JBL boombox charging problems (very low amps to battery)

[ApertureGuy]

Hey guys,

I'm not that experienced in electronics so I would love some help with a problem I'm facing.
I recently bought a JBL boombox speaker from a seller that stated it didn't charge.
My thoughts were that this person probably was one of those people that discarded things as soon as they stopped working ad the thing simply needed a new battery.
I purchased a new battery and installed it.

Now the problem is that while the charging lights blink, the charge on this battery also doesn't seem to increase.
I pulled out the old multimeter and checked the cables and they seem to be fine.
I also checked the voltages on the pins that lead to the battery while charging and they seem correct.
The problem is that there is only about 0.2 amps going to the battery instead of the 4.5 the charger is supposed to provide.
What could be causing this problem?

I hope I gave enough info, but if anything else is needed please say so!

[TheMG]

First thing I would do: check voltages!

Per manufacturer's specs the power supply should put out 20V at up to 4A. Does it put out a nice clean 20V relatively free of AC ripple when plugged in to the device?

https://www.jbl.com/on/demandware.static/-/Sites-masterCatalog_Harman/default/dw9a6c0de6/pdfs/JBL_BOOMBOX_SpecSheet_English.pdf

Also, the battery voltage. Even though it's a new battery, maybe it's been sitting around a little while and is pretty much completely discharged? Charging circuits for li-ion will normally significantly limit the charge current if the cell voltages are below a certain point (very deeply discharged) or imbalanced (in the case of series-connected cells).

If all of that checks out, it may be time to start digging into the charging circuit, or power management circuit if it's got one (for instance, to lower the charge current while the speaker is being played at high volumes to ensure sufficient power goes to the audio amplifier).

That's about all the advice I can give, as I have no experience with that product and no service manual seems to be available (that I can find anyways).

[Masakyo]

Hi, have you found a fix for your issue? I’m experiencing the same problem where due to a lost charger the boombox was left without charge for a while and at very low voltage. I opened it and revived/charge the battery using a SkyRC iMax B6 Balance charger. The battery seems to be fine fortunately. Just that this new (cheap) multi-volt charging gets the white light blinking but doesn’t seem to add any charge. I tried this after charging the bb battery upto 7.8v. Now am charging it to full 8.4 using 4a and see if this new charger can pick up the charging from there. I’m also thinking of taking it to a friend who also has a bb with the original charger.
I’d love to know if and how you’ve fixed your problem. Merry Christmas & A Happy New Year! 🎄✨🎁💐🎉🙏🏼

[mindaugask]

I have the same issue. When boombox is off, it draws around 22mA, when I turn it on it's around 42mA, seems like normal standby current, but does not seem to charge, although it turns on and draws battery power as well as it works when plugged in as current draw seem to fluctuate with sound level and goes well into 2amp territory when I crank up the volume.

I did not manage to find boombox service manual, although xtreme service manual is available. As xtreme does not have any kind of battery gauge, so it's very likely that boombox uses similar system. Xtreme uses TI BQ2461X battery charge controller which should start charging if battery voltage is above set threshold and it is not overheated.

I disassembled my boombox trying to isolate the problem, well I didn't have to look far, picture attached. It's BQ24617 standalone battery charger that's fried, will try to replace.

Edit: I've replaced BQ24617 and R97. Seems that the unit was connected with reverse polarity. Charge controller has no reverse polarity protection designed for it. Works correctly now, chrage current around 1A+ and reducing approaching to full charge.