PINNED - Lithium battery conversion/info

[shirley_hkg]

BM . Several of us have been in the endless wait for PL8, including myself. . Any alternative or temporary measure will be a great help.

Let's go practical.

[terry2]

You don't need another JST on chair side.

Need only one to feed PL8, and you have it already.

I should of said that I want a female JST-PA to male XH 2.54 so I can use my cell monitor when out on a long drive..
My monitor is a ISDT BatteryGo

[terry2]

BM . Several of us have been in the endless wait for PL8, including myself. . Any alternative or temporary measure will be a great help.

Let's go practical.

I agree.

[Burgerman]

There may well be. But in the past I tested dozens of brand name chargers. And most dont allow us to correctly charge lead or lithium ion phoshate properly or in some cases at all.

And almost non have PC control or graphing etc. Which helps us find a multitude of issues that we wouldnt ever find any other way. Like expressos addon pack in a different thread.

But to know whould require a bunch of testing. And buying expesive chargers.

Obviously we are looking for high power. 8S or better. Proper programability. But the real problem is in the phione books of code that we cant see. We cannot know what will cause problems without testing. The PL8 for e.g took 2 years of eMails and testing and several new firwares before I got them to sort al the issues out that affected us. And so that it works reliably on lithium, and was ABLE to charge lead at all.

[Burgerman]

I agree.

Of course you do. Ignorance is bliss! Thats why homer simpson hammered that pencil back up his nose. He was happier being stupid. Hated the world when he understood it. Most of the world are innorant and happy. And poor and have lots of problems in life that "are not their fault"... Its a matter of luck to them.

I suggest a BMS and a dumb charger. Its cheap, cheerful, and its simple. Just what you like. Of course you will have a potential mass of problem esp over tme. No way to see it starting to happen. But if you are not interested in learning some stuff, then thats the best way for you. Thats what 3/4 of the planet do.
But dont say you were never warned!

Theres thousands of posts on lithium battery problems on all the EV forums! Almost every one (inc fires), destroyed batteries, short range, charge and cutting out issues are always BMS related in the end. It works sometimes, for some people some of the time. If you choose well, have a big enough pack, and build it CAREFULLY. As for al the rest, theres 100k pages of "issues" to read! Thats not reliable enough for me.

[terry2]

I agree.

Of course you do. Ignorance is bliss! Thats why homer simpson hammered that pencil back up his nose. He was happier being stupid. Hated the world when he understood it. Most of the world are innorant and happy. And poor and have lots of problems in life that "are not their fault"... Its a matter of luck to them.

I suggest a BMS and a dumb charger. Its cheap, cheerful, and its simple. Just what you like. Of course you will have a potential mass of problem esp over tme. No way to see it starting to happen. But if you are not interested in learning some stuff, then thats the best way for you. Thats what 3/4 of the planet do.
But dont say you were never warned!

Theres thousands of posts on lithium battery problems on all the EV forums! Almost every one (inc fires), destroyed batteries, short range, charge and cutting out issues are always BMS related in the end. It works sometimes, for some people some of the time. If you choose well, have a big enough pack, and build it CAREFULLY. As for al the rest, theres 100k pages of "issues" to read! Thats not reliable enough for me.

Shirley ask you something and you go off in to the distance leaving no answer other then another tangent.
And calling people stupid for no reason.

[Burgerman]

No. I answered him clearly and completely. The fact that YOU dont understand the answer is not me going off at a tangent.

[ICEUK]

PL8's keep coming up on ebay, I have brought 3 so far, all work well. You can get one for £150 mark, I use the 24volt 50 amp PSU fro lm Revoelectix. http://www.store.revolectrix.com/Produc ... er-Station

[Scratchy101]

Would this be a suitable charger for a 24V 8s eve-LF105 LiFePO4 battery pack?
https://www.amainhobbies.com/hyperion-eos-0840i-multichemistry-dc-battery-charger-8s-40a-1000w-hp-eos0840i/p520593

Features:
“EOS PC Tool” Charger Control Software: The “EOS PC Tool” software gives you unparalleled ability to operate the charger through your computer. You can monitor pack voltage, cell voltage and other data during charging. View your charge date in real-time graphs. You can initiate, control charging, and update firmware from the “EOS PC Tool” too.

“EOS Connect WiFi Module”: Charge using your Android or iOS Smartphone. By connecting the “EOS Connect WiFi Module” to your EOS 0840i you can control charge rates, settings, and watch real-time data all from the convenience of your Android or iOS smartphone. (HP-EOSWIFIMOD sold separately)

Terminal Voltage Control (TVC): Terminal Voltage Control is the end-voltage of the pack when finished charging, users can change voltage settings of packs during charging. Recommended for expert use only.
Battery Internal Resistance Meter: The user may check each cell's individual internal resistance. This reading is in milli-ohm units.

