Trouble with TPA 3116 amplifier powered by 6S 25.2V 15A 18650 Charger

[Garric]

I am having trouble getting my DAMGOO TPA 3116 Bluetooth amplifier board to power up from an Anmbest 6S 25.2V 15A 18650 charger PCB BMS protection board. The battery pack is wired according to instructions with six 18650 rechargeable batteries. I have charged the battery pack. It tests at 19.4 volts with a multimeter. The amplifier board powers up with no problem from a 12 volt power supply, or even a 9 volt battery. When I wire it to the Anmbest 6S 25.2V 15A 18650 charger PCB BMS protection board, it will not power on at all.

 

[Nigel Goodwin]

I am having trouble getting my DAMGOO TPA 3116 Bluetooth amplifier board to power up from an Anmbest 6S 25.2V 15A 18650 charger PCB BMS protection board. The battery pack is wired according to instructions with six 18650 rechargeable batteries. I have charged the battery pack. It tests at 19.4 volts with a multimeter. The amplifier board powers up with no problem from a 12 volt power supply, or even a 9 volt battery. When I wire it to the Anmbest 6S 25.2V 15A 18650 charger PCB BMS protection board, it will not power on at all.

You've answered your own question, the battery pack is completely flat - 19.4V is no use for a 25.2V battery pack. Perhaps you have a duff cell?, or you've wired it wrong?.

 

[Garric]

Thanks! I am going to guess that is probably due to the fact that o used a 12 volt transformer to charge the cells. (I am waiting on a 24v charger to arrive).
Once I get a full charge in the cell, should I expect the cell to stop powering the amp when it gets back down to 19 volts?
Q- Would I be better to just go with a lower voltage battery setup altogether since the amp is rated from 4.5-27 volts?

 

[Nigel Goodwin]

Thanks! I am going to guess that is probably due to the fact that o used a 12 volt transformer to charge the cells. (I am waiting on a 24v charger to arrive).
Once I get a full charge in the cell, should I expect the cell to stop powering the amp when it gets back down to 19 volts?

Yes, the protection board will disconnect the battery pack when it gets too low - to protect it (that's it's function).

How are you charging the pack?, I'm somewhat concerned about you not using a proper Li-Ion charger - and it's VERY important you charge then correctly,

Q- Would I be better to just go with a lower voltage battery setup altogether since the amp is rated from 4.5-27 volts?

No, you would just reduce power (massively) for no advantage - you don't want the amp to work when the battery is completely flat, what would be the point?.

 

[Garric]

Nigel,

Up to the moment I read your concern, I had been charging them with the AC/DC adapter pictured below. (Out of safety precaution, I am going to leave it unplugged until I hear back from you.) Is there a charger specifically for Li-Ion batteries?

I checked the cells and wiring. They seem to be correct. I have the cells connected to the board in sequence according to wiring diagram. The cells individually have a charger of 3.9+ volts (is this normal for 18650?).

the end state I am trying to get to is, a Bluetooth speaker set up that I can use either plugged in to the wall (powered by AC/DC adapter) or unplugged (powered by battery pack).

 

[Nigel Goodwin]

Li-Ion cells are nominally 4.2V (hence 25.2V for the six in series), and are considered 'flat' by around 3.2V or so - and if you discharge them more than that you damage the cells. This is one of the main functions of the protection board, to prevent over discharge damaging the batteries.

Li-Ion batteries have VERY specific specialised chargers, basically a constant voltage (25.2V in your case) and a constant current (probably around 520mA for a 'friendly' and long lasting charge). The pack charges at the constant current until the terminal voltage (25.2V) is reached, then switches to voltage mode - the current will then gradually drop, until it's fully charged when it's down to about 25% of the original charge current (so about 130mA), and charging should switch OFF then.

I'm a bit bemused why would expect to charge 25.2V batteries with a 12V supply?.

 

[Garric]

Best explanation for why I thought I’d be able to charge the battery pack with a 12 volt charger is...I am brand new at electronics and I figured I would be able to get the 4.7 volts needed from the battery pack to power the Bluetooth device...Basic ignorance!

I really appreciate the advice and mentorship. I have been scratch my head on this one for a couple days. I am ordering a proper charger now. Once I do get it, can I get your review of my wiring schematic before I reconnect everything? I am still a little unsure on how in connect the Bluetooth and the wires from the AC/DC power converter to the protection board.