special pleading

[neptronix]

Even with lead acid batteries those mobility carts are prone to tip-over. If a person wanted they could add a bunch of water jugs to lower the COG when using lithium. This would add pennies to the cost.

Lol yup, he's one or two bricks or thrift store arm weights away from a LFP experience. :lol:

 

[flippy]

I rekon many single payer healthcare countries will not face this problem but in 2nd/3rd world countries like america you are royally frocked if this happens.

I'd like you to refrain from insulting the country most of our users live in like that in the future. Not necessary to go there in a problem solving thread.

considering we are talking about modifying devices people use for medical reasons and the way american healthcare works its a valid point to make.

that you dont like to be confronted with the shitty reality that is the american healthcare system is a personal thing, i am strictly talking about the legal ramifications of these modifications if an insurance company gets involved.

and as you stated: most people are american. so its nothing less then prudent to warn people of considerable risks like their coverage getting denied. something people often tend to forget. same thing happens overseas, if you drive around on a souped up scooter or an unsafe car and something happens the vechicle insurance will utterly destroy your (financial) life.

And no, i dont think american shitty healthcare system is funny, but that does not mean i cant poke a bit at it.

Even with lead acid batteries those mobility carts are prone to tip-over. If a person wanted they could add a bunch of water jugs to lower the COG when using lithium. This would add pennies to the cost.

lead is litteraly 11 times more dense then water.

How? I linked to cells which were just a normal 35Ah SLA and the first prismatic LFP I found that looked like it it could pack into a similar shape. I didn't go shopping; I took the first examples that I found with dimensions and weights. The only selection I did was to avoid comparing cylindrical with prismatic for density purposes. Embedded links are still there in the above, unedited post. Have a look and do the calculations yourself, if that makes you trust them more. I was telling you what I already know from working with LiFePO4 packs, which is that they're heavy like other batteries. They contain a lot more juice than SLAs, but if you stuff a compartment full of LiFePO4 prismatics it will weigh close to the same as the compartment full of SLA-- about 3/4 as much according to the first back-of-the-envelope numbers I did. I think your "three or four times" ratio must be comparing volumetric energy density rather than physical density.

your link of lfp batteries is broken so might want to fix that first before ranting on.

but lets grab my numbers: a standard 12V 40Ah SLA battery clocks in around 15 metrics or 30~35 freedom units. a single 40Ah winston cell weighs about 1.5 metrics and you need 4, so 6 metrics. 6 metrics is about 13 freedoms. if i devide 30~35 freedoms by 13 freedoms i get about a third of the weight. and that is with good quality yellow cells, not the crappy purple cells.

SLA volume 5.5L
lifepo volume 3.5L
lifepo is only 40% smaller in volume for the same energy but its a third of the weight. not that great if you need weight. unless you want to pay a LOT more for cyclindrical cells and have shitty lifespan. but then you are better off with a honeycomb of 18650 cells. that does weigh a lot more and stores a LOT more energy.

 

[Chalo]

your link of lfp batteries is broken so might want to fix that first before ranting on.

Fixed. Here are the links in case you don't want to go back and look:

https://www.sunderbattery.com/product/lifepo4-battery-3-2v-100ah/

That's 1.65 g/cc, in French units.

https://www.deepcyclemarinebattery.com/reviews/mighty-max-ml35-12-12v-35ah-u1-deep-cycle-agm-solar-battery.html

That's 2.08 g/cc, in French units.

If you think these numbers are anomalous, I can go find another SLA brick and another LFP prismatic cell and compare those.

 

[nicobie]

Fun thread! (as I kick the horse one more time).

 

[neptronix]

considering we are talking about modifying devices people use for medical reasons and the way american healthcare works its a valid point to make.

I agree. It is a valid point to make.

that you dont like to be confronted with the shitty reality that is the american healthcare system is a personal thing, i am strictly talking about the legal ramifications of these modifications if an insurance company gets involved.

It has nothing to do with how i feel about my healthcare system. It has all to do with NOT starting a political flamewar on a thread where a user is asking for help on an EV by calling where he lives a second/third world country. This is not the appropriate section to go that far into political town.

And no, i dont think american shitty healthcare system is funny, but that does not mean i cant poke a bit at it.

You can poke at it, but be kind and not inflammatory and don't try to throw the thread off the track.. because you know that can easily happen here.. and the point of the thread is to help OP.

