PINNED - 230Ah (245Ah certified) A grade cells Amy, Docan

[Burgerman]

With R-Net, its possible in programming to set the lowest voltage before the chair stops rolling under load in use.
If you set this to 22V its max setting then it will stop at 2.75V per cell averaged across all 8 cells. At this voltage on a decent quality balanced pack the lowest cell should be well above the dangerous level. So this will effectively prevent you over discharging the pack and causing damage. It will also prevent you using the last few 5Ah? approx. But ask yourself, is that really an issue with a 244Ah (measured) capacity?

I wont be setting that as I may one day prefer to kill the pack in order to reach home. But thats me.

[slomobile]

With R-Net, its possible in programming to set the lowest voltage before the chair stops rolling under load in use.
If you set this to 22V its max setting then it will stop at 2.75V per cell averaged across all 8 cells. At this voltage on a decent quality balanced pack the lowest cell should be well above the dangerous level. So this will effectively prevent you over discharging the pack and causing damage. It will also prevent you using the last few 5Ah? approx. But ask yourself, is that really an issue with a 244Ah (measured) capacity?

I wont be setting that as I may one day prefer to kill the pack in order to reach home. But thats me.

WHAT! Thats an undervolt cutout! I'm not going to rib you too hard for suggesting it because we know your position on those and it does make complete sense if the operator cannot leave a dead chair. But since you suggest it as an option for others, for someone able to get out of the chair in an emergency, would you approve of a BMS that could send alerts before reaching the cutout? In case they happen to be nearing cutout but haven't been monitoring battery level.
Any shift on the "no BMS ever" position? Or maybe you can recommend one of those cheap battery monitors that give an audible warning at a configurable SOC.

What does the calibration factor in the Rnet screen do?

[Burgerman]

It messes with its complex peukert, voltage drop, lead battery guesswork calculations to display some nonsense on the screen...

Exactly what we cant know.

As for battery low voltage cut off that is all completely irrelivant! The whole point in fitting a battery that is huge means that theres no way on earth I can run it down to a dangerous point for the cells in a day. Probably several days. There isnt enough hours in a day, and I would end up with a pressure sore if I tried to do it on purpose...

The other reasons for fitting adequate capacity is that the bigger the battery the easier life it gets in regards its current draw per Ah. (low C rate draw = long life!). And its average daily discharge level will be very low. Again the lower the average daily discharge level, the longer it lasts... And IF I decide in winter to let it go a week before charging (which I would only do around my home, then the number of charge cycles is 7x fewer so while that is a higher discharge level, its less often. Again long service life.

If you do want to run it low, and having done this for years, I know approx how far to go before even looking, then you can use the simple cell log that I have here. But if you watch the normal battery guage, and you lose a light, then I charge it within a day or so...

BIG battery, not a problem!

IF you worry about this (and after a few months of use you wont) use a cell log like this, check it every 5 miles or so after you lose a couple of lights:

I used to, and still will keep in my wallet (its small) on a new pack that I a testing or if I am going a long way after a few days not charged. I no longer bother as I can corrolate the distance/battery lights on my chairs joystick, with state of charge as long as its in the top 2/3rds. You just get used to endless rolling!
Mines a bit scratched up and dull... From being carried in my wallet. Still works fine. Amazon cheap.

[Burgerman]

As for BMS I think they are a worse way to charge, and all the other functions they exist for are not needed if the battery is correctly sized. I think they are a fire hazard too. Plus they are huge if big enough to do the job. So I see them as a waste of space, fire hazard. That space is limited. Better used for Ah...

IF theres no option, say a larger cell count than makes sense to charge like a hobby charger can of if its intermittent power and irregular unknown charge times and rates, then a BMS may be sensible. So say solar or high voltage packs. Because other options dont exist.

My auto mower for e.g. It charged itself when needed. It needed a BMS. Which died and took its battery with it TWICE! I might add... In 4 years.

The other advantage of external balancing and charging via a hobby charger is that you can set a proper accurate cell balance point. No on off nonsense where it repeaedly tries to over then under volt everything and the charger knows when to end.

[White Lightnin']

I received my cells from Ezeal in Houston. They are a bit wavy on the sides, but not but bumpy. Are they ok to keep? Also when I ordered my multimeter I didn't know I needed to put the batteries under load and put an an AC current through them in order to test impedance. Can anyone tell me what values I need to use in order not to destroy the batteries and what I can use to provide the needed values. I'm still married after what I've spent so far, I hate to push things further by buying an impedance meter. What brand impedance meter is best?

[White Lightnin']

How do I get the date codes from the batteries? My phone doesn't recognize the UID code on the batteries.

[Burgerman]

Date codes, actual factory production specs, complete with impedance capacity etc were supplied by amy/docan via email. I just gave her the 8 cells codes (the letters/numbers) etched around the bar codes. You need good eyes.

To measure impedance you need an impedance meter about £24 on aliexpless see previous pages on this thread.

