Swappable battery -vs- Fixed Battery

[onloop]

LETS DISCUSS THE PROS & CONS OF:

Easily removable / serviceable battery
VS
Battery that is difficult to change/remove

List your pros/cons of each & discuss.

 

[Doctorbass]

LETS DISCUSS THE PROS & CONS OF:

Easily removable / serviceable battery
VS
Battery that is difficult to change/remove

List your pros/cons of each & discuss.

look like you could have started a thread just with "VS" and split it in every parts you need to compare :wink:

Doc

 

[onloop]

yeah... i suppose.... but i like my topics of discussion to be specific, it much easier to stay on track that way!

 

[onloop]

honestly I use to think that swappable batteries was a really good idea....

take for instance the phone industry... when i got my first samsung phone (after years of owning an iphone), the galaxy note 2, that offered the ability to swap batteries i thought to wow this is great!

so i went and bought an extra battery & a nice desktop/cradle charge thingo.... i used it every now & then... but not daily... mainly because the battery that came in my phone was able to last approx 2 days without recharge i simply found myself just plugging it in at night to recharge... the extra battery didn't get much use....

now samsung have just released the new Galaxy 6 and the one feature that is gone is removable battery? WHY did samsung do this? was it market research saying that the feature is not beneficial?

my electric skateboard has the ability to easily swap the battery, just remove two screws.... guess how many times i have swapped my battery? NEVER!

So is it an advantage on a skateboard or a marketing gimmick?
PROS
> if you want to travel a really long distance and the range of a single battery is not enough you can swap with a fresh charged battery out of your backpack
> if the battery dies you can easily (probably still need to undo some screws to remove lid) replace it... but honestly i think you could get the battery out of any electric skateboard fairly easily by undoing some screws and disconnecting some wires.
> maybe you want to reduce the weight, so you can have small batteries & big batteries?... honestly i would never want smaller battery, weight really isn't a major concern for most people... we are talking in grams.. just give us a bigger battery!...
> option of sharing.... give your mate your battery so he can get home.... i personally wouldn't trust anyone with my batteries
> remove battery for airplane travel?

CONS
> this would likely increase the cost of the product, as a special design is required to allow it to be user friendly, water resistant, strong...
> theft... easier to steal the battery?
> is carrying high power battery in bag a good idea when you crash?


I think that there are some other solutions that would make the removable battery feature completely useless...
1. make electric skateboards that roll with zero resistance... then if battery is drained you can easily push
2. just put bigger batteries on the board to start with... we are talking a few grams increase in weight
3. integrate solar regulators into the ESC so that auxiliary charging from sun can occur when riding
4. faster chargers.
5. push assist technology... range would be massively increased.... i think justin spoke about developing this... this would be a breakthrough in electric skateboard tech

 

[torqueboards]

I still prefer swapping packs. If your already going with custom packs you might as well swap packs.

That's similar to asking an RC car hobbyists, Quadcopter hobbyists to use only 1 battery pack. Not everyone wants just one battery pack.

10S 5000mah vs 10S 10,000mah is a big difference not a few grams.

Based off of Zippy Flightmax 5000mah 5S1P 20C - http://www.hobbyking.com/hobbyking/store/__8581__ZIPPY_Flightmax_5000mAh_5S1P_20C.html
1240g for 2 packs on 10S 5ah. 2.73lbs - 1.23kg
2280g for 4 packs - 10S 10ah. 5.02lbs - 2.27kg

As light as possible means a better ride. Riding a 10-15 lb board versus an 18-20 lb board IMO is a big difference. 2lb difference.

IMO... If you can ride your board with 10S-12S 4000mah or maybe 6000mah and carry a few extra packs to swap out when you want too. That's awesome.

I'm biased though.. I have about 20-25 spare batteries for Samsung Note 3. lol I enjoy swapping packs. Call me crazy but I can use the crap out of my phone and just swap a battery. I'd rather swap batteries all day vs carry a charger and/or stand by a charger.

