Front hull with embedded head light

thingiverse

This is a remix of the file "Chassis_2_V1" for Staind's RC Tank.\r\n\r\nI wanted to add some headlights and I found a cool looking USB bike light for about 6 Euro on Ebay. It is somewhat oversized, but I like this asymmetrical "hull mounted laser gun" look of the light embedded in the hull. \r\nThe light is held in place by a M3x5 screw, which is a bit of a hassle to unscrew. I recommend removing the right motor, to avoid breaking your fingers.\r\n\r\nThe next step is to replace the LED driver which requires pushing a little button on the back plate of the light to switch it on and off. A constant current driver operating from 6 V to 15 V should do nicely for powering it directly from the main battery and adding an RC switch to control the light by the transmitter.\r\n\r\nI printed the chassis without supports using PETG and lots of cooling.\r\n\r\nHere is the URL of the light:\r\n\r\nhttp://www.ebay.de/itm/MINI-USB-5000lm-XML-T6-LED-Fahrradlampe-Licht-Fahrradbeleuchtung-Fahrradlicht/142130574338?ssPageName=STRK%3AMEBIDX%3AIT&var=441208015357&_trksid=p2060353.m2749.l2649\r\n\r\nThe same light is also available from AliExpress. The size is 28 mm x 28 mm.\r\n\r\nEdit:\r\n\r\n2017-12-16\r\n\r\nAdded a back cover for the USB bike light. It uses the screws from the original back cover of the light and has an opening for the wires to the PCB which drives the LED. The PCB is glued into place in the ring on the inner side of the cover plate.\r\n2017-10-18\r\n\r\nMade some measurements of the light's current draw and power consumption:\r\n\r\nInput 5V from USB Power Bank\r\nLED current: mode 1: 0.3 A, mode 2: 0.6 A, mode 3: 1.15 A\r\n\r\nSo when powered from a USB source, the LED runs with a forward current up to 1.15 A. I personally would aim for something between 0.75 A and 1 A. Just to be sure. The difference in brightness is not really that great.\r\n\r\nAfter removing the built-in driver and control board with the bothersome 3-mode switch (which prevents the light from being controlled via an RC switch), I coupled the LED with this constant current LED driver:\r\n\r\nhttp://www.dx.com/de/p/3-6v-9v-800ma-regulated-ic-circuit-board-for-cree-and-ssc-leds-4-pack-3256#.Weee2DtpGpp\r\n\r\nIt says the output is 925 mA constant current, but like with all cheap Chinese circuit boards, the actual value might be somewhat different:\r\n\r\nInput voltage | input current | Power Consumption | LED Current\r\n4.5 V | 0.59 A | 2.6 W | 0.78 A\r\n5.5 V | 0.48 A | 2.68 W | 0.78 A\r\n6.5 V | 0.42 A | 2.7 W | 0.78 A\r\n8 V | 0.4 A | 2.73 W | 0.77 A\r\n9 V | 0.3 A | 2.9 W | 0.8 A\r\n9.5 V | 0.43 A | 4.14 W | 1.1 A\r\n10 V | 0.51 A | 5 W | 1.28 A\r\n\r\nSo between about 4 V to about 9 V input voltage, the driver gives a reliably stable constant current of about 0.8 A, which I consider a good trade-off between brightness, power consumption, and heat generation -> long-time safety for the LED. Perfect for powering the driver with a 2S LiPo.\r\nI would not recommend running the LED with 1.28 A @ 10 V input voltage, as it might reduce the LED's lifespan.