Levo Gen 2 Battery Management: to charge or not to charge, here’s the question…

[Helynt Melyn]

I live right by a small forest with a cracking short downhill course and some technical climbs. It used to be my acoustic-bike evening sport three times a week. I’ve been on it with the Levo and a good blast only knocks about 15 to 20% off the battery charge. If I stick to my three rides a week routine but on the e-bike, should I recharge after every ride ( ~80% back to full) or just once a week to get from ~40% back to 100% ready for the weekend fun? Does it make any difference?

 

[salko]

I would charge it to 80% and then use it for 3 rides and then recharge back to 80%.

 

[apac]

If only using 60% overall I would charge once back to 100% so the battery pack gets balanced by the bms.

 

[Mcharza]

And about once a month fully charge to balance the batteries

 

[Helynt Melyn]

Ok, is the partial charging a tactic for longer battery life by avoiding accelerated oxide(?) build up on the poles as 100% is approached? Sorry, really vague memories of battery stuff from uni. being taught to a Mechanical Engineer!

 

[boBE]

BU-409: Charging Lithium-ion

BU meta description needed...

batteryuniversity.com

 

[apac]

The battery will most Probably out live your bike So don't over think it. You need to charge to 100% fairly frequently as this is where the cells get balanced. The cell balancing only takes place at the very end of the charging process when the first cells reach 4.2v If you only charge to 80% every time then eventually the cells will go out of balance. balancing can only be done on cells that have a very very small difference in voltage and once outside a certain window such as 0.050v (yes that Small a difference) the bms becomes useless at rebalancing the pack.

 

[Helynt Melyn]

Thanks apac, that does make things clearer. I can see that running down over a few days then a full charge ready for the weekend and one afterwards will give the BMS the best opportunity and avoids heaps of cycling up & down by ~20%. I’ll keep it simple.

 

[MACSKI1]

Should the battery only be charged between 10 - 30 degrees Celsius ?

 

[apac]

Thanks apac, that does make things clearer. I can see that running down over a few days then a full charge ready for the weekend and one afterwards will give the BMS the best opportunity and avoids heaps of cycling up & down by ~20%. I’ll keep it simple.

The bms can only balance cells that are only very slightly different in voltage. balancing only starts to take place when the pack is pretty much fully charged. The battery management system usually 'bleeds off' a min-ute amount Of excess voltage off the highest cells. This can take hours or even days. Once the difference between high and low cell voltages becomes too large then the bms can do nothing. the difference between high and low for the bms to do it’s job is actually a tiny amount. As said above it's probably only about 0.050v or maybe a little higher.... 0.1v at the most.
If balancing is not done regularly the cells begin to drift apart and the bms can do nothing about it as the cell voltage differences are too wide apart…. Even though they are still quite close to each other?

 

[apac]

Should the battery only be charged between 10 - 30 degrees Celsius ?

Don't over think it. Charge at all reasonable temps. Maybe remove battery and charge in doors if you live somewhere really cold.