 

[flippy]

well, as shown by your reaction my way of touching the subject does have the desired effect of people actually thinking about it.
a short meniton and then glossing over the idea that america might not be number 1 at something would not have the same impact.

with subjects like this where getting your insurance denied because you messed around with your/their scooter is a VERY real and present danger it must be put forward with the attention that it requires. that it is a touchy subject for americans is a sad reality but not one that should be ignored.

prehaps, in due time when enough people actually care about it something might even change, but not if you are not willing to accept the reality of the system today. and if prodding at this gets the conversation going instead of trying to ignore it then that is a good thing.

we are not helping anyone here if they lose their home because the insurance decided to frock them over because they put in a battery -at our recommendation- and got into a fall or whatever.


i am sorry that your healthcare system sucks.

 

[neptronix]

I understand your feelings on the matter but there's a line between helping someone consider legal ramifications and insulting their country and taking the thread into political activism town. That line was crossed.

Let's carry on and keep politics out of this discussion. Thanks.

 

[AussieRider]

Now now kiddies, let's play nice.
Flippy ( or was it Chalo? ) Made a good point about discharge curves of LiPo vs SLA ( LAB for you Robin ).
With LiPo in your scooter, you'd be scooting away happily until the batts are discharged then just stop unexpectedly.
With SLA, the batts start to sag, the scooter starts to slow down & you have enough time to say " shit no! ".
Maybe even enough to slowly creep back home bouncing off the LVC ( Low Voltage Cutout ).
If you like the look of the Afikim sportster SE, look up the Pride Sportrider. Now there's a mobility scooter for ex bikers.

AussieRider

 

[flippy]

Now now kiddies, let's play nice.
Flippy ( or was it Chalo? ) Made a good point about discharge curves of LiPo vs SLA ( LAB for you Robin ).
With LiPo in your scooter, you'd be scooting away happily until the batts are discharged then just stop unexpectedly.
With SLA, the batts start to sag, the scooter starts to slow down & you have enough time to say " shit no! ".
Maybe even enough to slowly creep back home bouncing off the LVC ( Low Voltage Cutout ).

or... crazy talk here... look at your battery meter...

i know, its crazy to even consider. but one can dream....

 

[AussieRider]

Ouch!
Cars have fuel gauges yet able bodied drivers run out of gas every day.
Scooter users with vision impairment and / or other disabilities can find driving a scooter or powerchair more demanding than someone without a disability and be more concerned with driving rather than watching the battery meter.
Mobility scooter controllers, the Dynamic R series for example, can have the "battery full" & "battery empty" voltages shown by the meter adjusted to match the battery type but the relatively flat discharge curve and sudden drop off near depletion or BMS LVC can happen a kilometer or less after the meter shows low battery. I know, I've tried it on a scooter I fitted with LiFe out of curiosity.
SLA on the other hand with a more gradual discharge curve, start to sag & the scooter slows a bit rather than just shutting down giving a bit more warning.
Flippy, with respect to your knowledge & experience with EVs, don't get a job in the mobility industry.
You don't have the sympathy.

AussieRider

 

[flippy]

Flippy, with respect to your knowledge & experience with EVs, don't get a job in the mobility industry.
You don't have the sympathy.
AussieRider

fun fact: i have made several upgrades to scooters. and with most of them i simply set the battery meter to 1S higher then it actually is to make it read lower then the battery actually is.
generally i install a 15S meter on a 14S batter just to have a solid 0% buffer of 15% or so. and have a big 10mm bright red led and beeper when the voltage tanks below 3.3v on a cell with a simple cell alarm board. and a momentary switch to turn the alarm off for 5 minutes. that is how i did it for about half a dozen mobilliy scooters already.

dont confuse my lack of tact for not being practical. i have a pretty good grasp on how dumb people actually are and how to protect them from themselves.

 

[AussieRider]

dont confuse my lack of tact for not being practical. i have a pretty good grasp on how dumb people actually are and how to protect them from themselves.

My point exactly! Thanks.
These people are not " dumb ". They are disabled through age, accident or birth.
But, since you have a need for the last word for reasons of your own, back to you...

AussieRider

 

[Chalo]

These people are not " dumb ". They are disabled through age, accident or birth.

Most people are dumb-- irrespective of age, accident, or birth. It's just the way things are. When you set up a machine for someone in particular, you can take into account their intelligence, sensitivity, and abilities. When you set up a machine for nobody in particular, it's best to assume you're setting it up to be used by a trained animal.

