Use by people with mobility impairment.

[slomobile]

Battery modules with different use levels wear at uneven rates, and trying to use them together damages weak cells more.

With the current battery chemistries, it's not not a good idea to make packs modular like that. You 'pod' battery would have to be used more like a battery recharger than as part of a larger pack.

Otherwise you will have significantly shorter battery life.

-Crissa

Valid point. They will wear unevenly to each other, but evenly within the same pod. Being smaller, thus cheaper than a full pack, on wheels, and quickly removable, we've reintroduced user swappable batteries. Its like having a powerwall unit under each seat. Have a spare at home, another at work, just in case. Grab them all if taking a road trip. Leave most of them home for weight savings if you are hypermiling your commute.

They do not need to function as a unified pack. Quad motor, quad seat, quad battery. See where I'm going? Redundant cooperative systems. A 5th or 5th and 6th chunk remain with the vehicle to fill in for the first pods to drop below usable levels. A wheelchair user would wear down his pod much more quickly so he can swap his seating among the other pods to even out wear.

Don't look at it as swapping groups of cells within a pack.
It is a pool of packs at various SOC and SOH. Each with their own BMS.
And a pool of loads.
The vehicle is a match maker and switcher.
Each load(except the individual seat loads built into each removable chunk) is capable of running from any pack, and being switched from one pack to another when stopped at a red light.

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[Crissa]

Smaller battery packs would not have the same performance. You'd be limited to the power that you could move.

My motorcycle is powered by packs larger than are in chairs - three, actually - that weigh about fifty pounds each. The removable ones weigh about 70 pounds, and have about 15 miles freeway range in them.

It's just not reasonable.

-Crissa

 

[slomobile]

Smaller battery packs would not have the same performance. You'd be limited to the power that you could move.

My motorcycle is powered by packs larger than are in chairs - three, actually - that weigh about fifty pounds each. The removable ones weigh about 70 pounds, and have about 15 miles freeway range in them.

It's just not reasonable.

-Crissa

Round number estimate
2P 110S 4680 cells in 2 layers for ~400v 18Ah
20" x 21" x 8" 78.1kg or 172lb
That will fit in a chair, wheelchair motor peak current at 1/2C discharge, wheelchair motor max continuous watts for 18 hours.
That sounds like acceptable performance.

 

[Crissa]

Cell weight ≠ battery weight.

That pack is gonna be hella big and with a passenger exceed lots of path load limits.

Also, that limits your motor performance to like my motorcycle. Not exactly what you want pushing a truck.

-Crissa

 

[slomobile]

Cell weight ≠ battery weight.

That pack is gonna be hella big and with a passenger exceed lots of path load limits.

Also, that limits your motor performance to like my motorcycle. Not exactly what you want pushing a truck.

-Crissa

It is the same size as a 12v 50w solar panel but 8" thick. 4680 are structural, so the weight does not need to go up by much. My current chair is over 400lbs and I am 310lbs. It is way overbuilt. I haven't broken a path yet. 700lbs / 16"^2 tire contact patch = 43PSI ground pressure.
The performance of 4 motorcycles. Remember, this pack is only powering 1 of 4 wheel motors.

 

[Crissa]

The pack is structural, the cells are only structural at the scale of a car. Smaller dimensions, they might be too big to be effective.

You're talking about adding serious weight and complication to a chair, and then trying to drive a truck with effectively the power of a 600cc motorcycle.

-Crissa

 

[charliemagpie]

I cant see why a wheelchair can't have 4 legs like that Boston dynamics pack mule.
The chair could still have wheels. Or maybe it can be stable enough without.

It could go anywhere. The legs could lengthen to seat the person higher.

We have the volume to keep costs way down.

Like our Robot.. design to human form and can do most of what humans are doing

 

[Crissa]

Because that's super uncomfortable, charlie.

-Crissa

 

[JBee]

01

Round number estimate
2P 110S 4680 cells in 2 layers for ~400v 18Ah
20" x 21" x 8" 78.1kg or 172lb
That will fit in a chair, wheelchair motor peak current at 1/2C discharge, wheelchair motor max continuous watts for 18 hours.
That sounds like acceptable performance.

I think that is way to many batteries for a wheelchair.

220pcs of 4680 is 22kWh. Your wheel chair should only need 2-3kWh, or about 20pcs 4680 otherwise it's a racing wheelchair!

The "skateboard" idea was more to accommodate an optional offroad/urban crawl capability rather than to use it to slide battery capacity in an out of a vehicle. It is possible to use more than one battery module, at different charge states to power a vehicle, but it's not normally done simply because it's not cost effective and can degrade individual module performance prematurely.

The other simpler way is to have fast charging capability using the 4680 in the chair, so you can charge your chair from the EV whilst driving on the road, so long the trip is 20 minutes or so you should get 80% SOC on the chair. So with 3kWh on the chair, you would need about the full capacity of the CT onboard inverter to do so, so it should work.

