Help and suggestions for lithium or lead

[nealnlx]

Hi there,
im new here.
I just signed in after i been reading many things and posts here and on the website.
First of all let me congratulate you Burgerman for what you did and do in not been stucked by what this indstrie and what they want us to use.
We are not like cows that they feed with what they want and we have to be happy with just those low quality trations, you know what im trying to say right?
Im a tetraplegic or quadriplegic as many like to say. Im on this new life since 97 so its been a couple years now. Time flyes...
In arround 2000 i guess i got my first and still only power wheelchair, a Levo LCM confort. A standing up wheelchair that is so important to me.
It was the only one, kind of, available on the market at that time and since i liked it i toke it with joy.
Always suited me well. whether it was on fisical therapy or on my bodybuilding trainings it always did me good.
The problem is the same as we all complain about, lack of range and speed for when we are in a hurry and can't run from the rain, for instance.
Mine has two batteries like most and it is: two 24v 26ah
So you can imagine how far can i go...
At the beguinning it was ok.
When we are new to this life and we can see that we can not only go around but also can get up again, you dont think much on range wise, leave it to a second thought because you first want to do things again.
But as time goes by the needs also come by, and we start to need more. More power, more range, more capability in general.
Dispite i wanted to upgrade and tweak it here and there to make it more equal to my needs, i never did anything to it.
And that is for two reasons: first im a teraplegic (c4-c5 complete), and dispite i move well and many even say im a paraplegic (bullshit), im not. I need my fingers to move so i can have that hand dexterity so needed for this things.
Along with that the second reason is that im a big noob on electronics and new generation electrical stuff.
I can turn the light on and off, and thats it...kiding, but yes, i know nothing about it.
I knew it would be possible to change and make things way better and working properly and safe.
I know that, as many other things i envision and i know it is doable. I simply cant do it myself alone.
When i saw the web site and saw what was done and thought that here is a guy that thinks like me and puted his hands to work and got it done.
So, now i have my wheelchair on some store for some repairs.
It has to get some new parts like backrest, some ajustments (that i cant do ny myself) and with that also the electric part.
Some time ago my joystick light indicators started to blink and showed me no response to my commands, like going back and foward or anywhere else.
The standind feature also stoped to work and batteries have died.
I sent it for a full check up and to see what was happening. There they told me it would need new batteries, new charger and new reprogramming because it was all mess up i think.
Well, it is there now... and since it is there i thought, its the right time to make it go better. Otherwise i will always end up buyng those 26amps crapy thing that cost me arround 500euros for two. Yes, those sons of bitches steal that much from us that dont even have it. But if we need our legs...suck it up and pay right?...
And this is where i come to you asking you for some advices...
I have a lot of questions and many depend on what the response is like. Depending on that i may have two choices, stay with lead batteries but this time some better ones according to your help to choose.
Or go the extra step and convert it to lithium so i can have proper power and proper range for better independency that i dont have.
So, the very first question is:
Wether is lead batteries or lithium, if i want more than my actual 26amps and go for lets say 100amps, do i have to get a new controller unit?
And if so, and since my wheelchair has the stand up feature, what would i have to do to make it work as well?

I leave you for now with these two easy for you questions and hope you can help me on the other ones i have to make
Hope for some soon words
Thanks

[shirley_hkg]

Better post pics of your chair here, pics on all sides and in various positions of seat.

Preliminary, a small add-on will double your existing range already. Is it enough ?

[flagman1776]

The Basics:
Your current controler does not care how many Amp Hours your batteries are or the chemical composition. Any nominal 24 volt battery set up will work. The battery limitation is what will fit in the chair's housing without modification. Some battery compartments can be modified or an add on pack (perhaps located behind the chair).
We like LiFePO4 (Lithium Ion Phosphate) as it is the safest chemistry... as BM says, this is important when you are sitting on it & can't get up if it catches fire.
Most prebuilt "Lithium" packs use a BMS board (Battery Management System). BMS are not the best way to control charge but they allow use of a dumb charger (cheaper)... using a dumb charger will require long charge times, as long or longer than lead.
The best way to charge Lithium including LiFePO4 is a smart charger. A smart charger charges better (extending cell life) AND faster.

[Sully]

My opinion; as Shirley said pictures at the very least. First of all I seriously doubt any "OFFICIAL" Wheelchair vendor will assist you in doing what you want to do.

