Very interesting. Thanks
El mié, 22 oct 2025, 0:15, Scott McDonnell <[email protected]> escribió: > Same seller that I bought from. > > I haven't cracked it open to investigate. I may do that to figure out a > way to get around the always powered on. It could be that my particular > battery bank has a low trigger point. > > You actually may be right about the efficiency. Good points. I will have > to investigate further. But for $12, it was a cheap solution. I am certain > that I could do better with a custom design, but not for anywhere close to > $12. > > And outside of the flat response (though it is not THAT flat) a battery > pack already has a boost circuit in it to go from the 4.7V lithium voltage > to 5V. So it will likely hold it up to 5V until the very end. So there > probably isn't any visible drop until it shuts off. I didn't consider that. > > This does raise an interesting idea, though. Instead of using the switch > in the power jack to disconnect the batteries, perhaps a mod is in order > which can just switch over to the alkalines upon external power disruption. > This is usually a pretty simple circuit like you would find on an arduino > which chooses USB voltage or DC input based on which one is greater. > On 10/21/2025 5:39 PM, B9 wrote: > > That looks great, thanks for the link! > > The one you linked is the same seller as the one you tested, right? I'm > always suspicious of stuff on Amazon these days. No idea if it's going to > do something out of spec, not work at all, or simply catch on fire. > > I am surprised that the design is such that the cable itself is drawing > non-negligible current from the USB battery. Have you measured actual > wattage? I thought most buck/boost chips had low "quiescent current" modes, > but I'm no expert. > > If it was designed poorly, the conversion to 6V might be inefficient and I > suspect you'd actually get better battery life by just using the 5V from > the USB directly. > > Even with an ideal circuit, I'm curious how much extra life, if any, one > gets by increasing the voltage to 6V. The lithium ion voltage curve is > mostly a flat line and then a precipitous cliff at the end. That's why you > can't trust the red low power light on your Model T to give enough warning > with LiIon batteries. What's more LiIon batteries have an internal > discharge cutoff point to prevent damage due to low voltage. > > Or so I've read. (This is not my field of expertise and I do appreciate > any corrections.) > > --b9 > > > > On October 21, 2025 1:19:24 PM PDT, Scott McDonnell > <[email protected]> <[email protected]> wrote: > >> I am going to bet that somebody already found this, but I will tell the >> group about it just in case. >> >> If you are looking for a power adapter to run your M100 from a USB battery >> bank, this is the ticket: >> https://www.amazon.com/dp/B0BJDRV4H5 >> >> Boost to 6V and it is already center negative so you don't even need to >> crack it open and flip the wires. >> >> Of course, you can run the M100 from the 5V directly, but you will get more >> life out of this as the M100 shuts down at 4.8V from my understanding. >> >> The only drawback is that it will draw power from your battery bank the >> entire time it is plugged in since it draws enough current by itself to keep >> the battery bank turned on. >> >>
