lithium battery power on lifestand LSC?

[shirley_hkg]

Make sure your chair WORKS with only ONE 24V supply , before going lithium .

It will be complicated if it doesn't ..

Do the above first . Then you should measure the battery compartment and seek advise on cells .

[jehan]

okay Shirley, you want to see if the chair works with one bank of batteries which is 24 V 18 H ? ....… I'll try it… What's the reason?

Funky keyboard seems to have converted to lithium on the same wheelchair 5 years ago and had no problems…

each battery compartment is currently accommodating lead batteries 370 MM long, 76 MM wide, 185 MM high ....but according to funky keyboards measurements it can accommodate 228 MM height… I will recheck that

if the battery compartment actually is over 200 MM height then each bank can accommodate 4 prismatic cells of 60 AH each
https://www.ev-power.eu/LiFePO4-small-cells/Prismatic/LiFePO4-High-Power-Cell-3-2V-60Ah-Alu-case-CE.html#tab2

and 2 battery banks (of 4 cells each) makes for a total of 8 cells of 60 AH each which is 24 V 60 AH pack, 12 AH more than the headways

is this the way to go? anything else I should be looking at?

[Burgerman]

I have no idea what is to be ained or learned from this.

[shirley_hkg]

okay Shirley, you want to see if the chair works with one bank of batteries which is 24 V 18 H ? ....… I'll try it… What's the reason?

To charge ONE 24V lithium (ie, 8S) is not simple .

If you need TWO , charging will be very user unfriendly .

if the battery compartment actually is over 200 MM height then each bank can accommodate 4 prismatic cells of 60 AH each
https://www.ev-power.eu/LiFePO4-small-cells/Prismatic/LiFePO4-High-Power-Cell-3-2V-60Ah-Alu-case-CE.html#tab2

and 2 battery banks (of 4 cells each) makes for a total of 8 cells of 60 AH each which is 24 V 60 AH pack, 12 AH more than the headways

is this the way to go? anything else I should be looking at?

Those are very OLD . I suggest you should look at the EVE-LF90 in the link .

BTW , you may talk to forum member ''Furio'' . He is in INDIA too and he has bought some good cells.
https://www.wheelchairdriver.com/board/ ... &start=120

[jehan]

oh… maybe I see what you're trying to say

I am only charging one 24 V 60 AH pack which consists of 8 cells connected in series.… Instead of two 24 V 18ah which is the current wiring… I guess this will have to change

physical location will be 4 cells on the left bank and another 4 on the right bank

below is the DX controller connections… Will it work?..... Don't see how it would be different if I were using the headways… Just just won't be using the XLR plug to charge through the DX?

[Burgerman]

Correct. As long as you feed it 24v it will work. Unless the voltage falls, too low, under load. As it will with all those nasty cheap & too small lead batteries.

[jehan]

can we please leave the nasty batteries aside and get a .

[Burgerman]

Nasty!

3 months? Not sure if you are religous being in india but lots!

What are the 3 dimentions of your battery space?

[jehan]

my measurements from an earlier post... This is the total measurement for 2 batteries

each battery compartment is currently accommodating lead batteries 370 MM long, 76 MM wide, 185 MM high ....but according to funky keyboards measurements it can accommodate 228 MM height… I will recheck that

will recheck the height if it is more than 185 MM (should be 228 according to funky keyboard measurement)

[jehan]

Hi John, finally got a chance to look at the battery box sizes

Each box dimension
Length = 362 MM
width = 78 MM
height = 203 MM

And there are 2 battery boxes

How many cells can we fit?

Thanks

[Burgerman]

8X THESE? https://www.ev-power.eu/LiFePO4-small-c ... se-CE.html

Best ask shirley as he has access to many more and better prices cells.

[jehan]

8X THESE? https://www.ev-power.eu/LiFePO4-small-c ... se-CE.html

Those will fit BM…

Shirley had mentioned another battery by EVE energy LF 105 , here is a 90 AH version, model number LF 90…
Resistance reads at 0.6 mohms at 30% SOC
maximum discharge = 3C

LF90(3.2V-90Ah).pdf

(326.75 KiB) Downloaded 208 times

Shirley, are the LF105 available?


