Technical Progress Part III: Lithium Battery

As with our previous posts, you can skim the photos and captions for a quick read or dive into the text for more details.

The power capability of Boosted's drivetrain would be useless without a battery that can match it.  From an iPhone to a Tesla Model S, the battery is often the unsung hero, usually quiet and hidden and only noticed when it stops working correctly.  Today we explain the performance and specs we needed from our battery, how we prototyped it, how it changed as we prepared for production, and how we tested our new design.

The final production battery and drivetrain.

Design Principles

To accelerate up hills, our drivetrain delivers an incredible amount of mechanical power.  To make this possible, the battery needs to deliver thousands of watts of electrical power, far more than most batteries are designed for.  Some batteries can deliver a lot of power for a brief amount of time, but since a long hill climb can take seconds or even minutes, we need sustained high power.  And while going down hills, the regenerative brakes need to be able to send substantial amounts of energy back into the battery, effectively requiring it to charge very rapidly.  This type of high power discharging and charging would damage most batteries, but since it's normal operation for us, we need to reliably deliver this performance over hundreds or preferably thousands of cycles.  

Riding uphill needs powerful motors AND a powerful battery.

It's important to differentiate between power and energy, since they aren't interchangeable words.  When we say energy (you pay your utility company per kilowatt-hour of energy), we're talking about the range of the board.  Double the energy and you'll double the range.  But power (which is usually measured in watts or horsepower) is how fast you use energy.  A high-power drivetrain is useless without a high-power battery, but with both you can go faster up steeper hills. 

When we say powerful, we mean a different scale from most devices.  From left to right are AAA, AA, and 9V alkaline batteries, an Apple USB charger, a small and cheap AC-DC converter, a high-quality AC-DC laptop power supply, and the battery cell we use for our pack.  This cell can produce 230W continuously or 384W for a 10-second burst.

Secondary to delivering the necessary performance, the battery needs to be as light and compact as possible.  In our last technical update, we discussed why this is important to maintaining a great longboarding experience and keeping the vehicle as portable as possible.  The biggest differences in performance vs. weight come from different types of battery chemistries, and here are some of the most commonly used ones. 

  • Sealed lead-acid, or SLA, is very cheap but very heavy.  It's most commonly used for starting cars, and also found in low-cost electric scooters, bikes, and skateboards.
  • Alkaline is usually not rechargeable and is most commonly seen in small electronics in AA, AAA, C, D, and 9V formats.
  • Ni-Cd is rechargeable and cheap but hard to recycle.  They used to be common in electronics and remote-control toys, but aren't nearly as weight-efficient as lithium batteries.
  • NiMH is rechargeable, moderately powerful, and commonly used for modern rechargeable AA-sized batteries.  
  • Lithium-ion is the most expensive but it has the highest energy and power for its size.  This is why it's the most common battery for modern phones, laptops, and electric vehicles, despite higher costs and greater engineering challenges.

From the beginning of this project, we've made decisions by asking ourselves "what would we want on our own personal longboards?" and then building it.  In this case, especially with our obsession with portability and handling, the answer was simple:  lithium-ion.

The battery must be compact enough not to touch the ground during hard carving, even with deck flex.

The most important design constraint was safety and reliability.  High-power lithium batteries need more care than the average car battery, with more complicated charging procedures and safety electronics between the battery and the rest of the system.  This was our number one priority, so it came first over performance and weight.  So our design parameters, in order, were:

  1. Safety and reliability during charging and operation
  2. Sustained high power over many charge/discharge cycles
  3. As light and compact as possible


Most short trips around the home or office are only 1-2 miles (0.6-1.2 km).  About 1/4 of US commutes are under 5 miles (8 km).  And most public transit stations in urban areas are within similar distances.  We found by testing early prototypes that a 6 mile (10 km) range was more than enough for short trips and commutes, especially with a fast and portable charger.  For traveling more than that distance, a longboard usually isn't the vehicle of choice.  

Since we didn't give the board any more range than needed, the battery remains incredibly light and compact.  It still handles like a great longboard, it's easy to push, and it's easy to carry.  Our test riders told us that the portability and handling of the board was way more useful than having a 10 or 20 mile (16-32 km) battery at the expense of added weight.

