X8 configuration

[Burgerman]

Very odd.

Add this to the registry by clicking it and agreeing.
It will ad a thing called TAKE OWNERSHIP to your right click menu.

Then go to the file c:/windows/winhlp32.exe or whatever its called, and right click it and choose TAKE OWNERSHIP.

Then try installing the updated help

Run only the INSTALLTAKEOWNERSHIP.REG file here.

[Fred005]

In a few months I'll buy 8 230Ah cells.
Because of many reasons, personnels reasons, I want to instal BSM. Even if I've understood why many of you don't use BSM.

So my question is:
I think to connect 4 cells in serie, and manage these 4 cells with 1 BSM 4S.
4 other cells with the same configuration.
My 2 pack, or 2 batteries will be connected in serie too, to obtain 24V.

I will disconnect the link between 2 batteries to charge each battery with 12V.

Will my skecth ok or not ?

[Burgerman]

No! I hate the damned things. Will what you propose work? In parallel maybe maybe not.

It depends on the charger you use. How does it determine when to stop? And how stable is its voltage as one of your BMS modules keeps chopping off the power while the other stays connected? Does it emain at a stable voltage or hunt up and down to find a new balance? Or does it decide charge has ended?

Once you fit a BMS you are in the lap of the gods. They are not called Battery Murdering Systems for nothing.

You will need to test. If I did that on my bench power supply that was set to 28.4V exactly which is is very stable as you remove and add a load, then it would be OK. If you call what a BMS does OK.

[swalker]

What Burgerman said is correct.

In addition, should you happen to find a pair of BMSs that work for charging the batteries (you won't , but just for the sake of argument lets say you do), you will likely find those BMSs will throttle the output when you are using your chair in high power draw situations.

To my knowledge, there is no BMS available on the market suitable for the needs of a wheelchair LiFePO4 battery pack. The only solution currently available is to use an appropriate charger (PL8) and to use your brain as the BMS.

I have a Magic Mobility X4 (the predecessor to your X8 model). I have 8 LiFePO4 prismatic cells connected in series without a BMS to power it. That setup works really well. Charging with a PL8 and keeping track of things while I am using the wheelchair is very simple. I encourage you to consider going this route.

The only real challenge I face is cold weather. You should not charge LiFePO4 cells below 32 F (0 C) and should not store them below 14 f (-10 C). I encounter those temperatures, so have to make sure the wheelchair is indoors or the cells are heated for storage and charging. I have gone on rides at 0 F (-18 C) without problem, but that is starting with the wheelchair at room temperature and being sure not to stop during the ride.

Steve

[Fred005]

It depends on the charger you use. How does it determine when to stop? And how stable is its voltage as one of your BMS modules keeps chopping off the power while the other stays connected? Does it emain at a stable voltage or hunt up and down to find a new balance? Or does it decide charge has ended?

It's a Victron 12V/30A x 3. Not the best one maybe but not the worst for sure.

I understand what you said me, BurgerMan and Steve. Yes.
I can use my brain as a BSM, or I think I can, I hope too.
It's only I'm worried to dammage my cells, wich will be expensive, if a day I can't take care about my batteries voltage because situation is complicated.
Also, an other reason is I've 2 Victron charger, since some years, 1 is intalled in my small ''power box'' at the rear of X8. This charger is very reliable because I never had problem with it despite the fact that X8 shakes it a lot. Will a PL8 so reliable ?

Well it's not for today I'll buy new 230A cells, so I've time to think about all problem/solution.

Thanks again for your help. Have a good day.

[Fred005]

I just downloaded the PL8 user manual.
PL8 is not connected to AC ? It needs an DC power source ?

[swalker]

That is correct. The PL8 obtains power from a power supply. Revolectrix sells a power supply suitable for use with the PL8. That power supply costs about as much as the PL8.

Oddly enough, the power supply sold by Revolectrix is not capable of powering the PL8 to the PL8's fullest capacity. However, in the US (where Revolectrix is based), typical house wiring provides a 15 amp circuit at nominal 120 volts. So, the Revolectrix power supply is reasonably adequate for many US-based users. I have two of them and they have served me well.

Many others on this forum use different power supplies. The "Shirley" power supply is pretty popular. I am sure someone will chime in shortly to provide details on that and other options.

Steve

[Fred005]

Ok, Steve, and thanks.

Not easy for me, for what I do with my X8, to bring the PL8 and a power supply. I don't need them for each of my hike but often, maybe 70/100.