The problem with increasing the available power is SPACE. Understanding how to find the available space to increase your capacity. Now lithium batteries will be lighter, and will change your chair's balance, but will give you more AH's (distance) available.

It is my opinion you first have to ask your medical equipment store if they will assist you. Or find someone who has a bit of knowledge and ability to do such a project. With anything you do to your standing chair will make something else change. You have to predict what those things will do and compensate for them.

Another thing is put in your location (nation at least), the differences in what can or might be possible are different in most places on this planet, so knowing where you are helps from giving some sort of advice that is not possible. It already sounds like your physical abilities make you pretty much dependent on others to accomplish most of the tasks you will need to do to make the modifications you wish to do.

[nealnlx]

Better post pics of your chair here, pics on all sides and in various positions of seat.

Preliminary, a small add-on will double your existing range already. Is it enough ?

Hi
I dont have pics of mine but after some search found some online the are the same. Well, the footrests and the armrests are not the same but e are not working on those parts so it doesnt matter. The rest of the wheelchair it pretty much the same.
Ill show some pics...

[nealnlx]

some more

[nealnlx]

again

[nealnlx]

and finally the last pic...

The joystick is the same, the battery charger is the same, everything is equal the same.

You can see how it is when standin. I dont kno if that one is fully up but if it is mine goes even straighter.

Also found some pdf's showing the battery case and compartment from where i toke a few screenshots.
As you can see the black box sits on the metal frame which sits on the wheelchair frame.
The batteries can be mounted on boths ways, straight or sideways and it still lefts a bit more space.

I dont know the exact measurementes of the inner part of the wheelchair. Like from side to side, from motor to motor, but if i can gain a couple inchs there i can modify that metal frame to make it wider and possibly longer to fit a bigger configuration.
That the easier part for me...

[nealnlx]

The Basics:
Your current controler does not care how many Amp Hours your batteries are or the chemical composition. Any nominal 24 volt battery set up will work. The battery limitation is what will fit in the chair's housing without modification. Some battery compartments can be modified or an add on pack (perhaps located behind the chair).
We like LiFePO4 (Lithium Ion Phosphate) as it is the safest chemistry... as BM says, this is important when you are sitting on it & can't get up if it catches fire.
Most prebuilt "Lithium" packs use a BMS board (Battery Management System). BMS are not the best way to control charge but they allow use of a dumb charger (cheaper)... using a dumb charger will require long charge times, as long or longer than lead.
The best way to charge Lithium including LiFePO4 is a smart charger. A smart charger charges better (extending cell life) AND faster.

Thanks for this great answer...
In my head and from what i recall from my electric lessons in schooll i had in mind that the controller would maybe accept any amount of amps. But that maybe got me in the question of what if... and nothing better than ask the ones who know it better.
Part of my doudt was also about the standing up feature, if it would still be able to function or would it have to have some reprogamming or software reconfigurations. If the right answer is not, then ist a huge releave. I need and im missing staning up a lot.

BM is right, safety first. I dont want to give reason to anyone say that my ass is on fire, for sure...
I been reading a lot about this and headway cell that really look like to be the way to go. Also read some complaiancy about those BMS boards stuffs, some say its the best to contro charges and discharges, outher say its not. I dont even know in detail what it really does, so i dont even comment. But if someone teache me good ill learn.
I dont remember exacly about my charger that they say at store that is lost somehow, but i think it is a 7A one. Its the on on the pics.
Is smart chargings the same as fast charging?

[nealnlx]

My opinion; as Shirley said pictures at the very least. First of all I seriously doubt any "OFFICIAL" Wheelchair vendor will assist you in doing what you want to do.

The problem with increasing the available power is SPACE. Understanding how to find the available space to increase your capacity. Now lithium batteries will be lighter, and will change your chair's balance, but will give you more AH's (distance) available.

It is my opinion you first have to ask your medical equipment store if they will assist you. Or find someone who has a bit of knowledge and ability to do such a project. With anything you do to your standing chair will make something else change. You have to predict what those things will do and compensate for them.

Another thing is put in your location (nation at least), the differences in what can or might be possible are different in most places on this planet, so knowing where you are helps from giving some sort of advice that is not possible. It already sounds like your physical abilities make you pretty much dependent on others to accomplish most of the tasks you will need to do to make the modifications you wish to do.