LiPo Battery Meter: This useful feature give the user the ability to analyze the batteries total voltage and individual cells voltage

[Burgerman]

I know a little about hyperion chargers. I helped the director of the company sort oyt the lead charge algo, beta tasted maybe 30 firmwares, and got involved in the BT thing...

Things to beware of.
1. I have a pile of 14S dead hyperions. So buy a few.
2. They can charge lead properly, and also Lithium Polymer.
3. They didnt used to have any way to set a termination current. And so you cannot choose when it ends charge. So it either ends and then continues at CV indefinitely. So not great for LiFePO4 packs. Or it can be set to end but it does that as a percentage of charge current. So its wrong.. Esp in big packs.
4. It used to be limited to a lesser capacity that the bateeries we use. So it ends before its charged depending on pack size - current firmware? No idea. It also used to have a too small 300mA balance current. And it dod it only at CV. But I think they now start balancing earlier and thats no good for LiFePO4 either. All depending on firmware. So the only way to find out is to buy, test properly. And I dont need to do that yet!

Lipo battery meters dont work on LiFePO4 chemistry.

[Scratchy101]

I'm in the process of gather info to assist in the custom build of an Invacare Arrow.
I've been slogging through several dozen pages of this thread, including pages of off-topic subjects .

I'm looking for EVE-LF105 LiFePo4 batteries to purchase, as well as the back-ordered PL8.
I am considering using these fiberglass and silicone baking sheets as battery separators:
https://www.amazon.ca/gp/product/B07FS4 ... GVIC&psc=1
Cut in half, they should fit nicely between these batteries.

[Burgerman]

Very short wheelbase. Needs the drive wheels further back, and the seat and footrest further back too. Or it will rock over uneven footpaths etc and feel unstable I think.

Also I would keep the wood.

[shirley_hkg]

No problem. Same chair I use.

[daunjan]

I'm in the process of gather info to assist in the custom build of an Invacare Arrow.
I've been slogging through several dozen pages of this thread, including pages of off-topic subjects .

I'm looking for EVE-LF105 LiFePo4 batteries to purchase, as well as the back-ordered PL8.
I am considering using these fiberglass and silicone baking sheets as battery separators:
https://www.amazon.ca/gp/product/B07FS4 ... GVIC&psc=1
Cut in half, they should fit nicely between these batteries.

Check here for the pl8 are available, I got one coming while revolectrix sorts,my backorder... http://www.wheelchairdriver.com/board/viewtopic.php?f=2&t=9880

For the cables.. . from progressiverc
>FMA USB Adapter to pc.. instock but low.. .
https://www.progressiverc.com/fma-usb-fuim3.html
>PowerLab 6 3' Balance Extension Cable... max order 4x
https://www.progressiverc.com/fma-powerlab-8-3-balance-extension-cable.html

....

[ICEUK]

Is it better to charge lithium every night? I only take about 30-40 ah per day.

[Burgerman]

No!

If you want lithium to last a decade rather than dying after 1 flight (heli, been there!) then they LOVE to be nursed.

That means they dont like any extremes.

Such as being 100% full! The opposite to lead. Charging to say 95% full easily doubles service life. Stock charge voltage is supposed to be 3.650V. I always charge at 3.550. Thats a small difference. But the lowest at which proper cell balance is done. So a compromise that helps the live longer.

Such as being discharged deeply. The same as lead. Less important though because you may get 5000 cycles at 70% discharge 2000 at 80%. And still get 1000 to 1500 at full 100% discharge, down to a MINIMUM of 2.75V. At 3.1V per cell we are safe and helps for a longer life. Again a compromise.

And they also hate high discharge currents. So the bigger the pack, the less C rate you are discharging them at. So a 200Ah pack means you are being nice to each Ah. At highest possible you are taking just 1C. Thats great for ling service life too. And range.

So to STORE a lithium battery they should be sat anywhere between 30% and 70% charged. Long term. So using a battery in a chair for a day, or a month, without charging it, as long as you dont discharge too low is beneficial to the battery. Again the opposite to lead.

[ICEUK]

Thats what I thought, I tend to charge every 2-3 days. I only asked as I was speaking to someone who said it should be charged everyday.

I am going to convert my other wheel chair to lithium, are there any other alternative connectors that we can use? I was going to use a anderson connector and something different for the balance wires,.

[Burgerman]

Theres many different connectors. But for the sake of repeatability and simplicity the best ones so far are these:


http://www.wheelchairdriver.com/BM3-con ... DCABLE.jpg

Single 40A capable connector with balance included and relatively low insertion force. I only use these now. Female half on the chair obviously!

