CustomCarputers
02-08-2008, 08:09 PM
DC-DC Converters
A DC-DC converter does exactly what it says. It takes in DC power of a certain voltage (usually 12 volts) and outputs not just 12 volts but other voltages, commonly 5 volts and 3 volts. Your computer needs several voltages to operate, not just 12 volts. The DC-DC converter supplies each of the various voltages needed to run different parts of the computer including disk drives, USB ports, etc.
A DC-DC converter is more efficient than an inverter, discussed below. However, there are several types of converters and an explanation of the differences is beyond the scope of this discussion. Go to the wikipedia for more information on regulators.
What makes choosing a DC-DC converter so confusing is that they often combine different functions in the chain shown above, into a single product. This makes comparing features difficult. The table attached to this post lists popular DC-DC converters and their functions:
Many commercial units have other features such as low battery monitoring to shut your PC down if the car is off and the PC is turned on or in standby mode. This prevents the PC from draining the battery.
Other devices such as digital startup/shutdown controllers (DSSC’s) or power controllers (CarPC EZ) are not PSU’s but control the sequencing and control of power, such as preventing “thump” when the amplifiers in the car are on but the PC hasn’t yet powered up. These are not strictly DC-DC converters but they work with the components in your system to control the power flow.
User feedback (qualitative) indicate that the Opus is the “Cadillac” of converters, followed by the M1-ATX. The Carnetix is used in conjunction with an existing power supply, such as one that comes in a Casetronix case or a PW-70 type supply. The ITPS is inexpensive but widely regarded as worthless. Here is a link to how to wire an Opus to your car. The other devices are wired in a similar fashion.
All regulators cause the voltage input to drop as it feeds through the regulator. The ITPS is particularly egregious in this regard as it drops voltage by approximately 1.5 volts. When the car is operating, the alternator generally puts out 13.5 volts. This drop then supplies 12 volts to the system. However, when the car is off, the voltage is only 12 volts from the battery and the ITPS only supplies 10.5 volts to the system. This is not sufficient and can cause random freezing and cause failure of data writes to the hard drive.
Calculating how much power your system draws
Keep in mind that the maximum wattage DC-DC power supplies can muster at this writing is around 150 watts with one or two (Maestro, DSATX) emerging in the 200 watt range. This is generally insufficient for Pentium 4 systems. Here are some calculators:
1. Power Supply Calculator - Journey Systems. LLC. Providing Custom PCs, Servers, Laptops, Workstations, Gaming PCs, Quality Custom Computers with 3 Year Warranty (http://www.jscustompcs.com/power_supply/)[/URL]
2. [URL]http://users.erols.com/chare/elec.htm (http://www.ohmygodmyarmfelloff.com/MP3Car/PSUpower.asp)
A DC-DC converter does exactly what it says. It takes in DC power of a certain voltage (usually 12 volts) and outputs not just 12 volts but other voltages, commonly 5 volts and 3 volts. Your computer needs several voltages to operate, not just 12 volts. The DC-DC converter supplies each of the various voltages needed to run different parts of the computer including disk drives, USB ports, etc.
A DC-DC converter is more efficient than an inverter, discussed below. However, there are several types of converters and an explanation of the differences is beyond the scope of this discussion. Go to the wikipedia for more information on regulators.
What makes choosing a DC-DC converter so confusing is that they often combine different functions in the chain shown above, into a single product. This makes comparing features difficult. The table attached to this post lists popular DC-DC converters and their functions:
Many commercial units have other features such as low battery monitoring to shut your PC down if the car is off and the PC is turned on or in standby mode. This prevents the PC from draining the battery.
Other devices such as digital startup/shutdown controllers (DSSC’s) or power controllers (CarPC EZ) are not PSU’s but control the sequencing and control of power, such as preventing “thump” when the amplifiers in the car are on but the PC hasn’t yet powered up. These are not strictly DC-DC converters but they work with the components in your system to control the power flow.
User feedback (qualitative) indicate that the Opus is the “Cadillac” of converters, followed by the M1-ATX. The Carnetix is used in conjunction with an existing power supply, such as one that comes in a Casetronix case or a PW-70 type supply. The ITPS is inexpensive but widely regarded as worthless. Here is a link to how to wire an Opus to your car. The other devices are wired in a similar fashion.
All regulators cause the voltage input to drop as it feeds through the regulator. The ITPS is particularly egregious in this regard as it drops voltage by approximately 1.5 volts. When the car is operating, the alternator generally puts out 13.5 volts. This drop then supplies 12 volts to the system. However, when the car is off, the voltage is only 12 volts from the battery and the ITPS only supplies 10.5 volts to the system. This is not sufficient and can cause random freezing and cause failure of data writes to the hard drive.
Calculating how much power your system draws
Keep in mind that the maximum wattage DC-DC power supplies can muster at this writing is around 150 watts with one or two (Maestro, DSATX) emerging in the 200 watt range. This is generally insufficient for Pentium 4 systems. Here are some calculators:
1. Power Supply Calculator - Journey Systems. LLC. Providing Custom PCs, Servers, Laptops, Workstations, Gaming PCs, Quality Custom Computers with 3 Year Warranty (http://www.jscustompcs.com/power_supply/)[/URL]
2. [URL]http://users.erols.com/chare/elec.htm (http://www.ohmygodmyarmfelloff.com/MP3Car/PSUpower.asp)