Bruno Bronosky Posted May 17, 2019 Share Posted May 17, 2019 My daughter has lost the charger to her AirWheel X3. I'm wondering... 1. Is the power brick is a generic power supply and all the charging circuitry (including the cutoff logic) is in the AirWheel body? If this is the case, I should not have any problem charging it or timing the charge to full. 2. Does the internal charger (assuming my first question is true) have its own current limiter? Most consumer electronics will not be damaged by a power source with a high current capacity as long as the voltage is correct. The V = I x R equation ensures this. However, that assume that the limiting resistance is in the consumer. If the device is expecting the supply to provide the resistance that limits the current and the supply is expecting the device to provide the resistance, this can be a problem. Please advise. 1 Quote Link to comment Share on other sites More sharing options...
Chriull Posted May 17, 2019 Share Posted May 17, 2019 54 minutes ago, Bruno Bronosky said: My daughter has lost the charger to her AirWheel X3. I'm wondering... 1. Is the power brick is a generic power supply and all the charging circuitry (including the cutoff logic) is in the AirWheel body? If this is the case, I should not have any problem charging it or timing the charge to full. 2. Does the internal charger (assuming my first question is true) have its own current limiter? Most consumer electronics will not be damaged by a power source with a high current capacity as long as the voltage is correct. The V = I x R equation ensures this. However, that assume that the limiting resistance is in the consumer. If the device is expecting the supply to provide the resistance that limits the current and the supply is expecting the device to provide the resistance, this can be a problem. Please advise. Charging liion needs a constant current first and then a constant voltage: https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries 1 Quote Link to comment Share on other sites More sharing options...
Bruno Bronosky Posted May 19, 2019 Author Share Posted May 19, 2019 On 5/17/2019 at 5:32 PM, Chriull said: Charging liion needs a constant current first and then a constant voltage: https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries Your statement is true. But both of my questions remain unanswered. What a lithium ion battery needs is assumed. The questions are about where the logic is that meets the needs. Is the logic in the BMS internal to the AirWheel, or is the logic in the external PSU? 1 Quote Link to comment Share on other sites More sharing options...
Chriull Posted May 19, 2019 Share Posted May 19, 2019 6 hours ago, Bruno Bronosky said: Your statement is true. But both of my questions remain unanswered. What a lithium ion battery needs is assumed. The questions are about where the logic is that meets the needs. Is the logic in the BMS internal to the AirWheel, or is the logic in the external PSU? The logic is in the PSU. They have this max current limit for the CC phase and a max voltage for the CV phase. And the "low current" threshold to cut off at the end of the CV phase. The BMS just has for each cell an overvoltage protection, that can cut the charge input. 2 Quote Link to comment Share on other sites More sharing options...
esaj Posted May 19, 2019 Share Posted May 19, 2019 (edited) Most bench power supplies (I'm assuming you mean what I understand to be a bench power supply, aka laboratory power supply) have current limiting, ie. they are constant current / constant voltage (CC/CV) power supplies, although there are some cheap models that have no limiting. Another issue is the relatively high voltage required for charging (I think Airwheels use 16S batteries = 67.2V max). Typical bench supplies are low voltage that can go maybe up to 30V. Even my industrial-grade programmable rack-mounted power supply can only go up to 30V. I have a couple of CC/CV 0-100V / 1A / 100W linears for higher voltage usage. IF your bench supply can go high enough in voltage, but has no current limiting, I'd be very careful trying to charge lithium batteries with it, although it is possible, but you need to turn up the voltage SLOWLY, keeping the current at low amps (say, 2A or less), and adjusting the voltage up until you hit 67.2V, then just leave it charging (although do monitor it so you can cut the power in case of trouble). Not something I'd definitely try unless you're familiar with how li-ion charging works and the risks involved, especially since I have no idea if the Airwheel BMS has reverse protections or such. Edited May 19, 2019 by esaj 1 Quote Link to comment Share on other sites More sharing options...
Bruno Bronosky Posted May 28, 2019 Author Share Posted May 28, 2019 All the bench supplies I could find had a 30v max. I ended up buying a MPPT "Solar Charger" and driving it with a laptop brick instead of a solar panel. https://imgur.com/gallery/HqlyisA 2 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.