Help and suggestions for lithium or lead

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Re: Help and suggestions for lithium or lead

Postby nealnlx » 30 Nov 2015, 20:21

LROBBINS wrote:
My chair have one box on the left side that has a on/off switch. When i try to climg on to hard curbs and it is in a bigger effort it just shuts down.
Thats when some good samaritan have to reach the on/off button and turn the power on again.
Then the joystick can be turned on and is like reseted to minimum speed. I have put it fast and furious again. Not that fast and neither furious but thats what we have...
What is that box cut off thing by the way?

Hard to know for sure without seeing it, but from the description this sounds like a circuit breaker that is cutting off all power when it senses that too much current is being drawn. It could be undersized, or it could be old and tired - especially if it's been tripped many times. If it is a circuit breaker, somewhere on it it will say how many amps it should continuously carry. It will trip after a significant delay at twice that current, and much faster the more the current exceeds its rating. If it has gotten weak, it may trip at a much lower than rated current.

If you suspect that it is tripping too easily, it is probably easier to just replace it rather than try to test it - for that you'd need a peak-hold ammeter to see what current was actually flowing just when it trips. If it is a standard type, you should be able to find a replacement at an electronics supply for a price much better than what a wheelchair dealer would charge. Even if you can't find it there, you may be able to find it online from a wheelchair parts supplier (such as Monster Scooter); they are not the cheapest source, but still better than the dealers.

Ciao,
Lenny


I dont know if its a circuit breaker or not. But from my expirence it those what i said.
Seams that mine is connected to the power module from what i can see, the pic i show below, the cable goes on its direction...
I dont even know what a circuit breaker does, but from what it sounds, looks like it works kind of like a fuse. It sees that theres is a overload somewhere (dont know where from) and switches off the eletrical circuit to avoid biger damages.
Go thing is that its resetable like turning on again so we ont have to carry fuses around where we go.

I dont know how much mine can handle. Also dont know yet how much my power module has in amps matter. But lets say that my controller is a 50amps, so it can only sucks out 50A max from the baterry at a given point, when in effort. So does it mean my circuit breaker also is 50A so that way it shut all down in a case of a overload to protect baterries to get that big puch that maybe they could not handle?
If so, it means that a circuit breaker is another protector when it come to the BMS issue.
Having this much protections such as the power module controller that only comands the entire chair to drain only untill the amount of amps it is suposed to, the circuit breaker with the same principle, a large Ah capacity and large C rate cells that have the double or more times the capacity that the circuit can drain it (remind me if im forgetting something) to prevent it to discharge so drasticly and kill the baterry, what job can a BMS do in the midle of this?
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Re: Help and suggestions for lithium or lead

Postby LROBBINS » 30 Nov 2015, 20:35

The purpose of a circuit breaker is not to protect the battery from a heavy load, but to protect you from the fire that might break out if a + and a - wire shorted. Its rated value is usually near to the current-limit set in the controller (assuming that the controller actually is current-limited; current standard wheelchair controllers are, many hobby controllers aren't, and early-days wheelchair controllers weren't). If the controller doesn't limit current, that breaker becomes your primary protection from damaging the batteries or, more importantly, from frying the output stage of the controller itself. People do try to make a BMS substitute for current-limiting in the controller, but it's a lousy way of doing things because, just as a circuit breaker opening or a fuse popping, you just plain stop when the overload happens, while a proper controller keeps you from ever getting into an overload situation.
Ciao,
Lenny
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 30 Nov 2015, 20:36

But lets say that my controller is a 50amps, so it can only sucks out 50A max from the baterry at a given point,


No a 50A controller sends a Max (limited to) 50A to each motor. So 100 total. But here is the weird thing that you will struggle to understand. For technical reasons, 50A at a stalled (or slow turning) loaded up motor, may only be half of that at the battery. As you speed up, the motors get a wider pulsewidth, or if you want, a bigger voltage, so then the 50A at the motor may really be 50A at the battery. Hope that didn't hurt too much!

So does it mean my circuit breaker also is 50A so that way it shut all down in a case of a overload to protect baterries to get that big puch that maybe they could not handle?


