I’m working on a project, where I want to go from 5 Lithium-ion cells in series, to 5 Lithium-ion cells in parallel, for versatility purposes i.e. in time, I want to be able to change the output voltage from 5-60V, hence the step-up voltage regulator approach.
What I want to achieve is: To connect a 3.7V Lithium-Ion powersource, to a DC motor (from a powertool) rated at 18V. Later I would like to repeat this for other voltage motors as well.
Is it realistic to build this on a print at the size of circa 10x10x1 cm or 4x4x0.4 inches
For now, I have tried to use an off the shelf Pololu U3V70X Step up voltage regulator with some success. I can get the correct output (18V), however at a very small Amperage, not enough to run the motor. I have also tried to put 3 regulators in parallel, to get higher Amps with some success, but this is not optimal as the Voltages need to be perfectly adjusted.
I have tried to put 3 regulators in series with individual cells as a source, this is needed as the voltage regulators share a common GND (GNDin = GNDout), with an output of 6V each = 18V. This works, however, I still find the Amp output to the low side as I would like to reach 20A max discharge, as this is needed when i start this specific motor.
I can se from the answers, that one of the main concerns are the stall currents of 130A.
A few specs for my setup:
Current working setup from the battery manufacturer: 5x LGDBHE21865 2.5Ah in series = 20V (5x4V) * 2.5Ah = 50Wh Std. discharge 500mA Maximum discharge 20A Link to cell specs: https://secondlifestorage.com/showthread.php?tid=1938
Wanted setup: 5x LGDBHE21865 2.5Ah in parallel = 4V * 12.5Ah (5x2.5Ah) = 50Wh With a step-up boost controller taking 4V->18V with approx. 2.5Ah and stil a max discharge of 20A
Mabuchi RS-775WC-8514 Vin = 6-20V Imax 18.7A
Voltage regulator specs: 3x Pololu U3V70X Adjustable Step up voltage regulators Link to Voltage regulator: https://www.pololu.com/category/243/u3v70x-step-up-voltage-regulators