Fooling with the RC cars I learned you have to be careful with the LiON stuff. If they catch fire things get interesting real quick. I was spooked to try to jump start as I'd read reports of that frying the LiON batts.
I ended up getting the NOCO 5 charger. Amazingly it said if I ordered today I'd get it today and sure enough I did. It's charging the battery now although I think it's gonna take about 5 hours to get it full. Pretty happy with the little unit. Super compact and nice connectors, but I do wish it had the readout on it for voltage, temp, etc. 13,000 amazon reviews said it was great though.
Got this one:
https://amzn.to/3WFIuBu