RVD
1 kW
I realize that I'm talking about a quadcopter/drone and not a bike but I figured some of you might be interested anyway.
I have recently started flying drones and one of the interesting aspects of the phantom 3 that I fly is that it has a 4s 4480 mah lipo battery. It has a proprietary BMS to make it a "smart" battery. The connectors are also proprietary (similar to traxxas but not quite). They also charge $149/battery. From what I can gather, it charges each cell up to 4.3v and discharges down to about 3.3v (which is when the reading hits 0%). It also appears to have an automatic kill / shut off if it detects <3.0v/cell. There are also some discharge features (e.g. after 10 days of non-use, discharge to 3.8v for storage mode), etc. DJI also recommends discharging to 8% and then fully charging every 20 cycles (i didn't think this was necessary with lipo...).
But the interesting part is that there have been many cases recently of people reporting that their drone simply stops flying mid-air and drops to the ground (obviously causing all kinds of damage, etc.).
After some research it appears that:
1) dji uses voltage to guess the % of battery life
2) if the battery is low on voltage (say 3.5v/cell) and max throttle is applied, that can result in voltage sag bringing down the battery to <3.0v/cell causing the unit to shut down (mid air, etc.).
3) dji updated firmware last week to address this by limiting the throttle when voltage is low (users have taken this to mean that their drone will be "slower" now so this sucks)
4) dji recommends that you never take off unless you have a fully charged battery. people have reported taking off with a 60% full battery only to have the drone fall from the sky 10 seconds later while going full throttle up.
Seems like a bit of a cluster. I'm not sure what DJI should do but I would hope they can put in some type of system that measures amps used instead of voltage to get a more accurate battery % reading as well as remove the shutoff at <3.0v (seems better to have a damaged battery than a drone falling from the sky).
Just thought y'all might be interested in case you decide to get into flying drones around to follow you on your bikes. I haven't tried that mode yet but one of these days I'll have the drone follow me while I ride my BBS02 mid-drive bike.
I have recently started flying drones and one of the interesting aspects of the phantom 3 that I fly is that it has a 4s 4480 mah lipo battery. It has a proprietary BMS to make it a "smart" battery. The connectors are also proprietary (similar to traxxas but not quite). They also charge $149/battery. From what I can gather, it charges each cell up to 4.3v and discharges down to about 3.3v (which is when the reading hits 0%). It also appears to have an automatic kill / shut off if it detects <3.0v/cell. There are also some discharge features (e.g. after 10 days of non-use, discharge to 3.8v for storage mode), etc. DJI also recommends discharging to 8% and then fully charging every 20 cycles (i didn't think this was necessary with lipo...).
But the interesting part is that there have been many cases recently of people reporting that their drone simply stops flying mid-air and drops to the ground (obviously causing all kinds of damage, etc.).
After some research it appears that:
1) dji uses voltage to guess the % of battery life
2) if the battery is low on voltage (say 3.5v/cell) and max throttle is applied, that can result in voltage sag bringing down the battery to <3.0v/cell causing the unit to shut down (mid air, etc.).
3) dji updated firmware last week to address this by limiting the throttle when voltage is low (users have taken this to mean that their drone will be "slower" now so this sucks)
4) dji recommends that you never take off unless you have a fully charged battery. people have reported taking off with a 60% full battery only to have the drone fall from the sky 10 seconds later while going full throttle up.
Seems like a bit of a cluster. I'm not sure what DJI should do but I would hope they can put in some type of system that measures amps used instead of voltage to get a more accurate battery % reading as well as remove the shutoff at <3.0v (seems better to have a damaged battery than a drone falling from the sky).
Just thought y'all might be interested in case you decide to get into flying drones around to follow you on your bikes. I haven't tried that mode yet but one of these days I'll have the drone follow me while I ride my BBS02 mid-drive bike.
