I've had 50% good with off brand batteries. Mainly for the black & decker 40V & 20V powertools. The issue I have is that the 40V needs to be positioned on the charger in a way it will charge, otherwise it will "error", but when charged, it lasts as long if not longer than the B&D battery. The 20V don't seem to last as long as the real deal, charges fine.
You pay your money and take your chances. Who can you complain to if your results are disappointing?
,I had some luck with some 12V Dewalt batteries off Amazon. At least there I could read reviews though with the way Amazon listings work, sometimes it's clear the reviews are not for the product you are actually buying.
Cheap knock off batteries will work but they are almost never rated properly. Batteries from the manufacture are expensive because of the testing and quality. Cheap batteries will work but they also can catch themselves on fire or explode. Is it worth 100$ to burn your garage, house or vehicle down?
I'e seen noname batteries set garage/houses on fire here in Honolulu over the last 5 years. The owner either put the batteries in the charger and went to bed or went out only to return to his house on fire. Stick with manufacturer's batteries.

I'e seen noname batteries set garage/houses on fire here in Honolulu over the last 5 years. The owner either put the batteries in the charger and went to bed or went out only to return to his house on fire. Stick with manufacturer's batteries.
Same mixed experience here with batteries of all kinds. Some cheap ones are ok, some are not. For the most part by the time you consider any losses or early deaths with the cheap ones and time spent trying to resuscitate them, I've found it's more productive to get the genuine ones if funds allow it. I'm always on the lookout for cheap deals or deals where a "tool only" comes with a battery or a battery set comes with a free tool.
Metabo has introduced (and patented) a new battery technology for their cordless tools, call LiHD. It uses a 10% larger Li battery cell (20700 vs 18650).
Would never ever leave the no name batteries on a charger unattended.![]()
NiCad batteries don't "vent with flame" when overcharged. Also, if you are using a factory charger then this is not likely to be an issue. I have no concerns regarding using my aftermarket batteries in the OEM charger. Cheap Li-ion batteries are a different matter as Li-ion batteries can and do vent flammable gasses when overcharged. That is why charge protection circuits are a big deal with Li-ion batteries.
Most or all of the knockoffs are going to be Li-ion
Would never ever leave the no name batteries on a charger unattended.![]()
I don't think what I quoted is enough to get a patent. Gotta be more to it than that.
Disclaimer: I'm not an engineer, just a long-time product guy who is around a lot of really-talented engineers and has had some (likely imperfect) osmosis happen over the years. /disclaimerThey can catch fire in the charger or in the tool while in use.
I didn't dig enough to find out about the patent. "Patented “AIR COOLED“ charging technology" is what they are referring to.