Hi, I was wondering if its true that if you recharge a battery(say lithium ion) before it has completly run out that it will lower tha batteries life? I have had bad luck with battery luck with my phone,mp3 player, camera, you name it. so i guess my question is what is a good way to preserve battery life for as long as possible? thanks
Ahhh… the much discussed and much-debated ‘memory effect’…
In the case of Li-Ion batteries, I believe the advice is to keep them topped up - deep-cycling results in a shorter life - the opposite of what is claimed to be true for Ni-Cd.
Mangetout is correct. Full discharge is recommended only with nickel-cadmium rechargable batteries, but hardly anyone uses them anymore. Lithium-ion rechargables do better the less you discharge them.
From here: http://www.mpoweruk.com/life.htm#dod
“Mobile phone users typically recharge their batteries when the DOD [depth of discharge] is only about 25 to 30 percent. At this low DOD a lithium-ion battery can be expected to achieve between 5 and 6 times the specified cycle life of the battery which assumes complete discharge every cycle. Thus the cycle life improves dramatically if the DOD is reduced. [italics mine]
Nickel Cadmium batteries are somewhat of an exception to this. Subjecting the battery to only partial discharges gives rise to the so called memory effect (see below) which can only be reversed by deep discharging.”
Note this can “result in a shorter life” the same way that playing in traffic can result in a shorter life. Deep discharge can kill a Li-ion permanently. They (more, their close relatives Li-polys) are attractive to aeromodellers because of their energy density and light weight, but they have to be watched carefully because it’s thank you and goodnight if the voltage drops too low.
I have an MP3 player with a Lithium ion polymer battery. The battery lasts about 6 hours before the device turns off on low battery power. 6 Hours is usually plenty of time for me. One day I needed a longer playing time, and rather than run it on battery power I kept the device plugged into the battery charger while I was playing it. Afterwards when I was running on battery power alone the battery meter on the device showed it was dropping the amount of charge quicker than normal, and it only played for 4 hours. After about of week of the normal routine (fully charging at night, playing until it turned off in the day) the performance returned to 6 hours. Are these batteries designed to be charged and used at the same time? Obviously it works that way, but am I causing damage to the battery when I do?
It is quite possibly the case that, although you had the thing plugged in, it was still implementing some kind of charge>discharge>recharge cycle; so the 4-hour discharge time may have been because it charged fully, then played for two hours without charging (even though it was plugged in), then played for the remaining four hours of the charge after unplugging, if that makes sense.