You are right, vendor dont assist on anything else but making you buy new parts.
Today i was more than an hour on the phone with some so called technician and the guy knew even less than me. I felt good for not being so far from the knolegement, but felt terribly bad because if those guys are the one that are supposed to make things work and happend, then we all are in verry bad hands. I felt bad for the one that pay and dont even know what they are giving theire monney for...

When you talk about chair balance you want to say that basicly it only will get lighter and therefor less effort for the motor and batteries and so on, right?
No, its plenny to say that they dont know nothing about lithium. He told me to buy some packs like the one used on bikes. I asked myself if i really was lestning to that.
Can you explain me better what do you mean by this, "With anything you do to your standing chair will make something else change. You have to predict what those things will do and compensate for them." ?

Im from Lisboa, Portugal. Typiclly a sunny wheather and warm place to live. Well, now we are getting in to winter so rains and its a bit colder as predictable.
Yes my physical abilities are compromised, but its mostly my fingers that, as part of the package i got, dont collaborate as neede. They are functionall, but not active, if you know what im trying to say.
But as told here and like i been reading, to put toguether all the cells looks like easy. Using the screws and folling the drawing/diagram would not be that hard. Would it?

By the way, you guys that know everything about this should make some tutorials or video-tutorials about this and many other project and share with us who want to change thing for a better usage as well.
What do you guys say?

[ex-Gooserider]

In essence any change you make to a chair that is more than trivial, is going to have some impact on the way it works... Chair design is a huge collection of compromises that are trying to balance all the different factors like size, weight, functions available, and so on... It is vital to look at what you are changing and ask what impact it will have on the way the rest of the chair works...

Off the top, switching from lead to lithium WILL make the chair lighter, but you need to also ask if it will cause the chair to be less stable since the center of gravity will be moved up? This is especially critical for a standing chair as you want to be sure it is stable when standing.... (Note that while BM's battery pack for the BM3 is 50lbs lighter than the lead bricks it replaces, he put 30lbs of that weight BACK on the chair to keep the COG low enough for the chair to remain stable...)

At least in the US, most vendor mechanics have had very little training, and what they have had is not related to 'theory' but more how to go down a diagnostic checklist and swap the parts that it says... Even if they know better, they are not ALLOWED to do anything that isn't "in the book" as an approved procedure for liability reasons.... It is crazy in some ways, but there is less liability if a 'non-professional' mechanic changes something on your chair and it is damaged or you get hurt as a result, since the non-professional didn't know any better but the professional should have known not to do something that wasn't 'manufacturer approved'

'Nandol' is another one of our members that lives in Portugal, not sure how far apart the two of you would be, but if not to far you might be able to connect with the guy that he has doing a lot of work for him.

ex-Gooserider

[nealnlx]

You are verry right on what you are saying. I agreen with that.
In a lack of the presence of my chair so i could show you better ill post a couple of pics so you can maybe understand what im trying to say and do.

