How did you determine this ? A battery does not “send power”, and it’s unlikely they were significantly over voltage, a device connected to a battery uses as much power as it needs.
The photo’s in this thread…
show damaged transistors, they are part of the H-bridge circuit that controls the motors on ports 1 and 10.
This is almost always caused by damaged motor wires, something like this.
While it is highly unlikely the batteries were significantly over voltage if they were using the appropriate batteries instead of some other batteries, batteries most certainly do sent current and power. Batteries provide a potential difference. That potential difference will force its way into driving current if it can, even if a device wouldn’t normally want that much. Similarly, a device might want more than the battery can provide under the circumstances, and the device will not get what it needs. But, again, it is highly unlikely proper batteries could provide too much potential difference and blow out a Cortex. I’m not even aware of any way of potentially pulling this off with proper batteries, though I could do it trivially using the wrong batteries.
However, as a general rule in electric circuits, inductance can fry things pretty easily. The induced EMF from a rapid change can spike, and that spike can do a lot of damage. That’s why coils are usually built with safety diodes, paths to reroute the current from such a spike so that it doesn’t fry things. Could it be that one of the motors is damage so that does create high-EMF spikes that affect the Cortex? I would find that far more likely than the batteries being of too high voltage (assuming proper batteries).
ok, I do understand circuit theory and how batteries work, I was trying to dumb it down.
The parts used in the cortex can withstand 8A continuous current (roughly twice motor stall current) and something like 48A pulsed current. They also withstand several times the normal operating voltage of the battery. Yes, there will be high emf spikes, lots of information about that here on vex forum, one such thread (with links to others)
However, I think every time I’ve seen these components damaged in either the cortex or the MC29 (same parts) it has been traced to a damaged motor, that is. motor or wires shorted somehow.
Yes, that was why my first group of questions included asking about the motor and motor controllers individually working? I first figured there was a short somewhere, or maybe multiple shorts.
This is weird. So, if it’s the battery, how was it damaged? Wire connections?
@Got a Screw Loose
@callen
@jpearman
To fix my phrasing the cortex wanted to much battery power or something along the lines. In sense we had two motors hooked up to a cortex port 1 and port 4, neither wire was damaged. we had a simple command of run the motors when the joystick is pushed, after 2 minutes it blew two fuses that work with the motor. From what I saw is that when we did the testing both batteries had a knife stab in them, which we are still determining who did and why it occurred and it first blew the fuse on the top then the one on the bottom and all the motor ports got extremely hot. My theory/explanation is either A) The punctured battery caused it. Because two cortexes can’t be that faulty, it has to be something wrong with the battery, we had a total of 4 cortexes two were destroyed due to this reason.
Firstly, let me get off topic here for a second. I have never actually successfully been tagged. The “Got a” is linked, but the “screw loose” isn’t. It’s kind of weird. I kind of suspect it has to do with my name’s length and/or spaces. Are you tagging me manually, or selecting my name from the drop down list? I’ll make a new thread, but first I want to know what’s going on.
Back on topic, evetrything works fine after you swapped out the battery and coupled it with a different cortex? If possible, could you also post a picture of the battery that was ruined? Just want to ensure we are all envisioning the same thing.
@Got a Screw Loose
I am doing the tagging by drop down i just write got and then it finds you name.
Back on topic: No we are currently still trying to find a new battery currently i don’t have the battery on hand because the kit is at a team members house, i’ll be getting the battery on monday then i will send you a pic.
@Got a Screw Loose
It’s been solved
we think the weight of our double reverse 4 bar is too heavy so we are adding extra motors to help lift it up.
Great! But it could also be too much friction in the mechanisms surrounding it. Or other issues. If you want to add more motors, go ahead. But there may be easier mechanical solutions.
To give a status update here was the problem,
My Team and I essentially didn’t symmetrical built it so the claw portion was like 10in wide meanwhile the top was like 12in which caused a whole problem.
