.........A Lithium battery must NEVER be continuously "trickle charged" and there is no reason to trickle charge because a charge lasts for years (if the battery is not used). This is what The Battery University says about it: "Li-ion cannot absorb overcharge, and when fully charged the charge current must be cut off. A continuous trickle charge would cause plating of metallic lithium, and this could compromise safety". But I agree they do not talk about a lower than normal charging voltage.