Overall, from a laymans and non-user perspective, I think that wheel chairs need to be much lighter and flexible than what I have seen so far, and given the low speeds that they travel at much lower power levels will result, leading to further cost reduction and simplification.

In general power levels are not as high for personal vehicles in comparison to full sized cars. For example the fastest "human powered vehicle" is some 80mph (130kmh). Humans can produce around 400W constant for minutes at a time, some up to 1000W peak for a few seconds, yet that power level, if encapsulated with the right design can achieve quite significant levels of performance. If you had a constant 1-200W power consumption on a efficiently designed chair, you could be doing some decent +10mph speeds comparable to an ebike.

A modular battery approach could still work for wheelchairs themselves, but I think given the level of power required on a wheelchair in comparison to a car, adding the wheelchair pack to run the car from it, doesn't seem like it's worth the effort.

 

[charliemagpie]

Because that's super uncomfortable, charlie.

-Crissa

Not really,
Todays tech can make the steps smoother.... but I didn't elaborate.

Why not own 2 wheelchairs.

My wife is a carer, looking after a Quadraplegic. I have gone on 2 cruises, and a few trips with them. Some places he can't get off.. there is no wheelchair access.

It would be great to take out the 'legs' on special trips.

Ie. To the beach., picnic.. or simple to a place where you havent been before, and the legs enable you to go to areas you may have been worried to go.

For them its an option o say, Yes I can do it. Or no, I stay here.

 

[JBee]

Not really,
Todays tech can make the steps smoother.... but I didn't elaborate.

Why not own 2 wheelchairs.

My wife is a carer, looking after a Quadraplegic. I have gone on 2 cruises, and a few trips with them. Some places he can't get off.. there is no wheelchair access.

It would be great to take out the 'legs' on special trips.

Ie. To the beach., picnic.. or simple to a place where you havent been before, and the legs enable you to go to areas you may have been worried to go.

For them its an option o say, Yes I can do it. Or no, I stay here.

You really want a "hollow" Optimus suit for that type of thing I think. Maybe Gen 2 Optimus which is really Gen 1 Iron Man suit, just without the guns

 

[charliemagpie]

You really want a "hollow" Optimus suit for that type of thing I think. Maybe Gen 2 Optimus which is really Gen 1 Iron Man suit, just without the guns

I need a fat suit.

 

[Crissa]

Not really,
Todays tech can make the steps smoother.... but I didn't elaborate.

Then you're not using the Boston Dynamics' motion!

Right now is an interesting time, because new technology is dipping into availability and cheapness while established makers have kept prices high because some insurance will pay it.

The new styles of walkers and supports coming out, keeping or allowing people more vertical, as well as going out where the terrain is more rough... it'll be pretty exciting.

We have a family friend who's been in a chair since he was little, and he always had ultra-light ones he used in endurance competition. After seeing those, I have constantly wondered at why for the last decade chairs remained so expensive (and poorly designed) when their parts weren't actually so expensive.

Hopefully that'll change.

-Crissa

 

[slomobile]

I cant see why a wheelchair can't have 4 legs like that Boston dynamics pack mule.
The chair could still have wheels. Or maybe it can be stable enough without.

I'm not saying it cannot be done, but here is a point of reference for stability.

My chair is a Permobil M3. It is an extremely good and stable chair by US standards with programming to prevent driving in unstable configurations, 2 center drive wheels and 4 casters at the corners. I wasn't going to wait for insurance so I just bought a nearly new chair from a widow. That means it was not custom built for me, but was under a year old, it had all the features I was looking for, perfect condition, even the right color and 30 miles on the odometer. Upon delivery, I accidentally flipped the chair over backwards twice within the first 10 minutes by using it normally. That is supposed to be impossible. The previous owner of the chair was a double leg amputee under 165lbs and never had any problems with stability.

I reclined the seat to where it was comfortable and headed up the gentle slope of the driveway, and immediately flipped over backwards. Luckily someone was standing behind me and caught my head before it hit the ground. We tipped the chair back onto its wheels using a winch. I looked over the chair for damage, found no obvious cause and immediately flipped it again the same way.

The solution was to lower the seat 2", move it forward 2", and enter my actual weight into the programming. That is all. That is the difference between potentially deadly and stable. I've not had any problems with instability since. The chair has a 10" lift function. It is able to drive slowly while lifted. I believe with the correct user weight setting and COG adjustment it is safe. I've used it to see above a crowd once, but I was freaking out every second I was up there, and have not used the lift since.

Boston Dynamics robots are amazing. I want one badly to experiment with. But my knowledge of them is limited to the results they have chosen to share. I've not seen them carry heavy living dynamic loads. Only well secured static inanimate loads. It would take a bunch of unscripted positive results before I would trust a legged robot to carry me.

 

[JBee]

I need a fat suit.

So you need the military upgraded Iron Man suit for heavy calibres?

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