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lithium ion battery charging best practices

If you want to store lithium-ion batteries properly, you should pay attention to some small basic rules.

Tradesmen who are only active on warm days, like to put their accustomed hand tools in the basement, or simply leave it in the garage after work is done. When the warmer days come, and there is much to be done, the batteries do not seem to have the necessary endurance, as in the previous year, or give no sound at all.

Lithium-ion batteries should always be given a certain attention, because quite as insensitive, as the manufacturers gladly specify, the batteries are ultimately not.

No memory effect, no self-discharge, and immediate availability after months! These are the arguments of the promising product descriptions. Such allegations tempt the users and lead to negligence.

But if you trust these details, the fun can end up being expensive. Replacement batteries can cost nicely and well the price of a new device including batteries, which makes an exchange prohibitive.

These problems often occur with devices that are supplied with two batteries (or more). If the devices are rarely used, the second rechargeable AGM battery charging can also be forgotten, which causes a deep discharge for a fast and safe farewell of the (second) batteries.

Causes of the defect of a lithium-ion battery

The storage of a fully emptied or a fully charged battery significantly shortens the service life. The electronics prevent a deep discharge during use, but not during storage.

If a lithium-ion battery is stored in the discharged state, the self-discharge of the batteries ultimately results in a deep discharge, which makes the battery finally. This type of storage is particularly susceptible since the batteries are no longer usable after a deep discharge. Even the charger will not recognize these batteries and no more attempt to load them.

Fully charged batteries are permanently under high voltage. The high voltage within the batteries ensures a fast aging and thus a high capacity loss.

How to store lithium-ion batteries correctly?

To get lithium-ion batteries healthy from the winter sleep, there are only a few small things to consider.

The correct charge state for storage is about 40%. In this condition, it can not reach a deep discharge for an extended period, and the internal voltage is not so high as to damage the battery.

To store the batteries properly, you should choose a cool and dry place. You can store the batteries in the refrigerator, if necessary if the batteries can be removed – as with a cordless drill. However, I would not recommend this, since the batteries are, after all, a tool that has not lost in the refrigerator. Also, the batteries are made of dangerous chemical substances, which can not escape, but leave a rather queasy feeling. Also, it does not look particularly nice if the entire lithium-ion batteries are stored between the ham and the cheese from the workshop, which can lead to certain disputes between persons in the household.

A storage temperature of approx. 15 ° C is sufficient to store batteries properly. At this temperature, there is a low self-discharge of 1 – 2% / month. If batteries are to be stored for a very long period, they should be recharged to a charge level of 40 – 60% at least every six months.

How long can you store lithium-ion batteries correctly?

If you buy a rechargeable battery with two batteries (or more), you could store the second battery and later, when the first battery is defective, take out and use as a new battery.

Not even close! Even if you store lithium-ion batteries properly, the batteries age and lose their capacity. In addition to their limited number of charging cycles (like any other type of battery), lithium-ion batteries also have a calendar lifetime. This means that the battery that you store properly will age just as fast as the one you are using.

Therefore, if you want to dispose of your used battery after about three years, so that you can then pick up the stored battery as a replacement, you can also dispose of the stored battery immediately.


To store lithium-ion batteries correctly, the following basic rules should be observed:

  1. Dry and cool at max. 15 ° C store.
  2. The charge state should be about 40%.
  3. When stored for a long time, recharge it every 40 minutes to 60%.
  4. Do not store for too long, as the batteries have a calendar life and therefore aging as fast as batteries are in use.

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