 

[tung256]

i work in the telecom industry so i can tell you why samsung s6 battery is nonswappable.
samsung is gunning for the premium market this time around with the s6. after years of people griping how plastic and cheap their previous galaxies feel, samsung went ahead with metal and glass for the whole phone. big mistake because the phone is now much much easier to crack upon impact. and off course it's just not possible to pop the back and slide in extra memory nor swap out batteries. this is where hardcore fans of samsung feel alienated...

im all for swappable batteries. i have no intention of carrying extra batteries around. but ultimately the batteries will loose their charges and needs to be replaced. it's a nuisance to go into a special shop or send the whole phone back to the company for service. i can just get a battery off from amazon or a local shop and replace my phone's battery within minutes.

in the end, it's about having options. people love having choices, or the illusion of choices. this is why android phones are dominant in the mobile world or why Windows is in the PC world. nobody likes to be tied down. (the only reason i got an E-Go is because im lazy to figure out stuff. but i will build once i figure it all out)

 

[chvidgov.bc.ca]

Its always nice to have a few charged up packs lying around when you have nine ebikes! Swappable, although lately I have set up specific bikes with more dedicated packs, with the possibility of subbing in an external pack in when required or running parallel with the dedicated pack.

 

[onloop]

why carry extra (battery) weight on your back? this puts your center of gravity much higher, meaning it will impact your balance when riding aggressively...

ALSO two batteries means you need to buy another charger... thats if you want to charge simultaneously... which i assume you would otherwise it could just be one single large battery... as charge time is same.

i think if you really need interchangeable battery it should just clip into/onto the skate deck / components chassis ... with all the money these kickstarter campaigns raise they should be developing some cool battery clip/quick release system for eboards....go from 5AH, 10AH 15Ah using 5Ah modules that simply just click onto deck at the lowest point.... they could make some real good money just selling battery add-ons


anyway.... in terms of weight, let me tell you a little story...
Johnny lives 30kms from work and currently uses his old school non-electric skateboard that weighs just 4kg to get there..
Johnny really loves skateboarding but 30kms is pretty far way to travel!
However Johnny is not too worried because the ride to work has some long, but not overly steep hills, so he gets to ride down them on the way but has to carry the 4kg board up them on the way home.
On Johnnys birthday he gets a gift from his mom, yay it's an electric skateboard!
Johnny asks "hey mum, how far does this thing go on one charge?"
Johnny's mom says "15kms Johnny"
Johnny asks his mum another question "so how much does this weigh"
Johnnys mum says "only 8kg"
Johnnys sighs, and says "arh thats going to feel REALLY heavy carrying up the hills on the way home compared to my old deck that weighs half as much at only 4kg"
Johnnys mums says "I'm really sorry johnny, Unfortunately I can't take it back!, I am also sorry to say johnny, they did have another model that was only 1kg more and could travel twice the distance of this one, because it had twice the battery capacity, so you could do 30kms on one charge, but i was worried because you previously complained about carrying your 4kg board so i didn't want to get you anything too heavy"
Johnnys pissed off!... he screams "MUM, you silly bitch i need to travel 30kms to get to work! and this piece of SH*T you bought only goes 20km so i now have to carry twice the weight of my old board up hills. if you had of bought the slightly heavier one i could ride it the entire way and never have to carry any weight ever as my electric motors would do all the work"

the moral of the story is ...if i ask you to choose between carrying around an 8kg (17 pound) weight for a few hours VS 9kg (19 pound) weight, of course everyone chooses the 8kg one... but if i then tell you that if you choose to carry the 9kg weight, instead of the 8kg, you get a lift all the way home without carrying any weight at all!... most people would be like "dude! thats nothing, give me the F'ing 9kg one"...

i hope you like my story..

