December 13, 2018

A beginner guide to electric skateboard battery

There are some questions that I have when I started out learning about eskate:
1) What are the things that separate good batteries from the bad batteries?
2) How could a non-DIYer read battery in commercially available boards?
3) How do you compare batteries on different brands of electric skateboards?

This post is written for newcomers to the electric skateboard world, riders who are not looking to build or tinker with their electric skateboard but nevertheless want to know what they are putting their money into and want a crash course to understand batteries and how to compare batteries between commercial boards.

For someone new, trying to understand the battery of an electric skateboard can be an overwhelming experience. Besides electrical terms such as “ampere”, “ampere hours”, “voltage watthours”, etc; we also see terms like “10s2p”, “18650 cells”, and “continuous discharge” that simply makes no sense to someone without a working knowledge of batteries.

I will try to make this short and concise, and hopefully, by the end of it, you will know what you are shopping for when you are looking at battery specifications.

Image result for BATTERY TECHNOLOGY & CAPACITY

1. Good Batteries VS Bad Batteries

Batteries have an impact on performance such as torque, speed as well as durability, life-cycle and safety. The quality of a battery pack also affects the significant of voltage sag.

Voltage sag – A phenomenon where you experience a drop in performance when the battery is asked to work harder or when the battery is drained to a certain level.
Some of the eskaters that use poorer batteries will see the board drop in both torque and top speed once the battery level drops below 50%.
Voltage Sag will happen to any battery, however, the better the quality of the battery and the stronger the battery pack, the lesser the impact the sag will have or later on in life the voltage sag occur.

One of the infamous battery stories that we see in the Eskate world involves the Evolve board battery.
The Evolve community found that the stock (10s1p prismatic pack Li-ion battery) was not performing up to the board’s premium tier. Evolve riders frequently found the board failed to handle inclines that it should be able to, given its powerful specs. At times, the battery level would also drop when going up hills, making the board automatically switch into a slower riding mode – something that frustrates countless Evolve riders.

Custom battery upgrades became a thing and after the upgrades, the performance difference is day and night. The sag went away and performance dramatically improved. This is one example of how the quality and size of a battery pack can impact the performance of a board.

Another case study involves when Meepo first implemented a battery upgrade, going from v1.0 to v1.5, they saw an increased in top speed, torque and decreased in voltage sag. This all happened when the other parts of the board, including the size of the battery, were kept the same.

My point is, batteries can make or break an electric skateboard’s performance.

2. Understanding battery specifications

          Battery Specification of the MetroBoard

Right out of the gate, there are a few specifications that, once understood, can improve a person’s battery literacy.

Voltage(V)= The torque that a board gives. Also improves the efficiency of the battery hence range.
Industry standard = 36V.
If the voltage is too low, the board will not have enough torque.
If the voltage is too high, the motor/ ESC can not handle it.

Ampere(A)= The current that a battery can give. This affects the top speed.
Continuous discharge current = The ampere that the battery can provide continuously without overheating. Most electric skateboards need their batteries to be at least 30A continuous.

Ampere Hours(Ah)= The charge that a battery holds. This affects the range.
(Number of Ampere that a battery can put out if it was to fully discharge in one hour, hence Ampere/Hour)
1000mAH = 1Ah

Example of battery options listed in “Ah”

Ampere Hours is definitely one of the most used specs when a company markets their board.
It is also a more reliable reflection of the range than the marketed range, and it also shows you if a company is inflating their board’s range.

5700MAH battery out ranged 6500MAH battery? What?

WattHours(Wh = Ah * max voltage)=  Size of the battery. The power that a battery can output in one hour.
WattHours is the total battery size and an even better indicator of range.
General rule of thumb is WattHours/ 10=Range(in km) .
Air travel regulation mostly limits battery to 99WH and under, though for different airlines different rules apply. Check out my eskate air-travel guide.

Series and Parallel (eg 10s1p, 12s2p) – are the configuration for how the battery cells are connected. How the cells connect impacts the Voltage and Amperes Hours. It’s a bit technical and more important to builders than buyers so I will not break it down in this article.

3. Understanding Battery Types

LiPo, Li-ion, and LiFePo are 3 types of battery that are commonly used on electric skateboards.

Among these 3, Li-ion battery is the most common among commercial boards, while LiPo more popular among hobbyist – and there are reasons for that.

LiPo

LiPo (Lithium Polymer) batters are cheaper and have less voltage sag.

LiPo, however, have significant downsides that limit their use in commercial boards.
For one, they are less safe and could start a fire if not handled properly – something that no company wants as a liability. They also require a user to drain the battery to a specific charge for storage, so they just aren’t for the everyone. On top of that, they have a shorter life-cycle compared to a Li-ion and LiFePo4 battery.

As battery prices are pretty much fixed (for the moment), some companies will try to circumvent the size and price problem by using Li-Po instead of Li-ion eg, the Pomelo board is a recent example.

Li-ion

So a Li-ion(Lithium-Ion) battery is basically what everyone is using right now. Although it is weaker than the LiPo as I mentioned, it has a longer lifecycle, is easier to handle and is a lot safer.

The 18650 cells and 26650 cell that you sometimes see in the battery conversation are just the types of the cell inside a Li-Ion pack, with 18650 being the most common cells used.

These cells are what’s inside a Lithium Ion battery pack.

LiFePo4

LiFePO4 (Lithium Iron Phosphate) is a newer battery technology that gives you the power of a LiPo and the lifecycle and safety of a Li-ion. Best of both worlds? What is the catch then?
There are two main downsides. One – they are expensive to produce and; two – they cannot be sourced easily so not many companies use them – Boosted and the Arc Boards being the main two who do.

4. Understanding Lithium-Ion Cells

I bet you have heard marketing phrase such as “Same battery that powered Tesla!”, “Powerful Sanyo!”.
For instance,  Meepo are using the “Samsung 20R”, an upgrade from the old “LG MH1” while also offering the “Sanyo 20700B” for extended range. What do those brands and designations even mean?

Snipped from Meepo sales page

Well, when a company is touting the battery they use in their pack, they are talking about the individual battery cells they use. Most of us are not aware that there are different batteries made by big and small brands, and they all have different performance.

Think of it as a smartphone, just like the Samsung Galaxy S9 is better than the Samsung Galaxy J7; the battery cell Samsung 20R is better than Samsung 35E. And LG, Sanyo, Panasonic and other smaller brand makes their own batteries of differing quality.

However, since most eskate company are not disclosing which cells they use, reviews of a board’s performance are still probably the best test of the battery quality.

This article is written BY Paxson lim and previously published on www.electricskateboard.com

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