For me, my knowledge and my purpose, BSM is maybe not the best solution however the only one I can see today.
But, I'm open for other ideas/suggestions.

[Burgerman]

The PL8 doesent need a power supply. It will run from a car or truck, 12 or 24V and will charge at any voltage you want. Will balance cells. And will PROPERLY charge your batteries where a BMS wont.

So will run directly off your spare battery to top up your lithium... It will also work the other way around and charge your lead batteries from a car, truck or your 4x4 buggy. It pumps power from one place to another... And every charge and balance parameter can be configured to your needs. And so can termination current. Essential for correct charge of lithium as well as lead. Will also charge any other chemistries.

Is it reliable? Its only hobby grade. I have 4 for a decade. Used for hobby stuff, get banged about, and also for chairs. Never had any issues. What can kill them is cheap AC power supplies. Spikes etc. Running from batteries I never saw a failure. They are also for testing, measuring battery discharge capacity, graphing and watching balance / charge / discharge curves and all controlled by and programmed with PC.

And light. 1LB? Maybe less. And 40A 30V+ 1344 watts capable. Get 2. It will fit in your pocket almost. And so flexible that you will wonder how you managed without.

[Fred005]

Ok, BurgerMan, but I don't always have access to DC 12/24v or to my battery box.
Sometime yes, sometime only AC 240v.
It's why I need to find a very versatile option, giving me acces to DC 12/24v, or/and AC 240v too.

In my small box, at the rear of X8, I've my Victron charger, working with AC 240v, and (I copied your idea) a 2m length cable I connect on the Anderson inside my small box, wich can provide me 12 or 24v from a car, truck, battery ....

With my actual configuration I'm 100% free to charge X8 with many source.
And it's what I want/need when I'll instal 8 x 230A cells. With or without (!!!) BMS.

[Burgerman]

You CANNOT install with no BMS even for a single charge without a proper cell balancing charger though. A small portable AC to 24V DC power supply can power the PL8. Even a small laptop one if not in a hurry. You would need no heavy victron or inverter.

[Fred005]

You CANNOT install with no BMS even for a single charge without a proper cell balancing charger though.

I know and understand that, and it's not what I want to do.

I'll consider all your suggestions.
What I need/want is a system very easy to use, without thinking/care to much to my batteries, and it's why I was thinking BSM is not so bad for that. For exemple, with my actual LiFePo4 and their BSM, I know exactely what I can expect about endurance, according with the field where I go. That's is perfect and what I want, with a few more endurance, wich will be increased with 230A cells.

Also, I build my charging system in order every body, even a 10 years kid, can charge my X8. No need to explain, no possibilities to make a mistake: left battery Anderson connector is red, right one green. Impossible, except with a hamer, to make a mistake when connecting both batteries in serie, or when connecting my onboard charger, the same for the cable wich can be connected to a car or truck or tractor, etc. I'm far to be a genius, I copied many ideas from BurgerMan about that.

It's why, for the moment, I think building 2 x 12v 4s barreries with their own BSM is not a so bad idea.
Maybe with a PL8, a AC to DC 24v power supply my batteries will give me a few more endurance, I know, maybe their life will be 2 or 3 years longer (what about my life ... Maybe not more than 5/7 years ...), and maybe, a day, without taking care of my fuel gauge, I'll damage 1 or more cells.

You, BurgerMan and some others, you're passionate by technology (we just have to see photo of your room, house BurgerMan to understand that !!!), NOT me !
My truck in US, is a 1996 Land Cruiser. No electronic inside, except my GPS. 500 000 km, including 300 000 km in Africa, Middle East, Canada (not always and far, on black road).
This truck has been a lot lot lot and more modified by me.
1 small exemple: no steel spring for my suspension, I installed 4 air spring. These 4 air bag spring could be managed by an electronic box, but they are managed by 4 manual faucet. Never had any kind of problem since 20 years and 400 000 km, since I installed my air spring.
It's only an exemple to explain who I am, what I need, whant.
It's why I asked about my sketch and 2 BMS (even if the actual system I'm using is the same, but not home made).
But, I understand all what people here explained me about BMS, PL8 and more.

Have a nice weekend.

[Burgerman]

Its a BMS not BSM...

I know exactely what I can expect about endurance, according with the field where I go. That's is perfect and what I want, with a few more endurance, wich will be increased with 230A cells.

