I hear that battery maintenance is important part of getting the most speed out of your car, but i'm not really sure what a good maintenance plan is.

What is the best charge rate 1c, 2c, 10 amps, 25 amps, 40 amps????
Discharging rate???
Should i cycle my packs and how often?
Whats a good internal resistance for a pack (2s shorty lipo)

Any other tips that would help a racer get the most from their battery investment in terms of speed first and longevity second would be greatly appreciated.

Thanks

The best thing you can do for your lipos is to simply use them. Don't store them without a storage charge on them, don't over discharge them (don't run to your ESC's cut-off), etc. Unless you're hyper-serious about stock racing, you don't need to get into the mechanics of squeezing every little drop out of your batteries. Just charge at 1C - 5C and don't worry about cycling/discharging.

I run stock and charge at 2C (as opposed to 1C) just for the sake of time. I could get away with more, but it's just not a factor for me. My motor is plenty fast/punchy without playing games with my batteries, and since I'm not putting down 15 - 20 perfect laps to begin with, my batteries just aren't a factor. Seriously - one crappy lap erases all the battery voodoo yoo doo in the pits. If I was running perfect races every time and losing by a few seconds to someone who was cooking his batteries, I'd reconsider, but only after every other possible advantage had been explored (motor, totally free drivetrain, bearings in tip-top shape, blah blah blah).

I only run for 15 minutes or so, which means I don't even need to worry about putting a precise storage charge on them unless I'm not going to use them for a couple weeks. In other words, it's rare for me to pull more than half the capacity out on a practice run or race.

Good internal resistance is mid- to low single digits. Don't even sweat the IR until you're in the high teens, keeping in mind that a "cold" (unused) pack will have a higher IR, and that the quality of your connections when measuring IR is crucial. Also important is that the cells are close to each other (in terms of IR).

And of course always balance charge... because why not.

Best lipo tip......... Do not leave your batteries fully charged at home.....

As mentioned above, never leave lipos fully charged.

Always balance charge to ensure all cells are equally charged. Always storage charge after use.

All the key info is in the first two responses, but here is some additional material I've come across to maximize the lifespan.

Battery degradation happens from 5 main culprits:
Under voltage
Over voltage
Improper storage voltage
Temperature
Cycles

Under Voltage -Usually can be avoided with a proper cut off. For racing, it's a balance of not letting the pack get too low and risking an early cut-off that ends a good run. This usually isn't a problem in stock, but 4wd classes can be harder to balance. 3.2 volts per cell is a good setting, but if you can bump it up to 3.3 or 3.4 without risking an early shut down, it helps improve overall lifespan. Since speed controls don't monitor individual cell voltage and your charger balances them when charging, take a volt-meter to your pack at the end of a run and see if the cells are similar in voltage to make sure they are evenly matched to reduce the risk of inadvertently over discharging a cell.

Over Voltage - Balance charge every time and you will be okay, but if you want additional cycles out of the pack, lower the voltage settings in the charger. I usually run mod and have no problem making our 7 minute mains, so I've actually set my charger to 4.1 volts per cell for the cutoff when charging. No real loss in run time and I will obtain more total cycles out of the pack. This is the same thing most electric cars do to extend the life of their batteries. The Chevrolet Volt only charges to 80% capacity (~3.9 volts per cell) and the cutoff voltage is 20% (~3.4 volts per cell). The Tesla Model S, X, and Y all let you select how much of the pack you want to use and they recommend using more conservative settings unless you will be going on a long trip and need the full range. The closer to fully discharged or fully charged the pack is, the more degradation occurs.

Improper Storage Voltage - Definitely don't store fully charged or discharged packs more than a day or two. Keep the packs between 7 volts and 8 volts for short term storage (1 to 7 days) and use the battery storage feature on your charger whenever you won't be using the packs more than a week. Check them once a month to make sure they haven't discharged themselves too much.

Temperature - Hot and cold temperatures can be damaging, but avoiding overheating the packs is more important. Keep packs between 50 and 100 degrees F (15 and 35 C) for the absolute best lifespan. Don't leave packs in hot cars in the summer or freezing temperatures in the winter as these are sure fire ways to noticeably reduce the lifespan of the pack.

Cycles - Not much you can do here. Using the battery is the reason you bought it, but you can maximize this by avoiding the conditions listed above.

Replace every year/2. A new cheap battery will outperform an old 'good' battery.

We have a good read on LiPo's if you are new to them: https://www.rcjuice.com/lipo_battery_basics