It actually turns out that a longer-range battery pack is easier to engineer, since you can use several regular, low-power batteries in parallel to get high power for the drivetrain.  The biggest challenge in designing our battery was getting this incredible amount of power without resorting to using a much larger and heavier pack.  

We measure the range using a 175 lb (80 kg) rider on flat, smooth pavement at average riding speeds.  Riding very fast, on rougher roads, with a heavier rider, or up hills will decrease that range.  

Prototype Battery

Our very first prototypes were built using the lightest and highest performing batteries available:  lithium polymer (or li-poly or LiPo).  These are most commonly used for expensive remote-control airplanes and cars, with a battery as small as a deck of cards able to deliver 1.3 kW of continuous power and 2.5 kW of burst power.  We mounted a 6 mile (10 km) battery to our drivetrain and it worked incredibly well.  So well, in fact, that every board we built between the first board in 2011 and our second beta run in June 2013 used LiPo packs.  So why change?

The lithium-polymer charger for our prototypes was cumbersome to use.  

There are several varieties of lithium-ion batteries, and most lithium-polymer batteries use lithium cobalt oxide (LCO).  The high power variants used in the RC world can easily be damaged or even catch on fire if they're overheated, overcharged, or punctured.  So they need to be monitored while being charged with a special "balancing" charger.  These chargers, and the need to always be with the board when it was charging, was a frequent complaint from test riders.  We also sometimes had to replace batteries that became physically damaged, "swelled", or had individual cell errors.  And it was difficult to calculate the battery's state of charge without more advanced electronics.

High-power lithium-polymer batteries are easy to damage without proper care.  These are some of our test batteries that are no longer functional.

To hold the battery to the board, we designed a fabric pouch with button snaps.  This was a light design that was decoupled from the board flex and easy to fabricate in small quantities.  But it had no mechanical protection, didn't look that great, and provided no water resistance.  

LiPo batteries were housed in a fabric pouch with button snaps.  This was easy for protoyping but not durable for long-term use.

Production Battery

We first tried to find an existing battery pack that met our requirements.  We found small packs that couldn't output enough power as well as high power packs that were large and heavy, but nothing met our needs and we knew a custom solution could work.  So we decided to pursue a completely custom battery that had never really been built before.  The design involved choosing the right battery cell, adding a battery management system (BMS) and enclosing the pack in a protective case.  And, of course, we would need to extensively test this new design.


After realizing the inherent risks in some lithium chemistries and finding it difficult to source low volumes of high-power cells, we decided to use a different lithium-ion chemistry known as lithium iron phosphate (LFP or LiFePO4).  This provides safety and high power, though at the expense of slightly more weight and bulk compared to LCO.  With a few suppliers to choose from, we optimized for reliability and performance with a very high-quality cell that we could easily obtain in the volumes we're producing.  We use 12 cells in series, each with a nominal voltage of 3.2V, for a total pack voltage of 38.4V.

Some of the lithium cells we considered for our battery design, both in pouch and cylindrical formats.  


The battery management system, or BMS, is hardware and software that keeps the battery operating safely and effectively.  It protects against failures like
  • undervoltage, where one cell drops too low
  • overvoltage, where one cell is charged too high
  • overcurrent, where too much power is drawn from the pack
  • overtemperature, where the pack overheats
  • short circuit, where the positive and negative terminals of the pack are connected

To protect the cells, the BMS can turn the entire pack's ability to charge and discharge on and off.  It also controls charge cut-off, balancing of the cells during charging, and state-of-charge (SOC) calculations to determine how much range is left on the longboard.  The BMS has its own processor and talks over CAN bus, a robust automotive-grade protocol, to the main motor control processor.  

Surface-mount components were hand-assembled onto the BMS during early testing.  Production BMS circuit boards will be assembled by machine.


The enclosure design started with deciding how to arrange the 12 cells for maximum clearance from the ground and wheels and then adding space for a charging port and an on/off button.  To quickly mock up different cell configurations, we cut PVC pipe to the same dimensions as the cell and taped them together to check for fit.

PVC pipe mockups of battery cells, taped in different configurations, were used to prototype and test before building a single battery.

A flat rectangular block was the simplest layout that met our clearance requirements.

Once a cell layout was decided, we moved to CAD models and eventually 3D prints to test how different designs looked and felt in person.  We even created a CAD model of the BMS circuit board to make sure it fit correctly into the enclosure.  

