BINGO! You hit it on the head, I was indeed pulling from B battery. I just tried using the whole 24 volts to supply power to a BEC. The unit BEC worked without blowing either fuse now attached to the power leads for the BEC.
I completely agree the controls should be on a separate battery. I also suspect it will chase away some of the occasional motor jerking I seem to run into. On a side note, I noted that my Sabertooth made a popping noise a little bit ago. I figured I blew the control unit. I decided to peel it apart to take a look see. Turns out the post for the negative connector had a faulty solder joint or perhaps (most likely) damage to my faulty hookup describe above. A dab of solder and back to work it went. I'm beginning to take a liking to this Sabertooth. Thanks for all your help Frank! On Apr 2, 11:07 am, Frank Pittelli <[email protected]> wrote: > I suspect the problem is that you are drawing your 12v signal from the > wrong battery. Basically, you need to make sure that all circuits use > the same "ground". Specifically, suppose you have two 12V batteries, A > & B, connected in series as your main 24v power supply. Let's assume > that the negative terminal of the A battery is your 24v Ground and the > positive terminal of the B battery is your +24V. In that case, you > should tap all 12v signals using the "A" battery, not the "B" battery. > Otherwise, the ground for the 12V systems will be 12v higher than the > ground for the 24v systems. Many ESCs connect their input and output > grounds together, thereby causing a dead-short if you tap 12v from the B > battery. > > I strongly recommend that people use completely separate batteries for > their electronics and controllers, leaving the main batteries to drive > heavy loads, like motors and solenoids. That not only protects you > against system wiring problems, but it also keeps the electrical noises > and heavy current pulses caused by power hungry motors away from your > sensitive electronics. > > Case in point, one of my C6C customers was using the C6C to drive a big > robot. Worked fine most of the time, but it sometimes caused problems. > After asking about his circuits he told me about a BEC he had > installed to "make things simpler". I recommended a separate battery to > eliminate electrical problems caused by the motors drawing down the > voltage in the main batteries. He swore that the BEC would prevent such > problems. I told him that the common ground had no protection and > therefore he had no protection at all from electrical disturbances of > all kinds. He said he thought it was something else. Two months later > he wrote saying that he finally tried the separate battery and it worked > perfectly ever since. > > Frank P. > > On 4/2/2011 9:37 AM, Rusty Bates wrote: > > > > > > > > > Hello all, > > > I installed a Sabertooth 2x25 a few weeks ago. The unit appears to do > > fine other than a few jerks from the motors on occasion, I believe it > > may be radio interference. I'm using a FM ground Freq radio purchased > > just for this unit. I still need to tie in some caps to the motors and > > make sure the radio antenna is installed correctly so at this point > > I'm not really concerned about it. > > > But and a very big but here, I ran into something the other day that > > gave me pause. > > Although the Sabertooth has a BEC, I have been using the battery pack > > that came along with the radio to power the receiver. This setup is > > fine and I've experienced no issues other than mentioned above. > > > The next step was to install my sound unit (a home brewed unit using a > > few PICAXE chips and 2 Vmusic sound modules) into the tank, again > > using the battery supplied for the receiver. The unit has a 12 volt > > regulated power supply included and uses a simple Y connector for the > > radio signal. I've used this unit with success in my past setup using > > Joe Sommers ESC. I tested the unit without applying power to the ESC. > > The unit worked fine! > > > But then I decided to apply power to the Sabertooth and run the tank. > > It took about 3 seconds before the negative wire leading to the sound > > unit began smoking. Lucky for me no damage occurred to the receiver or > > ESC. I figured I wired something wrong, but upon inspection decided > > every thing was as I have had before in a past setup. > > > I then removed the sound unit from the system and decided to install > > my home brewed BEC circuit (A simple 12 volt regulator circuit > > supplying 4.5 volts) into the receiver. Once again I tied the power > > supply to one battery for a 12 volt source. Power up the ESC and > > watched smoke as the NEG wire to started to sizzle. Again no damage > > to the either receiver or ESC. I tested both units wired as before > > with the original receiver battery and then with the on board BEC and > > the ESC and REC seem to operate thankfully. > > > I use two 12 volt batteries for a 24 volt system. I'm about 95% sure > > that in the past I simply tied the power supply (12 volt input) for > > the sound unit to one battery. Not sure why I didn't just power the > > sound control unit with 24 volts as the 12 volt regulator will accept > > up to 35 volts. Be that as it may, I'm still pretty sure it was only > > supplied 12 volts. > > > Now I know from building the sound control and even a smoke control > > unit that the entire circuit has to share a common ground or else the > > PICAXE chip will not work correctly with the radio signal. But this > > has burning up of the negative wire has me spooked. And yes before I > > go any further I plan on installing a control fuse in the negative > > side to help prevent any further damage. > > > So I guess one of my biggest questions is could the circuit being > > fried is due my hooking up only side of the battery set to the sound > > unit? Could the ESC cause this short of shorting? > > > Any help, thoughts would be greatly welcome! > > > Rusty -- You are currently subscribed to the "R/C Tank Combat" group. To post a message, send email to [email protected] To unsubscribe, send email to [email protected] Visit the group at http://groups.google.com/group/rctankcombat