 

[torqueboards]

5 lbs of batteries in a backpack wouldn't throw off your center of gravity. 10 lbs, yes I agree it would. Although, the added 10 lbs on your board or even 5 lbs - doesn't help either on your board and definitely makes your board less maneuverable and heavier. Unless your doing power slides.. it's much different doing a powerslide on a 15-18lb board versus a 3-4 lb board... You can still carve and manuver with a 5-10lb backpack on you. Sure, you can't lean as much since your top heavy. To carve for fun only takes your legs. Your upper body doesn't have to move much.

What if you only need to ride 5-6 miles one day? You still carry enough batteries for 20 miles?

How a typical skateboard/longboarder drops their board on the ground before riding.. Your going to drop 5 to 10 lbs of battery from waist height? I'd rather drop 2-4 lbs from waist height and keep my battery packs at the back/bottom of my board to where I'm only dropping 4 lbs from 6" off the ground.

I agree - clip ons would be great. However, depending on how it's made a clip on is definitely much more prone to breaking. I would prefer a cord/wire to connect to a battery pack easily preferably also connect to a BMS while the packs are easily swappable with a single cord or cable. With a cord/cable it's less likely to come apart from riding vibrations.

Great story and in the case of a 3lb different. I definitely agree.

However, imagine most people don't ride 10-15 miles straight. Some people actually have to carry their boards up stairs and/or into grocery stores and/or around an entire mall.
w
I would prefer to carry a 14 lb board and 3-4 lbs extra in a backpack.

I think all options are great and I'm all about carrying more power and distance capacity on my board. But it's nice to have both options. I like the modular setup of having different capacity packs.

 

[justin_le]

I think you need to discern a bit between swappable batteries and replaceable batteries. There isn't much need at all to have hot swapping of battery packs in any EV. You make sure that your battery has enough capacity for all the travel that you'd do in a day, and then simply charge it at night. If you were going to carry a 2nd battery with you on a trip to swap with the first one when it runs out, then it is foolhardy to do that. Instead you should have both batteries mounted together and running in parallel so that it behaves like a single battery with sufficient range for your needs, and then the average 'C' rate during discharge will be just half as much, as well as the pack's internal resistance. So you have less voltage sag under load and much better cycle life from the cells then if you drained one battery first, swapped it, ad then drained the second.

But the example of smartphones here is a case where the batteries are not just non-swappable, they are non-replaceable. When the integrated phone battery is at the end of it's calendar/cycle life in 2-3 years, then there is simply no way for a normal user to replace it with a new battery. I don't like it but apparently that's fine with throw-away consumer electronics products that become obsolete in a couple years anyways. However vehicles can and should last for DECADES. All the hardware on them is serviceable and frankly most components (like the motors) will last forever. The batteries don't last forever though, they just last a couple of years, and it's essential that users have ability to replace their pack when the original one is worn out. Could you imagine making a car where the tires were fixed and couldn't be replaced once they got bald, making the entire vehicle a write-off when everything else about it still runs fine?

If the battery is fixed and integrated in the vehicle with no means to remove and replace it, then the entire item is just a throw away disposable product. I haven't seen that happen yet with e-boards the way it has with phones and laptops, but it would be a real shame if it did. There is a business case for it (oh, your battery is worn out, well you can't replace it so why not buy our latest newest model of XYZ instead?!), and it sure screws the end-user!

 

[onloop]

I think you need to discern a bit between swappable batteries and replaceable batteries.

Good point... So two examples.

The new "monolith" eboard on kickstarter has a compartment to easily access / swap the battery in the field... Presumably with zero tools or technical know how. They say: "A depleted battery can be swapped in seconds with a fresh backup in one of three sizes. From pocket sized to full sized, Monolith owners can choose the battery that matches their daily needs."

