Tuesday, 10 June 2014

Attempted Water Damage Repair on an External Battery Bank

I had a Lerway 10000 mAh external battery bank for my cellphones and other devices; that is, until this Sunday when it took a shower in some sprinklers along with my LG Nexus 5. By the time I had removed my devices from the small puddle, the battery bank smelled of burning silicon and was warm to the touch. I did not have much hope for it to be recovered.
The charger (in black)
I was able to salvage the Nexus 5 by opening it up and scrubbing away the water damage with rubbing alcohol. I figured I would try this with my Qi battery bank.
Despite spending 3 days in rice and silica packets, water still remained
The case of the bank was quite simple to open; I just shimmed and popped the black portion off. I carefully removed the battery (which appears to be completely fine) along with the Qi components (green PCB) and power regulation components (blue PCB). Let's take a look at the damage. First, the Qi components.

Mineral deposits on the logic gates and chips
Not horrible, mineral deposits on the Qi processor, power leads and other IC's.
Overall, not as bad as I expected on this end. This is mostly because this area of components is further away from the entry points for the water which were the USB charging ports. Now we'll take a look at the power regulation components. This is the area which was warm and stinky upon removing the charger from the water.
Extensive mineral deposits on the right portion of the board.
This PCB took the brunt of the water and unfortunately happens to handle most of the higher voltages and current. You can see large mineral deposits near U2A on the right side of the board. You can also see some discolouration near U6 at the bottom; this should have been my first indication that something was very wrong... Aside from the fact that the device wouldn't charge after 3 days in rice.

I gathered my cleaning supplies; I used a can of air duster to blow out remaining water particles, a set of oral cleaning devices (Sulca Brush and regular toothbrush), and of course the rubbing alcohol (95%).
Fun!

Do not drink this.

Brushie Brushie

Good for tight places

So after all that work, were my efforts in vain? Yes. The charger displayed the same behaviour. I examined the power regulation PCB closer and found that a chip had been severely burned. Upon touching it, a portion of it crumbled and I knew I had a lost cause.
See U6 to find the damaged component
Replacing this component is beyond my skill and knowledge of electrical engineering. Solution? I will buy the cheaper white version of this product and transplant it into my black case. I hope you found this interesting!

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