Amazon Fire tablet without battery

I am using a fire HD8 tablet as a HA dashboard wall mounted (always on) and I have been using it like this with some automations.

Charge when it drops to 20%
Stop charging at 80%
Repeat infinitely

But now the battery doesn’t even last 30 mins anymore and I don’t want to have it on charge all the time, I simply don’t trust it after seeing my laptop battery swell enough to open the case.

So I opened up the table and just disconnected the battery but now it won’t power on while plugged in, I see the amazon logo for about 2 seconds and then nada.

Any idea if there’s a trick to get it to turn out sans battery?

I’m rather doubtful that it will work. Tablets, much like phones, expect to have a battery. It’s part of the power conditioning circuitry itself.

It’s a shame, having to buy a battery only to waste it again and again…

Built in UPS… that’s how I view those sort of things. If you’ve got it on a smart outlet or something (which I assume you do given that you state you’ve been cycling the charging dependent on the charge status) then you’re still actively using the battery.

Yeah I was wondering if someone smarter than me can tell why I can’t simply hook up the 5v USB cable +/- to the battery +/- connector, since the battery is 3.7v-4.2v looks like

I’m trying to do the same thing. and this is what I’ve found out:
Tablet is not like a simple led, which probably need constant current with some voltage requirement. Tablet has a dynamic way to do things, like when started, when streaming video etc, at different time it might require different current.
The voltage requirement is pretty clear, but the peak current requirement is not something u can find printed on battery or tablet manual. Battery can support high peak current(as long as it’s not constant), but your charger may not be able to do it.

Hello. Yes You can power it thorugh a 5v phone charger but You have to take apart the electroic board of the battery and apply the 5v where the battery terminals were connected to its electronic board. However on my fire HD10 9th generation i encounter a problem: if there is a power outage, i can turn on the tablet afterwards, only if i manually disconnect and reconnect the connector shown in the photo from the earlier posts. i did not find a workarround this. maybe a button press combination would solve the issue but i did not figure it out yet.

That’s good to know, might try it out on a hd8 I don’t use anymore.
The way I have my tablets set up is a 230v sonoff smart switch behind them in the wall and a 5v usb connected to it which I trigger on and off based on battery level.
This might fix your power problem too.
I think sonoff also do a usb version

the problem is the link between the battery cable and the motherboard., that is the place to be having a switch to do a toggle on off, and then restart the tablet.

I see what you mean, so if it loses power no matter how, it won’t come back until reseating the cable?
Sonoff also have a DC smart switch (relay) I think, so maybe you can add that at the red or black terminal of the battery and toggle it that way?

Yes. That would be a solution but with alot more space needed for the switch. I found another alternative which suits me better: using a tp4056 charger i actually use this module for powering the tablet and in the same time it charges the original battery. If there is a power outage this module will automatically switch to the battery much like a UPS. Te size of the module makes it the perfect candidate for my reduced space.