And the thing on your chair that cuts out, is a breaker. These are bi-metallic strip switches. A 50A one may take 100A or more for short periods without issue. But will trip at 50A continuously. They take heat over time to make them trip, or large intermittent currents. Its not there to protect the battery, but the cables, or the motors in extreme situations. Replace with either a new one, the same Amp rating, or replace with a slightly larger fuse such as 60Amp. My chairs have no breaker, only a fuse. The idea is that a fuse fails before the battery cables melt!
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Re: Help and suggestions for lithium or lead

Postby nealnlx » 30 Nov 2015, 21:06

LROBBINS wrote:The purpose of a circuit breaker is not to protect the battery from a heavy load, but to protect you from the fire that might break out if a + and a - wire shorted. Its rated value is usually near to the current-limit set in the controller (assuming that the controller actually is current-limited; current standard wheelchair controllers are, many hobby controllers aren't, and early-days wheelchair controllers weren't). If the controller doesn't limit current, that breaker becomes your primary protection from damaging the batteries or, more importantly, from frying the output stage of the controller itself. People do try to make a BMS substitute for current-limiting in the controller, but it's a lousy way of doing things because, just as a circuit breaker opening or a fuse popping, you just plain stop when the overload happens, while a proper controller keeps you from ever getting into an overload situation.
Ciao,
Lenny


Same idea that i thought it woul do. When i said protect the baterry i mean, it and the all circuit because many things can melt and catch fire before it gets to batetty, so yes you are right and my thinkings were not for from it.
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Re: Help and suggestions for lithium or lead

Postby nealnlx » 30 Nov 2015, 21:43

Burgerman wrote:
But lets say that my controller is a 50amps, so it can only sucks out 50A max from the baterry at a given point,


No a 50A controller sends a Max (limited to) 50A to each motor. So 100 total. But here is the weird thing that you will struggle to understand. For technical reasons, 50A at a stalled (or slow turning) loaded up motor, may only be half of that at the battery. As you speed up, the motors get a wider pulsewidth, or if you want, a bigger voltage, so then the 50A at the motor may really be 50A at the battery. Hope that didn't hurt too much!

You didnt catch me that much of guarded. Yesterday for mere ramdomness i ended up reading one article where you talk about controllers and how they say they are 100amps but then they only kind of run at half of voltage per motor at some time.
I got the big picture on the article about that. They can really use those 50A but that doesnt mean it will give all the power when needed as presumed that it should.


... Replace with either a new one, the same Amp rating, or replace with a slightly larger fuse such as 60Amp. My chairs have no breaker, only a fuse. The idea is that a fuse fails before the battery cables melt!

Remember im a tetra, so changing fuses its not a verry practical thing for me to do.
I cant even reach that on/off switch. Only got stucked once, and was one kind american girl and her 20s to 30s that got laid on the ground and looke for a missing button. Not a pretty thing to do to a woman. The best thing was it was summer here and as hot as it is she had a light open dress and ended up showing my way more than i expected.
For turning on a switch i think the prank trick may result, for changing a fuse...they will refuse in a second, and i get no sympathy and will still get stucked.
So ill keep the breaker.

I presume my controller is not a 100A and i plan on buying one since my is down as well.
Should i change the circuit breaker for a 100A as well or keep on the same numbers i have now?
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 30 Nov 2015, 21:53

If you use a 100A controller, you will get no benefit from it unless your motors have a low enough impedance to "suck" 100 Amps from the battery each. That means say 6 to 8mph 4 pole motors usually, and group 24 70Ah batteries. It also means heavier cables.

>>>Remember im a tetra, so changing fuses its not a verry practical thing for me to do.

Never happened to me since 97. That's the point... Correctly sized they will not trip unless there's a fault.
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Re: Help and suggestions for lithium or lead

Postby nealnlx » 30 Nov 2015, 22:07

Same year as mine...

So for me to benefit from the 100A controller i would also have to change the cables?All cables?
And where can i find new ones suitable for this purpose?
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 30 Nov 2015, 22:15

If the motors do not pull 100A or more when stalled, you will see no difference. And your bigger controller will be wasted and there will be no advantage.

Motor cables and battery power cables. http://kojaycat.co.uk/epages/950000457. ... nned_Cable

The things are generally all matched.

2 pole motors (high impedance) usually are on 4 to 6mph chairs. With small controllers and smaller 55Ah or 70Ah batteries.
4 pole motors, low impedance high Amps, usually have 100A or 120A controllers and thicker cables, and 70Ah batteries.
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Re: Help and suggestions for lithium or lead

Postby nealnlx » 30 Nov 2015, 22:35

As i told you one that pm i sent you before, my controller is dead as they said to my, an the cost to reproggrame it is 600euros, they say...
Wel, for that i can buy another one bigger in amps making the step for a new upgrade on the motors later on when its possible.
I saw that any 100 and some pounds can buy a used one on ebay. Being all functional and in proper order, its a big drop down on the cost of it.
So why give 600 to rapir one low to mi rage if i can buy a second hand one top range of the same model?

The cables i would need to change would be the whole chair or what?
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 30 Nov 2015, 22:47

Motor cables and battery power cables.