Mockups were made using foam, 3D-printed ABS plastic, and heat-shrunk plastic before the final part was injection molded.

Once we were happy with the enclosure, we paid for the injection mold tooling and got our first shots of the enclosure.  We use the same rugged glass-filled nylon as the electronics enclosure.

The battery pack integrates the cells, BMS, on/off button, and charge port.  Its processor communicates with the motor controller using CAN bus.


In addition, the balancing charger with buttons and a screen has been replaced with a simpler laptop-style charger.  The standard charger should complete a full charge in about 90 minutes, faster than most other electric bikes, scooters, and skateboards. 
The new charger is similar to a conventional laptop charger with a simple barrel plug, with a huge improvement in the charging experience.  Here are some of the final test boards being charged.

Fixed, not Swappable

The LiPo battery we used for most of our testing was always swappable, and we planned to keep it that way in production.  But during the engineering phase of the project, with the heavy vibration and potential for a water splash onto the battery, we discovered that a connector was much less reliable, and therefore not as safe, as soldering the battery wires permanently.  And we also noticed that of the 40+ riders using 20+ boards for errands, commuting, and fun, only one ever asked for a second battery.  Finally, each battery also needs the BMS to be attached for safety reasons, so the cost of a second battery (along with enclosure and BMS) would be prohibitively high.  Since safety and reliability is paramount for us, and since our test riders have been happy without swapping batteries, we've decided to remove the connector and make the battery fixed and non-swappable.

Testing and Results

We tested the battery on the benchtop using high-power supplies and loads. 

A laptop and XBee radio were set up to download wireless telemetry from the electronics during road testing.

We tested the new battery design on the benchtop using our motor dyno and also solid-state loads, and of course we've spent hundreds of hours outside with test units.  Expect a future blog post about our testing equipment and the interesting things we've learned.  

The end result of this testing and development is a battery that works incredibly well, with the ability to supply thousands of watts of continuous power from only 12 small cells, an easy on/off switch, easy and rapid charging, and a beautiful design.  Our cells are rated for thousands of cycles, so we expect each pack to last for years of daily use.  And most importantly, we have a safe, high performance, and compact battery that preserves the design vision we had for the lightest, most powerful electric longboard ever made.

