Battery care - Best practices for long storage (off season)

When it comes to your brand new Esk8, one of the most common issues that we face is riders reaching out to us in the spring as they pull their decks out of winter storage eagerly preparing to ride in the new season. Riders pull their decks out of storage only to find that their deck will not power on! What is going on?

Deep discharge damage

When lithium battery packs area allowed to drain to zero capacity, and then allowed to remain in this state for prolonged periods of time (weeks or months), the entire battery pack can sometimes be rendered useless and needs to be replaced. This is known as Deep Discharge, and is a phenomenon common to all lithium power packs, including your Macbook or your Tesla.

1) Why or how does this happen? - Lithium battery packs are made up of individual cells that are arranged in a series. All of these cells work together to get you the power that you need. This power is all managed by a Battery Management System, which is a little computer on a chip board usually installed into the battery pack and is part of the battery pack itself. This system manages the proper voltage output of each individual cell and prevents it from being overcharged (dreaded lithium fires) or under charged by cutting off from the series, any individual cell that is problematic.

This Battery Management System uses a small amount of power constantly even when your deck is not being used or ridden. This amounts to maybe less than a percent loss of power everyday. This is barely noticeable however, if you place your deck into long storage (winter season) for many months, and if the battery was at low capacity when entering long storage, this can lead to a situation where the batteries fully discharge to zero while in storage, effectively entering deep discharge territory.

2) How to prevent and maintain battery health

Charge your deck to around 80 percent capacity, avoid charging to 100 percent as this puts voltage pressure on your battery. Generally this is no big deal but if going into long storage, that pressure will be maintained for a longer period of time and is not idea.
As lithium batteries do not like inactivity, every 4-6 weeks if you could, check on the deck, note the amount of power lost and make sure it is not too low.
Throttle the deck for a minute or two, discharging the battery somewhat and simulating activity in an otherwise inactive state (long storage)
Charge the deck back up to 80 percent

If you follow these best practices you will keep your battery healthy and ensure no damage over the storage season and be good to go in the spring.

3) Exway preventative systems to help out

Exway BMS are programmed to discharge your battery from 100 percent down to about 80 if the system detects inactivity for prolonged periods of time. This is for riders who are always ready to go with their decks charged to 100 percent who end up not going anywhere for a while. The deck will detect the inactivity and automatically discharge to below 100. If you notice this, this is not a malfunction but a measure used to prolong the life and performance of your battery.

Fast Charging

Exway has designed and sells a variety of fast chargers that can shorten the amount of time it takes to charge your deck, in some case by 160 percent and in recent years even faster than that.

1) Why not fast charge all the time then?

In general fast charging is not good for your battery, which makes fast charging a trade off between the convenience of topping up quickly at the cost of reduced battery capacity and performance .

2) Why does this happen?

Lithium plating - charging is about pushing lithium ions through a graphite anode. When done at higher speeds not all ions can pass through and end up collecting all along the surface of the anode forming lithium plates. These plates reduce the capacity of the battery as well dendrite begin to form and these dendrites which are needle like structure that spread out and can cause short circuits as they puncture the seperation.
Heat generation - heat is always bad news for batteries. There are optimum operating temperatures and then less than optimum temperatures but still ok. But Fast charging really heats up the battery and amoung other things speeds up degradation of the cathode structure and electrolyte breakdown . This is a form of cumulative damage. So the more you charge under these conditions, the progressively worse your battery becomes.
Mechanical stress - When fast charging, the insertion and extraction of ions causes electrolyte to expand and contract. Rapid and extreme expansion and contraction will cause the electrodes to crack.

3) Conclusion

the greatest factor to battery degradation is lithium plating although heat plays a big factor as well. Fast charging comes at a cost and if you own a fast charger you should only use it when you need it. Imagine a long distance ride, or group ride where you don't want to be the one holding everyone up. or Imagine you are at a pro race and need more voltage in between race heats. These would be examples where a rider may feel that the fast charging is worth the battery damage.

The information above applies to all lithium battery packs regardless of brand. These issues exist for any esk8 or lithium powered device.

If you have further questions please contact Exway Canada support:

Exwaycanada@gmail.com