ZL1NCs Information Pages
a collection of useable information
Six tips for extending lithium-ion battery life
But first some blurb!
The specific energy of a Lithium-ion battery is twice that of NiCd, and the high nominal cell voltage of 3.60V as compared to 1.20V for
nickel systems contributes to this gain.
As at January 2013 typical gel-cell (SLA) 12V battery energy storage cost is about 38c per Wh (watt-hour) - NZ & USA prices are within 2% - compared to
$3.73 per Wh for lithium ion batteries. In terms of weight SLA batteries deliver 36 Wh per kg (2.2 pounds) and Li-ion batteries
deliver 118 Wh per kg (2.2 pounds).
The lithium-ion battery works on ion movement between the positive and negative electrodes. In theory such a mechanism should work
forever, but cycling, elevated temperature and aging decrease the performance over time. AND studies have
revealed that the lithium ions responsible to shuttle electric charge between the electrodes begin to migrate from the cathode and
permanently settle on the anode. This results in the cathode having a lower lithium concentration than a new cell, a phenomenon
that is irreversible, so the battery is now incapable of holding as much "charge" and is now becoming toast.
Reduce this risk by following the steps below !
1: Keep your batteries at room temperature
That means between 20 and 25°C (68 - 77°F). The worst thing that can happen to a lithium-ion battery is to have
a full charge and be subjected to elevated temperatures. Heat is the biggest villain for reducing lithium-ion
battery life. Lithium-ion suffers from stress when exposed to heat, so does keeping a cell at a high charge voltage.
A battery dwelling above 30°C (86°F) is considered elevated temperature and for most Li-ion, a voltage above 4.10V/cell is
deemed as high voltage. Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time
can be more stressful than cycling.
2: Think about getting a high-capacity lithium-ion battery, rather than carrying a spare
Lithium-ion batteries deteriorate whether they're being used or not. So a spare battery won't last much
longer than the one in use. Remember this when you buy lithium-ion batteries.
Get ones with the most recent manufacturing date.
There is another consideration when choosing between one high capacity battery OR two lower capacity batteries. Think of the "hit" to the
longevity of a high capacity battery if you "hot-charge" it VS the deterioration of a spare battery just sitting on the shelf at 40%.
If you are after convenience of minimal down-time, go for two lower capacity batteries.... Food for thought!
3: Allow partial discharges and avoid full ones (usually)
Unlike NiCad batteries, lithium-ion batteries do not have a charge memory. That means deep-discharge cycles are not
required. In fact, it's better for the battery to use partial-discharge cycles.
There is one exception. Battery experts suggest that after 30 charges, you should allow lithium-ion batteries to almost
completely discharge. Continuous partial discharges create a condition called digital memory, decreasing the accuracy
of the device's power gauge. So let the battery discharge to the cut-off point and then recharge. The power gauge
will be recalibrated.
4: Avoid completely discharging lithium-ion batteries
If a lithium-ion battery is discharged below 2.5 volts per cell, a safety circuit built into the battery opens and the
battery appears to be dead. The original charger will be of no use. You will need to "jump-start" the battery with a standard charger
or other current source before continuing with the corect charger.
5: For extended storage, discharge a lithium-ion battery to about 40 percent and store it in a cool place
I've always had a spare battery for my Baofeng, and I am guilty of storing the spare battery fully charged. That means
oxidation of lithium-ion is at its highest rate. Storing lithium-ion batteries at 40 percent discharge and in
a cool place (even in the refrigerator, but not not freezer) is recommended if you live in a hot 25°C (77°F) place.
6: Don't charge lithium-ion batteries when they have just been in use
If you have been using your battery when you get the low voltage warning, let it have some cool down time BEFORE charging.
A portable device should be turned off while charging. This allows the battery to reach the threshold voltage unhindered
and reflects the correct saturation current responsible to terminate the charge. A parasitic load confuses the
charger (and me!).
Getting 500 charge/discharge cycles from a lithium-ion battery is common. Just keep follow this guide!