So as you can see the pictures its pretty simple...
All that is prety straigh foard to get out by hand. I think only the battery support frame has a fe screws but nothing major. Its just to make it not shaking and kep it on place when going on litle bumpy roads.
Nothing of that interferes with any available function and overall chair size.
For making it more scape capable and therefor more battery capable as well, the only thing i would do would be making the battey support frame as wide as possible untill it closely but not touching motor, and make it longer. So in the end insted of, lets say, a 16 by 12inches i would have maybe 20 by 14 or 15 inches if possible. That way i could pack in a lot more battery and would have the same everything since i never touch the chair's frame and structure it self.
Keeping it safe and stable and all function is a must for me. Since its not a simple powerchair that basicly goes back and foward, with all the credits for what it does for sure, having a standing feature is a plus thinking concern i always have to keep in mind.
I know that lithium make it lighter and when for most that would be a headache because of how stable it can be, for me it is a not that big of a problem.
I tell you why... i dont know if you have one or ever tryied a stand up chair, but specialy the most recent and newer ones have one big disadvantage on my point of view.
If you play a bit of attention you can see that most tends to avoid to have those litle caster wheel on the from. The mid wheel drive have about six wheels, two big at the mid section, two on the back for not tiping overs and stuf and two at front but behing the footrest.
The front wheel drive mostly have about four wheels, two smaller at the back and the bigger ones at front, also behind footrest.
Why does it happend? Well, for me i think two things. First because of the design. Manufactures always trying to improve a bit of design where they can, here and there so they can make it visiual atractive as well. Looks also sells...
And second and most important, i think many manufactures dont realy build and develop theire chair with guys like us that would give them a real feedback in real time along with the building time.
What they mainly do it is, they build a chair and then probably call some guy to test it and tell them what it feels like so they can make some arrangements here and there. And that a huge diference...
They can be all engineers and everything an have good ideas, but the truth is that they dont really know what some small need are and how big of a diference it make to have it on a chair.
I dont know if it was on purpose or not, but in my case my chair have have those litle caster wheels. Its a rear wheel drive and has eight wheels in total.
On the back two anti tip like the one on manual chair, next the two bigger power wheels, on front two regular smaller wheels behind footrest and then on the footrest it self have those two litle and so important caster wheels. They give me all the stabiity i need when im standing up.
When others dont have it for the look and many other reasons, mine do and i really like those plus two.
Make no mistake, my chair has a lot of wrongly build stuff that it would be much better if they would called a guy like us to develope it when they where designing it, but ok, at least they did on thing right. May be with out that intention but it works.
And i tell you this, i have it for fifteen years more or less and i tested it when standing in all ways possible, even on roads with big decline.
I trained with it when standing and do bicep curls with sixty pounds with no problem.
Two lead batteries weighth less than that and i would not they to courl an empty barbell on any chair without some casters like those.
The only way i can fall off is if someone pushes me from the side. But thats because it is not as wide as it is long, sure...
So the weight deal is not that much of a issue for me. But if some day it is, yes i can only add more weith as well.
The overall idea is, ligher goes further and at same time when going up hill its less effort for the chair also. That with the much bigger capacitty in range wise is a dream for everybody, i think

You are right again, and maybe wordwide right.
As i said before, i was more than one hour talking to the technician of my chair store and after five minutes he told me that they only work with good batteries, some SPS lead ones that he knows it is good. That was when i raised my ears and got like "what?". If thats good quality what can you call to the pure lead ones on remarcable brands?
I told him that what was important would be the internal resistance so that basicly the juicy is flowing well and contantly when needed. More or less...
He agreed and when i ask him if he knows that why is he saying that those thousand Homs are good if they can not even be truted in terms of real Amps usages. Like i could buy a fifty Ah one but with such high internal resistence they would die at half way.
Asked him if he knows ant odissey, exige, optima or some of those more regular knowned, and he told me he wold only work with the ones he knows of.
At that time o felt bad for how much they real rob from us asking the price of hign end for the crappy ones.
whem im the one who knows nothing about the toppic...i studdied auto mechanics as one of many things, and building a car or whatever i know how to, elecrics...i twist my nose. Had lessons of that as part of the school program but dont remembrer much.
So, when im the dumb one, there i was kind of traching a technician the diference of it and better they are. Along that a asked about motor check up to see how well or not they are. And the answer was astonishing. The guy only said to me he is not a chair expert, he only receives them when they need repairs, see whats needed, buy new, mount and thats all. But mainly only change a battery here and there.
My chin dropped on how this industry is...
He said that no one rapair motor or stuff like that, if something is wrong they buy to the manufacture and put a new part.
Ok but my chair is old, dont have waranty anymore so i can change it an dont affect any waranty issue. Even that way or i buy new or find someone at my own that does such jobs.
Sad but true...
That is why i trust much more guys like BM that have build and rebuild and tested things on his own than these liar vendors that only suck our monney.
Just an bit of a pics for you to see. My chair needs a back rest that is around 140euros, the two crapy lead 12v 26a batteries he sells around 500 euros both (i see them fifty bucks at ebay and amazon all day long), new original battery charger from the chair arround 270euros, and to reprogamm my conttroller unit a PGDT VSi is arround 600euros. Now watch the magic thing, total of the cost rapair is 2000euros.
How funny is that?
With that mony i can probably convert it to lithium with as many headway cells as i can fit on the box and still reprogramm the controller and get the rest fix.
Am i verry wrong?
That only proves that they are not interested in help. They could verry well have a parallel industrie of repairing and make things work. They just dont want to. All they wanna do is to get as much as they can from us. Why? Because two things... One most people are not well informed. And two, they know that we need chair to live so they charge us kind of with what they want, and since we really need, we pay...
So yes, you are right. They dont do that kind of things, but they should.

