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Introduction

Like most of us, I've used lithium ion batteries in many everyday devices. I also use a few lithium polymer batteries in RC-airplanes. In the last years I read about their correct usage and charging. These are some of the things I learned:

  • Discharging a cell below minimum voltage kills it (capacity decreases.)
  • Overcharging a cell above the maximum voltage kills it.
  • That is why you use a balancer while charging a pack of cells in series. It balances the cells to an identical voltage level by discharging the higher-voltage-cells.
  • There's nearly no memory effect. No need to discharge before charging.
  • For long term storage charge it to 65-80%. Not less to avoid undercutting the minimum voltage. More voltage would mean more wear and ageing, because of a higher amount of chemical reactions.
  • You should wait some time after using a battery before charging it again.

Question

How long should you wait after usage before charging?

For example, if I use a battery powered string-trimmer or lawn-mower and the battery has gone empty (and probably quite warm,) how long should I wait before connecting it to the charger?

I guess reasons you should wait are temperature, or ongoing chemical reactions. Also I think you should wait longer if the battery had to deliver very high-current like the lawn-mower or a fast rc-airplane which will lead to higher battery temperature.

Sidequestion: If it's about temperature would it help to put the battery in the fridge after use, to be able to charge it earlier?

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  • \$\begingroup\$ Please provide a link or citation to the source that told you to wait between discharging and charging. \$\endgroup\$ May 29, 2018 at 19:32
  • \$\begingroup\$ Interesting that I've heard all these before, but the last one. I think it's because it is indeed about temperature and as such considered to be "common sense" kind of thing. Meaning - you do NOT have to wait if the battery is cold already. I might be wrong, though. \$\endgroup\$
    – Maple
    May 29, 2018 at 19:34
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    \$\begingroup\$ AFAIK the reason for the "wait before charging" advice is to let the cells cool back down to room temperature prior to charging (batteries heat up under significant load, or just due to the waste heat of the device they are powering). That said, I'm no chemist. \$\endgroup\$
    – jms
    May 29, 2018 at 20:06
  • \$\begingroup\$ @ElliotAlderson A friend told it to me, but its also numer 12 here: thedronegirl.com/2015/02/07/lipo-battery which says "Never charge a battery that is still warm from usage, and never use a battery that is still warm from charging." \$\endgroup\$
    – Stefan I
    May 29, 2018 at 20:56
  • \$\begingroup\$ @Stefan the time you ask for depends on the specific battery, use case and charging method. There won't be a one for all answer. \$\endgroup\$
    – datenheim
    Jan 24, 2023 at 6:32

2 Answers 2

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High or low charges on a stored lithium battery stress it, even with the battery otherwise idle. The best way to store lithium-ion or lipo is at about half charge and close to 0C (32F) without actually freezing it. Note that there's a lot of superstition about batteries, and you'll get different answers from different places, so don't be afraid to verify.

Also:

  • Charge only at room temperature
  • Use at room temperature or slightly below
  • You'll get a lot more charge cycles if you keep it between 20-80% charge.

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries is a good detailed source.

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  • \$\begingroup\$ Hi, thanks for the answer and it's very interesting, but not what I asked. My question is like how many minutes should I wait after using a device (and the battery gets warm) before putting the battery in the charger. \$\endgroup\$
    – Stefan I
    Jun 19, 2018 at 14:51
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    \$\begingroup\$ Sorry, got sidetracked by your side question. It's always best to charge the temperature around 25C, although it will warm up some from the charging current. I'd say let it sit around (preferably inside with the A/C) for maybe 15 minutes if it's warm to the touch. \$\endgroup\$ Jun 19, 2018 at 15:20
  • \$\begingroup\$ Would charging a battery that is still warm to the touch from usage (a single cell LiPo of a small rc helicopter) for one minute before disconnecting the battery from the charger be problematic (I did exactly that by mistake)? \$\endgroup\$
    – Aqqqq
    Nov 16, 2020 at 20:24
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All lithium ion cells will have a data sheet from the manufacturer almost always available online.

The full data sheets will define the manufacturer's recommended parameters for a "standard charge" and for a "standard discharge", and often for rapid charge and maximum continuous discharge as well. They will also list the guaranteed remaining capacity after "x" number of these standard charge and standard discharge cycles and the temperature and length of time the cell was allowed to rest in between each charge and discharge. Obviously its in the manufacturer's best interest to use the method that allows them to advertise the best cycle life. The shortest amount of time I've seen a manufacturer use is 15 minutes, the longest 1 hour. The rest period is often longer for one stage vs another, and the rapid charge and rapid discharges usually have longer rest periods as well.

If you know what cells are in your battery pack you can check the manufacturer's recommended rest period. If don't know 30 minutes will cover most cells. 15 minutes is the lowest I've seen recommended. And these are at fairly low charge and discharge rates, usually something like 0.5C charge and 0.2C discharge, with temperature maintain at 25°C

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  • \$\begingroup\$ Could you add references for the mentioned waiting times? \$\endgroup\$
    – datenheim
    Jan 24, 2023 at 6:30

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