This to me seems like a marketing gimmick... Of course The one piece carbon fibre deck needs a hatch anyway for them to be able to put stuff inside the cavity... so i suppose the marketing guys thought why not capitalise on this and promote it as a feature...lets just hope the battery that comes with it is decent capacity... If people are forced to carry extra batteries in their pockets I think they are screwing everyone..... I say just jam as many batteries as possible in the deck and then promote that they offer market leading range also make it so end user can get it out.... Or come up with a sweet clip on booster pack so that if the range is not enough for your requirements you can buy more WH and semi/ permanently clip it on.

I think it's cool that you can swap the battery I just don't think people would if the battery was a decent sized one to begin with.

I just think if an eboard has the correct amount of capacity you don't need to carry batteries or offer hot swap anything... Freely ride a few hours and charge nightly it's that simple.


Boosted on the other hand is an interesting example. They don't advertise swappable batteries and they don't sell new batteries... So it would seem they don't want you to fiddle with changing batteries.. They say " A larger battery would make the board heavier and less portable, negatively affecting the ride and performance. Swappable battery packs are an exciting possibility but it will take longer to develop a reasonably priced, well designed, quick release battery that can withstand the shock and vibration of riding."

Who know what marbel are going to do..?


So clearly there is some huge difference in offering here between these major names in eboard manufacturing.... What does everyone else think about this?

 

[agraham]

Here's a couple more stories...

I'm going to work on the train and need to carry my board on the train and in the office and only need to get across downtown. I want the board to be light with a small pack.
I want to zip out to the supermarket but I know I have to carry my board around the market with me plus a basket of groceries - it would be nice if I could use the small pack for this trip.
I want to go for a ride today and what I'd like to do is go downtown, then to the burbs and hit some hills, then back home. At no point will I be carrying the board but I need a lot of range. Now I want to put in the large pack. Failing that I'd like to bring a second pack. Even if I don't have to swap it in, I won't have range anxiety.

This isn't theoretical - I'm just heading out now with my Boosted to go downtown and around Vancouver's Stanley Park but I know I won't have the juice to get back home so I'm planning to hit a coffee shop at some point a grab 30 minutes of juice.
I wouldn't want my board to be any heavier - it's right at the limit for something you can pick up and throw around easily which is important to me - but at the same time the range sucks - I really wish the battery was swappable.

 

[justin_le]

This isn't theoretical - I'm just heading out now with my Boosted to go downtown and around Vancouver's Stanley Park but I know I won't have the juice to get back home so I'm planning to hit a coffee shop at some point a grab 30 minutes of juice.

Ha, too funny, that is also on my agenda on this fine saturday afternoon in Vancouver. I don't suppose you'd be interested to meet up at some point next week and do a short test swap of each other's boards? I haven't ridden or even seen the famed boosted board yet and am keen to do so, and would be curious to hear of your opinion comparing it with this.

I wouldn't want my board to be any heavier - it's right at the limit for something you can pick up and throw around easily which is important to me - but at the same time the range sucks - I really wish the battery was swappable.

Well there we have it. But rather than swappable, it would still be better if there was simply the facility to add a 2nd booster pack in parallel with the main battery for when you needed the extra range trips. You can in fact do this pretty easily if you open it up to access the + and - battery leads going into the motor controller and splice some wires to that to bring them out to an accessible connector. The 2nd battery could sit on top of the deck where you don't put your feet, and you'd only strap it on when you were doing longer range trips.

It doesn't look like boosted gives a clear documentation on their website of total battery capacity, but from the pictures that seems to be 12 cells of 26650 LiFePO4 which would be ~38V 3.2Ah or about 120 watt-hours? I'd say the minimum for a practical commuter board is 200 Wh, and you can make a >200 Wh pack with modern 18650 lithium cells that is lighter than the 120 Wh of LiFePO4. Get nearly double your existing range with no additional weight.

 

[onloop]

I think it is fair to say that everyone will gladly accept larger batteries as long as overall weight doesn't increase....

"Cuz carrying heavy shiz around the mall sux"

As someone who loves solving problems with smart, simple design solutions ... I can't help but think about the questions product designers are asking themselves?

