PINNED - Lithium battery conversion/info

[Burgerman]

https://www.evlithium.com/catl-battery- ... ttery.html

These will fit. Low impedance. Ships from HK and email for price. M6 threads.

[shirley_hkg]

Don't like its web page. Address is fake. Fax number is in Shenzhen , not HKG.

[Burgerman]

Yes. They are chinese, have websites and stock in germany and other places too. How real it is who can know.

[Burgerman]

They are LiitoKala, I don't know if you also call them EVE.

I took a cheap gamble. Ordered 6 of these https://www.aliexpress.com/item/4001216474356.html
This is LiitoKala... They buy up old and outdated/used cells, recover them with new plastic wraps and sell as new. Scammers of the first order. Criminals in fact. I applied to aliexpress for a full refund of my 16 quid!

They are actually LG cells. Model : INR18650HG2 3000mAh
Internal resistance SHOULD BE 20mOhm each when fully charged. It actually measures 526mOhm!!!
They should fully charge in 1 hour and terminate at 50mA at 4.200V. They never get there after 4 hours...
They should be 3000mAh capacity. I have not tested yet. But will test if I can get any of them to ever reach 50mA termination point. I doubt they will.

Dont buy from LiitoKala scammers.

[Burgerman]

Just ordered a set of 6 Sony cells. These are VTC6 3000Ah minimum, and more importantly they are 20A capable, 30A capable if limited by a temperature sensor to 80C maximum. Because they are just 12 to 13mOhm per 18650 cell.

At great expense, from a vape shop in the UK. Lets see if they are what they claim to be.

https://www.thunderheartreviews.com/201 ... -test.html

[Burgerman]

hey are actually LG cells. Model : INR18650HG2 3000mAh
Internal resistance SHOULD BE 20mOhm each when fully charged. It actually measures 526mOhm!!!
They should fully charge in 1 hour and terminate at 50mA at 4.200V. They never get there after 4 hours...
They should be 3000mAh capacity. I have not tested yet. But will test if I can get any of them to ever reach 50mA termination point. I doubt they will.

Dont buy from LiitoKala scammers.

That was 2 of them. And they were 2505mah when super slowly discharged.

The other 4 on the other hand read 23mOhms each. And will charge and discharge at normal rates. They measured approx 2850mAh. So probably a little old, but at least close to spec. I will use those. After cycling a few times they may in fact improve. The first two can go in the bin.

[Burgerman]

https://lifepo4.com.au/shop/cells-lifep ... ive-grade/

If you plan on buying cells, WATCH these videos carefully.

Remember that a modern chair can take 200A plus at times. From a smaller cell than this guy is testing. This is why good cells with low internal resistance matters. And why using a BMS will cause you roblems. Much greater issues on less than pefect cells too.

[shirley_hkg]

Know the strength of the welded strut of most prismatic cells.



youtu.be/uaebFJQchao

[fishinjunky]

I miss building the lifepo4 battery I really enjoyed building the battery with my mom. I would honestly build them for others if i could. But I agree with BM that people need to build themselves so they understand everything.
But in 3 years I'll be building another one when I'm able to get a new chair.
I'm curious if anyone else is like me an really enjoys building lifepo4 batteries an things like it? Or do you see it as a chore?

[Burgerman]

I enjoy fixing, modifying, improving everything. Its far less easy since landing in a chair. But previous hands on skills doing everything from model planes, building V8 powered drag cars, building nitrous systems, automotive rolling road dynamometers, and a million other things such as central heating, air conditioning etc all helped enormously. I can delegate design, understand stuff and know what is available, what works with what etc. So I can instruct others to do my impossible stuff.

But yes I enjoy it. Also helps having the space, and good tools.

[shirley_hkg]

220Ah for a friend's OTTO BOCK B3 with long and narrow compartment .
Gum fish / gasket paper between cells , and all are contained in an U-shape plastic duct .
Initial charge . MOS_less BMS for charging only. Direct output to wheelchair.

[fishinjunky]

220Ah for a friend's OTTO BOCK B3 with long and narrow compartment .
Gum fish / gasket paper between cells , and all are contained in an U-shape plastic duct .
Initial charge . MOS_less BMS for charging only. Direct output to wheelchair.

you an bm always build really nice looking packs

[michaelg]

Hello, I'm new here and am not sure this where I should post this question but I have decided to go ahead and convert to lithium and would appreciate some advice. I live in the US and have a quickie s636 and am thinking of purchasing 8 Eve batteries from here: https://www.18650batterystore.com/products/eve-lf105

I was going to go with the icharger x8. I'm a little confused as to what to do for a power supply. The x8 can take a max input of 35 amps. Does that mean I need to make sure the power supply doesn't exceed 35 amps? Should I go with a 12v or 24v power supply? I was thinking of this one: https://www.progressiverc.com/collectio ... wer-supply

I would like a way of keeping track of the voltage throughout the day. Is there a recommendation on a simple battery monitor? How do you all keep track of voltage/ battery life?

