outhouseengineering
New Member
- Joined
- Jan 23, 2021
- Messages
- 2
Good morning. Somewhat a digression from the systems themselves but here in New England it is cold working outside many days in the winter months. I am looking to utilize the multiple 20 & 18 volt power tool batteries in hand to power my 12 volt, 85 watt motorcycle heated jacket liner. To date, there doesn't seem to be manufactured battery packs that will handle this load for at least 6-8 hours. Yes, there are many lower wattage 12 volt clothing lines, which do not have as much resistive heat designed in them and will allow a longer run time, but at a significantly reduced heat output. And the battery packs from my clothing line are in the neighborhood of $ 250 and then comes the need for a matched controller and remote at additional cost.
I am thinking of how to utilize a DC-DC chopper (Buck Converter) to achieve a reasonable wattage output at a regulated 12-13.5 volts. Given the power tool batteries are either 20 volts or 18 volts, depending on brand, and have ampere hour ratings between 5 & 6 ampere hours, I am assuming I can pull close to an hour of full 85 watt draw from the 18 volt/6 ah power tool battery if using one of these DC-DC voltage reducing converters and expecting some losses due to transformation inefficiencies. My math - ( Jacket: 12 volts X 7 amps = 84 watts) (Battery Draw: 84 watts / 18 volts = 4.7 amps) (Duration of Power Draw: 6 ah rated battery / 4.7 amps = 1.28 hours) Seeing as I normally run the jacket at a lower (medium) heat, which has the controller basically turning on & off the power at varying intervals, I am thinking I will probably squeeze a bit more time from a battery. And when the power of one battery is depleted, I simply swap it out for another.
So given the approach, and my limited research online of DC-DC converters, I am seeking any experienced feedback on these DC-DC converters, which seem fairly inexpensive, as to whether I can utilize one of these and more specifically what the input voltage specification should be. I am totally confused as to whether one rated at 48 or 24 volt input needs to have a continuously regulated 48 volts DC, or regulated 24 volts DC, for the input or if my input voltage could fluctuate as will be the case with the discharging and decreasing voltage of my input voltage source. And if the input voltage can have a fluctuating range, within reason, does that in turn affect the output voltage? I will note that I have considered the likelihood that at some point the supply battery will either discharge to an inoperable level, or in the case of these lithium power tool batteries, just shut off when they fall below a set point. I do realize that at some point in reduced supply voltage, I can not expect an operable load supply voltage. This may also assist others in different applications as well.
Thanks for any thoughts.
I am thinking of how to utilize a DC-DC chopper (Buck Converter) to achieve a reasonable wattage output at a regulated 12-13.5 volts. Given the power tool batteries are either 20 volts or 18 volts, depending on brand, and have ampere hour ratings between 5 & 6 ampere hours, I am assuming I can pull close to an hour of full 85 watt draw from the 18 volt/6 ah power tool battery if using one of these DC-DC voltage reducing converters and expecting some losses due to transformation inefficiencies. My math - ( Jacket: 12 volts X 7 amps = 84 watts) (Battery Draw: 84 watts / 18 volts = 4.7 amps) (Duration of Power Draw: 6 ah rated battery / 4.7 amps = 1.28 hours) Seeing as I normally run the jacket at a lower (medium) heat, which has the controller basically turning on & off the power at varying intervals, I am thinking I will probably squeeze a bit more time from a battery. And when the power of one battery is depleted, I simply swap it out for another.
So given the approach, and my limited research online of DC-DC converters, I am seeking any experienced feedback on these DC-DC converters, which seem fairly inexpensive, as to whether I can utilize one of these and more specifically what the input voltage specification should be. I am totally confused as to whether one rated at 48 or 24 volt input needs to have a continuously regulated 48 volts DC, or regulated 24 volts DC, for the input or if my input voltage could fluctuate as will be the case with the discharging and decreasing voltage of my input voltage source. And if the input voltage can have a fluctuating range, within reason, does that in turn affect the output voltage? I will note that I have considered the likelihood that at some point the supply battery will either discharge to an inoperable level, or in the case of these lithium power tool batteries, just shut off when they fall below a set point. I do realize that at some point in reduced supply voltage, I can not expect an operable load supply voltage. This may also assist others in different applications as well.
Thanks for any thoughts.