Best Way to Convert 4S Lipo voltage to 13.8v SLA power?

[sikeston34m]

Originally Posted by lincpimp

A123 cells sound like exactly what you want. 3.3v nominal 3.6 fully charged. 1000 cycle life or so. Since it appears you will be charging them with a 12v style charger they will not reach full charge in a 4s config, but will likely last longer.

I had planned to make a 4s3p pack for my motorcycle, since the charging system should not exceed the max charge voltage.

Plus a123 are much more robust and can handle lower discharge better than lipo. Only downfall is weight and the round cell dimension. Neither should be an issue for your purpose.

I have considered the A123 26650 cell and even the 38120 10ah Headway Lifepo4 cell.

My problem is: the discharge curve for 4S Lifepo4.

When the 4S voltage sags below 12 volts, the motor is going to begin to feel tired.

It would probably stop operating altogether at 10 volts. So, despite the decreased performance, how much capacity is above 3 volts per cell?

A Lifepo4 pack would also be very costly, considering it needs to be a 40ah plus pack.

For a Lithium Ion pack, the hobby charger will be required. This is ok though.

With Lithium Ion, the biggest problem is the voltage converter. Hmmmmm...........