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lipomax · 03.09.2005, 06:45 PM

I'll try to explain in more detail: The lithium packs that we use are called "Lithium Polymer" packs, but they're really "Lithium Ion Polymer".

Each cell is generally rectangular in shape and pretty flat. Also, each cell is 3.7 volts instead of 1.2 volts. Hence the voltages: 3.7, 7.4, 11.1, 14.8, 18.5, 22.2...

Lithium packs originally were not able to deliver the "punch" because of their high internal resistance and small sizes so in order to make a large pack, they would get several small packs and then hook them up in parallel. That's where the xSyP comes into play. The "x" is the number of cells in series (the overall voltage) and the "y" is the number of cells in parallel (to reduce internal resistance by just having a bunch of cells in parallel... also increases capacity). These days, with the larger cells in production, there really is no need to parallel cells anymore. I'm generally just running 3s, 4s, 6s, or 8s in my tc4 and emaxx. So for me, the number is simply the number of cells hooked up in series or "end to end". However, a 6 cell pack of Lithium cells is 22.2 volts vs. 7.2 volts for NiMH.

The "C" that you see all the time is the capacity. When something can be discharged at 10C continuously, that means that a pack can discharge at 10 x the overall capacity. So, a 3000 mah pack can discharge safely at 30,000 milliamps (or 30 amps) continously. You don't want to overdraw a lithium due to their explosive and somewhat fragile nature. These days, the newest generation is safely discharging at 20C rate (so a 3000 mah can discharge continuously at 60 amps). That's continuous - so an occasional peak at 100 amps for a split second shouldn't do too much to hurt it... we'll see about that soon.

The best feature of Lithium packs is their energy density. They are about 2x the energy density of NiMH so given the same weight of batteries, you'll run 2x longer. The newer generation of packs are also higher power density too now. A 20 ounce pack which is roughly equivalent to 10 sub C cells can deliver peaks of over 2000 watts!

I hope this helps. BTW, Mike, I've added just a little bit of slip to the stock slipper and got those cheapo plastic shafts... I'm gonna give it a go this afternoon.

10L, 6s, 18/66 gearing.

	(#36)
lipomax RC-Monster Carbon Fiber Offline Posts: 191 Join Date: Feb 2005	03.09.2005, 06:45 PM I'll try to explain in more detail: The lithium packs that we use are called "Lithium Polymer" packs, but they're really "Lithium Ion Polymer". Each cell is generally rectangular in shape and pretty flat. Also, each cell is 3.7 volts instead of 1.2 volts. Hence the voltages: 3.7, 7.4, 11.1, 14.8, 18.5, 22.2... Lithium packs originally were not able to deliver the "punch" because of their high internal resistance and small sizes so in order to make a large pack, they would get several small packs and then hook them up in parallel. That's where the xSyP comes into play. The "x" is the number of cells in series (the overall voltage) and the "y" is the number of cells in parallel (to reduce internal resistance by just having a bunch of cells in parallel... also increases capacity). These days, with the larger cells in production, there really is no need to parallel cells anymore. I'm generally just running 3s, 4s, 6s, or 8s in my tc4 and emaxx. So for me, the number is simply the number of cells hooked up in series or "end to end". However, a 6 cell pack of Lithium cells is 22.2 volts vs. 7.2 volts for NiMH. The "C" that you see all the time is the capacity. When something can be discharged at 10C continuously, that means that a pack can discharge at 10 x the overall capacity. So, a 3000 mah pack can discharge safely at 30,000 milliamps (or 30 amps) continously. You don't want to overdraw a lithium due to their explosive and somewhat fragile nature. These days, the newest generation is safely discharging at 20C rate (so a 3000 mah can discharge continuously at 60 amps). That's continuous - so an occasional peak at 100 amps for a split second shouldn't do too much to hurt it... we'll see about that soon. The best feature of Lithium packs is their energy density. They are about 2x the energy density of NiMH so given the same weight of batteries, you'll run 2x longer. The newer generation of packs are also higher power density too now. A 20 ounce pack which is roughly equivalent to 10 sub C cells can deliver peaks of over 2000 watts! I hope this helps. BTW, Mike, I've added just a little bit of slip to the stock slipper and got those cheapo plastic shafts... I'm gonna give it a go this afternoon. 10L, 6s, 18/66 gearing.