I tried the NiCad vesion of the jump starters https://10carbest.com/best-jump-starters and was not happy, same with the motorcycle battery type. Only the wet cell battery holds a charge over several months, the Li-ion type be fine as far as holding charge. BUT... Even when a battery holds a charge the small ones are often not up to the task of starting with a totally dead (headlights left on) battery. The small batteries just don't have the capacity, so I would revert to using jumper cables to start from a running vehicle. I eventually decided the best utility was to have heavy duty Marine type batteries with a good charger. This way it does double duty as power outage backup with an inverter, as well as mobile/home jump starting. The only downside is I don't have an extra battery with me when I am out and about, but 90% of the time there are other vehicles or I can call for wife to come help with jumper cables. At home a Marine battery is heavy but easy to use for jump starts and has massive capacity for hard starts. Overall I think the battery charger will give you many more years of service for both car and home use, especially if your primary car starting issue is cold starts at home. If primary issue was dead battery in remote location then the jump battery would be a better idea. The mention of Lithium batteries makes me think of all the 18V cordless tool batteries I have. Anyone know of anything that makes use of cordless tool batteries to directly power USB, cigarette lighter plug, AA charger, etc? Not to jump a car battery but for other low wattage 12v jobs.I suggest you to watch an interesting video on this topic from Youtube