As long as zero bulges, and all lookin pristine and brand new they will be good.
You dont need a imedance meter to do 1 pack. Just get the spec sheets for your individual numbered cells. As I did.
THESE numbers! https://www.wheelchairdriver.com/board/ ... &mode=view

Everything I measured, capacity, impedance, just matched the manufacturers test data within 1 percent. 244Ah, as per spec sheet. Same impedance as shown. Flickered between 21 and 0.22mO every cell. Super low!

Save your money and keep your wife! As long as they look NEW.

[White Lightnin']

Thank you! We will celebrate the grim tragedy that happened 24 years ago (our marriage) this year. After this long I'd dearly miss her.

[shirley_hkg]

White Lightnin'

Check your mailbox.

[White Lightnin']

I received eight cells from Ezeal last Tuesday and all look new. Seven cells measured 3.293 volts and one measured 3.292 volts. I measured the values with a Fluke 115 multimeter which arrived at my house today. I can now take the receipt for the multimeter back to Home Depot for a partial refund of the purchase price because it went on sale the week after I purchased it last week. So if any are interested there is currently a sale. I've ordered charging equipment that should arrive in a few weeks. I'll get started charging the batteries when I get the charger.

[shirley_hkg]

You may start assemble your pack. Wrap insulation, make inter connects …

[White Lightnin']

Thank you for reminding me I have a great deal of work to do. I also need to buy materials and tools yet.

[White Lightnin']

Can someone tell me what they are using for a circuit breaker in this battery circuit please? If something goes wrong I may not be able to get out of this chair fast enough to keep from getting burnt.

[emilevirus]

Can someone tell me what they are using for a circuit breaker in this battery circuit please? If something goes wrong I may not be able to get out of this chair fast enough to keep from getting burnt.

No, I tried that and it creates too much resistance. Voltage fluctuates and charger isn't happy. I changed to a fuse. All good now.

[LROBBINS]

Automotive midi fuses are convenient and 150A should give decent protection. At Burgerman's suggestion I put mine in a removable link so that if I want to be sure that the power's off when working on the chair I can easily pull the fuse. I have it inside an Anderson SB50 (bolted into the contact pins) that plugs into another SB50 in the connection between the 2 groups of 4 cells and bolted on the outside so it's easy to remove or replace the fused link.

[Burgerman]

Even with lead, circut brakers are at best problematic.
Since it just a set of contacts lihtly touching inside. Attached to a bit of a "bimetalic" strip of metal. They have a high resistance on purpose! As they are meant to warm up under load and the bimetalic strip bends because of this. Breaking the contact.

So if you take 3 identical ones, and measure them they are all different resistances. Because "points" are very bad electrical joints.
Worse, this changes drasically over time. As they warm up, cool down, and heat causes oxidation. So now we also have some that will trip REALLY early when hot. And some that will take the rated current... And you cant tell which.

And this resistance means that when charging, with a cell balancing BMS or hobby charger the cells appear unbalanced as the resistance between the two battery halves shows the difference in voltage under charge load. So I would never put one on a lithium battery (or lead).

A fuse is a far better bet. I am an animal and with endless wheelies, which take the MAX possible out of the system, and 120A cotrollers with everything set at 100 percent, i never got a 125A fuse to fail. And so belt and braces, I use 150A ones now.

Thats small enough that any shorts will cause the fuse to blow. before the cables will melt. And big enouh that no user will ever pop one through use!

Having one in an easy swap anderson connector as a simple loop just means that you can chop off all power in the event you wish to do so.

[shirley_hkg]

No, I tried that and it creates too much resistance. Voltage fluctuates and charger isn't happy. I changed to a fuse. All good now.

That's really is, if put it between cells.

Therefore, you can only put it at either ends, 0V / 24V, and the balance wires spot on the cell terminal.


If using JK BMS, there is wire resistances parameter that can be set to eliminate such adverse effect pretty acceptably.

[White Lightnin']

Does anyone know where I can buy some connectors for making the battery pack? For four batteries I only received two connectors.

[Burgerman]

Do we mean cells? A battery is a bunch of cells to form a battery.
Why 4 cells? That makes a 12V battery.
What size are these connectors/cells?
Where did you get them, were they sent short?
Personally I would use them only if they are flexible in all directions. Or would use simple ring terminals and silicone cable.

[White Lightnin']

I received two boxes of four cells each. The eight cells in series will give me twenty four volts or thereabouts. The connectors look like flat bar stock roughly 1/8 inch by 5/8 inch by 2 inches with a hole drilled near each end to fit over the battery terminal. I'm afraid to connect the cells together with these because they will break the terminals loose inside the cells. For some reason I only received two connectors in one of the boxes. Should I be using connectors on the end of wires to connect the terminals of the cells to keep from breaking the terminals? I tried to buy some ten mm2 wire on amazon, but I can't get it shipped to me without an English address to ship it to. I've been planning to use 6 gauge wire instead.

