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I purchased a Li-Ion battery powered lawnmower. I'm not entirely sure what the actual exact battery chemistry is, but I believe it is not lithium iron phosphate due to its voltage typical of non-LiFePO4 batteries.

I was advised by a relative that I shouldn't store the batteries of the lawnmower in cold storage during the winter. The temperatures can easily get below -20 degrees Celsius here during the winter.

However, when thinking about this again, electric cars use lithium ion batteries too, and they can be used in very cold temperatures. Not only stored, but also actually used (for example, you can charge your electric car at any temperature). However, electric cars sometimes use a slightly different battery chemistry, like lithium nickel cobalt aluminium (NCA) oxide for Tesla.

Is it in general possible to store a lithium ion battery with unknown exact chemistry in very cold temperatures, if the charging and use happens at near room temperatures? For practicality, I was planning to store them fully charged (minus whatever minor self-discharge they may have), and at most less than a year at a time, as the next summer I again require the lawnmower.

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closed as off-topic by Leon Heller, laptop2d, Dmitry Grigoryev, Finbarr, Bimpelrekkie Jun 5 '18 at 9:44

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  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Leon Heller, laptop2d, Dmitry Grigoryev, Finbarr, Bimpelrekkie
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  • \$\begingroup\$ To my knowledge the battery does not get damaged by the cold, it is just that the capacity (or ESR? not sure) gets worse and as a result the battery doesn't last long on a single charge. There is also the question of balancing effort of storing the battery in a warmer environment for the winter versus the potential cost if it does impact battery life. \$\endgroup\$ – Joren Vaes May 19 '18 at 10:28
  • \$\begingroup\$ "electric cars use lithium ion batteries too, and they can be used in very cold temperatures." - only because the batteries are kept at a nice temperature by heaters and thermal insulation \$\endgroup\$ – jms May 19 '18 at 10:29
  • \$\begingroup\$ The additional effort is quite minimal (very easy to remove the batteries), so if there's any chance they will get worse, I think I'm going to store them in a warm environment. Any sources to back up the comments, thus allowing an answer? \$\endgroup\$ – juhist May 19 '18 at 10:30
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    \$\begingroup\$ Storing (not using) batteries at low temperatures is beneficial though, as it reduces the rate of various degradation mechanisms and self discharge. I don't know if -20°C is too cold though. electronics.stackexchange.com/questions/121511/… \$\endgroup\$ – jms May 19 '18 at 10:33
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    \$\begingroup\$ What does the lawn mower manufacturer state in the user guide? If not stated, contact them with this question. \$\endgroup\$ – AlmostDone May 19 '18 at 10:49
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It would be best to store them over the winter at 30% to 60% charge in a place that doesn't get much colder than 32F/0C. Do not store them in the mower. Remove the pack for storage. The mower may draw some small current when the pack is connected.

I am not sure whether extreme cold could damage the battery. It may be OK, but I can't confirm it. That is why I am recommending 32F/0C as kind of a known safe temperature. Don't panic if the temperature dips a bit below that. The batteries don't contain water and the electrolyte will not freeze at that temperature.

The one thing you MUST NEVER DO is charge them when they are cold. By cold, I mean close to the freezing point of water. Make sure the whole entire battery pack is warmed up to around 40F or 5C before charging them. Give the pack plenty of time to warm up if you move it from a very cold area. The center of the pack may take a long time to come up to temperature. The battery charger or pack will probably not let you do this anyway, but it is the single worst thing you can do (short of outright abuse), so don't rely on the system to protect you.

Discharging them while cold will not hurt them. You can mow outside when it is freezing if you yourself are hardy enough.

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