Series Lipo packs- How to know how much voltage is too much?

[adrock8519]

Hi, I just wonder how do tell if you are making too many series connection with Lipo packs. I know they have a C rating but surely there must be a limit to the amount of volts and current you can pull through them?
Kr,
Adam

 

[miuan]

You don't pull volts through a battery. You pull current. The maximum current you can pull is the Capacity times C-rate, e.g. 5000mAh times 20C = 100 Amps, but make sure you pull less than one third of this for extended periods, otherwise the packs die an early death. You can series as many as you want provided all the cells in series are well matched for capacity and C-rate, and their voltages are balanced. The voltage limit is your charger, motor and controller.

 

[dogman dan]

The cheaper motors I've had reach their limit long before the packs do.

But its worth noting that if you want better wiring, the higher c rate packs come with thicker wire and bigger connectors than the 20c stuff.

IMO, 20 c stuff for mundane ebikes, commuters, grocery getters. If you are building a performance bike, get 30c or more, and then you get the 8 g wire.

 

[adrock8519]

cheers guys. So the voltage is just like the speed of the electric and that doesnt have a resistance force. However the amperage is the pressure that causes resistance and there for heat waste etc,?

 

[Ykick]

Let’s introduce you to Georg Ohm’s law…

https://en.wikipedia.org/wiki/Ohm%27s_law

http://www.hamuniverse.com/ohmslaw.html

http://www.electronics-tutorials.ws/dccircuits/dcp_2.html

 

[miuan]

cheers guys. So the voltage is just like the speed of the electric and that doesnt have a resistance force. However the amperage is the pressure that causes resistance and there for heat waste etc,?

Speed of electricity is about constant. Voltage is pressure, not amps. What causes resistance is limited conductivity of batteries and wires alike. The more amps you pull thru various conductors the bigger part of your total voltage is lost as heat.