18650 Battery powered mowers storage voltage for winter?

[tearapin]

I have a 60 volt lawn mower. The battery packs are a bunch of 18650 cells. The charger is equipped with 3 led lights. Bad status, charging and complete. No voltage readout. To get maximum life out of my batteries I am wondering what the proper storage voltage should be for winter. Let's just say for sake of converstation that "proper" storage voltage should be 50 volts. Any method to get to this besides stopping and starting the charge then using a meter to get to 50 volts?

Any tricks or experience with this to get maximum battery life?

 

[redmondjp]

It's more about the state of charge than the voltage, but if your unit doesn't provide you that information, I'm not sure what to suggest with regards to the voltage level. The interwebs state that optimum long-term storage is at 50% charge, so, knowing your total mowing time on one charge, you could mow for 50% of that time before you put the mower away for the winter, and then fully recharge it in the spring.

 

[uart]

I'd store them at about 3.8 volts per cell (by that I mean the number of cells in series). Not sure how many cells in your 60V battery, but assuming that it's 15 in series (actual number of cells would be a multiple of 15 as there would be many in parallel) then I'd consider 15 * 3.8 = 57 volts.

Here I'm assuming that the cells are nominally about 4 volts per cell. In that case the fully charged voltage would normally be about 4.15 volts per series cell, so about 15 * 4.15 = 62.25 volts at 100% charge (though could be slightly less or more depending on the charger).

At your suggested 50V level, the volts per cell is only 3.33 volts. This is a bit low in my opinion, and you could risk losing some cells due to under voltage if stored too long.

Aging due to voltage stress in storage is fairly minimal below 3.9 volts per cell, so while 3.8 per cell is still a pretty decent state of charge, it's also a very safe storage level.

 

[DerekV]

54-58v should be fine. Pop it off the charger every 15 mins to check voltage with a multimeter. If it’s within that range, consider it good. No need to go overboard with it. Bring the battery inside vs. the shed during the off-season.

 

[Citation]

Rather than over think it, if the battery has 3 lights, run the mower until only 2 are on. It's not critical to store it at 40-50% (though that is best). It's critical to not store it at full or empty. If you run the mower down until it shows 2 or 1 lights you are likely fine. Also, if it gets really cold in the garage store the batteries someplace cool in the house.

 

[Innovate1]

I'm not sure how fast the batteries will loose charge in storage. You might want to check midway through winter and charge them a bit to bring them back up to mid capacity.

 

[M635_Guy]

Rather than over think it, if the battery has 3 lights, run the mower until only 2 are on. It's not critical to store it at 40-50% (though that is best). It's critical to not store it at full or empty. If you run the mower down until it shows 2 or 1 lights you are likely fine. Also, if it gets really cold in the garage store the batteries someplace cool in the house.

This is a terrific answer.

 

[merkyworks]

Winter storage mean you add fuel stabilizer.

Oh wait this is battery powered, hold on your telling me you have to do some elaborate storage routine song and dance for them fancy battery powered tools. Wow it’s like changing power delivery systems was pointless, who knew