Battery storage, charging and life spam

[Juliano]

What is the best to way to extend battery life on an EUC? I have a 9B1 E+ and ride it to work with 7km every day so a typical battery charge lasts at least 3 rides. For battery overall life (not considering safety of riding on a full battery everytime), should I recharge every night, only when empty or it does not matter?

[DangerousDick]

From my experience with Radio Control toys using LiPo's for around fifteen years now we never let the charge go below 20% (not necessarily the power shown through the app!) and unless using on a 'regular' basis leave the 'storage charge' at 50%.

Storage should be cool and dry.

Damage occurs if left at full charge and the temperature drops - the chemical make-up of the cells is damaged.  As long as there is minimal fluctuation in temperature between charging and using then there is no worry

We also charged at 1C in the early days but you can't change that on the Ninebot (unless you use your own charger which I wouldn't recommend in this instance) to extend any life but the newer cells can take anything up to 5C without any loss of efficiency.

Personally, I charge whenever it's got less than 50% but try to leave it until just before I need to use it - so far so good for me, but it really is early days yet.

[Keith]

My background is also many year's of electric RC and almost word for word I would say, from experience, exactly the same as DangerousDick. 

If I understand correctly, cooling a battery lowers the safe fully charged voltage, so charging to full then allowing to get cold effectively creates an overvoltage state which can damage cells. Running batteries very cold also increases internal resistance and can do damage. Ironically, at a storage charge ( around 3.8V/cell) they store better if kept cool (less voltage loss and chemical reaction.) Discharging below 20% also seems to cause a small but accumulative degradation. Below 10% is even higher degradation. Taking the batteries down to significantly less than 3V per cell off load can immediately cause irreversible damage. Most model flyers have managed to do that once!

So outside temperature has an impact on best practice, in cold conditions, ensuring the batteries are warm before use where possible and keeping charge between (say) 90% and 20% as much as possible will help. In warm conditions charging each night and not allowing to go below 20% is probably better. 

[esaj]

On top of what's been mentioned above, I also believe that storing in HIGH temperature (in general) and especially with high charge to be dangerous/damaging to the cells. In general, storing batteries for long time with full charge degrades the overall capacity over time, so for longer term storage, the batteries should be kept around "half charge" and kept in a cool (room temperature is still probably okay) place, but not freezing and not too hot.

Temperature	40% charge	100% charge	Table 3: Estimated recoverable capacity when storing Li-ion for one year at various temperatures Elevated temperature hastens permanent capacity loss. Not all Li-ion systems behave the same.
0°C 25°C 40°C 60°C	98% 96% 85% 75%	94% 80% 65% 60% (after 3 months)

Source: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

[Donafello]

http://gizmodo.com/sonys-building-a-battery-with-40-higher-energy-density-1748668432

 

A step in the right direction