I found another set with similar dimensions and 90 AH capacity.... But no clue about the seller
resistance is 0.6 M ohms at 0.2 C (is that the same as 30% SOC above in the LF 90)
continuous discharge = 2C
maximum discharge = 3C
https://www.alibaba.com/product-detail/Kylin-Power-LiFePO4-90Ah-Rechargeable-Battery_60744788314.html?spm=a2700.galleryofferlist.normalList.105.5b1e6f67uQmQtC

Which one looks good to you?

[Burgerman]

200*130*36mm

8 of these ill fit??? I thought you had small battery spaces?

Each box dimension
Length = 362 MM
width = 78 MM
height = 203 MM

They might I cant get my head around it! You need 4 per box.

[shirley_hkg]

105Ah are rare and not ease to come across good quality one.

Go get the 90 or 75 Ah . 75 has higher C rate .

[jehan]

200*130*36mm

8 of these ill fit??? I thought you had small battery spaces?

Each box dimension
Length = 362 MM
width = 78 MM
height = 203 MM

They might I cant get my head around it! You need 4 per box.

2 batteries together is
130 MM long
72 MM wide
200 MM tall

4 batteries together is
260 MM long
72 MM wide
200 MM tall

My box dimensions are
362 MM long
78 MM wide
203 MM tall

[b]So the real problem is the height depending on the connector… Will need to recheck how much space there is above the box… Could have cutouts for the connectors?[/b]

[Burgerman]

You are wasting 100mm.

Also THOSE cells are uninsulated. The casing is metal. You will need to insulate with say 1mm of anything non conductive on bottom, sides, minimum. Or,

[jehan]

105Ah are rare and not ease to come across good quality one.

Go get the 90 or 75 Ah . 75 has higher C rate .

Thank you Shirley, my dynamics DX power module can handle up to 80 A, I'm not sure if I have the 60 or 70 A version

Do I really need the 75 AH high rate discharge version or am I better off with a larger capacity 90 AH battery?

Do you know a reliable source where I can get these?

[jehan]

You are wasting 100mm.

Also THOSE cells are uninsulated. The casing is metal. You will need to insulate with say 1mm of anything non conductive on bottom, sides, minimum. Or,

Yes I am wasting 100 MM, couldn't find anything closer than this… Will look around

Even with the one MM insulation per side, I should be okay on the width because there is about 6 MM left and will need maximum 4 MM.

Where do I find custom battery sizes?

[Burgerman]

You need to look around, and do drawings, see what can fit in your space. The insulators need to seperate all cells from each other.

[shirley_hkg]

Go get 8 of these 90Ah cells .
His dual 18Ah lead already gave him 3 days use.
A 90Ah set is adequate for his entire week .

[Burgerman]

Maybe, it will work OK, but C rate x capacity is not great. Remember it takes a couple of hundred amps to turn in place... Or wheelie. I am not worried about range, more longevity.

Lithium likes to be charged gently. Discharged gently (well away from max C) and kept between around 25 and 85% full. Then they last indefinitely... Do the opposite, a few months. Most cycle life figures are given at a very low discharge rates like 1/10th C or similar.

So larger is usually lots better than you would expect because it reduces all the extremes, and even lasts days longer before charge.

[jehan]

Shirley, I get 1 day use of running in and around the house on the dual 18 AH lead batteries.... Not 3 days, and I charge every night

BM, when I go larger in length of battery to about 175 MM (from 130), the width also goes up to 50 MM and then I can only accommodate 2 batteries in each box

I found some 90 AH batteries with a claimed maximum discharge of 10 C , but it's hard to tell if that's really the case
http://www.evlithium.com/LiFePO4-Battery/472.html

And the weird part is even the 75 AH battery are the same dimensions
http://www.evlithium.com/LiFePO4-Battery/453.html

Lithium likes to be charged gently. Discharged gently (well away from max C) and kept between around 25 and 85% full. Then they last indefinitely... Do the opposite, a few months. Most cycle life figures are given at a very low discharge rates like 1/10th C or similar. ]

If that's the case, then maybe better to go with a battery with a higher C rate rather than outright capacity? Both the links posted above have the same C rate, but how accurate is that?

