Hi, I have made something that consist of a YX-850 Power Failure Switch Module that can charge the battery and switch to the battery in case of DC Power Failure, 11.1V 3S LiPo Drone Battery that I have tried making it hot-swappable and that battery is connected to a 3S 20A BMS with its P+ connected to an Adafruit INA219 (in order to check the voltage of the battery) and the Adafruits VIN is connected to the BAT+ of the YX-850.
My problem is that it seems that the battery isn't charging at all, the XL4016 buck (that is connected to DC) shows green LED which might indicate its in CV mode and not CC mode, and the INA219 is also reading the voltage from the DC as well (unless I turn off DC and it switches to the battery).
A 3S LiPo battery needs to be charged to exactly 12.6volt, with a well defined (linear reduced) charge current profile between 12volt and 12.6volt and a reduced current below 10.5volt.
I don't see how your setup can do that safely.
Leo..
I've checked the voltage of what my XL4016 is outputting and it is getting to around 12.9 from the wall which should be sufficient enough since it is also powering my ESP32 and other things aside from charging the LiPo? And I also have it at 1C charging which is around 2A as well. I have been checking the voltages of the battery through the BMS by probing the B- and B+ and it seems to be around between 11.8 to 11.9V so far.
What do you think seems to be the best way for this to be similar to a UPS with what I have so far? The reason I went with LiPo due to it being readily available and is easy to hot-swap (due to the XT60 connector and JST-XH)
The difference between 12.6volt and 12.9volt on a 3S LiPo battery could be an explosion and a fire. Lipo batteries need special chargers with current profiles, not some DIY setup.
A lead/acid or even a LiFePo4 battery is much safer to experiment with.
Leo..
Okay. I guess the best for this is for the battery to act just as a backup and not something that can be charged by my system then unless there is a balance charger on the side.
I only know balancing boards.
They work by diverting (bypassing) charging current away from cells that have reached their maximum voltage, allowing time for other cells in the pack to catch up.
Maybe it should be called a ballance discharger.
Problem is that those systems rely on a reduced charge current when approaching max battery voltage, to not overheat the individual cell ballance dischargers.
If you keep charging with max current to 12.6volt, then you could damage your balancing board with the possibility of driving one cell above the danger level of 4.2volt.
Leo..
What kind of BMS and battery you have. Typically balancer needs to be connected to battery balance wires, otherwise it doesn't charge.
Something like this?
Something like this and I soldered an XT60 male connector to B- and B- and also a 4 pin JST-XH female as well to B- B+ and B1 B2 depending on where the cells, which I tested.
Yeah, I kind of realized that and I have no plans on doing it like I suppose to do which is charging the battery while the DC is on. Which is why, I think, just using the LiPo battery as a backup (not something that can be charged by the YX-850 itself) is fine? As long as there is a charger like an imax b6 on standby to charge the actual battery instead?
I'm wondering as to how Li-ion batteries bad with the YX-850. I am seeing so many projects with it with 18650s (in which I guess Li-ion as well). If you're talking about LiPo in particular then I see that's a case.
What would be my approach in this if I were to go a different way?
The power input is connected directly to the battery through a diode, so unless the input voltage is less than the lowest battery voltage there will always be current flowing into the battery.
LiPo batteries are Li-ion
What would be my approach in this if I were to go a different way?
Depends on what you are making. What are you making?
I just need something that switches to a 12V battery whenever DC fails even if there if it is not fully uninterrupted and if possible, it is easy to swap. Like so far, from my testing, yeah it does switch whenever I switch off the DC power. But in terms of knowing the long-term risk, I am not sure because this hasn't been tested for long periods of time.
We did but I kinda wanna see how it goes with my plan with the something uninterrupted and other stuff. And yes it is somehow uninterrupted, just that the charging thing doesn't work and I am not able to read the voltage of the battery as well (because like you said the power goes through the diode to the battery).
And at the same time, we can defend our papers for this project anyway. In such that using a 12V fail-safe electric strike is the go for this, just so that there is no need for backup power anyway.
