Further adventures! I’ve installed a pair of 706090 batteries (after soldering on leads with the correct polarity). Now I’m going to dig around in the forums to see if I can figure out how to get the charging system to charge the things (they shipped at over 4V when I probed the terminals. I’m down below 30% (per the battery status indicator) but when I check battery status on the tiny OLED, they’re still registering around 3.7 or 3.8V. Is there anything special I have to do to get the charging/voltages kind of ‘aligned’ so that I can trust the battery indicator?
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The relationship between cell voltage and remaining capacity is not a linear one.
Did you already go through a full charge/discharge cycle?
Do your batteries not last as long as you expected them to?
I don’t know how far down I should run the batteries - I do know that there will be some watermark that once I fall below it, the internal rp2040 won’t have enough power to run any more (which will then mean I have to take the batteries out and charge them externally). They’re at about 25% right now (per the indicator) but the voltages still read right around 3.7V, which means they’re not charging via the power board (or not charging very much). I’ll report back with clearer numbers/values.
I finally worked up the courage to install my 706090 cells. The OLED screen had them bottom out at 7% for over a day, so I don’t think that was accurate. When I let it charge overnight, they topped out at 94%, so I’m sure they need to be recalibrated.
In a previous thread, Amospalla recommended disabling upower to let it run down to zero. If I do that, are the batteries’ protection circuits going to be enough?
I have my device playing a live feed on YouTube to run my new batteries down. As an alternative, is it okay to let the device suspend and then restart charging?
Lastly, I’ve noticed lately that the charging LED seems to “breathe” on about a 15 second cycle of dimming and brightening. Has anyone else seen this? I suspect I just hadn’t noticed it doing that before.
I let it run down until the device shut off. The UI was reading 6% while the batteries continued to drain. One reached 3.1V, but the other hit 2.7-2.8V while the OLED screen read 0% for a minute or two before the device shut off. I’ve read that 3.0V is a recommended “floor” for discharging a 3.7V battery, so I hope I haven’t damaged that unit. I tried unplugging either battery to see if I could run it briefly off of the battery with the higher reading, but it wouldn’t turn on without both connected.
I now have it on the charger. I got almost a solid 5 hours of continuous video play out of the two 706090 units I installed, which seems pretty decent.
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when i added my custom ones i ran it until it shutoff automatically like 3 times from full to dead, after that they started working well and after a few more complete drains they were rock solid.
i’d recommend after you install to fully charge, run till dead, then repeat that 10 times just to let things settle. mine are 8200mah apiece, and i get nearly 10 hours out of them if the screen goes off, if it’s on that drops to closer to 6. since i let mine idle a lot it last a while, but the trackball bounces around in my pocket thinking the mouse is moving so i likely lose some time there.
your mileage may vary but still, best of luck!
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