Please suggest a known source?… Thanks

[Burgerman]

Well we dont have one. All these new sizes and C rates just fell out of the sky recently. And we only have their word on specs. And the chinese are good at exhadurating... So who knows. Your battery area is problematic.

C rate is kind of like the equivelence to impedance in lead batteries. The big difference being they do not like going anywhere near it in practice. At least if service life matters. So its always best to add C rate and capacity. Because double the capacity, means you only NEED half the C rate for the same performance/longevity.

[jehan]

Hi… My controller is 70 A… Can I get away with it 90 AH 3C max discharge rate or do I need to find a 90 AH 5C continuous discharge battery?

Most of the 90 AH batteries I see are 2C continuous discharge with a 3C max like these
https://www.alibaba.com/product-detail/Kylin-Power-LiFePO4-90Ah-Rechargeable-Battery_60744788314.html?spm=a2700.galleryofferlist.normalList.105.5b1e6f67uQmQtC

And the 5C one is from EV lithium
http://www.evlithium.com/LiFePO4-Battery/472.html

In case anyone has had experience working with them…

[Burgerman]

Hi… My controller is 70 A…

Per channel. 140A total. And it can do that on every ramp, zero speed turn, etc.

Theres no firm limit.
Any of those cells will work. But to get the advertised 2000 cycles, and good performance you need to discharge at well below the max advertised rates.

Lithium prefers to be discharged at a L O W rate. Like fractions of 1C if you want a long life.
It prefers to be charged at low rates too. And it prefers to never be full, or empty. So it likes to be somewhere in between.

So while you can use any cell, the further your 140A demand is away from its cont rating the better. That means a high rate cell or a bigger pack. both things help keep it low. So while the 90Ah cells are good, if you could find higher rate cells, or fit more Ah in that space, thats better still.

[jehan]

Check specs for L135F72

I have found 72 AH lithium phosphate prismatic CALB cells being sold locally from an ev car manufacturer.so it's easy to source and will come with some kind of guarantee… Though I'm pretty sure they will not honour it because it's being used in a wheelchair.

It's the same size as the 90 AH battery but for some reason this EV manufacturer prefers to use the 72 AH

[Burgerman]

As long as you can get that 72Ah in it will be fine. 90 better obviously. China is where these all come from, the 90 ones are just newer tech with higher energy density.

In the same way that the early rechargable AA cells were 500mAh. Now 2500 to 3000mAh AAs are common.

[jehan]

hi all,

My 15 V 30 amp power supply (which is at least 15 years old) is starting to fail and cannot supply 13.5 V for no longer than a few minutes.

I'm looking for a power supply which is adjustable for voltage (13.5 V) as I am running lead batteries (four in parallel) along with the power supply,as a backup for the PL8.

So far, that's worked really well and when the power goes out, the PL8 stays on with the lead batteries.

I am in the process of switching to lithium with a 8S 72 AH pack and need a power supply to support it.

So far I've found

https://www.rcpitstop.co.uk/logic-rc-fusion-600w-adjustable-power-supply-7687-p.asp

http://www.chargery.com/adapter.asp
the S 600

any suggestions?

thanks

[Burgerman]

I'm looking for a power supply which is adjustable for voltage (13.5 V) as I am running lead batteries (four in parallel) along with the power supply,as a backup for the PL8.

Thats the wrong way to do it.
You need a 24V (27V power supply) to power the PL8. Or you will limit its power and reduce efficiency.

So far, that's worked really well and when the power goes out, the PL8 stays on with the lead batteries.
I am in the process of switching to lithium with a 8S 72 AH pack and need a power supply to support it.

So far I've found

https://www.rcpitstop.co.uk/logic-rc-fu ... 7687-p.asp

Dont buy, fragile, all fail.

http://www.chargery.com/adapter.asp
the S 600

Doesent work (link)


You need a shirley supply... Or a http://www.wheelchairdriver.com/BM3-con ... arging.jpg type supply.

[jehan]

hi bm.... Always good to hear from you.

I see what you mean about getting a higher voltage.

Is this the link to Shirley's power supply that you were talking about?

http://www.wheelchairdriver.com/board/viewtopic.php?f=2&t=7670&start=60

please send me the link to the power supply in your picture