Tomapowa
Jan 14, 2009, 01:04 AM
Not a high-tech project but I often get asked this question re: powering high-current models.
Here's an idea I use on all my high powered models (6s-14s) which allows me to power up (i.e. "arm") my models without having to take off a wing or canopy. Currently, very few products are sold that allow you to safely and efficiently switch high voltage/current systems. As most of us know, there is not an easy way to get around (i.e. arrest) the dreaded "Spark" when connecting large batteries to models, and hence tend to ruin connectors over time (be sure to occasionally check them!... my heli friend lost his $1400 heli due to a "carbonized" connectors). Such spark arrestors have previously been discussed here in RC Groups (http://www.rcgroups.com/forums/showthread.php?t=759403&highlight=spark+anti) and a few applications have been mentioned. I opted to use Anderson Power Poles (better contacts and higher current rating) and a new arming switch sold by MPI (http://www.maxxprod.com/mpi/mpi-21.html ... see bottom of page). As for the spark arrestor, I used a 1.8 ohm 5 watt resistor, which by use of a momentary button, is applied across the arming circuit (allows the ESC's onboard filtering capacitors to gradually charge instead of trying to instantaneously charge, hence the spark). To arm my model, I simply press this momentary arming button, then while held in, I attach the main arming jumper, releasing the momentary button. This main arming jumper is made from two Anderson Power Poles and a short wire jumper. I have this setup installed in over 6 larger planes of mine and has worked flawlessly. It also makes it very easy to disconnect power upon landing. Thought I'd pass on the idea...
p.s. Here's another cool link that contains some info on spark arrestors, including a neat calculator to determine the resistor size needed for certain applications:
http://scriptasylum.com/rc_speed/_nospark.html
Here's an idea I use on all my high powered models (6s-14s) which allows me to power up (i.e. "arm") my models without having to take off a wing or canopy. Currently, very few products are sold that allow you to safely and efficiently switch high voltage/current systems. As most of us know, there is not an easy way to get around (i.e. arrest) the dreaded "Spark" when connecting large batteries to models, and hence tend to ruin connectors over time (be sure to occasionally check them!... my heli friend lost his $1400 heli due to a "carbonized" connectors). Such spark arrestors have previously been discussed here in RC Groups (http://www.rcgroups.com/forums/showthread.php?t=759403&highlight=spark+anti) and a few applications have been mentioned. I opted to use Anderson Power Poles (better contacts and higher current rating) and a new arming switch sold by MPI (http://www.maxxprod.com/mpi/mpi-21.html ... see bottom of page). As for the spark arrestor, I used a 1.8 ohm 5 watt resistor, which by use of a momentary button, is applied across the arming circuit (allows the ESC's onboard filtering capacitors to gradually charge instead of trying to instantaneously charge, hence the spark). To arm my model, I simply press this momentary arming button, then while held in, I attach the main arming jumper, releasing the momentary button. This main arming jumper is made from two Anderson Power Poles and a short wire jumper. I have this setup installed in over 6 larger planes of mine and has worked flawlessly. It also makes it very easy to disconnect power upon landing. Thought I'd pass on the idea...
p.s. Here's another cool link that contains some info on spark arrestors, including a neat calculator to determine the resistor size needed for certain applications:
http://scriptasylum.com/rc_speed/_nospark.html