I've got one of those too. Not nearly as clean, but works fine.
Honestly though, my current go-to is my "old" Harbor Freight trickle charger. It's pretty much a constant current source limited to about 1/2 Amp up to about 12.5 Volts, and then drops the current off above that. By the time you get to 14V it'll give the battery whatever it'll take (which is usually in the milliamp range).
At one point, I burned it up. Not sure how, but I let the smoke out. So I figured (since they're disposable) that I would just buy a replacement at HF. Well unfortunately, it turns out that they changed the design... The "old" one still has a step-down transformer in the wall-wart, but the "new" one is a semi-conductor switcher like the other new junk.
Hated it. (Men On Film).
I mean, don't get me wrong... it's all cheap Chinese junk. But the older junk is better than the newer junk. They took most of the copper out and replaced it with Silicon.
So in the end, I reverse engineered my "old" HF charger and fixed it. Anyone surprised? Here's the old one all fixed and also sporting a potentiometer mod to adjust the output voltage:
And here's the new one. Flyback switcher with opto-coupler feedback loop. Don't like it at all: