PINNED - Lithium battery conversion/info

[expresso]

Ok but in the link above the one you found 2k PSU - thats just a PSU - needs to be connected to the Charger ?

i can ask Shirley if he can get one already modified done with nothing for me to when i get it other than just use it -

about the link you found - - that looks simple nothing to do other than turn it on - and adjust the volts amps etc,

i really dont have any lead chairs to charge - other than my only indoor chair -

the above link - if unable to get a Shirley model - which one would be the best pick in terms of Volts - Amps - there are many to choose from

27v - 74A ? or one of the others - in this example - would it mean for me on 110V it would max out about 35A ?

[expresso]

i never do much stuff like you guys - projects etc, - since i started this with lithium - thats all i used them for - but never know - when it can be useful for other stuff.

i will ask Shirley what he can do -

thanks

[Burgerman]

Heres 1 example.

Heres my attempt at nickel plating. My first attempt and TOTAL settings guess!
2.7V actually 3.0v but limited by the Amps set to 0.3A. Turns out this is too high, it plated in seconds.

I tried plating a coin and ignoring all the acid bath cleaners, and distilled deionised water baths etc.
I simply cleaned it with washing up soap, as used for dishes, with scotchgbright cloth. For all of 15 secs...
Then straight in the plating bath, after a rinse under the tap. And no gloves, handled by fingers etc. Everything wrong!

So power on for 30 seconds, and at 30C (too cold by all accounts, needs to be 50C? But I have no patience!).

Its super shiny, and totally covered, and its so easy. I dont know what the fuss is about.
Now all my money will be worth more and shinier than other normal peoples money...

FIRST EVER ATTEMPT, 1 WEEK BACK.
Nickel plated copper coin.

[Burgerman]

Obviously, the plating is not intended for my money! That was a test. But to nickel plate any copper, brass or steel parts. So that they have a shiny chrome like plating that prevents oxydation and looks pretty. Every washer, bolt and nut, or part for hobby stuff. For instance I have a new chinese hit and miss engine on the way. The brass parts will go brown and oxydise. The steel crankshaft will rust. So I will bright nickel plate all those parts.

Theres many coatings.
You can cote in copper easily. But it goes blue and is soon covered in a mass of blue powder. Copper oxide..
You can cote in zinc or a zinc yellow passivate. But it soon goes black and dull.
You can coat in silver or gold. But its soft, and wears off easily. And its $$$$$$$ to do.
You can cote in cadnium. But its not bright, and it dulls fast.
You can cote in chrome. Many chemicals, and its all harmful acids and many baths. And its not easy to do at home.

OR you can plate it in NICKEL which stays silver/grey and looks similar to chrome but is less blue.
You can also do BRIGHT NICKEL by adding a few extra chemicals that make it look very shiny, or by buying the whole green electrolyte in a bottle ready to use. Its harder wearing than zinc, etc and is good for electrical parts and so on. The other advantage is that its stupidly easy!

[Gnomatic]

So what about nickel plating bare copper bus bars that come with various LiFePO4 cells? Will that "fix" them to your liking?

[Burgerman]

The issue with those is that the cells move and the bus bars are rigid. And that they do not sit flat on the terminals so they likely only touch in a couple of places. Because all those battery termonals are not in the exact same plane. So probably helps, but I still dont like solid bus bars. I like a bit of cable between them!

Visualise 2 cans of paint with lids on. And sit them on some not quite level waste ground Now sit a wooden plank on top. It only touches on a few points. But two short bits of plank sit in perfect contact with the tops of the cans. But now they dont line up with each other perfectly in all 3 axis.. So you need a flexible bit in the centre.

Theres a thread here somewhere where shirley built a battery with heavy solid copper bus bars. He swapped to terminals and wires when he couldnt get neat graphs and sensible balancing. It was all over the place. Losing the copper bus bars fixed it totally. He may be delayed right now in the rioting in HK...

[expresso]

But there is i believe Snaker is using them and dosnt have those issues - i think it can vary with the buss bars used - etc,

i got them with my Cells - i am going to try to use them just to connect two cells together making one 200ah Cell 3.2v - then use cables to connect the 8 Cells - i will be using lock nuts on top and glue in the grub screws first -

unless i see if they are not making contact good enough - then i would consider making the cables instead but using the small buss bars i received would make it neater and easier -

[Scooterman]

The issue with those is that the cells move and the bus bars are rigid. And that they do not sit flat on the terminals so they likely only touch in a couple of places. Because all those battery termonals are not in the exact same plane. So probably helps, but I still dont like solid bus bars. I like a bit of cable between them!

Visualise 2 cans of paint with lids on. And sit them on some not quite level waste ground Now sit a wooden plank on top. It only touches on a few points. But two short bits of plank sit in perfect contact with the tops of the cans. But now they dont line up with each other perfectly in all 3 axis.. So you need a flexible bit in the centre.

Theres a thread here somewhere where shirley built a battery with heavy solid copper bus bars. He swapped to terminals and wires when he couldnt get neat graphs and sensible balancing. It was all over the place. Losing the copper bus bars fixed it totally. He may be delayed right now in the rioting in HK...

They're probably okay for solar banks that don't move. Especially if strips are laminated and have a hump in the middle like a caterpillar.

But as you say BM, solid bus bars not good for mob equipment with poor suspension

[Scooterman]

Heres 1 example.

Heres my attempt at nickel plating. My first attempt and TOTAL settings guess!
2.7V actually 3.0v but limited by the Amps set to 0.3A. Turns out this is too high, it plated in seconds.

I tried plating a coin and ignoring all the acid bath cleaners, and distilled deionised water baths etc.
I simply cleaned it with washing up soap, as used for dishes, with scotchgbright cloth. For all of 15 secs...
Then straight in the plating bath, after a rinse under the tap. And no gloves, handled by fingers etc. Everything wrong!

So power on for 30 seconds, and at 30C (too cold by all accounts, needs to be 50C? But I have no patience!).

Its super shiny, and totally covered, and its so easy. I dont know what the fuss is about.
Now all my money will be worth more and shinier than other normal peoples money...

FIRST EVER ATTEMPT, 1 WEEK BACK.
Nickel plated copper coin.

When I was younger and had dreams of being a rock star, TWANG! TWANG! I wanted a chrome scratchplate as mine was plastic. I cut a shape out on cardboard, took it down industrial estate, and they nickel plated one for me

[Burgerman]

Nickel plated cardboard?

[Scooterman]

Nickel plated cardboard?

Not just any old cardboard, corrugated cardboard

I think it was brass or something similar

[Scooterman]

Nickel plated cardboard?

Not just any old cardboard, corrugated cardboard

I think it was brass or something similar. What do you think BM?

[Burgerman]

If they nickel plated it it could be steel, brass, copper or stainless, etc. But, there are ways to nickel plate plastics, or any material. Even cardboard if you really wanted.

[Scooterman]

If they nickel plated it it could be steel, brass, copper or stainless, etc. But, there are ways to nickel plate plastics, or any material. Even cardboard if you really wanted.

Ah! Is that what them chrome like plastics are coated with? Often cheap stuff from China which looks to be chrome plated metal, turns out to be black plastic with a chrome-like finish.

[Burgerman]

mORE LIKELY THATS CHROME ON TOP OF NICKEL OR COPPER.

[Burgerman]

You spray the plastic part with a metalised paint first. So it conducts. Then copper or nickel. Then chrome or gold etc.

[Burgerman]

Dont like 2 tone pound coins. Mine are all now nickel...

[Burgerman]

I am not defacing it, I am improving it!

Yes in theory. In practice it will never happen.

[Scooterman]

People used to make finger rings from an old (or new) coin. Some kid at school had a ring made from a pound coin.

[shirley_hkg]

Clearly that device is unsuitable, but I do wish someone could find a cell balancing board that would: (1) start balance only near or at the end of CV, (2) dissipate or exchange enough current to balance reasonably quickly (would 3A be enough?). It should be rugged enough to be mounted in the chair and not need any user attention (after initial programming). As it would only be doing something when connected to a charger, it can be a passive balancer that just dissipates energy from the highest cell - the mains watt-hours wasted would be tiny in any case.

There are lots of cell monitor/balancer boards out there that use an Analog Devices or TI chip that can do the above, but that can pass only mA of current. One of those chips plus 8 MOSFETs and 8 resistors would seem to be all that we really need, but I'm not up to designing and testing same (at least not with too many other projects underway). So, with all the "stuff" that's out there, isn't someone making a simple board like this?

The only thing that has kept me from going LiFePO4 has been the fact that we can't have a setup that only I can hook up for charging. It's hard enough to get people to remember to push the rocker switch on her dumb charger (and even I have forgotten once in a while), no less follow a sequence of who connects to whom followed by one or more button presses. It's not just that I'd rather not have yet another daily chore. Perhaps if I were 40 or 50 y.o. that would be OK, but I've already got 73 behind me and Rachi is going to still need her chair well after I'm gone.

You will get one , very soon.

This new breed of BMS I mentioned earilier in page 162 , is available now. I need to change the power module to a 18Vdc---36Vdc , 5V / 5A one for our application.

Which model will fit ?

[LROBBINS]

Shirley,

Am I correct in thinking that the power module you refer to is just for the "balance at end of charge" function and that I could use the ZXD as the charging source?

Do you have any specs for what you've found?

Maybe it's time for me to order some cells as the Odyssey's in Rachi's chair are getting "tired".

Ciao,
Lenny

[shirley_hkg]

Lenny , it's a BMS for dumb chargers .
It runs on 5V from your pack, via an isolated step-down module .
It can do 1S --- 24S.
It doesn't control the discharge, so no unexpected power cut . It has 3 alarms to warn you low cell volts . You can set it to disconnect output after the third alarm sounded.
It has bluetooth communication with cellphone , displaying cell voltages and beep.
It doesn't drain the highest cells during balance .
It has 4 charge states (can be disabled seperately) :
1, bulk charge ,
2, absorption with full throttle . On /off , like usual , to let the highest cell is nearly full till it can't accept more.
3, absorption further for the highest cell "via controlling the charge rate" , so no more ON /OFF.
4, it starts to scan all cells , and charge the LOWEST CELL INDIVIDUALLY @2A max, one at a time. You program it when to stop, say within certain voltage drop.
It can take 50A charging .
It costs ≤ £30, and measures 100 X 100 X 20.

I need to change the Lucent LW010A981 to a 24V model . Any recommendation ?

[Burgerman]

3, absorption further for the highest cell "via controlling the charge rate" , so no more ON /OFF.

HOW? Most chargers will not respond well to being controlled and will try to correct the voltage from increasing as the load falls, by reducing current, and then think its time to switch to float... Or end the charge at around 1A. So I cant see how this is possible. Charge will end when the "charge is controlled" at the BMS before the cells get balanced. I can see how it could work with a power supply, but not a generic charger. Because it will turn off!

4, it starts to scan all cells , and charge the LOWEST CELL INDIVIDUALLY @2A max, one at a time. You program it when to stop, say within certain voltage drop.

By using battery power or charger power?
Because without the charger, which will turn off, you can only balance the pack below 3.6V. And as soon as it falls below 3.5V balance doesent work. So pack will stay unbalanced... You cant balance a LiFePO4 using its own power. That could work on lithium ion, or on lipo. Not on lifepo4. Because 3.45 to 3.6v is under 1 percent of capacity. So I remain unconvinced!

[shirley_hkg]

Good questions. I will raise them there . May be a power supply is more appropriate .

[Burgerman]

I suspect the only way. But then, what determines end of charge? Ideally it should be: Once all cells are balanced to cery low current of say 3mA, around 3.55 to 3.6V, and only when CV current is at approx 300thC. What determines end point?

[expresso]

BM - how do these graphs look to you - ? this is the 105ah pack in my 646 - its first and only full pack i done so far going on 4 years in use

does it look Ok still ? i notice for the first 10 min the line is a bit off - then levels out - these are headways 15ah cells

[Burgerman]

As good as new. 4 years? Not bad. I have some double that. Still good. It might outlive the chair.

[expresso]

thanks - since this was my very first pack ever - besides the very first 36ah to test the waters first - then went right to this 105ah

i ask because i know better now and i know i could have used and should have - thicker cables - and tinned lugs etc, so if i ever have to redo this pack - it will get a make over.

cant complain and impressed that i was able to do it - with help from here of course -

[terry2]

I just went to charge my pack up and saw that the internal resistance on cell 3 is sky high

Going to check the connections before carrying on charging.
I hope the pack is not fucked!

[Burgerman]

It will be your connections, or if you crimp stuff - that.

Does it charge and drive normally?
If so dont worry much. Its VERY hard to get accurate resistance readings on susch low values.