but it is incorrect to call all Lithium batteries "Li-Ion", just like its incorrect to call all sealed lead-acid batteries "Gel Cells" (ignoring the differences between Gel, VRLA, and AGM). There's the Li-Ion system/chemistry that is used in a lot of consumer devices (such as what Brian tested). *These tend to have a much better track-record than many of the "Lithium Polymer" batteries (but at a lower energy density). *Some people use "Li-Po" and "Lithium Polymer" interchangeably; while other groups use "Li-Po" to designate Lithium Phosphate formulations. And to make matters worse, "Li-Po" and "Lithium Polymer" batteries themselves are now coming in different formulations. *The earlier "flat rectangle" cells from makers like Kokam were cutting edge for awhile and used by many in the R/C modeling world; but have proven to be highly flammable under high charge/discharge loads. *One of the telltale signs for these cells is that they provide 3.7 volts per cell (a slightly awkward voltage for many applications). Different Lithium formulations tend to provide slightly different voltage on a per-cell basis. *No particular per-cell voltage equates to safety - but its a handy way to check what kind of cells you're getting if the manufacturer isn't really specific about which brand or formulation is being used inside the battery pack. The LiFePo4 that is discussed in the Soaring magazine article is one particular formulation. *I haven't had a chance to research it in detail, but it does look safer than some other "Li-Po" systems. *If the price comes down I'd certainly consider buying the new cells; but as Brian pointed out the newer high-density SLA cells are pretty nice for the price! --Noel Is there any info on performance of these technologies relative to each other in freezing temperatures? |
#33
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a Li-Ion in a lead acid world.
On Nov 15, 7:59*pm, "Matt Herron Jr." wrote:
On Nov 15, 2:49*pm, "noel.wade" wrote: I just wanted to repeat something bildan stated: THERE ARE MANY TYPES OF LITHIUM BATTERIES. The term "Li-Ion" gets tossed around a lot, but it is incorrect to call all Lithium batteries "Li-Ion", just like its incorrect to call all sealed lead-acid batteries "Gel Cells" (ignoring the differences between Gel, VRLA, and AGM). There's the Li-Ion system/chemistry that is used in a lot of consumer devices (such as what Brian tested). *These tend to have a much better track-record than many of the "Lithium Polymer" batteries (but at a lower energy density). *Some people use "Li-Po" and "Lithium Polymer" interchangeably; while other groups use "Li-Po" to designate Lithium Phosphate formulations. And to make matters worse, "Li-Po" and "Lithium Polymer" batteries themselves are now coming in different formulations. *The earlier "flat rectangle" cells from makers like Kokam were cutting edge for awhile and used by many in the R/C modeling world; but have proven to be highly flammable under high charge/discharge loads. *One of the telltale signs for these cells is that they provide 3.7 volts per cell (a slightly awkward voltage for many applications). Different Lithium formulations tend to provide slightly different voltage on a per-cell basis. *No particular per-cell voltage equates to safety - but its a handy way to check what kind of cells you're getting if the manufacturer isn't really specific about which brand or formulation is being used inside the battery pack. The LiFePo4 that is discussed in the Soaring magazine article is one particular formulation. *I haven't had a chance to research it in detail, but it does look safer than some other "Li-Po" systems. *If the price comes down I'd certainly consider buying the new cells; but as Brian pointed out the newer high-density SLA cells are pretty nice for the price! --Noel Is there any info on performance of these technologies relative to each other in freezing temperatures? Lot's of info in the manufacturer's spec sheets. Cold weather performance is critical for EV batteries. New announcements are being made daily. New technology batteries are complex and it's best to avoid generalities. The rule of thumb for EV's is you lose ~10% range starting out on a freezing day but much of that is recovered as the battery pack "self- warms" from the current draw. It's likely the same for glider batteries - you launch with the battery in use and the internal electrochemical reactions generate enough heat to avoid the worst of low temperature effects. |
#34
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a Li-Ion in a lead acid world.
On Mon, 15 Nov 2010 14:49:06 -0800 (PST), "noel.wade"
wrote: The LiFePo4 that is discussed ... vent mode on ... I know that many folks think m=M (milihertz megahertz)(mHz MHz) but why does anyone use the chemical symbol for polonium in the lithium iron phosphate batteries? I guess it looks better to have a pattern? LiFePO4 (technically the 4 should be a subscript, but that is reasonable within the limits of ASCII) is the correct formula. PO4 is phosphate. vent mode off, sorry ... |
#35
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a Li-Ion in a lead acid world.
LiFePO4 (technically the 4 should be a subscript, but that is reasonable within the limits of ASCII) LiFePOâ‚„ |
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