Thank you and forgive me if these questions have been answered elsewhere. I have read and learned a lot on the site already.

[Burgerman]

OK.
In that chair where you have group 24 battery space, you can fit 8x 230Ah cells (and you should for a huge bunch of reasons).
E.G. these: https://shop.gwl.eu/LiFePO4-cells-3-2-V ... html?cur=1

As for power supply then 35A is the least I would consider. I use a couple of 0.to 40A, 0 to 40V adjustable bench supplies. And I also use a cheap but really well built reliable ZXD power supply/3 stage charger and that is adjustable from 0 to 60V and from 0 to 50A and is also a great 3 stage charger for lead too all rolled into one. Theres a frew hreads here talking about these and they come from a member called shirleyHK in hong kong. As for supply voltage then 24v or up is best. At 12V you need double the amps, and thats causes losses and heat. So its OK for charging at a low rate or a small pack but for reliability its best to use around 24 to 30V. Depending on charger.

Also consider this.
To charge a 230Ah pack, at 40A is still considered a low rate.
So thats 40S x 28.80V (3.600V per cell) = 1152A output from the charger. Then theres the approx 85% Charger efficiency, so you will need an extra 15% from the power supply. So thats 1324 watts. Divide this by the power supply voltage to give actual amps from the supply.
1324 div by 24V = 55Amps...
1324 div by 12V would need 110A!
1324 div by 30V = a more sensible 44A. And the shirly power supply can do 50. At least in Europe.

So you can figur out whats a good idea as you can see how to calculate it all above.

As for measuring voltage, well you can. But unless you are measuring individual cell voltages that is not going to tell you much important. The voltage stays much the same for 2/3rds the capacity. Very flat discharge curve. Relying on voltage to deterine capacity is very very inacurate.

Plus if you fit a large enough pack like the 230Ah cells then you will never need even think about the battery range. Or ever look at a meter. Because you will get 5 to 6x as much as a brand new set of 80Ah group 24 lead bricks. Around 80 to 100 miles real world normal driving.

But if you still want to know, then a cell log for 8S is cheap. Anything from around $5. But you wouldnt even plug it in unless you first lost at least 1 light on your usual joystick battery meter. And YOU will be worn out or out of daytime before this happens.

[Burgerman]

ALSO... I posted this elsewhere.

Rule of thumb 26.15V (chair stopped for a while to let things stabilise) equals to 75% DOD - safe and allows enough in reserve that no need to monitor individual cells. This is RESTING voltage. So recharge if it doesent go up beyond 26.15v after waiting a short while (5 to 10 mins?)

25.70v rest voltage = 88% discharged. You never want to go less than this for several reasons.
1. it shortens service life to go lower.
2. it allows enough in reserve that a single cell will not likely drop below a safe voltage level.

So you just need a decent volt meter. Dont trust some un-calibrated eBay nonsense unless you test this yourself against a known reference.

For e.g: I use the PL8 charger to remove 75Ah from a known good 100Ah pack. So that is 75% discharged. Then I read the voltage from whatever device you use to do this. Also LOOK at the LED lights on your controller so that you can also use these as a guide. Those all vary depending on controller and its configuration etc. But if you test yours individually in this way, you will know whats really safe on YOUR system. But a seperate voltmeter is better. A cheap LED Ebay one can be used. But if your joystick lights drop at this 75% point then that is good enough.

Or make a note of joystick lights, as soon as you lose one, RECHARGE and see how many Ah you put back read from the charger. Thats likely a big percentage of the pack. Do the maths! You will soon learn what AH returned equates to a light (maybe 2 lights) actually is.

If you have fitted the 230Ah cells linked above, then you need not worry. YOU will tire out long before the battery! Thats why you should fit 230Ah cells in the first place. Or at least as big as possible in your setups space. It pretty much garantees that high discharge C rates are impossible, (so long cell life) and that average depth of discharge is very low (again long service life) , and that you dont really need to monitor the pack during the day at all. So garanteeing no damage, no range anxiety, and a 10 to 15 year service life with great reliabiliy. Its the way to go.

IF you wish to use that extra 25% range, (a typical extra 20 miles, after alredy using approx 60) then you would be well advised to use a cheap cell monitor so you can be sure you never allow the LOWEST cell to go below say 2.7V. At this point you will have typically 80 miles range. And thats a bit crazy. Obviously individual chairs an users vary a fair bit. So do your OWN checks as you use the chair and make a note of voltages before charging and the Ah returned.

[shirley_hkg]

It's not related to "michaelg" post in any way. It just happens.


My fried ignored my favourite CATL and bought 8 EVE-230 cells. (£400)

I helped to fit them into the stock battery boxes of a Invacare ARROW GB.

Will be using ZXD2400 with a BMS.

(Charger in the pic was dumping a little from it, before put into his ARROW.)

[shirley_hkg]

PL8 helped to determine its capacity.

Cells' voltage began to deviate after 215Ah dumped.

[shirley_hkg]

226Ah.