Thats one of the problems you DONT know what to expect.
If you have a cell with higher self discharge for e.g you may have 30 miles range today. But the next time you charge it full, the BMS fails to balance the low battery cell with high self discharge adequately. Then you may go 20 miles and the BMS sees that one cell drop below the safe limit. At which point it pulls the plug and you dont go home.

And its also why your pack will be constantly pulsed above a nice sensible 3.55V per cell. Up to even 3.8 or 3.9V on the highest cells repeatedly as it keep disconnecting the charger and reconnecting in a sad attempt to balance it. Also how do you know if it ACTUALLY gets balanced befor the charger turns off? The charger has no way to tell. And most switch off far too soon. Or stay on indefinitely. So either leave it unbalanced or hold it at too high top voltage for too long. Or both! So doing their best to kill your cells. Or give unpredictable range when you least expect it.

[Fred005]

Its a BMS not BSM...

I know exactely what I can expect about endurance, according with the field where I go. That's is perfect and what I want, with a few more endurance, wich will be increased with 230A cells.

Thats one of the problems you DONT know what to expect.

I wanted to say, since I used my actual LiFePo4 equiped with -maybe- bad BMS, my endurance is at 5% +/- the same. Wich is good enough for me.

For sure it'll be more acurate with your system, however it seams, for me, to be more complicated to manage.

I've time to think and think again for the best choice wich will suit me and my request.

Thanks again for your positive answers.

[Burgerman]

I have a pack with a BMS here. From my mower. If I charge it weekly it stays in balance. Or doesent get far out. Mostly. If I leave it a couple of weeks one of the 7 cells drops to around 50%. The charger charges as normal, tells me its done. The BMS dosent have adequate time to fix this huge imbalance. So now I get half the runtime on a full battery as one cell is half empty when the BMS and charger think its all done... When this unexpectedly happens to you you are stranded right?

So sometimes I get 1 hour. Other times I get unexpected 25 to 30 mins. And run one cell right down to 2.5V in the process. And then when charging one cell only gets to 50% full. I would have no idea that this was happening if I only relied on a BMS. But I fix the problem by charging it properly with the PL8 periodically. That charges till all cells are at 4.200V plus or minus 2mV. It does to accurately and proportionally throttling the charger so that the 1A balance capability is able to stop the high cells repeatedly going over the correct max voltage unlike a BMS... It stops charging only when:
ALL cells are equal.
ALL cells are within 2mV of the choosen CV voltage (4.200V in this case)
ALL cells are drawing the same or less that the termination current of around 1/400th of the Ah capacity.

So you may think you are going to be consistent to 5% just because it has been so far. But you dont know what will happen if its been stored. Or if a cell develops a slighty higher self discharge. Worse, many BMS attempt to balance all the time. That can put the pack miles out of balance while you use it or store it because when a LiFePO4 cell is below 3.45V its actual voltage DOES NOT equal the state of charge. Its quite possible for voltage to decrease as it charges on some cells or increase as it discharges. The stupid BMS tries to level the voltages and puts the whole pack out of balance.

But feel free to carry on. I am just trying to explain what actually happens so you are aware of SOME of the issues with your setup. And you are worried about damaging your lithium cells. Well a BMS will!

[swalker]

It is your wheelchair and your money. You should do whatever you think is best in your situation.

Be aware that in my opinion you will likely encounter two issues with BMSs currently available.

1. You stand an increased chance of discovering at an inconvenient time and/or place that your cells have become unbalanced and your battery pack will not work.
2. You will likely decrease the life of your LiFePO4 cells so that they are less cost-effective than lead acid

In exchange, you will have some of the advantages of LiFePO4 technology without having to care about the technical details.

Steve

[LROBBINS]

Fred005,

I am a bit confused about your charging issues. With a 240 AHr pack even a power hungry chair on difficult terrain can go a very long distance between charges. That is likely to be at least a full day's use, so I do not quite understand why you need to carry charging equipment with you.

[Burgerman]

Or how he will charge that from a single used 73Ah lead brick...

[swalker]

Fred005,

With a 240 AHr pack even a power hungry chair on difficult terrain can go a very long distance between charges.

He has a Magic Mobility X8 wheelchair, which has 4 motors. I can't speak directly for the X8, but I have the previous version of that chair, the X4.

My X4 wheelchair would go 4 miles on a pair of good MK group 24 gel batteries. It now has a 176 Ah LiFePO4 pack, which I have tested to a maximum range of 33 miles. I would not plan to take it further than 25 miles on a charge, just so I have some reserve capacity.

