Revolectrics

[Burgerman]

Funny how those of us with some real understanding like myself, and lenny, or shirley, inc 2 of us that have been doing this stuff for 20 years absolutely get it. And its plainly obvious and really simple to understand. And yet the ones that keep posting garbage like you do never explain anything, and are to ones that dont have a clue how anything works isnt it...

Sometimes you MUST LEARN some stuff. Not everything IS simple enough to dumb down to a low level so mr. average can understand. Believe me I have tried.

[Burgerman]

You need to balance the pack every charge. Unless you KNOW it was in good balance already and DO NOT fully charge it. And only do that a few times max.

Terry, what's the balancing current on the OverkillSolar BMS?

Steve

Only a tiny 80mA according to shirley, and only then if its a long way above the correct voltage. So its useless on a big pack. Esp if less than perfect/new. And already balanced by something else first. Hence he big list of warnings. But its got BT and nice graphics!

One more time for you.

It's programed by Overkill USA and you upload the latest settings from overkill site.

https://github.com/FurTrader/OverkillSolarBMS

WE KNOW. I read all that long before you even heard of it.

But unlike you, some of us understand how the BMS actually works. It doesent make a damned bit of difference if god almighty programmed it. That does not change its electrical capability one bit. If you had any clue about how anything worked you would already understand this. I have explained it in 10 different ways in this thread alone. Yet STILL you dont understand. Some people are simply not capable it seems.

[shirley_hkg]

But again. I am not saying dont use a BMS just that you should be aware of the issues instead of being in denial and thinking its some ind of fight.

Yes. There are BMS
that could still do the job , though may not be as good as a PL8.

The battery :

It's a 70Ah pouch cells , with loose, messy connections.
It's pre-balanced by PL8 , and is removed 60Ah out if it , and it is also deliberately unbalanced by taken 3 to 5 Ah amongst cells 3 to 8 as well.

It is an every way out of balance pack now .

[Fred005]

No its not.You can 99.9% charge a lifepo4 Cell (or a bunch of them with inadeqyuate balance capability. For a lot of the time.
But as soon as a cell reaches 99.9 full that cell then shoots up from 3.4V to a really high point. In seconds, after charging for many hours at 3.xx volts. That massive sudden rise at the last 0.01% is the problem. You obviously still put back most of the charge. But you damage a cell or two every time you do it. OR worse you never get it fully balanced. This gets worse every charge. And then one day you suddennly stop as a low cell that you didnt know you had (caused by a high one preventing a full charge on the others) makes your chair stop unexpectedly.

Theres 3 things lithium ion cells hate. Which severely shortens lifespan. Being full. Or above around 3.5V. ESPECIALLY if overvoltage and for long periods.
Being empty or below around 3V which happens to some cells if they are not correctly balanced.
BEing discharged at a high rate. Which means a pack that is double the size is twice as good. As you are only pulling half the amps per Ah. It also lessens aveage depth of discharge so no cell gets low which they do not like.

But I am wasting my breath. You will get nowhere near the 2000 cyvles you expect. And maybe you will get a breakdown or failure due to damaged cell long before you expect. And maybe it will just stop in the middle of one of your hykes far sooner than you expect.

But again. I am not saying dont use a BMS just that you should be aware of the issues instead of being in denial and thinking its some ind of fight.

No, you're not wasting your breath, be sure.
But, after 50 cycles completed, absolutely NO difference.
Ok 50 is not 2000, but ... it's 1/40, so not nothing.
And, I'm sure, 99.99%, it'll be the same for my LiFePo4 after years of good duty. I can be wrong, future will say.

Did I said I'm in denial of anything here ? I don't think so or at least not about this thread.
I'm aware of the issues. As I'm aware PL8 is over and if today I had money to buy 8 230ah cells, I'll have not a lot of options, and one of these is the BMS.

I'm aware too, hiking with 2 good legs is much more funny than 4 motors and 2 LiFePo4, but no other option too for me ...

