2022 02 02
We like the XFinity Battery
2Ah, 4Ah, and 8Ah (if you are lucky enough to be able to buy them)
Mechanically they are great, they clip in neatly, and they are quite sturdy.
Fantastic for lights, motor drives, little projects, ….
and then you find that the 4Ah and 8Ah batteries look like they turn off momentarily about every 30 seconds (about every 60 seconds for the 8Ah battery) …
so lets have a look, the following is using a 4Ah Battery …
XFinity Battery 4Ah Battery
XFinity Battery No Load
This is the output from the battery with no other connected load, just the CRO.
Yes, that is 10V.
CRO Probe set to 10x
XFinity Battery – On Connection of 220R Load
This is what happens at the battery terminals when you connect a 220R load.
The output falls from 10V to 0V on connection of the load, and about 120ms later the output turns ON to 20V.
and then about every 30 seconds with that 220R load connected, this is what happens at the battery terminals ..
XFinity Battery – 220R Load Periodic OFF Pulse
so about every 30 seconds, the battery terminals drop to 0V for about 800us (0.8ms) and then back ON to 20V.
In some respects this isn’t exactly expected behavior.
(From hereon, I’m going to call this the “Periodic OFF Pulse”)
And for primitive loads, such as a motor or a light, this is not really able to be noticed by a human.
But for some electronic loads, this isn’t helpful at all.
ok, deep breath, what happens when the load is removed and the 30 seconds expires ..
XFinity Battery – No Load Turn OFF
so thinking about this,
I am going to take the point of view that the battery goes to “SLEEP” every 30 seconds, and if sufficient load is present, restarts after 0.8ms.
and I’m going to take the point of view that this minimises the load when the battery is sitting idle for long periods.
ok, so whats the minimim load that the battery will restart with ..
XFinity Battery – 10k Load Periodic OFF Pulse
This is the Periodic OFF Pulse with a 10k load.
I leave it to you to try Periodic OFF Pulse response with other resistive load values.
so armed with the information above, I thought I would try a simple circuit and check battery terminal response
XFinity Battery – Simple CCT Test
XFinity Battery – Simple CCT Periodic OFF Pulse
and as expected, the 10k across the battery is enough for restart, and the 2200uF capacitor holds up power to the load during the Periodic OFF Pulse.
So based on this concept, we can decide how to manage any electronic load for an XFinity battery depending on your needs.