That is not a problem for me, as my body cannot tolerate more than about 20 miles in that chair in one day. But, if I had the physical ability to be in the chair for a longer ride, I would really like to do so. In that case, I would be looking for a place to recharge the wheelchair enroute.

By the way, I see how to fit a 200Ah LiFePO4 pack, but I am not aware of any 230 or 240 Ah cells whose size will allow 8 to fit into my X4's battery compartments. Perhaps the X8 is arranged differently, but according to the specs, the X8 has slightly smaller battery compartment than the X4.

Steve

[Fred005]

Fred005,

I am a bit confused about your charging issues. With a 240 AHr pack even a power hungry chair on difficult terrain can go a very long distance between charges. That is likely to be at least a full day's use, so I do not quite understand why you need to carry charging equipment with you.

With my actual LiFePo4 equipment, depending of the area where I ''hike'', depending of the D+ and many other characteristics of the field I've 8 to 12 hours endurance.
So, not so bad for a full day's use as you said.
But, 40% of my hikes are longer than a full day. So, even with a 230A pack I need to charge my batteries.

Your question/remark is very very interesting, because you point exactely my X8 usage wich is very different from 99% of other wheelchair users.

Have a nice Sunday.

[Fred005]

Or how he will charge that from a single used 73Ah lead brick...

As I said you before, with my single brick lead I charge what it can give me, not more, for sure. Don't play to much with that, please, my legs are disabled, not (too much !) my head/brain ....

[Fred005]

Fred005,

With a 240 AHr pack even a power hungry chair on difficult terrain can go a very long distance between charges.

He has a Magic Mobility X8 wheelchair, which has 4 motors. I can't speak directly for the X8, but I have the previous version of that chair, the X4.

My X4 wheelchair would go 4 miles on a pair of good MK group 24 gel batteries. It now has a 176 Ah LiFePO4 pack, which I have tested to a maximum range of 33 miles. I would not plan to take it further than 25 miles on a charge, just so I have some reserve capacity.

That is not a problem for me, as my body cannot tolerate more than about 20 miles in that chair in one day. But, if I had the physical ability to be in the chair for a longer ride, I would really like to do so. In that case, I would be looking for a place to recharge the wheelchair enroute.

By the way, I see how to fit a 200Ah LiFePO4 pack, but I am not aware of any 230 or 240 Ah cells whose size will allow 8 to fit into my X4's battery compartments. Perhaps the X8 is arranged differently, but according to the specs, the X8 has slightly smaller battery compartment than the X4.

Steve

Thanks to God, thanks to you Steve.
A least 1 guy who knows what I can do, need, want.
Many of you are very accurate about technologie and I read with a lot of attention all your tips.
But, as I wrote before, my needs are very different than BurgerMan's needs for exemple.

Around 20 years ago, I was working in Iran. Flying a Lama helico.
Lama was an old helico but very powerfull for flying in mountain area with cargo sling.
Then my company bought the new Ecureuil, Squirrel, B3.
30%/h less fuel, less noise, and same power even a bit more.
After 5/6 weeks the turbine doesn't want to start. 3 weeks on ground waiting for an electronic card same dimension than a Visa card.
The same problem with the Lama, I never seen during 20 years flying with it ...
It's only an exemple.

For answering your question, Steve, my X8 is 10cm longer. I cut the frame to add 10cm. Because of that my batteries box is 10cm longer too. Around 38cm length. My X8 is also lighter from 40kg than it was originally.
When US boundaries will be open I'll go back in Vegas, where my Land Cruiser is, and I'll visit you, Steve, if you agree. You'll see my X8 !
I also have the project to climb Pikes Peak with my handbike, and P.P is in your State, Colorado !

[Fred005]

You can see on these photo, rear mudguard are not at the same place than yours. I'll post a photo from the side wich is more expressive.
You can see too, on second photo, my disability allows me to have some position wich help me, a lot, when field is not horizontal.
Each user is different, so each need is different.
My need is to be as much as possible happy, even with this fuc...ing disability. And my racing wheelchair, my handbike, my X8 F+, are doing that very well. A girlfriend could be a plus !!!!

[LROBBINS]

My confusion has been amply resolved.

But now a couple hair-brained ideas, one of which will definitely need Burgerman's opinion.

(1) Suppose that you have a power supply + PL8 at your home base to do full charges with balancing. Then when out and about use the old Pb battery + PL8 to add a bit extra as needed. This will never balance if you've drained more than the Pb can supply, but will at least protect your cells while as much power as possible has been added. The PL8 is very light and small.

