I’ve had a GB50 for about 18 months and it has worked fine, been used a handful of times to start smaller car engines with weak batteries, and a bunch to start smaller equipment (mower, small diesel tractor). Last week I was helping a friend with a ‘69 Caddy with a 472in^3 that wouldn’t start, new battery that was reading less than 1 volt, completely dead. For kicks I put the NOCO on and it did crank the car, but it was to slow to start, and only did that three times before it was used up. I had to utilize the “dead battery override” switch to even get it to register being hooked up. I can’t really blame the booster pack, that was asking more than it’s rated for AND I can’t vouch for certainty that it was at 100% charge, I generally try to top it off every few months but don’t recall when I last did so.
Looked at NOCO on Amazon recently and was surprised at the variety of models…..GB40, 45, 50, 55, etc. all the way up to a GB250 capable of cranking diesel engines up to 16L….or so it claims!