Another newby question: overcharging battery

[Al-Rider]

Perhaps it's a stupid question, but what happens if I forget my battery plugged to the charger in the garage for a few days? Do I risk damaging it?

 

[Kaelidoz]

The charger will auto shut-off. No the best for the battery life to leave it at 100% for a few days tho.

 

[TheBikePilot]

It’s best to leave your batteries in a warm place at around 80%, so if your garage is cold remove the battery and store it in the house. Simples.

 

[Kaelidoz]

I believe it's best to keep it between 40 & 60% if you intend to leave the battery unused for an extended amount of time.

I think the 80% thing comes from the advice of not charging the battery over 80% to increase its longevity (and not letting it discharge under 20%).

 

[MattyB]

I believe it's best to keep it between 40 & 60% if you intend to leave the battery unused for an extended amount of time.

Correct. The only problem is that the percentages we are all in the context of the charge termination and discharge cutoff voltages the BMS has been programmed with, NOT necessarily the actual maxes and minimums for a battery of that cell chemistry. To understand this better we need to know the average cell voltage when the BMS seems the pack both fully charged and empty. My Dad and I are going to see if we can get at least the 100% cell voltage figure tomorrow on his Bosch powered Trek.

 

[pgtips]

Store your battery at about 30-60% in a dry cool place. Lithium batteries don't like to be stored in a hot environment.
Coming from rc planes and rc helicopters I been dealing with lipo batteries for over 10 years. Winter I store the batteries in the garage, summer in a dry cool place.
Look after lithium batteries or can end up in disaster!!

 

[Al-Rider]

So, if I understand you correctly, if I average a ride a week, the correct charging procedure should be: after the ride charge the battery only up to 30-60%, store the battery for the week and then, the night before the next ride, charge it to 100%?
Seems pretty strange

 

[R120]

You can get a bit obsessive over the whole charging thing - i ride my bike two to three times a week minimum sot and to charge it up as soon as i have finished as nothing worse than forgetting to do so.

If i know i wont be riding the bike for a while, if its anywhere above 2 bars/30% i just leave it at that and then charge it before my next ride.

Different brands give different advice, but seems to be a consensus that leaving it around 60-70% charged is about right for long term storage.

The one rule i stick to is not leaving it in a cold place for storage, i spent enough time in the alps to see what cold temps do to batteries.

 

[MattyB]

So, if I understand you correctly, if I average a ride a week, the correct charging procedure should be: after the ride charge the battery only up to 30-60%, store the battery for the week and then, the night before the next ride, charge it to 100%?
Seems pretty strange

Not strange at all - this is exactly how lithium chemistry batteries like to be treated. Lots of info online about it; here’s a good source...

How to Prolong Lithium-based Batteries - Battery University

 

[pgtips]

You can get a bit obsessive over the whole charging thing - i ride my bike two to three times a week minimum sot and to charge it up as soon as i have finished as nothing worse than forgetting to do so.

If i know i wont be riding the bike for a while, if its anywhere above 2 bars/30% i just leave it at that and then charge it before my next ride.

Different brands give different advice, but seems to be a consensus that leaving it around 60-70% charged is about right for long term storage.

The one rule i stick to is not leaving it in a cold place for storage, i spent enough time in the alps to see what cold temps do to batteries.

Like I said earlier. Lipo batteries we always stored them in the garage in the winter times, A for safety and B to prolong life. . Rc packs are not cheap, like £90 a pack for 4 minutes fly lol.

Lithium-Ion
The possible storage temperature range for Lithium-Ion batteries is is -20°C to 60°C but for prolonged storage period -20°C to 25°C is recommended and 15°C is ideal. Cells should be stored with a partial charge of between 30% and 50%. Although the cells can be stored fully discharged the cell voltage should not drop below 2.0 Volts per cell and cells should be topped up to prevent over-discharge. The maximum voltage should not exceed 4.1 Volts
Battery storage.

 

[Al-Rider]

Ok guys, thanks a lot for the tips. Strangely enough there's very little information about correct charging procedures on manufacturers' and ebike websites.

 

[R120]

Giant have the best guide i have seen - interestingly their charger also has a storage mode than charges the bike to the level they feel is optimum for storage:

How to Charge your E-Bike | Giant Bicycles United Kingdom