A teardown video of a solar battery charge controller from Electronupdate:
A solar battery charger: one side goes to a Solar Panel, the other to a lead-acid battery. A charge controller allows the battery to be safely charged.
Snagged off of Amazon. Seemed really cheap at $17.36.
A look at the assembly quality tells me why. Bad soldering, mechanical errors, wrong wire sizes….
What is baffling, however, is that many of these workmanship issues (beyond the missing “fuse”) are just due to lack of attention… i.e. it would cost no more to do it right.
More info at Electronupdate blog.