Five test units with the production battery waiting for delivery.
89 responses
I'm glad that you got everything sorted out making sure that it is done the first time it goes out to customer i'm hoping I will get mine by the end of this november so I can try it out without having to worry about rain keep me posted and good job to everyone ....
Would you consider switching to LiFePo4 batteries instead? They aren't too much worse in terms of energy density, but are much safer.
Cant wait to have a go :-) Wonder what the import duty will be for the UK :D
Will the charger work in Europe, (230 V/50Hz compared to 110 V/60Hz)?
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Wow, all this seems like a ton of painstaking work (or maybe two or three). I'm also impressed by your dedication to giving the best riding experience!
I so love your board I just wish it had more range I need to get me home at night when I work at the bar like swappable battery's I'm still going to get your killer board but I'm sad it will not get me home I got a ZBoard Pro then I got a ZBoard San Francisco it weighs way to much so that's way I was looking at the boosted board and the hill climbing because I live in Halifax NS, Canada and got lots of hills I got to get a new electric board to get me home but I'll use the boosted board for fun
Travis, the LiFePO4 chemistry is the one we're using. Mårten, yes, the charger will work in Europe.
Very beautiful. Can this polymer battery drive your motor ?
Given that charging at each end of a commute may be a regular thing, maybe the the charger should be incorporated into the Boosted so you'll never forget it and be unable to charge. Or you could make it charge (painfully slowly) from a USB connection :-)
Fantastic update! It's rare you find a company that updates their customers so thoroughly and regularly. I'm excited to get my board. 6 miles is perfect for my use (some business, some personal). Maybe for people that want extra distance you can have a plug in port so they can plug in a temporary external battery pack. I know it's not an elegant design solution but some people might need to go a little further. I used to live in San Francisco and I used my Segway four days a week for work, travelling about 8-12 miles/day.
Fantastic. Thanks for the update. Be sure to post if you take your demo boards up the coast. There's more than a few of us here in Eugene, OR that would like to give it a try.
I really appreciate the updates and it helps appreciate the engineering that much more. I also appreciate the design principles, and practical choices made. I eagerly await the end product.
Couple of questions; when the batteries do run out, am I coasting in "neutral" or pushing against the motor to charge the battery? Perhaps the better question is; is there a neutral mode? I've got a 9.5 mile commute and i love to imagine i could conserve the battery in the middle section.
When can we order in Brisbane Australia . ????
When can we purchase in Australia ?
The current range will work for me since I work and skate on a college campus. One question, do you think you'll sell additional chargers? That way I can keep one at home and one at my office. All I would need to tote would be my board. Can barely wait for winter delivery... シ
Looking great guys... Keep up the awesome work. Great choice on the battery technology and enclosure. Really pumped for you to start shipping out the pre-orders. Congrats on the progress.
Good Job. I'm ready :)
I'm still in the waiting. I wonder for real when I can get one. Because I use for work. Because I'm waiting for you guy I'm not getting a electric bicycle. I'm waiting almost a year.
Thanks for this fantastic update! For me I need exactly 6 miles one way to work so I want to confirm that your range is still that or slightly better. Con you confirm? And I would be a fan of selling extra chargers so I can keep one at work and one at home. Can you confirm that as well? I'm dreaming of the day very soon whee the BOOSTED BOARD becomes my primary commute vehicle on days that are not raining or snowing, which should be at least 130-150 work days a year.. You guys rock!
Amen to quality engineering! They're using LiFePO4 packs already! And bah humbug to folks like me who don't RTFA closely! ;)
It is cool, how can I buy one? I'm in China
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I really love the design but 6 miles is not very far...
Great post, y'all!
I really appreciate the depth and frequency of the updates! Few questions: - Has the controller changed at all in design or functionality from what's on kickstarter? - Can we customize our order to be different long board from Loaded Boards, such as The Bhangra? Pretty please?!! - Do you have plans to develop a short board in the future? Keep up the good work guys, and I can't wait for mine!
Great update, what is the FINAL EXACT weight of the board ? Can the board be taken on an aircraft as hold baggage? Actually, how do you guys ship them overseas?
really exciting to ear can't wait
Great job ! Thanks !!
Looking absolutely amazing but hurry up I will be over fifty by the time I get one
If you calculate with 6 miles on flat clean nice asfalt would the normal range be 4-5 miles. In US it´s probably OK, you don´t walk to the postoffice or to buy a croissant, you take the car. If not you would need to charge it at the postoffice and re charge it in the bakery. Everything you want to reach should be within 2 miles or take the car. I live in Sweden and do not have all of small errands like bakery, postoffice, newsstand a s o 2 miles away. Could you deliver a solution for extra power snap-on, for loading while not skating, as an option. Excuse my english. Best regards Janne
The boards really look the business. When is the first production run ready for UK delivery?
Wow~ but I think it will be expensive
Wow, nice work and design. Can't wait to play with this. One question, when it runs out of power, will it be painfully sluggish or can I "put it in neutral"? Also, any ideas what an extra charger will cost? I would probably populate all my standard destinations with a charger...
supporting the project from Japan :) Looking forward for the final product!
Awesome development guys. Keep up the good work!