[shirley_hkg]

I set charge volt @3.48V and balance starts @3.39V deliberately, to see how it performs at low charge volt.

Took 4 hours to rebalance the pack again .

No cell experiences higher than 3.48V throughout the charge.

Cell volts are solidly packed together , and have to wait 60 mins to drop to 3.43V for BMS to remove over-volt cutoff and continue.



See the log by PL8.

[Fred005]

But again. I am not saying dont use a BMS just that you should be aware of the issues instead of being in denial and thinking its some ind of fight.

Yes. There are BMS
that could still do the job , though may not be as good as a PL8.

The battery :

It's a 70Ah pouch cells , with loose, messy connections.
It's pre-balanced by PL8 , and is removed 60Ah out if it , and it is also deliberately unbalanced by taken 3 to 5 Ah amongst cells 3 to 8 as well.

It is an every way out of balance pack now .

Yes. There are BMS
that could still do the job , though may not be as good as a PL8.

This ''may'' is very important.
This thread is fantastic and I'll not be suprised if after some days/weeks, mind will change, a bit.

[Fred005]

I set charge volt @3.48V and balance starts @3.39V deliberately, to see how it performs at low charge volt.

Took 4 hours to rebalance the pack again .

No cell experiences higher than 3.48V throughout the charge.

Cell volts are solidly packed together , and have to wait 60 mins to drop to 3.43V for BMS to remove over-volt cutoff and continue.



See the log by PL8.

Very good news !

[shirley_hkg]

Provide you don't apply a BMS blindly , and make adjustments to get around its weakness.

[Fred005]

Provide you don't apply a BMS blindly , and make adjustments to get around its weakness.

Off course.

What is the make of your BMS, please ?

[Burgerman]

https://www.wheelchairdriver.com/board/ ... &mode=view

This will never result in a fully balanced pack at that voltage. But close. The result of shirley messing around with the start and stop votages on that BMS is that the cells experience continual bouncing up and down for many hours, but that average volts is at a level where it eventually balances. Close though it may be. But bindly setting his exact start and stop release points (voltages) on your own pack wont work. You will need to assess and adjust your own. And you MUST monitor it and watch what its doing. And alow as long as it takes to let balance complete. This extra 4 hours is harmful in itself though. LiFePO4 does not like to be full for a long period or be repeatedly bounced.

To do this you need to be able to very finely adjust the chargers CV voltage. And make sure it does not turn off and think charge is over before balance ends. So really you need a power supply to do this rather than a charger. And then YOU stop it once balance has happened. DONT leave it connected! Allow the thing to relax after balance is achieved. This isnt just a case of slapping a BMS on and hoping for the best. DETAILS matter. But shirley understands the details...

But WITH CAREFUL MANAGEMENT and setup it can work. Although not as well as the PL8 or other balance chargers do. Because they dont jump up and down, they can choose an exact voltage and just hold each cell in place in turn as they become full. So a higher voltage can safely be used. That results in the end part taking much less time. And no bouncing up and down. So much kinder to the cells.

[Burgerman]

What he is talking about is THIS https://www.wheelchairdriver.com/board/ ... 8&start=30

Read full thread. It works a little differently to all the cheap BMS we have been talking about on here and has a higher than 1A balance capability because it shunts power from cell to cell. Still cant control charger though hence the continual bouncing. Read and absorb all before jumping to premature conclusions. There is no dumbed down simple answer!

https://www.wheelchairdriver.com/board/ ... 8&start=30

[ex-Gooserider]

Dumb question - but possibly something that might lead to a solution?

What happens if one charges a pack w/ such a supply set to the exact voltage of the pack at full charge (i.e. 8 x 3.6V) - bad w/ no balance wiring, but what happens if one feeds that voltage to a BMS?

Would it work to have some sort of microprocessor reading the voltage at each balance wire and turning on a dump load for the high cells (sounds like what the BMS is doing)? There is obviously a limit on how much power you can pull w/ the dump load, namely the current capacity of the small guage balance wires, I suspect the PL8 is near that limit @ 1A... It might also be possible to have a current sensor on the supply and throttle it some how (some sort of input to a Shirley supply?)

