Nowdays refers to lithium polymer RC batteries. Often sourced at hobby king.
Describes the quantity of amps a battery can put out without major damage. 1c means a 5 ah pack can put out 5 amps, 10 c means a 5 ah pack can put out 50 amps. 30c, 150 amps.
"S" means cells connected in series. So a 4s 5000 mAh pack is a 4 cell pack made of 5 ah pouches connected in series. Each cell charges to 4.2v max, so a 4s pack charges to 16.8 v.
Series connecting packs.
Usually bikes run on 36v, 48v , 72v etc. So several smaller packs are connected in series to make a higher voltage pack. Two 5s packs in series make a 36v 10s pack. four 5s packs series connected make a 72v 20s pack. 6s packs can be used for other, not so standard voltages. 12s is a nice voltage in between 36v and 48v. 18s can be nice, faster than 48v, but not so fast as a 20s pack. 48v is awkward, 14s is safe for most 48v controllers. Some get away with 15s, and some don't.
Paralell connecting packs.
Many buy lipo in a commonly avaliable 5 ah pack. If you need 10 ah or more, the packs are paralell connected first, then paralelled packs are series connected to run the bike at the desired voltage.
Charge lipo to 4.2v per cell maximum. Some charge to 4.15 or 4.1 v per cell to maximize lifespan.
Lithium batteries are damaged by a complete discharge. The golden rule is never below 2.7v. for lipo. However, there is virtually no useable charge left below 3.5 v. You will go from 3.5v to 2.7 very quickly so consider 3.5 to be the minimum usable voltage. Like the charging, cycle lifespan is thought to increase considerably if you don't discharge a battery 100% . For that reason, many consider a 5 ah pack to have 4 usable amp hours, and discharge only to 3.7-3.8v as their minimum charge voltage.
Depth of discharge. Consider 3.5v to be 100% discharged.
Cycles generally means the number of 100% discharges expected. If you only discharge 50% theoretically you get twice the rated number. 500 cycles is a common spec for lipo.
4 mm bullets
Bullet connectors are common on hobby king lipo packs. To hook up your lipo, you may need some more of these, or some other type of connector to replace the bullets so your battery can be connected to your controller.
One way to connect two or more 5 ah packs to creat a 10 ah or larger battery . Often created by soldering many bullet connetors to wire, and then soldering the wires together. Connects several packs to one wire. You need two, one for + and one for -.
Kentuky fried fingers. The result of a huge spark, when you screw up and connect the + and - of the same battery. Can happen easy when series connecting packs and you get confused which wire to connect.
After KFF, the shorted pack often melts one of the tabs connecting the pouches. The pack will now appear to be 1 cell smaller to the voltmeter since one cell is now disconnected.
A bad cell often puffs up, as gas is formed inside the pouch. Sometimes salvageable, but usually indicates a cell that will never go the full cycle life. Charge puffies outside, or in a safe area.
A charger intended for charging lipo batteries, and often other types as well. A 6s charger will charge up to 6 cells lipo packs, 8s will charge 8 cell packs, etc. They come in a variety of wattages. 50 watts is sloooow. 150 watts is tolerably fast. Some chargers are as powerfull as 1000 watts, and charge very fast.
Meanwell power supply. A brand name for a switching power supply often used to power lipo chargers. Lipo chargers typically run on DC power, so you need a power supply that matches the voltage the charger likes. 12v power supplies are suitable for the smaller wattage chargers, while larger more powerful chargers may run best on about 20v. A 350 watt power supply can run several 50 watt chargers, two 150 watt chargers, or one 300 watt charger. Power supplies can be used to bulk charge without using a charger.
After series connections are made, it is possible to charge the pack straight from a suitable power supply. Often other electronics are added to shut off the charge when the pack is at the desired voltage. Explaining how to bulk charge is beyond my expertice and experience.
Last edited by dogman
on Mon Apr 04, 2011 3:37 pm, edited 5 times in total.
THE LIPO RULES. NEVER ABOVE 4.3V NEVER BELOW 2.7V DON'T PUNCTURE
Ideal charging /discharging range for Lipo, 3.65v minimum 4.1v maximum
See battery technology section, FAQ thread at the top of the page for lipo noob info.