Beat my CATL (222)

[shirley_hkg]

Terminal voltage 24v

[michaelg]

Thank you! All that is very helpful. I'm not sure I can afford the larger Amp batteries but I feel like the 105s will still be a huge upgrade for me.

So what I understand is: get a 24v power supply. The Amp output of the power supply will determine how long it takes to charge. Lower Amp, longer charge. It's better to get something in the 40 Amp range.

Does anyone know how much shirleyHK sells his power supplies for so I can compare with what I'm finding online? Thanks for the help!

[Burgerman]

Its false economy to fit smaler packs than you can physically get in.
Because theres 3 things lifepo4 doesent like.

1. Heavy average discharge currents. Fitting 230Ah ones reduces this to half! Actually less. Per Ah.
2. Being FULL. If the pack is twice the size you only charge full HALF AS OFTEN!
3. Being EMPTY. If the pack is double the size the typical days use avoids going anywhere near this empty point. And if you do, and charge half as ofter then you discharge low half as frequently too. It lowers the frequency of heavy discharges and reduces average depth of discharge.

So if its possible to replace 80Ah lead with 100Ah lithium then yes it will be better. But not much better and they will be worked harder, have much less range and die sooner than a 230Ah pack.

Also at BEST with lead you get 50Ah use befor the chair stops. Because peukert. With 100Ah lithium, you should get double the range but you dont. Because you cannot run it low without permanant damage so you leave say 20% in reserve for safety if you have any sense. So then you only get about a 50% range gain. Your 15 miles becomes around 22/23.
With a 230Ah pack, a USABLE 200Ah leaving a massive 30Ah in reserve you get a 400% range increase over lead. 200Ah div by 50 usable Ah.

80Ah lead = say 15 miles.
100Ah lithium (20% in reserve) = 22.5 miles.
230Ah lithium (a full 30Ah reserve!) means 90 safe miles. Which you will never do! So charge every week. Then more cycle life!
Double the cost = double the lifespan, and at least 4x the range gain. 100Ah makes little sense when you look at the figures.

[ex-Gooserider]

Don't worry about having a power supply with a higher AMP output value than the charger, as long as it is a 'constant voltage' type supply (or run in CV mode when it's a mult-mode supply like the ZXD's) the charger will only draw as much current as it needs...

Somewhat more importantly, you should keep an eye on the power supply INPUT specification, and avoid ones that require a higher current input than the wall outlet can supply (typical US outlet is 15A @ 110V), or you are likely to blow fuses on the wall side...

ex-Gooserider

[shirley_hkg]

105Ah seems a big leap from GEL.

Other than capacity , C-rate of cells matters too.

(expresso) did only fit his 646SE with 108Ah, using Headway 38120 cells . That served him really happy for years.

A123(20C)/Headway(10C) rated. They can deliver big current and withstand abuses.

EVE-105, meant for storage, is rated @3C. I think 8 of them to drive 636 with power seat will be a hard job.
IT also has only 5mm deep M4 threaded terminals , which should not be taken lightly, especially for novice.

but I feel like the 105s will still be a huge upgrade for me.

[shirley_hkg]

Does anyone know how much shirleyHK sells his power supplies for so I can compare with what I'm finding online?

Your call for ZXD2400 is answered below.


https://www.wheelchairdriver.com/board/ ... 61#p196261

[michaelg]

Thank you ex-gooserider, that's is helpful information. I'll watch for the amps on the input side.

Thanks for making me think about the c rating shirleyhk. I wasn't thinking about that. It's a lot of information to take in and sort out but I'm slowly making sense of it. Thanks for the info on power supplies.

[UnicornBurner]

Progress!
We made our first pack and are working on the cord end that will plug into the PL8. Thank you to you all for the helpful information and to Shirley for his assistance with the PL8s ZXDs and EVERYTHING else.

[UnicornBurner]

Cable is done. Charging time! Fingers crossed.

[Burgerman]

All connections on balance and power soldered?
All cells initially fully charged?
Using one of my presets?

All should charge and balance on first charge and ballance should be achieved withing a short while on all cells.

2nd charge after removing say 20 or 30Ah should charge and balance perfectly and CV stage should take 20 to 30 mins before ending. At 3.600V per cell.

[Burgerman]

One thing.
The connectors for the PL8 for the charge wires are going to a) melt. And possibly melt the PL8 outputs too. And b) fall out and touch. Which will short out the battery and cause smoke and worse...

You *must* use these intrinsically safe ones, and these have longer contact area than most other connectors and they can stand the 40A charge without problem. As used and recommended by the PL8 manufacturers. https://www.ebay.co.uk/itm/284977340763
Or...
https://www.ebay.co.uk/itm/204359317492
https://www.ebay.co.uk/itm/404362417398

[UnicornBurner]

Yes, everything is power soldered.

We are looking into the first charge and I was planning to search the thread to find your preset menu….unless you have it handy and want to repost.

In terms of the connection plugs melting. Are you concerned about the silver ones we will plug into the PL8 that lead to the battery?