How can we improve range but also not increase vehicle weight.... "hot swap batteries"...they say... Well maybe not, I believe the answer might be to make skateboard parts weigh less so that a standard larger battery doesn't increase weight beyond what is comfortable to carry....i suppose Its natural instinct to not think about weight reduction and just offer the ability to hot swap batteries, because, well, it sort of solves the problem... Sort of... Except that fact you are still actually carrying the weight of additional batteries, just on your back... So i think the design challenge is not a question of whether there is enough battery capacity being provided to our end users, it seems the real complaint/problem is too much weight, right?.

So get the weight down and then have more capacity as a standard feature.... so how to get weight down?
1. Less batteries... yeah batteries weigh a lot... but we all want more range.. and i don't believe hot swapping is the best solution... a well designed booster pack might be nice... but i think we can do better.... so lets look elsewhere..
2. smaller / shorter deck... the deck on a standard longboard is the largest single item, an 8 ply maple deck of around 95cm long is about 2000 grams or 20% of the total weight, so make it smaller, but now there is less room for the larger capacity batteries... so what else?
3. Make the deck weigh less. Great idea! with the use of composite materials this is definitely a key to improving the WH to Total Weight RATIO... or as i like to say the WHW-RATIO
4. Wheels.. a set of four 83mm wheels commonly used on eboards (without bearings) is about 800 grams or 10% of the total weight (approx 8000 grams) of an average dual drive electric skateboard with 240wh of battery. i think a new type of wheel could be developed that would be 50% lighter... so with some rough calculations, if one gram = 0.18watt hours you could get maybe an extra 70WH just with lighter weight wheels and zero net weight increase.
5. trucks... im not sure you could save much weight here without compromising the strength, however i have read about someone who made a carbon fiber trucks. read >here<
6. lighter motors, don't think that is a good idea.

So I say forget hot swap batteries, focus on really lightweight wheels & quality composite decks (that have a little bit of flex) that also have massive battery storage compartments.... literally the entire deck should have battery in it.

I suppose some supplementary problems also need to be addressed...

So why is carrying an item that weighs marginally (say 2 pounds) more than another item such a problem for homo sapiens...are we just a bunch of whingers?? NO i dont think so... I think the problem is related to the shape of a long board, they are long, duh, and the weight is not a central mass. Carrying any skateboard (non-electric included) for a long period of time gets annoying, they just aren't designed to be easily carried... and there is so much other cool sh*t to do with our hands....the weight of the wheels & trucks are at both ends and that weight wants to roll the deck out of your grasp (not to mention the grip tape constantly rubbing on your nice clothes..) so this odd-shaped mass puts constant strain on the wrist joint... the wrist is a sh*t joint.. it was not designed to bear lots of weight... homo sapiens much prefer loading weight down through the centre of the body onto large bone & muscle structures like the hips & knees.

So why aren't we designing skateboards that are better to carry? Richard at alien designed a nice little carry handle for his boards... would a handle solve the complaining about weight? probably not... I think a shoulder strap or bag is the best tool to help leverage the weight.

& there are definitely some cools bags available for carrying longboards, they are expensive though, obed springs to mind, but there are probably others doing a good job... if i knew i had to carry my board around a lot with me i would definitely get a bag.... then the weight would not be of any concern.

Now the next thing to think about is why carry anything anywhere?... you don't see people walking around with a bike under their arm... they lock them into bike racks...

So why not design electric skateboards that can be securely locked to a bike rack... make it hard for the bits & pieces to be removed and maybe integrate a retractable cable so you can lock it anywhere....

Also, why are there bike racks everywhere? For fu8k sake, why not skateboard lockers!... bastards... so some community based education initiatives need to happen discussing the benefits to society of electric skateboards as a viable mode of transportation... oh and how they hurt our poor wrists when they weigh too much..