Sorry for the extended words and hope you guys can help me on this one

[shirley_hkg]

I think your chair's motors are too weak to drain a 100A pack. That will be a waste of money.

A 40A add-on will be adequate for a day's use.

Simply put it on top of the battery box near the end. Charge it with the lead together. No separate charger is needed.

With a proper 3.65/2.5 BMS that can balance a 50A pack well @100mA ,it will lasts, long after your chair perished.

Really no need to THINK BIG.

[nealnlx]

Out of my curiosity and since im a nub on this things, why and how can you tell that my chairs motors are too weak to drain a 100a pack?
You really got my curiouse on that one...

Remember i also have the actuator to lift me up and down many times and another importante thing for me is that i live in a place that wherever i go i have to either go downhill or uphill.
Its all fun and games when he go downhill, until you have a two mile long uphill on a verry inclined road...
I dont know how much the motors play a rolle in that besides the ability to mantain the power or strenght to keep up. But for me and what i think, and please correct me when im saying wrong things, but if the battery dont deliver some good juice no matter what motor we have because we are not going to arrive home right?
Thats why i want the most i can get, of corse not wasting money on a thing that ill never get near to its limits.
And that is why lithium comes to my mind. Lets say a 80a pack is ok for my chair. With all the virtues of lithium and specialy its long life capability it os more profitable to use a completo pack of lithium than to stay on lead with a add-on and from time to time the lead dies and here we go again spending more money.
I think you get what i mean.
So with your help and guys in general, what size do you think a lithium pack would be suitable for my needs having in mind that i like to go out a lot and long distances, plus standing up when i get to a place or another and the long hills i always have to climb?


When i found those pdf files i got this information about my chair in general.
Take a look on the pics to see it.

[Burgerman]

Do you have 4x 12V 26Ah batteries at the moment?

Its trivially easy to fit a large lithium pack where a group 24 70Ah battery is removed. With smaller batteries it becomes more difficult to effectively use the spaces.
What are the EXACT dimensions of the 4x battery areas that you have?

You will need to measure.

If you want ultimate range, battery service life etc then forget add ons, and forget BMS systems. And simply fit as many Ah as possible into the space you have, charge with a quality cell balancing hobby charger.

Or...

Less good, more complex, do the same with capacity (as much Ah as possible), but use a BMS that will inevitably give problem sooner or later, kill battery faster, and add complications to the battery/wiring. It allows a cheap dumb charger to be used however with just 2 wires.

I see no advantage to this, less accuracy, less control, and less ability to monitor what is happening. And far less balance current. And some cells repeatedly held high while it tries to balance the pack...

If you want a simpler answer than this, you are out of luck! Its not a simple subject.

[Burgerman]

Quick google for 27Ah deep cycle shows that you will get the following in.

4 series, 3 parallel Headway 12Ah cells in place of each battery. So you will then have 4x 36Ah batteries. That will give you about 1.8x the range you have now. That's not great, but too much space is wasted with smaller batteries so a different cell type may work better.

That's 48x 12Ah cells. Or 856 euros. http://www.evassemble.com/index.php?mai ... ucts_id=21

Plus a 8s hobby charger - preferably a good PC capable one with PC control, graphing and logging etc. Such as the Cellpro PL8 that I use. http://www.store.revolectrix.com/Produc ... Lab-8_1307

[nealnlx]

Do you have 4x 12V 26Ah batteries at the moment?

Its trivially easy to fit a large lithium pack where a group 24 70Ah battery is removed. With smaller batteries it becomes more difficult to effectively use the spaces.
What are the EXACT dimensions of the 4x battery areas that you have?

You will need to measure.

For as much as i want to tell you the exact dimensions i cant because i dont have the chair with me. Is the that on store and i asked the guy monday to tell me those dimensions and still no response.

As seen on some pics above i have just 2x 12v 26ah batteries. Yes, just that short range.
But as i also said before, the black box that stores the batteries still have some room.
I think in total it maybe arround 40cm l x 30cm w x (nearly) 20cm h.
Again, this i can change and make it longes and wider as much as it can untill it goes from side to side close to the motors.