Hi guys, great update. For the people with concerns about the 6-mile range, here is my thought: Like an electric bicycle that you can still pedal when it runs out of juice, you can still push the board (and that's 10 times faster than walking) all the while keeping braking capabilities for descending hills. And am I right in thinking that if you give it a rolling start, therefore using up power just to maintain speed, it could have a range longer than 6 miles? Another question would be: What drains the battery the most, starting from a standstill or maintaining speed?
Super good job. An engineering masterpiece! I am on pre-order and waiting for that, "time to make a deposit" email and a confirmed shipping date. I feel like a little kid waiting for Christmas and can't sleep. Just think of all the fun waiting to happen. V/R Derek
I Live in Honolulu Hi. Yes! Why not as an Option to buy an extra battery pack that was interchangeable where you were limited to 5miles"slap a second battery on" UH Campus to Ala Moana Shoping Center 2.7miles. Terrain hilly, on another note is the regenerative braking help out. How does it work?
Wait for every throb
My son Mike has been keeping me apprised of your progress but today is my first opportunity to read the Boosted Blog. I'm a retired AF officer and all you have gone through is analogous to the low orbit satellite world in that they had to come up with a rapid charging system (each revolution about the earth is about 1 1/2 hours) and for noon/midnight orbits has only 50 min or so for charging. They also have high temperature issues when in sunlight and their need for high power while in sun and in darkness created a significant design challenge. They also had to develop ~BMS to maintain a continuous sense of the battery condition and level of charge. That all led to improved understanding of the need to avoid overcharging and the value of periodic full discharging. You've got a great product and a superb method of working issues - as well an exceptional method of allowing others to track your progress. God Bless you! JPH
I live in a hilly area (over 20 degrees hills for 10 blocks) and have a few questions regarding that. Would it be able to climb more than 15 degrees (based on the board specs) of hills for more than 5 minutes? How many charging cycles would the batteries sustain for such hill-climbing every day? What is the process of getting the batteries replaced?
A diconnected neutral mode will offset the lack of a swappable battery. I'm excited to get mine anyway but hope for a neutral retrofit option (and swappable battery option) later.
Thx 4 update Braham.
Thx 4 update,Braham..
It's summer downunder,out on my old board am/ pm waiting for my "Boosted" to appear.. Ps..I now " look" up hill....!!
Have you considered an external port for connecting a parallel external battery source? This would preserve the integrity of the current design, yet provide the flexibility to extend the range to the limits of optional external battery sources. I would think a waterproof posi-lock connector would work fine, with a dummy cap in place when not being utilized. Just a thought; I love your design! Keep it up!
Great work ! I just saw NBC Today Show showcasing your latest stage board - I thought too of an external battery source option. Your work is an inspiration in case anyone didn't notice. I'm a sixties teen in a sixteen teen body - I may need to buy alot of knee/arm protection soon. Cool, very cool!
Sounds great. Although the chance of needing a replacement battery will be slim, if the need arises, are there plans to support such a need?
I also suggest you guys to use the Solar powered skate board for constant charing to the battery..
I love this idea i wish it wasnt so expensive though.
Firstly, your product looks amazing, really well designed, thought out and put together,a totally slick and a high end product. I've been riding electric boards for a couple of years now, and love the experience, and would love to get on one of your boards (I have a GNARBOARD TRAILRIDER at the moment and love it) My concern is that you maybe limiting your market. Not everyone needs to travel a short distance from the train/bus/carpark to the office. I live on the Gold Coast , Australia and there's nothing better than getting up early and going for a long morning skate for a couple of hours, get some breakfast hangout etc. Some of us just want to get out and skate for hours and have fun :D We have km's and km's of beach side paths and roads to skate on, beautiful weather etc. With your knowledge and expertise I'd love to see you guys bring out a board that is high performance (45 + kmph) and long rang, use all the best gear and latest technology. An all terrain /off road version would be awesome too. Is there anything in the pipeline??
Hey guys! I was just wondering if the board can recharge while riding it. For example when going down hill or just riding it with using the battery? if not wouldn't it be a way to make the booster board even more green
hey,how many people preorder the boards?
Great work! Nice design, love it :-)
If you want to promote this, it need a cheap price.
When will the battery self regeneration (through braking) be touched upon?
I was 59 when I ordered the board. I am soon to be 61. Literally, in that time, I have gone blind in my right eye. When do you reasonably expect delivery of the third run? Respectfully, Gary W.
how about a blog update with the only topic that really interests us... when will boards be available. if you're not shipping soon, just let us know so we can go buy Evolve boards instead.
I have now given up waiting and ordered a carbon evolve board... shame really as I have wanted a boosted board for a lonnnnnng time now....
I'm definitely on the wait list already. That said, is there any chance BB will develop a hot swappable battery so we don't find ourselves SOLuck after six miles? I was hoping to use my board for professional applications, as being a cameraman, a board like this could revolutionize high speed tracking shots in tight spaces. Having a back up battery option would be key.
I agree with russ c !!! Sone times I just want to go out riding .... all day lol I want to be able to have extra power .... even if I have to carry it on a backpack and run a wore down my leg with a magnetic contact like on a Mac Book just I case I bail for what ever reason ....... EXTRA POWER !!!!!!
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Is a useful article, I found interesting thing, I'll come back. I also found another interesting things how to choose the right battery for solar system power here :
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