I seem to recall that Irving was working on reverse engineering at least some of the PL8 functionality - has anyone heard from him lately? I'm wondering how hard it would be to reproduce a SINGLE FUNCTION version of the PL8, that would ONLY charge a chair pack instead of being a 'does everything' charger like the PL8?

It would be a nice thing if we could come up w/ a home-brew charging solution so that we are not stuck being dependent on a single company that can decide to fold or change their products out from under us....

ex-Gooserider

[Burgerman]

What happens if one charges a pack w/ such a supply set to the exact voltage of the pack at full charge (i.e. 8 x 3.6V) - bad w/ no balance wiring, but what happens if one feeds that voltage to a BMS?

Thats exactly what hapens. How they "work". What then happens is that the BMS cannot throttle the charger so it has to cut of charger power off while the useless cell drain balance current pulls a high cell or two down to a sane level again. Then it reconnects the 40A charger which sends it all back into orbit and so it disconnects again and starts that 60mA draining thing all over again.

Yes you can do all of the above. They already do that.

So why not just put the BMS inside the charger where the two parts can communicate and use an on board processor to throttle the charger and balance the cells properly in a logical fashion without all the sticking plasters? That way the fans can cool the 1A or greater balance resistors/mosfets too and the whole thing can be done in a fully proportional and smoothly controlled way? And no burning people as they drive about... Wait...

Thats what a cell balancing charger is doing of course!

[CPguy]

The "Junsi iCharger 4010 DUO 2000W" has already been mentioned in this thread as not being a good replacement for the PL8. Does, by chance, someone have this charger? I would like to know if the PC software is powerful enough to meet the requirements of large pack charging and fast balancing?

[Burgerman]

They have modified the firmware on the iChargers. The lowest you were able to set the termination current used to be 10% OF CHARGE CURRENT. Obviously that will not work for large LiFePO4 packs.

So that now it can be configured to as low as 1%. Now that means that with the latest firmware you may well be able to charge to a low enough end current. If you carfully configure this. It will mean some mental calculations to adjust this percentage every time you change the charge current setting which is a shitty way to do things. But at least that can be made to work. As far as I know theres no PC software. Other than to upgrade the firmware when they fix things ssuch as this example here. What it realy needed was a manual termination current that you can set independently but it doesent allow that.

So if you ignore all the warnings about not using it for non hobby use, and connect power, balance, charge cables in the right order so it doesent go bang, then it may well work for our packs. I doubt its going to be as reliable though. Judjung by all the voided warranty warnings it comes with.

And there may be hidden firmware traps such as large capacity limits, and dozens more that may be hidden in the firmware. But at least now it is possibe to get a 1% of charge current as a termination level. So charge at 40A and it ends at 400mA which is a little early but workable IF CAREFULLY CONFIGURED IN THE ADVANCED SETTINGS.

http://www.hillrc.com/UploadFiles/4010DUO_Manual_en.pdf

[davidpaul]

Gosh some of the posts on here are a bit narrowminded and or offensive, you do realize there are many reasons why people are wheelchair users, I personally have explained before why I find it difficult to extract the info I need from long winded posts, there maybe many on here who like me have difficulties finding the info they need.

Many just want to charge their batteries, I suspect some like me don't really give a monkey's about all the fine details.

If like me they have memory problems it's close to a waste of time reading a post for hours only to forget most of what you've read by the time you've finished reading and by the next day more has gone, give it a few days and every has completely gone, that's why I need to ask what maybe considered "stupid questions"

I had wondered why there was such a long gap between now and my last visit some years ago, and I'm sure I felt then the same as I do now

[Burgerman]

Yet again.

Theres the dumbed down inadequate answer. Or theres the correct answer. Narrow minded does not enter into it in any way. The facts and logic and dont care about feelings. And facts do not "offend" anyone rational. Try not to mix the two up.