My intencion is to have some proper range (as much as i can) and also good power surely.
For that i was thinking to fill it up with the biggest lithium pack but all usable and not just for the big size spending money.
Combining those two needs i dont know how much would be needed. So theres also why im here for your help.

If you want ultimate range, battery service life etc then forget add ons, and forget BMS systems. And simply fit as many Ah as possible into the space you have, charge with a quality cell balancing hobby charger.

Or...

Less good, more complex, do the same with capacity (as much Ah as possible), but use a BMS that will inevitably give problem sooner or later, kill battery faster, and add complications to the battery/wiring. It allows a cheap dumb charger to be used however with just 2 wires.

I see no advantage to this, less accuracy, less control, and less ability to monitor what is happening. And far less balance current. And some cells repeatedly held high while it tries to balance the pack...

If you want a simpler answer than this, you are out of luck! Its not a simple subject.

Sorry my lack of knowledgement but whats the diference betwin those two and whats the main advatadge from one to another?

[nealnlx]

Quick google for 27Ah deep cycle shows that you will get the following in.

4 series, 3 parallel Headway 12Ah cells in place of each battery. So you will then have 4x 36Ah batteries. That will give you about 1.8x the range you have now. That's not great, but too much space is wasted with smaller batteries so a different cell type may work better.

Sorry again, but would you explain me this math?
So many reading and searching that im all crossed eyes now.


My idea would be...
If my battery box have like 40x30x18cm , i could get in there as muchs headway cell as i could.
I seen you kind of recomending the 12a ones more than once, and if i could i would even go for the 15a ones. But due to my dimensions and if i dont change the black box case i may probably fit in the 10a ones in a bigger quantity.
When they measure around 12 to 14cm i could fit two rows (in a sideways possition) lengthwise. And maybe would be like 10cell long by 4tall. Making it two times would be 80 cells total like 40 side by side.
See what i mean?

Now, how much power and range would it give me?
And would it suitable for me? Too much, too few?
What do you say?

[nealnlx]

Yes, the charger would be another chapter that i need you to walk me through and help me choose the best option.
When being tetra/quad it would not be verry functionable for me to have a buk of wires to hook up to each other.
So a good charger that is friendly usable and can be easy for my lack of experties would be great to plug and male it sing while i could learn something with the monitorizations you say.

[Burgerman]

Charger on my chair has ONE connector.

And to charge you press one button, twice...

The black end connects to the chair to charge.
The other end connects to the charger and stays connected indefinitely.



One connector has all balance and power wires.

See this page...
viewtopic.php?f=2&t=1813&start=620

And this charger...
http://www.store.revolectrix.com/Produc ... Lab-8_1307

Which can charge from your car, or at home at up to 40 Amps. And it is controllable and can be configured by PC as well as testing, monitoring and graphing of your battery and cell balance performance etc.

[nealnlx]

You guys really wanna give me a nice brain wash with all this ultra tech info
i might end up being an engineer in a few weeks, or not...

Your charger looks neat and simple. One plug, two clicks and thats all.
How long does it take to charge your batteries?

[Burgerman]

My batteries have to have approximately 3X the amount of power returned to them that a set of large lead (gel) wheelchair batteries do if fully discharged.

It takes around 8 hours for your mobility charger to charge a typical powerchair using lead batteries to a green "ready" light. At this point they are in fact not actually full but around 98%. A full charge on a lead battery ALWAYS takes around 16 hours. That last 1 or 2 percent takes forever. But we don't have that long, so the charger lies. This results in battery Sulfation over time and so shortens service life.

As such to charge my BM3 lithium battery I use the small Hobby PL8 charger*. It charges at a full 40A at full power, if you choose to. (I usually charge at half that). That can fully charge to 100 percent from empty, putting some 300% more back than a lead battery even holds, in 3 hours. Since the chair has 45 real miles of range, generally you only need to charge every few days or so. I do it while sat at my computer. If I need to go out and its at say 50% full, I don't care. It still has tons more range than any typical mobility chair left in it regardless. So in real terms, you can put a typical heavy days use back in an hour.

* Since my battery is 45V approx. and 13S I use 2 chargers at once. 2 connections.

