How long do I charge blackweb bwa17aa008 shower speaker in order to have full charge? What is battery life at full charge?

Blackweb is a Walmart brand made in China at the lowest price point. When they fail, you return them to Walmart for warranty replacement and explain you can't find the receipt. The will give you a store credit.

Or you just buy a new one.

There are some ideas here

https://www.google.com/search?q=Blackweb+BWA15HO1O+but+get+no+sound

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Blackweb is Walmart's bargain basement brand. The only place you would get that information is from the maker in China. Run a request through Google Translate.

Generic help and the manual in the link.

https://www.google.com/search?q=Blackweb+bwd19aaa06+speaker+wire+color+diagram

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Batteries do wear out and can die. Their longevity can be increased with proper care and charge/discharge cycles but no matter what, the chemicals will erode rendering the battery fubar. Needs replacement. After replacement I would read up on the characteristics of the specific type of battery (ni cad, nimh, lithium, lead acid, etc) and use the procedures best suited for max life for the battery. Example - ni cads like to be fully discharged for best charging, etc.

Go to moen website and locate your shower faucet. It will tell you what cartridge it uses and you can order the cartridge free of charge since they are guaranteed for life.

First thing to check is your charger. Those go bad all the time. Find another one and try that first. If that is not it then you have some bad batteries. If this is new within a year they should be replaced free. If they are older then you are on your own.

Batteries age and need to be replaced even rechargeable batteries included.

Lithium ION batteries are usually rechargeable. The use mode for these batteries is that there are a set number of recharges that equate to the life of the battery. Usually that life is approximately 1,000 charges.
If you use your battery to 50% then recharge, you can do this ~2,000 times. As the life of the battery is used up, the maximum charge lessens which means where you may have had 8 hours of play time when the battery was new, you will only have 6 hours as the battery life is used up.
In order for a Lithium ION battery to recharge there must be at least a small amount of charge left as a "seed" for that recharge. If you drain a L-ION battery down to zero, it may never recharge again or the max charge will be reduced to an insignificant amount of the original full charge. eg instead of 8 hours you may only get 15 minutes, or 5 minutes, or no minutes.
You are much better off recharging when 50% depleted than using it up til your product stops.
L-ION batteries cannot be repaired only replaced. Most cheap products using L-ION batteries cannot have their batteries replaced.

If the speaker is under warranty get it replaced.

Taking the speaker apart to replace the battery will compromise or even destroy the acoustic properties of the speakers. Big Blue Live Wireless Bluetooth Speaker

Lithium ION batteries are usually rechargeable. The use mode for these batteries is that there are a set number of recharges that equate to the life of the battery. Usually that life is approximately 1,000 charges.
If you use your battery to 50% then recharge, you can do this ~2,000 times. As the life of the battery is used up, the maximum charge lessens which means where you may have had 8 hours of play time when the battery was new, you will only have 6 hours as the battery life is used up.
In order for a Lithium ION battery to recharge there must be at least a small amount of charge left as a "seed" for that recharge. If you drain a L-ION battery down to zero, it may never recharge again or the max charge will be reduced to an insignificant amount of the original full charge. eg instead of 8 hours you may only get 15 minutes, or 5 minutes, or no minutes.
You are much better off recharging when 50% depleted than using it up til your product stops.
L-ION batteries cannot be repaired only replaced. Most cheap products using L-ION batteries cannot have their batteries replaced.

Places like Batteries + are able to replace some tablet batteries.