[White Lightnin']

I can bend the connectors with my fingers, but not easily. The cells are Amy, Docan cells.

[Burgerman]

Why not ask them to send the ones that you need?

Personally I would use ring terminals and wire. But either will work.

[shirley_hkg]

8awg is best.
Shortest pre-made one is 4", and it's $1 here.

You should have ordered parts you need , so I could ship with your chargers.

There are quite some parts you gonna need to set the PL8 system up, charge cables etc.

[White Lightnin']

I wish dropping my money on the floor would double it as quickly as it did those connectors. I have no idea why my fingers couldn't do it. I even tried more than once. Shirley, I'm glad you told me 8 awg is good enough, it sells for less money. I don't want to ask you for more favors than you've already done for me other than knowledge. I need that. BM has told me of some other things I need. On top of that I know I need more ring connectors and wire, some Anderson connectors and probably other things I haven't thought of or don't know about. What have I missed? This is another one of those projects I jumped into and had to figure out along the way. I get there after awhile. At least with this project I have help. When I started making my legs there was very little help. I had to stumble into an orthopedic shoe maker's shop whose sign I saw while riding my by bicycle before I got much help in getting extra materials to finish. A skiing buddy hooked me up with a prosthetist who looked at what I was doing and kind of laughed at it. I didn't care at least I could walk on it. As the years went by he told me that he needed to hand it to me that he had laughed at me, but what I had done was pretty much the standard for the industry at that point in time. I had spent twelve years trying to get the prosthetic industry to make a leg for me that worked before I did it myself. So much for deviation from working on wheelchair battery charging. If anyone can think of anything I missed, my eyes and ears are open. Getting information from others can be so much faster than having to make all the mistakes myself. I've had to complete projects both ways.

[shirley_hkg]

How would you like your charge cables ?

Your stuffs are on the way already.

[Burgerman]

I wish dropping my money on the floor would double it as quickly as it did those connectors. I have no idea why my fingers couldn't do it. I even tried more than once. Shirley, I'm glad you told me 8 awg is good enough, it sells for less money. I don't want to ask you for more favors than you've already done for me other than knowledge. I need that. BM has told me of some other things I need. On top of that I know I need more ring connectors and wire, some Anderson connectors and probably other things I haven't thought of or don't know about. What have I missed? This is another one of those projects I jumped into and had to figure out along the way. I get there after awhile. At least with this project I have help. When I started making my legs there was very little help. I had to stumble into an orthopedic shoe maker's shop whose sign I saw while riding my by bicycle before I got much help in getting extra materials to finish. A skiing buddy hooked me up with a prosthetist who looked at what I was doing and kind of laughed at it. I didn't care at least I could walk on it. As the years went by he told me that he needed to hand it to me that he had laughed at me, but what I had done was pretty much the standard for the industry at that point in time. I had spent twelve years trying to get the prosthetic industry to make a leg for me that worked before I did it myself. So much for deviation from working on wheelchair battery charging. If anyone can think of anything I missed, my eyes and ears are open. Getting information from others can be so much faster than having to make all the mistakes myself. I've had to complete projects both ways.

Thers many threads on this stuff. I suggest you read a lot. But forget about crimping things, and learn to or find someone that can.
You need cable, ring terinals, connectors, a 150A midi fuse and some of the heat shrink, charge cables, a hobby charger and power supply like the ZXD, or a ZXD and a BMS if you choose to do it that way...

All of this stuff apart from the charger and ZXD supply is cheap. I have loads of connectors, andersons, ring terminals, heat shrink etc on the shelf. Gets used all the time I just top it up as needed.

Duct tape, some thin plastic sheet, or fish paper, etc also...

[White Lightnin']

Shirley, I appreciate very much the offer you are making, but I was leaning toward what BM is saying. I am also waiting to see if your package is allowed in country. As you undoubtably know, a little of everything is being said. I want to wait and see what the truth du jour is at the time it arrives. I don't want to try my luck any more than I need to. There will be times in the future where I will have no alternative other than your help. I will truly appreciate it at that time. I will learn a lot the way I'm doing it now. At seventy years old I never thought the country would allow so many people to become as desperate as they are. It's a dangerous situation. From what I'm hearing, I'm waiting to find out just how lucky I am right now.

[shirley_hkg]

How would you like your charge cables ?

I meant we are happy to share what we've been doing, what connectors , etc .

[Burgerman]

From what I'm hearing, I'm waiting to find out just how lucky I am right now.

Elaborate!

[White Lightnin']

I received the box I was waiting for which means I’m lucky because the shipment wasn’t stopped just because it was from China. Lot of things going on in the US right now. I’m trying to figure out right now if everything Shirley and I agreed upon was shipped. He made a list of what we agreed upon was ordered and I paid for it. I only received one plastic bag of wires I’m thinking there should be two. I sent Shirley a note and I’m waiting to see what he says.