Or just set max amps to the same as your old controller.
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Re: Help and suggestions for lithium or lead

Postby nealnlx » 30 Nov 2015, 22:55

Sorry but what do you mean by, Or just set max amps to the same as your old controller
?
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 01 Dec 2015, 01:36

You must set any new controllers parameters up with a low level programmer. Or it will have various settings wrong, may not work at all, or may burn out your brakes. One parameter is max amp limit.
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Re: Help and suggestions for lithium or lead

Postby nealnlx » 01 Dec 2015, 01:47

how do i do that?
with that cable that connectes via usb and the chair joystick?
but do i insttal it on the chair first?
is there any kind of walkthrough page or thread around here so i can see it?
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Re: Help and suggestions for lithium or lead

Postby nealnlx » 02 Dec 2015, 21:55

guy any clue?
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 02 Dec 2015, 22:06

Yes. Fit to chair. Obtain the correct OEM level programmer - either PC or hand held - and configure.
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Re: Help and suggestions for lithium or lead

Postby nealnlx » 02 Dec 2015, 23:09

Thanks BM
i have to make a list of what i need, but first im asking you and guys (whoever wants to say something) about your opinion and best option for what i want and need.
So for i need the 100A controller and reprogramme it to the right settings,
Change baterry and motors cables to some heavy duty ones. Less resistance and better flow and less to none hopefully heat.
That cellpro 8 hobby charger looks good if i learn more how to work it out.
Maybe if i see a battery pach setup i can figure it out better.
Can you show me some pics of how does a final pack without BMS looks like?
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 03 Dec 2015, 01:06

http://www.wheelchairdriver.com/BM-MK3- ... rchair.htm

But any shape you choose to make it, Or them.

The only proviso is that it uses multiples of 8 to give 24V nominal.

You can use prismatic (rectangular) cells too, if it allows more Ah in the same space. These are often difficult size/shape however.
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Re: Help and suggestions for lithium or lead

Postby nealnlx » 06 Dec 2015, 01:16

That i know. Headways are the ones im looking for to build it.
But still waiting in my chair to come so i can know the exact dimensions.
That way i will know if i can put in like a pack of 80 10ah cells or 50 15ah to make the 100ah pack.

What i would like to see in pics is tha... you told me that in your setup you only use a single cable, like o computer com door, to charge the battery. But my question is, how do you do that if you need the thiker cables to fast charge and the thiner ones to ballance cell by cell?
So there is two cables, one to just charge and the second one that is the balance connector. Right?
Thats why i would like to see pics so i could see it better.
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 06 Dec 2015, 01:39

viewtopic.php?f=2&t=1813&start=620 All here!

I suggest you read every page of that thread, but here are the connectors I use now. 9 balance wires. 2 heavy 40A capable wires. And a spare one... Not cheap but I standardised these for all my chairs. Lithium and also eventually lead ones when I get around to it.

Image

Image
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 06 Dec 2015, 01:43

Image

ONE meter long. SAFETY shielded connectors at the charger end so no shorts. 40A fuse inside the sleeving.
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 06 Dec 2015, 01:46

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Re: Help and suggestions for lithium or lead

Postby Burgerman » 06 Dec 2015, 01:49

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Re: Help and suggestions for lithium or lead

Postby Burgerman » 06 Dec 2015, 01:53

Image

Plugs into one of these two 40A 1344 watt chargers. Overkill yes. But I don't just use these for powerchair but everything from cameras to quadcopters, mowers, etc. And 2 because they are limited to 8S batteries and one of my chairs uses 13S and so needs 2 chargers at once.

Doesn't need to be next to my bed as these lithium batteries last 45 miles or more and can be charged or topped up anytime fast say every few days. While I sit at my PC and monitor it.
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Re: Help and suggestions for lithium or lead

Postby nealnlx » 06 Dec 2015, 01:54

That is the page i saw and you showed me and yes it looks nice. But after i read more about the cellpro 8 charger i see that basicly we need to do a similar wiring to our pack like if it was to have a BMS, but only stopt there because the balancing itself is made by the charger which has its own balance port/connectors.
After that i got i bit confused to see that still would nee to connetc two cables to charge when you said that only use one.
Now, from what i can see, what you did on that cable is kind of bound both toguether on the same connentor making it a 2in1 am i right?
That is still why i would like to see pics of it connecting the battery to the charger in that easy simple way.
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 06 Dec 2015, 02:00

The charger has 2 large POWER 4mm connectors. You plug those in. Neg, and Pos.
It also has a small 9 pin balance connector. You connect that too.
And the cable I made has that as well. Look at the picture of the cable. Its just sort of self explanatory...

Image

http://www.wheelchairdriver.com/BM3-con ... le-40A.jpg

Its super simple! Once connected to the charger you never need remove it anyway.