"But why is it so complicated?"
Because it just is. Not everything is simple, sorry about that. If you dont like that tough. If the subject is too much for you again, tough. Find something that is at your level. Feel free to remain in the ranks of the masses that are clueless. And in the hands of the "experts". Suffer all the endless problems that all those around you do.

Knowledge is power. You dont want any thats your choice.
https://www.wheelchairdriver.com/board/ ... =5&t=10777 we just had a little talk about this on here.

[Burgerman]

Many just want to charge their batteries, I suspect some like me don't really give a monkey's about all the fine details.

And whats stopping you do that?
You dont give a monkeys if it damages them or is dangerous right? So carry on!

Dont need to read anything here.

[biscuit]

Find something that is at your level. Feel free to remain in the ranks of the masses that are clueless. And in the hands of the "experts". Suffer all the endless problems that all those around you do.

Knowledge is power. You dont want any thats your choice.

Actually those of us with memory and concentration problems mostly don't have them by choice.
Even though the sharp-witted get irritated by it.
We generally just have to shut up when we're out of our league.
But it's helluva difficult to follow all the threads.
And the temptation not to bother is great. Because most people do get by without bothering and it doesn't blight their lives.

[Burgerman]

Blight their lives? Depends on the subject. And if they even realise that it DOES blight their lives.

So what do I do?
Answer everything in a dumbed down way, knowing that its missing a lot of important info, to suit those that cant understand anything complicated? Thats rediculous isnt. Thers some that can follow it and want the info. Some subjects are just not simple! Lithium battery charging and BMS or Hobby chargers happen to be pretty complicated. At least if you want to do it right, get the benefits instead of all the problems.

Some want to know and understand. Others that dont care do not have to read. Not everyone is created with equal abilities. You can get all the wrong and dumbed down answers on this subject on youtube. Or your local wheelchair tech.

[sacharlie]

Many just want to charge their batteries, I suspect some like me don't really give a monkey's about all the fine details.

And whats stopping you do that?
You dont give a monkeys if it damages them or is dangerous right? So carry on!

Dont need to read anything here.

That is very irritating! Why do you insist on always doing that?

[biscuit]

Not at all!

So what do I do?
Answer everything in a dumbed down way, knowing that its missing a lot ...

This is a technical forum, so I'm not complaining.
There is so much information here that one can feel intimidated and frustrated. It is easy to get cross.
I feel for those who share their in depth understanding of things that they took a lot of trouble to find out, and for those who don't understand it.

Haha I'm not sure one's life is blighted if one doesn't feel that it is. That's a philosophical point.

[Burgerman]

What if I said I see most people struggle to live an easy life, struggle to keep a roof over their heads, struggle to pay bills, who get ripped off for everything around them waste money and effort and work hard to accomplish little. Where most of that isnt nessassary? Thats what I see. And the more that people have short attention spans, the less they listen to or WANT TO KNOW all the details that matter the more this is so. Some of it is about IQ. Most of it has nothing to do with IQ but that people have never been taught how to think logically. And run through life in a hugely bewildered and contradictory way. And they cannot see this any of this for the exact same reasons. Blighted? Yes. From an outside perspective.

Just one example. My 62 year old neigbour is very destraught. She is about to lose her house. Why? Because her husband didnt see the big picture. He didnt "believe" in the vaccine. In this country almost nobody is now dying from covid. Everything is basically over. Theres still lots of covid about. But serious illness and deaths are basicaly finished. He has been given 12 to 24 hours to live. He paid the mortgage. He didnt have any health insurance etc. Yes he didnt care about logic and reason. The tech details was too complicated. He "decided" it was nothing more than flue and wasnt worth worrying about. It was all a hoax and it wasnt going to affect him. Yes he has blighted his own and his wifes life. Through ignorance of the facts and inability to think logically. I forced my carers and actively persued the vaccine ASAP for myself and them. And am already doing so for the 3rd booster one. By finding out how to get ahead of the masses next month.

[Burgerman]

Many just want to charge their batteries, I suspect some like me don't really give a monkey's about all the fine details.