[steves1977uk]

I only asked as I was speaking to someone who said it should be charged everyday.

Then they are clueless about Lithium cells. I charge every 7-10 days since I'm indoors mostly now cos of Covid-19.

Steve

[Burgerman]

I am posting this to show why charging with a BMS or a dumb charger, with no graphics is not very wise. And exactly how much info you can get from a charge graph I have a problem.

This is my green chair. A lithium battery but its a 120Ah headway 8S pack. Its 10P or each parallel cell group has 10 cells connected together.

This was stored 8 months. At around 45 percent discharged. As you can see all the cells are very close. Except for 1 and thats cell (group) 8.
That group appears to be full long before the rest. Now theres two ways that this can happen.

1. A cell has failed, and now has less storage capacity or...
2. A cell has a loose or high impedance connection.

So how to find out which? Well if its a bad connection, stopping the charge. And waiting overnight will allow that bad connection to charge up the cells that are connected with a high resistance or loose bolt. And lo and behold they wil all be in balance like magic in the morning. (You can also run around each of the 10 cells in group 8, and measure exact voltages. All the same? Bad cell. One or more higher and lower? Bad connection.

Theres also a 3rd possibility. That all the other closer grouped cells have the same high self discharge, and only cell 8 is magically better. Well statistically thats all but impossible. So since a 5 hour rest almost levels these up, its a bad connection... And I suspect I know which bolt it is. I undid one recently and likely didnt nip it up correctly when connecting a battery lead. On an end cell. So that is group 8. Too many coincidences in logical reasoning. So an allen key will fix it.

[Burgerman]

Clue 2.

The blue cell group, no 8 here, is much higher resistance than the others. That also shows a bad connection probability.

[Burgerman]

And the final evidence that its a loose bolt or bad connection

Look at the blue cell. Its been charging this pack at around 5A for the last hour. Continually. While the blue cell is supposed to be full. That isnt possible. Because the balance drain current is 1A max. So the blue cell should have gone over its 3.550V setting. And now that the other cells are reaching theis full voltage the current IS falling. So that they dont exceed the cv voltage. So something must be draining the blue cell group (8) fast. Well what can that be?

Its the other half or the other cell or whatever that is connected badly. It is not full. So now the full part of group 8 is charging the less full part up slowly. And is pulling that blue line down due to the reduced charge current. So we have 4 bits of evidence that all fit together. Eventually the blue line will reach the 3.550 point again once the badly connected cell(S) become charged.

This is why having this PC software while charging is absolutely essential. It tells me a mountain of stuff. All it needs is logic and an understanding of basic electrical stuff (ohms law and batteries). It not only shows when things are not going right. But also what the problem is. And where it is.

[Burgerman]

And 10 mins later...

The blue cell has been dragged down further by the uncharged half of group 8. And its begining to return to the top. The curve can be seen to start.

A little LOGIC and a simple charge graph goes a very long way. Without this info, and using say a BMS you would never know. And would destroy the pack. I hope this was interesting for someone!

[terry2]

Good information there BM

I have 1 cell that has a small internal resistance different from the other 7.

I have put it down to the cell as no matter how many cables I make for it.
It stays the same. But my chair works ok for now

[Burgerman]

I wouldnt worry. Measuring resistances this low, is hard. Very hard. And not very accurate even with a very expensive meter. Because the connections and the wires you are connecting to get the measurement probably make up more of the resistance you are trying to measure than the measurement itself. And cables and connections all vary slightly at this low level. You are essentially measuring the voltge drop across a heavy cable. And its almost non existant. And extrapolating the resistance from that.

On lipo hobby 1 to 10Ah packs connected with 4 inch long heavy wires, its reasonably accurate. Down a few connectors and 3 to 6 feet of cable its at best an approximation, a guide...

[terry2]

Just rearranged my cells.
Now they are more secure and don't move a bit.
I also put rubber shock absolver under them.

[Burgerman]

You appear to have wasted half the space?

[terry2]

You appear to have wasted half the space?

If you remember I had the cells in my Puma 40s first.

[optical10]

well it's that time I guess to go lithium now my gel's have given up the ghost with a best part of a year on the dumb charger before I got the Shirley have now taken their toll
having read through the entire post again I take it these are still the best choice for the conversion "Portable 3.2 Volt 200AH Lifepo4 Battery Cells Li-ion LFP Battery For Home Energy Storage"?
If so has anybody had experience from this particular supplier, what are their bolts thread craftwork, transaction professionalism etc?
Any thoughts or any alternatives much appreciated.

[Burgerman]

Not yet but thats where my next ones are coming from. Be sure to mention this forum. They seem OK and have been around a while. Some users here used them.