That's a good way to get a lithium fire. Lithium batteries need careful monitoring to charge correctly. To give you an idea, 4.2V is 80% charged for a chemistry

That's a good way to get a lithium fire. Lithium batteries need careful monitoring to charge correctly. To give you an idea, 4.2V is 80% charged for a chemistry I worked with. 100% is 4.23V, so you don't have much margin for error.