2wGlider said:
Had no ideia that could happen... Besides the power output, my controller is working the same as before the modd, It seems to give the same reading everytime I throttle it.
Do you mean it reads the same current (using an external ammeter with it's own shunt, not reading the controller's shunt) after the mod as before?
If so, it means the mod didn't actually change the shunt resistance, or the controller is not using that shunt to control current flow.
If you mean instead that after the mod it reads the same (now higher than before the mod) reading using that external ammeter whenever it's used under the same conditions, then that is normal.
If you mean the controller itself reports the same (now lower than before the mod) reading whenever it's used under the same conditions, that's also normal, because the shunt resistance doesn't keep changing once it's modified, so it will keep reading the same (wrong, lower) current when it's placed under the same load conditions.
(well actualy now is acting weird, when I throttle the motor goes backwards an inch, thengoes forward lol)
That last is usually a sign of a hall sensor problem. Either a connection issue, a wiring problem, or an actual sensor failure, causing the controller to be unable to determine the rotor position, and so sending the wrong phase order signals and causing it to spin backwards until it reads the other sensors still working normally reporting the wrong spin direction and then it reverses and spins forwards.
This also happens in sensorless-mode of controllers taht support that, when they can't read the BEMF phase signals from the motor correctly at startup; as soon as the motor is moving fast enough it's much easiier to read and so then works normally. (which is why on (probably many) sensorless controllers, pedal-start is either an option that makes it work more reliably, or isn't optional but forced, whether or not the controller uses PAS input).
Do you mean it can go over 45A despite what the amp meter says?
A separate external ammeter will read whatever it is supposed to, as long as it is using it's own external shunt. But any readings the controller itself makes using it's own modified shunt are not correct, and since this modification is essentially uncontrolled, it's not even really easy to predict what the actual shunt resistance is, and thus whether the controller can even read current at all or do any protection (if the resistance is low enough, it effectively doesn't read current flowing, and the controller literally has no idea what is happening regarding current flow).
Some controllers have phase-current monitoring, via shunts or other sensors on the actual phases before they exit the controller, but most don't. Those that do are usually FOC controllers. So if the battery current measurement shunt is modified or unable to read battery current, it is still able to read motor currents, and protect the motor and the phase FETs, but can't protect the battery against excessive discharge currents.
Controllers without phase current monitoring (meaning most controllers) can't reliably monitor any current flow in the system at all once the shunt is modified, because the current they think is flowing is smaller (often far smaller) than what's really happening. They "guess" based on some math what the phase currents are based on the battery current and some info about what it's doing with the motor at the moment...but without the real battery current, all it's guesses are wrong.
Whether anything ever fails because of it depends on how close to the edge of the parts' capabilities the controller was designed to work to start with, and then how much the shunt mod changed it's resistance and thus how far off the readings are from reality, and then how hard the system is pushed and how often. Sometimes stuff blows up the first time it's tried, sometimes it never fails.
How exacly can the DD motor lock up ???
If the FETs in the controller fail, they will usually fail shorted. This essentially shorts the motor phases together. Doing that creates braking forces in the motor...shorting two phases is pretty severe drag but all three is like jamming on a brake. The faster the motor speed, the more current that tries to flow and the harder the braking forces that occur.
If you've never experienced this, and have the desire and time, you could disconnect the motor entirely from the controller, and connect the *motor* phase wires together, first a pair, then all three, and try to manually turn the wheel. The more powerful (torque) the motor design, the harder it will be to turn it this way. If you try spinning the wheel by hand and *then* short them together, you'll find it's even stronger. Don't try it while riding....
Just don't accidentally connect the *controller* phase wires together, because if power is present it may fry your controller and you'll need a new one.
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I was a litle afraid that my motor would burn up with 14S but its doing fine. Could I feed it with 15 or 16S safely if I keep the temperature low? Correct me If I´m wrong, with more amps you need thicker cables, with more voltage you need thicker insulation.
More cells in series isn't more amps. It's more volts. That doesn't burn up motors. It just makes them spin faster for the same throttle setting.
Your controller shunt mod is what makes more amps. That could, though if it hasn't already it's unlikely to.
The insulation on the existing wires, including the windings, is probably capable of handling a couple hundred volts or more, possibly up to a few hundred.
There's not really much specific reason other than finding a BMS to suit the unusual number of series cells to protect it, for using any particular number of series cells, beyond how much voltage you want your system to have to spin the motor at a specific RPM for top speed (which depends on the motor's kV (RPM/volt)), and how much voltage your controller is designed to take.