There are a couple of things that need to be done to keep Li-Ion batteries in good condition and get the maximum life out of the battery. Units should never be left in a fully discharged state any longer than necessary as this could lead to reduced life, and could cause permanent failure. It is better for the batteries to be fully charged than it is for them to be left at a low voltage. In order to mitigate this, we recommend that units be charged immediately upon returning from the field. This will serve to minimize the amount of time the battery spends in a very low voltage state.
The recommended procedure for long-term storage of our devices is to fully charge them and then once every other month (once every three months at the most), connect them to a computer or USB charging hub for 3 or 4 hours and allow them to fully recharge before once again storing them in a cool, dry place.
Storing the batteries in a refrigerator (or some other cold storage) really will not add much in terms on prolonging battery life. When the devices are in low power mode, they consume approximately 86µA (micro-amps) of current, which will give you about 80-90 days of storage before the device needs to be recharged. Storing them in a refrigerator might reduce that power consumption by 5µA to 10µA, which really only gets you about another 7 to 15 days of storage before the batteries are completely discharged. And actually, refrigeration can be detrimental because, as you probably know, there is added moisture in a standard refrigerator and if moisture gets inside of the devices and shorts out the electronics, the devices will need to be discarded. Allowing the batteries to completely discharge can also render them useless.
Leaving the devices connected to a charging source all the time will not damage them. The batteries do have a "shut off" mechanism that will keep them from overcharging, but it is not recommended for environmental reasons as this is a waste of electricity.
This chart shows impact of battery charge and ambient temperature on battery capacity during storage.
|Temperature||Remaining Capacity at 40% Charge||Remaining Capacity at 100% Charge|
|0° C||98% after 1 year||94% after 1 year|
|25° C||96% after 1 year||80% after 1 year|
|40° C||85% after 1 year||65% after 1 year|
|60° C||75% after 1 year||60% after 1 year|
After 300 charge/discharge cycles (charge to 4.2V then discharge to 3.0V) the capacity can drop to as low as 80%.
If your devices appear to have drastically reduced battery life, the batteries may need to be replaced. If this is the case, please visit our RMA site to begin the repair process:
If you need any further assistance, please go to our support portal at https://help.theactigraph.com/home. From here, you can view many helpful FAQ's and Troubleshooting Articles; log in to check any existing Support Requests; or create a new Support Ticket if you are unable to find a solution. You can also email us at email@example.com or give us a call at (877) 497-6996, Monday through Friday, 8 am to 5 pm CST.