SpeedEBikes
100 W
All of the controllers I have used have fairly high standby power requirements, ranging from about 2 to 12 watts depending on the supply voltage. If one forgets to turn off power the standby drain can completely discharge a pack in a day or two, especially if the pack was fairly deeply discharged in the previous use. Even with a BMS with per cell LVC, trickling a lithium battery down to the cutoff is hard on it, especially if the cutoff point is set aggressively low as is typical. Without a cutoff lithium packs can be destroyed and most other chemistries will be somewhat degraded by such a deep discharge. Even if no harm is done it is still annoying to find ones battery significantly more depleted than one was expecting. I usually leave my lithium batteries standing at around 3.7 v per cell which is sufficient to do my typical shorter errands on a moments notice without any charging.
My guess is the large standby power draw is due to sloppy controller design. It goes up fast with higher input voltages and I expect most of it is drawn by crude voltage regulators for the low voltage supplies.
Are there bldc controllers that do this right and only use a few milliwatts of standby power regardless of input voltage?
Are there any external devices that could be placed between a battery and the controller that could accurately detect an 'idle' situation and cut power? Can this be done by a drain brain / cycle analyst?
At worst, could a timer switch be used such as are put on heat lamps in bathrooms? I'd be concerned about inadvertantly switching off power while under load. Are there timer switches available that can cleanly disconnect a 20 amp draw at 75+ DC volts and would the switch see much of an induced voltage spike? Is abruptly disconnecting power hard on the controller and could it cause controller failure under any circumstances? I've had BMS units repeatedly cut power at full throttle without controller damage. But I've never had a wiring failure or BMS disconnect while blasting down hill when motor back EMF is super high. Are there timers with long duration settings, say 4 hours which would be sufficient to minimize risk of an inadvertant shutoff while in use?
How hard would it be to mod a controller to reduce standby power? Are there ICs available that can do efficient voltage conversion/regulation for the low voltage supply?
If standby power could be dropped to a fraction of a watt and with the addition of a flashing power LED and perhaps a piezo beep every few seconds after say 5 minutes of 'idling' I'd be pretty happy.
My guess is the large standby power draw is due to sloppy controller design. It goes up fast with higher input voltages and I expect most of it is drawn by crude voltage regulators for the low voltage supplies.
Are there bldc controllers that do this right and only use a few milliwatts of standby power regardless of input voltage?
Are there any external devices that could be placed between a battery and the controller that could accurately detect an 'idle' situation and cut power? Can this be done by a drain brain / cycle analyst?
At worst, could a timer switch be used such as are put on heat lamps in bathrooms? I'd be concerned about inadvertantly switching off power while under load. Are there timer switches available that can cleanly disconnect a 20 amp draw at 75+ DC volts and would the switch see much of an induced voltage spike? Is abruptly disconnecting power hard on the controller and could it cause controller failure under any circumstances? I've had BMS units repeatedly cut power at full throttle without controller damage. But I've never had a wiring failure or BMS disconnect while blasting down hill when motor back EMF is super high. Are there timers with long duration settings, say 4 hours which would be sufficient to minimize risk of an inadvertant shutoff while in use?
How hard would it be to mod a controller to reduce standby power? Are there ICs available that can do efficient voltage conversion/regulation for the low voltage supply?
If standby power could be dropped to a fraction of a watt and with the addition of a flashing power LED and perhaps a piezo beep every few seconds after say 5 minutes of 'idling' I'd be pretty happy.