Topping NX7 battery issue

[Endymion Joshi-Godrez]

(I POSTED THIS IN THE WRONG THREAD. PLEASE DELETE THE PREVIOUS ONE)

Hi everyone. I bought a battery-powered topping nx7 amp about 2 years ago. Over the past 3 months, the battery has started depleting rapidly, going from around 4 hours of use to around 1 and a half. I assumed this was because of heavy abuse causing rapid degradation. However, today, when the battery died, I spent around an hour walking home, before i could charge it. When I was about to charge it, I decided to turn it on again, and now it the green light was solid, indicating it had sufficient charge and has stayed green for around an hour. I then turned it off again, turned it back on, and it went for yet anothing hour. I've been constantly charging from the point I thought it died. It occurs to me now that there is the possibility that I have never let the battery drain completely.

Can anyone explain why this is happening, and is it advisable to drain it entirely to possibly reset the battery sensor? Ideally, i would replace the battery. The PCB is connected to the backplate, which is glued to the chassis. I can't get between the gaps of the chassis and backplate to remove the glue. I've contacted topping, but an independent answer would be appreciated.

 

[AnalogSteph]

It is quite possible that the battery controller is quite severely miscalibrated and may require a full charge cycle to get a grip on reality again. While it is not normally recommended to wring the last drop out of lithium batteries, every once in a while such a reset may be necessary. Even getting only 4 hours out of the unit indicates quite severe degradation though... nominal runtime is 10 hours in high gain and 20 at the lower gain settings. (A much larger relative difference again indicates either a high internal resistance or miscalibration, and without being able to measure the actual voltage in use it'll be hard to determine which.) If I am reading between the lines correctly the battery is likely to be a 1S arrangement with a nominal 3.7 V (perhaps two cells of 2000 mAh each in parallel for a 1S2P), so in many ways this should be less problematic than a 2S or 3S.

There are two approaches that come to mind when it comes to removing stubborn glue:
1. Isopropyl alcohol
2. Heat.
Not both at the same time, obviously, unless you fancy amplifier flambé.

Some other scenarios outside just degraded battery capacity that I would be potentially worried about:
1. A parasitic drain / short inside the battery. Does it go flat by itself?
2. Excessive current draw resulting from a partially shorted ceramic capacitor or the like.

 

[Endymion Joshi-Godrez]

It is quite possible that the battery controller is quite severely miscalibrated and may require a full charge cycle to get a grip on reality again. While it is not normally recommended to wring the last drop out of lithium batteries, every once in a while such a reset may be necessary. Even getting only 4 hours out of the unit indicates quite severe degradation though... nominal runtime is 10 hours in high gain and 20 at the lower gain settings. (A much larger relative difference again indicates either a high internal resistance or miscalibration, and without being able to measure the actual voltage in use it'll be hard to determine which.) If I am reading between the lines correctly the battery is likely to be a 1S arrangement with a nominal 3.7 V (perhaps two cells of 2000 mAh each in parallel for a 1S2P), so in many ways this should be less problematic than a 2S or 3S.

There are two approaches that come to mind when it comes to removing stubborn glue:
1. Isopropyl alcohol
2. Heat.
Not both at the same time, obviously, unless you fancy amplifier flambé.

Some other scenarios outside just degraded battery capacity that I would be potentially worried about:
1. A parasitic drain / short inside the battery. Does it go flat by itself?
2. Excessive current draw resulting from a partially shorted ceramic capacitor or the like.

Thank you for your insight, it's really appreciated. It seems it simply refuse to charge to full, as it takes less than 2 hours from "depleted" to "full" when it should take at least 5. Ive never charged it via a fast charger, but i have charged while it was running. Rarely mind you, but im going to guess thats what broke it. I'll try to remove the battery and replace it. If it's the controller, the entire board will need replacing, which will probably cost more than a new unit.