Is cheap batteries which is nice but short life span. Since this happened to me I replaced the battery again and given the machine is from 2006 and the battery was under 20 bucks I don't mind replacing it. It's an old 2006 Dell Inspiron so it works again after a new 20 buck battery from amazon.
Old chestnut with new slant. Old battery works (charging, discharging) normally, but duration has decreased and advice is given on battery icon to replace. New battery worked normally for a few months, then the charging led suddenly started flashing and battery icon gave message e.g. '70% available, plugged in, not charging' and the available % remains constant while on AC. Running on battery alone decreases available % normally. Running on AC with battery removed is normal and old battery still charges when installed.
I did not discharge the new battery below about 50% when the charging problem surfaced. The battery delivers current normally, but its internal circuitry apparently blocks charging, i.e. there is a virtual diode in series with the positve terminal, but this 'diode' function was only 'activated' after several charging cycles.
I have read that laptop battery circuitry is often programmed to render a battery useless after a certain usage. Could the above be a premature manifestation of this practice?

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