[nealnlx]

That part of a typical wheelchair charger taking 8hours to reach green ready light and that it is not really 100% because those left 2 or 1% take verry long to complete because it charges lets say on a verry lower rate so it wont damage the battery, sord of speak, and for a fully charge it takes dobble time of 16h, that i knew.
See, this much reading are making me an engineer soon...again, or not

Yes, i just saw a couple of youtube videos about this charger and you can make charge on a slow rate of 10a ou faster like 40 or 60a if im ot wrong.
Wont it damage the batterie? Or like the original typical charger it also slows down when it reaches 98%?
Can i also leave plugged like all night and morning with no problem or do i have to unplug it when its 100%?


"That can fully charge to 100 percent from empty, putting some 300% more back than a lead battery even holds, in 3 hours. Since the chair has 45 real miles of range, generally you only need to charge every few days or so. I do it while sat at my computer. If I need to go out and its at say 50% full, I don't care. It still has tons more range than any typical mobility chair left in it regardless. So in real terms, you can put a typical heavy days use back in an hour."

This is really important for me. Well for all of us, it should be always like that...
Thats what im looking for. Along with range and power, its importante to have a charger that really put in some extra juice when we need it faster. Either when on redline low battery or at a 50% its nice to have a tool that we can rely on.
And speaking of which, it is also extremely importante to have a pack that like you, when we look a the indicator and see 50% (half of fuel) we can still have a peace of mind that we can go for some good miles because it will last.
That for me is hugely importante.

I saw on a video that when you have a more than 24v you should have two connectors like you say you do, yes.

What do you think it would be a nice amount of Ah i should have on a pack to me, since i go up and downd hills a lot and also use the standing up feature tons of times and do want to fill like counting coins of how much more i can go and still be able to come back after?

[Burgerman]

You should ALWAYS fit as many Ah as humanly possible in the space available. And always more than the Lead.

So you need to measure.

[nealnlx]

Can you tell me/teach me how to do the matt do i can count how many cell i would need to make lets say a 100a or a 80a pack?
Im all confused with this now

[Burgerman]

A lithium ion phosphate (LiFePO4) cell has a nominal voltage of 3.2 to 3.3 volts. It is charged at 3.6V. It is 99 percent discharged by 2.8V. And dead flat by 2.5V or less. DO NOT GO LOWER!

To be equivalent to a 12V lead battery (13V full, 11.8V discharged, 14.4V charge voltage) you need 4 LiFePO4 in series. Called 4S.

For 24V then you need 8S. So you need to fit multiples of 8 in your chair.
Or make 12v packs (multiples of 4) like lead and then connect these also in series to give 24V (8S).

That will give you a voltage that is fractionally higher than lead, all the way to about 90 percent discharged. And that will work with a mobility controller.

If you make these groups of 8 with 10Ah cells, that gives you a 10Ah battery. If you use 16 cells, then you add the extra ones in parallel, and have 20Ah. Etc...

[nealnlx]

So for each 10ah a want to ad up i first need to make a little group of 4 cells to make one 12v 10a that i can next add to the prior one i've created, making of 8cells a pair of two 12v 10ah batteries that when in parallel will be a one 12v 20ah baterry, right?

As you said, that is for the 4s and for the 8s just do it in double, correct?

Now it make sence all the pile of cells. Always need 4 to make 1 first.

If im not wrong i tell you, next weak i want my diploma

[Burgerman]

Yes diploma soon.

Correct. But you really need 24V so think in terms of 8 cells.

[nealnlx]

My old days of school are coming back

My chair have 2x 12v batteries so all the wiring is arranged to work with 2 sets of 12v
Should i keep it this way by making groups of lots of 4cells to get as many 12v and Ah as needed or should i make groups of 8?

[Burgerman]

Doesn't matter.

Your aim is to fit as many cells as possible that ends up at 24v (8S) so that you maximize capacity.

To do that you can make 4x 6v or 2x 12v or 1x 24v if you want.

It may be that different cell types allow a better "fit" into your spaces, giving more Ah and as long as the total cell count can be divided by 8 then it matters not how you split it up.

To give you some idea, my currently being rebuilt BM2 used to have 2x 12V lead bricks of 55Ah when new. I am fitting 120Ah in its place. By being creative. The battery will end up a very odd shape. But will be divisible by 8.