Anyway... some food for thought... personally i would like a board that i can ride for 3 hours before it needs charging.. & never have to buy, or charge, or carry an additional battery... so i probably need about 700 or 800 watt hours of battery so my battery would weigh about 4.5kg

 

[torqueboards]

Good points. I think it's a good idea.

I would like to have 700/800 watt hours also . Would also like to "never" buy or carry an additional battery pack but that's not possible.

I do eboard curls + eboard front raises when I wait for the train. lol

Ideally, the answer is build a 20-35lb board and curl / front raise 35 lbs then the 25lb board is featherweight.

 

[melodious]

I have the answer. A longboard/mtboard backpack specifically designed to hold the weight of 30 odd pounds. A nice lumbar strap would be mandatory.

Last time I went to REI, I browsed the backpack section and couldn't find a single bag designed for this job. Even the snowboard packs weren't accomodating. Maybe, a big MAYBE, if you added straps to the existing lashes of a backpack, you'd at least have something. But I wouldn't run with a board attached :lol: .

 

[agraham]

Ha, too funny, that is also on my agenda on this fine saturday afternoon in Vancouver. I don't suppose you'd be interested to meet up at some point next week and do a short test swap of each other's boards? I haven't ridden or even seen the famed boosted board yet and am keen to do so, and would be curious to hear of your opinion comparing it with this.

Totally. Wow hadn't seen that build of yours. Looks amazing I'm very keen to try it out. Will PM you shortly.

Well there we have it. But rather than swappable, it would still be better if there was simply the facility to add a 2nd booster pack in parallel with the main battery for when you needed the extra range trips. You can in fact do this pretty easily if you open it up to access the + and - battery leads going into the motor controller and splice some wires to that to bring them out to an accessible connector. The 2nd battery could sit on top of the deck where you don't put your feet, and you'd only strap it on when you were doing longer range trips.

That's genius. I don't think I'll do that while my board is under warranty. I'm think of maybe just putting together a pack I can put in my backpack that outputs exactly the 43.2v of the charger so I can get a little boost now and then. Don't know enough about electronics to design it tho, assuming it's possible, so I'll create a thread here and hopefully some folks will help me out.

It doesn't look like boosted gives a clear documentation on their website of total battery capacity, but from the pictures that seems to be 12 cells of 26650 LiFePO4 which would be ~38V 3.2Ah or about 120 watt-hours? I'd say the minimum for a practical commuter board is 200 Wh, and you can make a >200 Wh pack with modern 18650 lithium cells that is lighter than the 120 Wh of LiFePO4. Get nearly double your existing range with no additional weight.

They say it's 99Wh which probably not coincidentally is the limit you can take on a plane and ship by air without dealing with dangerous goods papers.

 

[justin_le]

That's genius. I don't think I'll do that while my board is under warranty.

Buddy, this is the Sphere. You're supposed to rip up that warranty sticker and start hacking away!

I'm think of maybe just putting together a pack I can put in my backpack that outputs exactly the 43.2v of the charger so I can get a little boost now and then. Don't know enough about electronics to design it tho, assuming it's possible, so I'll create a thread here and hopefully some folks will help me out.

If you are planning to emulate the charger then that's a lot more difficult than simply running a 2nd pack in parallel. A 2nd battery need not be exactly 43.2V either. Standard 10S lithium packs are 42V hot off the charger and will work just fine with the board and board electronics. At run time your pack will be sitting at about 38-39V most of the time, 43V is only what it hits just at the very end of charging, and you can charge it just to 42V and it will still be 99% charged (3.5 V/cell).

They say it's 99Wh which probably not coincidentally is the limit you can take on a plane and ship by air without dealing with dangerous goods papers.

There is no coincidence at all there. But you can also have several <100 Wh batteries with you on the plane, so a removable 100 Wh booster pack would still give you full travel freedom and give you double the range once you have landed.

