LED light remains red?
Red led light remains on? Can I change the battery?
Is this a good question?
You can try.
Here’s a link to the ifixit 5w Mighty Dwarf Teardown guide.
It is not a repair guide, simply a guide that shows how to dis-assemble the speaker.
If you decide to try and open the speaker, once you have it open you can can verify that, as is shown in the teardown image at Step.2, the battery makings show that it is a 3.7V 650mA 802535 LiPo battery. The 802535 refers to the dimensions of the battery.
I cannot find an exact replacement for the battery but I did find this battery which may be a suitable replacement.
It is only shown to give an idea of the cost of the battery, there may be other suppliers that suit you better. Just search for 802535 3.7V 650mA LiPo battery to get results.
The example battery shown above has exactly the same dimensions and is of greater capacity at 850mA, which means that the speaker should play longer from a single charge. Conversely it will also take longer to fully recharge.
There is one problem if you decide to use this battery in that it only has a 2 wire connection i.e. +ve Battery (red) and Ground (or -ve) (black).
A lot of batteries have a third wire (normally a white wire) which is usually connected to a temp sensor housed in the battery casing and is connected to the circuit board so that the battery management circuit in the device can turn off the charging current to the battery if the battery is getting too hot during charging. I don’t know if this is the case in your speaker or not.
Some people have connected a 2 wire battery into a 3 wire battery circuit with no problems as it usually fully charges before it gets too hot. You just have to remember that it is on charge and keep check of it until it is fully charged and then disconnect the charger. Do not leave it on charge and forget about it. Once you have determined roughly how long it takes to fully charge, use a timer etc to remind you to check and switch it off charge when you go to charge it.
Past 24 Hours: 4
Past 7 Days: 10
Past 30 Days: 17
All Time: 79