(2) Again, do full charges with power supply + PL8, and when away from base use a "Shirley" supply to add back a partial charge without involving the PL8. The "Shirley" supply is a converted-to-programmable ZXD industrial grade supply and can be set up as a 3-stage charger. Set it to 28V (3.5V/cell) and 40A with 3rd stage programmed for 0.7X voltage and 39 Amp switchover. I have tried this while monitoring individual cell voltages. It obviously doesn't fill the battery nor balance as it essentially stops the charging as soon as it reaches Vcv, but I also didn't see any cells going to a too-high voltage. It's not quite plug and play as the ZXD has to be started with 3-stage turned off and then, once some current is flowing, you have to turn 3-stage on, but it involves only one power supply, no extra batteries and will add back a hefty chunk of charge in reasonably short time. The question for Burgerman, however, is what we would expect to see if starting with the batteries already heavily drained and with mis-matched cells. Is this going to send any cells "over the top" even set at 3.5V/cell average?

Lastly, a ZXD + PL8 would work well even when out in the wild (as long as some AC source is there). You don't have to connect it to a PC for that. Again, it's not plug and play, but once set up it's just a few button presses to get to a fully battery, balanced state. And, push come to shove you can connect the PL8 to any DC source (such as a car) and get a full charge that way.

The PL8 is not industrial construction, but looking inside it seems to be pretty well put together. Protect it a bit from physical shock if carrying it in the chair and it should be OK.

[shirley_hkg]

I will not rule out BMS entirely as people want just dump charger for their 200Ah pack , although I still use PL8 a lots .

Several packs were with it already , and nothing went wrong .

https://www.wheelchairdriver.com/board/ ... S&start=30

[Burgerman]

The question for Burgerman, however, is what we would expect to see if starting with the batteries already heavily drained and with mis-matched cells. Is this going to send any cells "over the top" even set at 3.5V/cell average?

The problem is that the difference between 3.5v and 3.6v on a 200ah cell is maybe less than 20mah. So if the pack is only 30mah or less out of balance some full cells will suddenly shoot up to way over 3.8v right at the end. And depending on state of individual cell resistance in use, and self discharge differences between cells this may or may not happen. But likely will. Watch the charger when most of the cells are at 3.500v a few secs later some suddenly shoot up high.

[shirley_hkg]

It has the new split type version , so you can mount the display /control panel with flexibility.

[ex-Gooserider]

A couple of thoughts....

1. I know Shirley had a few instances where he wired the BMS to only work when charging so that it couldn't cut the pack off while using it - is that relevant?

2. As I understand the BMS wiring, the wiring between a BMS and the batteries is the same as the wiring between a PL8 and the batteries.... If so, and since we are typically using that DB connector w/ large charging pins and small balance pins, wouldn't it be possible to make two charging cables - one to go to the PL8 as we are used to, and a second one that goes through the BMS to the Victron charger....

Then at home or when a DC supply is available, charge w/ the PL8 nicely to the proper voltages, balance, etc.... If only AC is available, charge with the BMS / Victron combo which isn't as desirable, but will get some charge back into the pack, and if you get proper balance regularly w/ the PL8, then the BMS balance issues that BM mentions seem less likely to be a problem.....

ex-Gooserider

[Fred005]

2. As I understand the BMS wiring, the wiring between a BMS and the batteries is the same as the wiring between a PL8 and the batteries.... If so, and since we are typically using that DB connector w/ large charging pins and small balance pins, wouldn't it be possible to make two charging cables - one to go to the PL8 as we are used to, and a second one that goes through the BMS to the Victron charger....

Then at home or when a DC supply is available, charge w/ the PL8 nicely to the proper voltages, balance, etc.... If only AC is available, charge with the BMS / Victron combo which isn't as desirable, but will get some charge back into the pack, and if you get proper balance regularly w/ the PL8, then the BMS balance issues that BM mentions seem less likely to be a problem.....

ex-Gooserider

It's exactely what I had in mind.

Well, I'll be back about your message later, for the now I've a handbike training for 70km in my not flat area !

Have a good day.

[Micka7405]

buenas noches amigos
me parece muy interesante tu trabajo
tengo preguntas
Tienes fotos de las modificaciones que alargaste?
¿Quién me puede explicar la compensación de los motores en los ajustes del módulo electrónico?

in english with Google

good night friends
I find your work very interesting
I have questions
Do you have photos of the changes you made?
Who can explain to me the compensation of the motors in the settings of the electronic module?