And whats stopping you do that?
You dont give a monkeys if it damages them or is dangerous right? So carry on!

Dont need to read anything here.

That is very irritating! Why do you insist on always doing that?

What?
Staing the obvious?
Again. Sorry if reality is irritating to you. You either WANT TO KNOW and learn or you dont. You cant have it both ways.

[Burgerman]

Another example. Endless debt. Related to not wanting to understand details. But slightly different. I see ways to blight lives all around me all day every day. It all comes down to lack of thinking skills, sceptisism, logic and reasoning skills.

Debt blights peoples lives. A THIRD of UK adults paid for their holidays with supposed interest free credit, ONE THIRD of the population are stupid enough to want to be in debt. The reality is that you just got ripped of by an extra 10 percent in holiday price for the privelidge. Lets say that 2k for a small family. Now you just had that stick shoved up your ass again and wiggled a bit more. You have 200 less for next years trip, AND are in debt all year so you cant save for it either. And 33% of the country are stupid enough to fall for this crap to take a holiday they cannot afford. This story was about holidays. But people do this for all kinds of things as well as holidays. A third of the country blighted by their own stupid life choices. And they CANNOT SEE THIS as the very same skills they lack, reasoning, are needed. Next they will blame "evil capitalism" for the fact they cant afford to live.

[biscuit]

World goes around even though it is populated by thickies.
Everyone is going to die of something. When they do, it is upsetting for the others.
Some of them haven't got enough morality to live within their means. They blame others for it.
Lucky for us we don't have to solve these problems.

Lucky for them too.

[CPguy]

@ Burgerman: Thank you for the detailed info on the Junsi iCharger! This is a TECHNICAL forum so I am very grateful for the info I get here.

[Fred005]

Yes, a technical forum, so ...
What do you think about that:
https://www.akku-lifepo4.de/shop/Aktiv- ... p355745121

Have a good day.

Fred.

[LROBBINS]

Here's a Google translate of the German on that site:

Activ Balancer module high frequency equalizer
-To actively balance the cells.
-Can also be operated without a BMS.
-Always keeps the cells at the same level and is recommended, as there can be problems with passive BMS.
-Modules are expandable and can be connected to each other, e.g. to balance 8 cells.
Data:
Manufacturer QNBBM
Consumption <50mW
Equalizing current balancing 300mV with 1A / 1V with 3A
Connection type terminals
Temperature range -40 degrees to +80 degrees

There's not enough information to know what it does, but the balance current is at least encouraging. Given that it transfers power from high cells to low cells (i.e. active balancing), being able to throttle the power supply may be of less concern, but a lot more information is really needed.

Here's an AliExpress link for the 8S version. https://www.aliexpress.com/i/32994480708.html There's even less information there, but perhaps someone would care to write to either supplier to see if more complete specs and/or a manual is available.

[Burgerman]

-Always keeps the cells at the same level and is recommended, as there can be problems with passive BMS.

THAT part scares me. If it does any balancing of any kind below 3.5V it will Put the pack out of balaNce all day long. And how does it control the charger? As lenny says lack of info to tell what it will do. Remember that if a cell tries to leap up high when its full, the charger keeps going at 40A or whatever charge rate, and that 350mA doesent stand any chance of controlling that. A normal BMS keeps chopping of power while the balance load makes the voltage of the high cell drop again. Then reconnects for an instant, and rinse and repeat. You get that overvolt/undrvolt sawtooth for as many hours as it takes to balance the pack. 1Ah out (just 1%) on a larke 200Ah pack such as we are using means 2Ah to fix. That takes 2 hours with a 1A balancer. It may take 6 hours after charing for this to do the same thing. The problem is that it looks like it will continue to try and balance (unbalance) the pack at lower than 3.5V all day aftar this. Maybe for weeks if unused. Resulting a=in a very unbalanced pack by maybe 10Ah or more after storage for a while.

Again DETAILS of what it actually does matter! Yes those ones many dont want to know about!