That just leaves that single D connector you connect to the chair to charge it. Look closely. It has 3 heavy connectors (2 used), and 9 thin balance wires all in one easy to connect plug! You don't need any of those boards or wires in front of my chargers. They are for different things.
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Re: Help and suggestions for lithium or lead

Postby nealnlx » 06 Dec 2015, 02:32

See? Nothing that i simple litle pic would not show better...
This image showing the entire cable it is self explanitory yes.
Since i only need to charge one battery i connect the balance cable to its corresponding port and then the power neg and pos ones to its ports.
Those MPA board are for you to charge multiple matteries. Right?
Yes, that cable looks really nice and simple to use.

Now i just need to know and learn more about the charging parameters and setups issues.
I know that charging cells and 3.55v is better so they dont go crazy, but can i still charge them fast like at 20a?

With this comes some new questions like how do i know if all cells are equaly well ballanced and what to do if one or more are lowerr than others?
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 06 Dec 2015, 02:54

Charge fast? Yes. Its best not to do so for longevity. But if I am in a hurry I charge at 40A. Otherwise I charge at 15Amps on a 72Ah pack, 20A on a 100Ah pack etc.
If you choose say 3.550 Volt, and set charger for 40A the charger will just throttle back and reduce power as the highest cell reaches 3.550V. The balance circuits will then drag the highest cell down as the charge continues until all read exactly the same.

There's 2 batteries being charged here. A 6 cell, and a 7 cell one. (it actually makes up my 13S BM3 battery. Its on charge now so I just did a screen shot).

The 7 cell one is almost topped up, and balanced almost, will remain at 3.550V (+/- 0.003V) until current falls to my chosen 50mA level, or CV and balanced, plus 8 hours whichever occurs sooner. Note BYPASS figures. That shows the percentage of the remaining 2.xA CV current being removed on a cell by cell basis. That will read all zeros once fully balanced.
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 06 Dec 2015, 03:16

Those MPA board are for you to charge multiple matteries. Right?


Yes I have 2 mower batteries, 6 quadcopter batteries, 2 drill, 4 Nikon camera, tens of AA, and AAA cells, some 9v rechargeable, 3 lead powered chairs, torches, 3 RC transmitters with 3 types of battery, 2 huge lithium packs, 45 and 24 volts, my van periodically FROM my chair as a power source, kitchen tools, my new scales for weighing seated wheelchair users, flashgun, multimeters, door alarm, many model aircraft and FPV monitors, and my ex gf lithium ion bicycle pack periodically when its on board BMS screws it up.

And I can charge any battery. And discharge any battery. Any chemistry, any size, and any variation. Anything with any cell count up to 8S per charger. And you can link them up to do 16 cell batteries or as many as you want. And choose my own voltages, Amps, termination method, level etc. And graph the discharge and measure the Ah and Watt hour removed and replaced. And do all of that from a power supply or battery, from 10V to 32V meaning I can go outside and charge my van from my chair at 40Amps... Or the other way around.

Its also as much power as its possible to get out of the wall if you have a pair. Each can do 1344 watts. Or 2688 watts OUT and about 3000 watts input. Meaning that's your 13A wall limit all used up! At least in theory. And so you can charge a full sized EV if you want.

Why do hobbyists need all this power? Because we use small batteries like 5Ah. But these can be up to 90 to 130C meaning they can give 5A out x 130 times! What's more many are 6 or 8C charge capable. So you would charge a tiny 5Ah battery used in a small model helicopter say, at 8C x 5A or 40A... If you charged 4 in parallel they COULD be charged at 160Amps if your wall wiring could stand the pace!

Sort of puts mobility chargers to shame really! They don't even charge the one type of battery they are meant for well. They are 5x more feeble on power. They can only charge at 1 fixed rate. There's no adjustment possible. There's no way to charge different chemistries, they cant cell balance or do lithium, measure anything, don't connect or cannot be controlled by PC, no discharge capability, no graphing, and they cost about the same. And they are not even very reliable.
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Re: Help and suggestions for lithium or lead

Postby expresso » 13 Dec 2015, 03:35

Burgerman wrote:Image

ONE meter long. SAFETY shielded connectors at the charger end so no shorts. 40A fuse inside the sleeving.



this is a nice Wire - i would have to make it just like that - problem is - if i can - - this has to be made - nothing can be purchased ready made this way ?
Quickie P222se - 60Ah ADD ON
Quickie S646se - 150Ah LifePo4
Quickie P220 - Indoor Chair
Bounder Plus - 180Ah LifePo4
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Re: Help and suggestions for lithium or lead

Postby Burgerman » 13 Dec 2015, 09:23

No. Theres a hundred ways you can make a cable or cables. This was the neatest and most reliable way I could think to do it. Took me weeks to order and get all the parts together from different sources and about 4 hours to make 2 matching ones that will do two 24v or 8s or less batteries.
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