 

[justin_le]

I think that there are some other solutions that would make the removable battery feature completely useless...
1. make electric skateboards that roll with zero resistance... then if battery is drained you can easily push

This I agree with for a lot of reasons. It's not only when your battery is drained, but there can be any number of other electronic failures that will leave you with an unassisted board, and the more rideable it is under human power the more robsust and less vulnerable as an alternative transport scheme. With belt drive boards, in principle you can have a quick belt removal process that would make it into a zero drag drive in those situations. This would be even less drag than an inline hub motor, which will always have the hysteresis core losses in the iron.

2. just put bigger batteries on the board to start with... we are talking a few grams increase in weight

It's more than just a few grams, but still not much in the grand scheme of things. Good quality lithium is averaging around 200 wh/kg these day. 1kg is about the same weight as the pair of shoes on your feet, and gives a solid 12-15 miles of range.

3. integrate solar regulators into the ESC so that auxiliary charging from sun can occur when riding

This would have basically zero tangible benefit. On a deck at best you could have 0.1 m^2 of solar, which in very ideal sunlight situations would be an extra 10 watts of power. It'd be useful if you are leaving your board out in the sun for an entire day to top up the pack a bit, but won't have any effect on your useful range while riding.

4. faster chargers.

Fast chargers are great, but they also weight more in proportion too. If you are carrying a backpack, then the 1kg weight of a Satiator isn't so bad and would mean you could fully charge up a boosted board pack in under 20 minutes. That's assuming that the cells can take it, which if they are A123 LiFePO4's would be no problem. A lot of the really high energy cells don't like to be charged more than a C/2 charge rate, and that puts an upper limit on how fast and powerful of a charger you can use.

5. push assist technology... range would be massively increased.... i think justin spoke about developing this... this would be a breakthrough in electric skateboard tech

It would help for sure if people can alternate between kicking the boards on the flats and gentle hills and having the assist more just on the steeper inclines. But you do consume most of your energy on the uphill bits, so overall I'd project this would bring the average usage from say 10 Wh/km down to maybe 6-7 wh/km. Unlike on a pedal assisted ebike, you can't kick assist very effectively at the speeds that most people like to go on the eboards, you need to slow down a lot for kicking to contribute.

It would be nice if there was some kind of easy way to do a kick 'velocity multiplier', like a track on the side of a deck that is coupled to the wheels or the road with a gear ratio so 10mph on the legs would be like 25mph to the road. But any contraption I can visualize to pull this off would be incredibly hokey to implement. Above a certain speed it would likely be more efficient to bring in a human energy contribution via a waveboard style motion instead of a kicking motion.

 

[agraham]

That's genius. I don't think I'll do that while my board is under warranty.

Buddy, this is the Sphere. You're supposed to rip up that warranty sticker and start hacking away!

You are right!

If you are planning to emulate the charger then that's a lot more difficult than simply running a 2nd pack in parallel. A 2nd battery need not be exactly 43.2V either. Standard 10S lithium packs are 42V hot off the charger and will work just fine with the board and board electronics. At run time your pack will be sitting at about 38-39V most of the time, 43V is only what it hits just at the very end of charging, and you can charge it just to 42V and it will still be 99% charged (3.5 V/cell).

I'm missing something here because you seem to be saying it's easy: pack will output less than optimal voltage, but still charge the board to 99% - but you started that paragraph by saying it's difficult.

 

[justin_le]

I'm missing something here because you seem to be saying it's easy: pack will output less than optimal voltage, but still charge the board to 99% - but you started that paragraph by saying it's difficult.

Sorry, I meant that emulating an actual charger is difficult, (something that you plug into the charge port which then charges up the onboard battery when it is flat) because you need a device with a constant current / constant voltage output characteristic which is quite the opposite of a battery pack. By parallel connecting the packs, you would be starting with them both charged up already. If the charging port uses a high amperage plug, then there is a good chance you could use that for the parallel connection of the 2nd battery for sure, which would mean extended range with no modifications to the board. But more often than not the charging ports are fuse and/or connector limited to just a few amps, not the 10's of amps that could be pulled in from the parallel battery.

