The simple model of continuous non-porous electrode was found to provide a reasonable theoretical description for the electrochemical process of lithium insertion into a convenient solid electrode, consisting of active material, fine carbon and binder, of the rechargeable lithium batteries with common Liquid organic electrolytes. The model uses only one experimental fit parameter-effective diffusion coefficient of inserted Li that can easily be obtained from galvanostatic charge-discharge data. Approximate simple equations were derived to calculate the charge conditions for secondary lithium batteries. it was shown that charging with linearly descending current results in more than 2.5-fold reduction of charging time as compared to the constant current charging at the same charge depth.