I tried to power the PI1541 through the USB port first.It was getting stuck at the "searching for" screen.
I checked the voltages on the USB pads and the GPIO pins and found out there is a 0.7V voltage drop between them.That shows the USB power protection and regulator circuit is using quite a bit of power.
So I connected the power from the tape port direct to the GPIO pins.
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It is possible to reduce the power consumption of Raspberry PI by disabling the HDMI,WIFI,Bluetooth,Ethernet and USB ports.I added the commands to config.txt file on the SD card.
dtoverlay=pi3-disable-wifi
dtoverlay=pi3-disable-bt
tvservice -o
dtparam=act_led_trigger=none
dtparam=act_led_activelow=on
tee /sys/devices/platform/soc/3f980000.usb/buspower >/dev/null
kernel_address=0x1f00000
force_turbo=1
I tried hooking it up to my LCD TV with the HDMI cable and found out it was still working.So these commands didn't do a thing.I will try to contact Steve White and ask him about this.