 

[flippy]

My point exactly! Thanks.
These people are not " dumb ". They are disabled through age, accident or birth.
But, since you have a need for the last word for reasons of your own, back to you...

jesus, stop being offended for someone else at the drop of a hat. read chalo's post. a person might be smart but PEOPLE are dumb. and you make a product for PEOPLE, never a person.

youtube basically exists because of how it shows people how utterly dumb people actually are.

just think of all the people you run into during the day and how dumb they are. it takes considerably less time to train a cat to shit in a box then it takes the average grown adult to learn HOW to put on a mask properly....

anything you make for someone else needs to be built with the idea that they have the intelligence of basically a toddler, because most people are...

 

[GIGATT]

hey folks I wonder if the original poster got his batteries in, I sure got mine!

Moreover please let's discuss politics and religion it is better than sports and weather ...Maybe.

Also some people are dumb, I cannot say all or most; I mean I can but that does not make it accurate.

Lastly, some people with mental disabilities are smarter than some billionaires for instance, when is the last time that you saw a person with so called mental disabilities run an exotic car into a tree or have a terrible plastic surgery and think it made them look "on fleek"?

In the event that I can make this mobility scooter faster .. I wonder how to increase the braking power.

have a lovely day folks

 

[neptronix]

I was facing disability myself at one point, and had to walk around with a cane in my 30's due to the effects of bone deformities that nobody knew how to deal with..

I looked at the market for mobility devices and of course was disappointed and figured that i should build one of my own using lifepo4 or lithium titanate for safety reasons.

Then i discovered this guy who had built his own mobility devices from scratch and used lifepo4 batteries and some hot rod motors. Perhaps this will inspire OP if he's not been scared off by the infighting here.

His site:
http://www.wheelchairdriver.com/



This guy carries the ES spirit, and a is big inspiration to add a mobility devices subforum here in the future.

 

[flippy]

In the event that I can make this mobility scooter faster .. I wonder how to increase the braking power.

if you have a standard DC drivemotor and reduction box it will be difficult to have electrical braking.

personally i would try to see if you can get some direct drive hubs in that size. that should make it extremely powerful and efficient, and you would get regen braking witht he right controller.

example: https://www.aliexpress.com/item/32648580258.html

 

[Chalo]

Electrical regenerative braking is the wrong kind of braking for mobility scooters and powerchairs. The most important braking for those machines is for getting a hard, precisely located full stop, and firm positioning to keep the scooter from moving when it's stopped or parked. E-braking is bad at that. For that, you need either good mechanical brakes or worm gear drive.

 

[flippy]

normal scooter drivetrains have pin-locks in the drivegear that lock it when then motor is not powerd. that drivetrain is also insanely inefficient.

you can also buy industrial BLDC motors that have integrated brakes. or use the controller to force the motor to hold position. that is something most high end controllers can do. especially with a pair of sevcons you can even use the steering angle to help steer the scooter with the motors. even my normal 35mph scooters with 4kW QS motors are nearly impossible to push just on their neutral regen braking. with brake regen the scooter acts just like the brake is engaged. they are VERY hard to move requiring your full weight and force to even get barely up to walking speed just on human pushing power. if you actually set the regen to the maximum the controller can do i have no doubt the wheel will simply refuse to move. it has several kW of holding power in that mode. arguable even more then a regular brake as it just gives you opposive power to keep the wheel from turning. good luck fighting against a controller that can pump dozens of amps in that motor to keep it locked into place. :lol:

not something anyone should do that relies on it for their daily transport and drive into your local wallmart at 20mph but as a "second" fun-scooter on the side for some longer trips to get some air its certainly doable.

 

[BobBob]

In the event that I can make this mobility scooter faster .. I wonder how to increase the braking power.

if you have a standard DC drivemotor and reduction box it will be difficult to have electrical braking.

personally i would try to see if you can get some direct drive hubs in that size. that should make it extremely powerful and efficient, and you would get regen braking witht he right controller.

example: https://www.aliexpress.com/item/32648580258.html

How about an electromagnetic brake as a fail safe? Then you can use regen and active motor braking with a backup plan if it fails
One i worked on had two flanges, friction material that sprung together and an electromagnet to disengage, so it failed safe.
Used around 5W from memory.
Setup was a little fiddly with feeler gauges to get the clearance right and avoid friction though they may have improved by now
Guessing these might be similar https://www.nithsdale-wheelchairs.com/electromagnetic-brakes.html

 

[flippy]

most industrial motors (parker just to name 1 brand) sells their motors with or without integrated brakes.