What's Inside a Cheapo Energizer NiMH Battery Charger?

June 10, 2022

What happens when your trusted NiMH AA charger is out of reach and you need rechargeable AAs right now?

You grab this from the grocery store:

The wackaging says "that's positive energy" to appeal to ravers or something.

The included cells are a stingy 1300mAh. Everything in the package has a persistent burnt fibreglass scent. The charger itself feels alarmingly lightweight. Is that because it's all SMD, or is it because they left out all the safety features? Or both?

For $30CAD with grocery retail markup, let's say there are $3 worth of components in this charger. It must be horrific on the inside. <rubs hands> Let's find out.

What's in the box?

• More burnt fibreglass odour.

• FR1: Fusible resistor.
  Silkscreen says 10R 1W; resistor colour code reads 5.6 ohms.

• Single-sided PCB with waterproof coating.
  

• KM and Micon electrolytic capacitors, rated 105°C.
  You didn't expect Japanese capacitors for $30, did you?

• U3: Elan EM78P143/SO14J 8-bit microprocessor w/one-time programmable ROM
  

• U2: Mystery IC with asymmetric leg count and two pins shorted. ????
  Did they sand off the label or is the waterproof coating in the way?
  

• Stray solder paste almost connecting C17 and R1 on the high voltage side. :-E
  

• Bridge rectifier tacked down with goat's blood?
  

• Transformer, neatly wrapped.
  

Compare it with, say, this counterfeit battery charger that exploded: [source]

Another counterfeit charger: back, front.

Genuine charger for comparison: back, front.

So?

I don't know anything about electronics but it at least looks like there's more protection and thought in the cheapo Energizer design than I expected. Could be worse, could be better, but not for $30 retail?

I don't know what to make of the shorted pins on Mystery IC U2. The unit charged a set of batteries without burning my house down.

The stray solder paste is alarming. Hooooopefully less fortunate cases would have been caught by a simple powerup test? I don't know what the name for that type of SMT manufacturing defect is.

I welcome corrections from all you EE types out there. :-)