I guess we'll see soon enough when you are stop by here with the boosted board unit and we can figure that all out! -Justin

 

[Vanarian]

Interesting thread, I didn't think it would go this far with infos !

I have two suggestions and one question :

-Why not simply pierce two holes at extremities of the board and put a bag clip at each end so you don't need to carry the board under your arm anymore, you hold / wear it like a bag when you enter a shop ?
-How about making a best use of regen ? Same battery size, get more miles. No additional weight.

My second suggestion is similar to "kick push assist" but just more conventional, you meet a downhill, you need to brake? Use regen to slow down or recharge a bit your batteries ? Though it doesn't answer the question "swappable or not ".

Now I got one question, I know many of you guys ride FWD board and I wonder how you feel it's behaviour when you brake or use regen ? Does it feels like it throws you out of the board if you're carefree ?

 

[onloop]

i am not sure anyone (except maybe justin, or vedder) can provide a detailed analysis about regen & explain if it is or is not beneficial on an eboard...

I mention these two people as they are probably the only ones with the instrumentation, knowledge and real life testing to give some data on regen.

here is a video by vedder that shows how much energy is generated from regen
[youtube]nGb-zt2Jp9k[/youtube]

in this 5 min video out of the total energy used to do laps around the street he was able to generate 14% of this back using regen.

all proper regen systems should be recovering energy when braking and/or rolling down hill, or rolling anywhere.... basically it should be generating power when ever you are not accelerating...

so in the real world this means when you roll down hills, or brake to come to a stop, or brake to reduce speed. Each person will get different result from regen depending on the terrain in which they ride... and how they ride.

14% energy capture is definitely better than nothing! and considering regen really doesn't cost anything to have.. (all decent ESC should be able to do it) but i suppose this also depends on your battery size to begin with... if your battery capacity is very small, like boosted... 14% is not much extra juice..

 

[justin_le]

-Why not simply pierce two holes at extremities of the board and put a bag clip at each end so you don't need to carry the board under your arm anymore, you hold / wear it like a bag when you enter a shop ?

I'm a huge fan of incorporating some kind of handles and/or straps in eboard builds. A shoulder strap is best because then you can just wear the board like a backpack and have both hands free when you are perusing the grocery store or whatever. But even just a simple handle cut out in the deck is a big improvement over the awkwardness of carrying a board without any handle.

-How about making a best use of regen ? Same battery size, get more miles. No additional weight.

Almost all sensible eboards make use of regen for braking, so the gains from this are already materialized. As I showed before it averages about a 10% energy recapture rate, it's not negligible but your not going to milk much more than this with any kind of further "optimization".

My second suggestion is similar to "kick push assist" but just more conventional, you meet a downhill, you need to brake? Use regen to slow down or recharge a bit your batteries ?

Again, that is already happening. For the boards we have now going down anything more than about a 2% grade hill involves regen braking and putting energy back into the pack. If all you did was go uphill then downhill then uphill then downhill etc. you would have like a 20-30% recapture rate, but in practice there's a lot of riding flatter sections which is why a 10% stat over the course of a trip is more common.

Though it doesn't answer the question "swappable or not ".

Well regen you have no matter what, but the shoulder straps help eliminate some of the downsides to a heavier board, encouraging you to use a larger battery that therefor doesn't need to be swapped. That said there is basically zero downside to the end user to have an easily swappable battery back. The downside is only on the manufacturer's end that the design and production is more of a challenge.

 

[LEVer]

Two of these on your board and two fully-charged in your backpack, I wonder how far you'll go.

http://www.homedepot.com/p/DEWALT-20-Volt-Max-4-0-AH-Premium-XR-Lithium-Ion-2-Pack-DCB204-2/204311278?cm_mmc=shopping-_-WhereToBuy-_-D25-_-204311278?srccode=cii_15053889&cpncode=33-38037094#product_description