Battery Life--Storage

[svHyLyte]

In the last few years I have purchased a couple of devices to make life aboard somewhat easier including a right angle drill we use as an "Electric Winch Handle" and an electric inflater for our dinghy. The "Winch Handle" uses 18 volt rechargeable batteries while we power the inflater with a rechargeable sealed 16 amp hour 12 volt battery.

As we may go quite some time between needing these items I'm wondering what is the best way to preserve the batteries. In past I have fully charged them and then stored them in a cool dry spot. When we do plan to use them, I put them back on the chargers to "top them up". Unfortunately, however, I have found the life-span of the batteries to be quite a bit less than I had expected and I'm wondering if my storage regime is faulty or if they need be "exercised" more often or what.

I will appreciate any suggestions by any one of the electrical wizards on the board!

Thanks,

s/v HyLyte

[David M]

I don't know what type of battery you have but I guess Lithium-ion since most battery powered tools seem to have them.

According to Wikipedia, Li-ion batteries lose about 20% of their ability to store power per year no matter what you do with them. They also don't have a "memory" like nickle-cadmium batteries do...which of course is a good thing, so partial charges and discharges won't hurt them.

The temperature chart shows that the colder you store them then the longer they will keep their charge.

Lithium-ion battery - Wikipedia, the free encyclopedia
Nickel-cadmium battery - Wikipedia, the free encyclopedia
Nickel-metal hydride battery - Wikipedia, the free encyclopedia

[GordMay]

Cool / Dry Battery Storage:
To prolong life, & reduce self-discharge; ALL batteries (regardless of chemistry) should be stored at less than 68 degrees F (20 degrees Celsius), where possible.
Storage temperatures between minus 4 F ( –20C) and plus 68 F (+20C) are recommended, with a relative humidity of less than 50%.

Most standard cordless tools come with either Nickel-Cadmium (Ni-Cad) or Nickel-Metal Hydride (Ni-MH) batteries.
In the past year or two, many manufacturers have offered a premium Lithium-Ion (Li-ion) batteries.
Li-ion batteries have a high energy density (energy to weight ratio), don’t suffer from memory effect, and have a low self-discharge rate (<5%/mo.*). Li-ion batteries tend to age by calendar, whether used, or charged, or not. The Li-ion battery has a time clock that starts ticking as soon as the battery leaves the factory.

* Compared to up to 30%/Mo self-discharge for Ni-MH batteries.