So I bought one of these a while ago...
http://www.matcotools.com/catalog/produ ... ER-SUPPLY/I bought this over the smaller one because I do a fair bit of diesel work. Didn't expect it to really work on a diesel, but bigger is always better, right? Anyways, first chance to use it was on a flat dead diesel, both batteries completely drained, about 25 below. Was able to power up the glow plugs, run a scan tool, buzzed the injectors, then cranked. Engine turned about 5 times, clamps were smoking, booster was drained. Lesson learned lol, not really designed for a diesel, but I was amazed it even turned the engine over. Since then, I've boosted quite a few cars, trucks and vans with no problems in all temps, run uv lights, boroscope, a smoke machine.... It boosts about 4 times before needing a recharge, although the recharge time is pretty long. I haven't used the usb or flashlight, kinda redundant for me, but I'm sure they are handy for something lol... Overall I'm really impressed with it, I'd certainly keep it in my pocket on the boat just in case!