PINNED - Lithium battery conversion/info

[Irving]

If you do get a bill, it follows later by mail.

It did today, for £28, of which £12 was Fedex' handling fee. So total cost for PL8 + bits was £234 against £265 bought locally (fast-lad.co.uk, though currently out-of-stock on some items). Even though shipping 'value' was 120USD so VAT paid on only £80, savings not quite as good as hoped, but still 12% off. Seems UK price has come down slightly, probably due to stronger Sterling improving exchange rate v USD. Would probably order 2nd PL8 from UK when required...

[Burgerman]

except that, "some you win...

[Irving]

Been mulling over whether to convert my Spectra Plus to lithium, ready for the summer - we like going for long walks around Kenwood House/Hampstead Heath/Primrose Hill but last year we had range issues which threatened to spoil the day out. I'll keep everything else stock for now. My carer and my son have both tried to get the battery tray out to measure it but its stuck so got a call in to NRS to come and sort it. In the meantime been trying to figure out what space might be there; The Invacare manual is useless, just says 2 x 30Ah, 2x40Ah as option giving maybe 25Ah usable. It seems that the physically largest batteries that fit are the GF12033YG2 Sonnenschein 38Ah at 210Lx 175W x 175H - I don't know what 'case size'/group that falls under. Anyway, on that basis I can get 8S 5P of the 12Ah or 8S 4P of the 15Ah Headway cells both giving 60Ah usable at ~500GBP. I'm minded that the 12Ah cells will be less stressed than the 15Ah though its more effort to assemble the pack.

[Burgerman]

I think you need to measure the actual space available. Often more height than the battery case size suggests, or there's an extra "bit" in some place that allows some extra space to allow an extra cell or two. Its often all you need to make up an extra group of 8 that otherwise leaves wasted volume.

Even if you can only get 60Ah in, it can charge faster than lead to 99 percent full at 40A from your car. With a PL8 charger for eg. So its trivial to put a lot back while you have a drink or something.

Again as long as you only charge to 90 percent you can do that directly from a car, at 100A if needed.

[Irving]

Hmmm... not so simple, the batteries go inside battery boxes that have chassis mounted sockets the loom plugs into. So using the whole battery tray means losing the boxes and making up a loom. The only possible redeeming factor is that the spare parts list gives parts for Anderson SB50 shroud and connectors so its likely I can get the mating connectors once I know what colour they are.

Here is a 4S5P 12ah cell pack inside the battery box. The way the 2 boxes are positioned, fore & aft, long side across the chair so giving a space 210W x 350L x 175H doesn't lend itself easily to adding another 'P' using the orange blocks.

[Burgerman]

This is always the problem with headway cells if converting a chair with small batteries.

Take a look at other cells, or prismatics?

[flagman1776]

It definately takes a certain amount of bravery to modify the structure to use every bit of available space.

I'm still hesitant about modifying the battery tray in my huge outdoor scooter... there's space there if I carve out just a bit of plastic. When the SLA batteries die, I'll have to take my "bravery" pills & make the cuts.

[Burgerman]

Having spent most of my 20 to 37 years of age pre accident, chopping up cars, bikes, often bought new specifically to cut up, to fit big v8 engines, nitrous systems, turbo systems and so on, I don't really have a problem with taking the hacksaw to a brand new wheelchair.

Its a mind over metal thing! A confidence thing too having done more major things. If you can see the result in your mind and know how to get there then don't be scared! I don't respect mass produced stuff one bit! Its easily replaced/repaired.

[Irving]

I have no problem hacking Just its not my chair, it technically belongs to the NHS so don't want to hack it irreversibly. Once I get the tray/battery boxes out and see how they are arranged/connected I'm hoping I'll be able to create a bigger pack and not have to hack the existing loom. So there may be options but just replacing the existing lead bricks with lithium limits me to 8S5P and 60Ah which is still a massive improvement in range of 2.5 - 3x. It'll still be a 70A, 180W per motor setup though

[Burgerman]

One of mine does too. Don't know which, they are all chopped, mixed up etc.

[flagman1776]

I'm just figuring the layout for a Headway LiFePO4 conversion on my big scooter replacing (2) group 27 SLA. It will fit (96) 38140 cells in a 12P, 8S layout for 144ah or (80) 40152 cells in a 10P, 8S layout for 150ah. Unfortunately there's a 2" D seat pedistal between the rows.

[expresso]

http://www.headway-headquarters.com/


If anyone here is in the states and want to order cells - i Just figured this out that - you may be better off getting them from this site - instead of HK - EV - if you dont want to deal with the shipping from HK - and what ever other fees that may be attached to your final cost - customs - what ever -

Now - the price is a bit higher - per Cell and you have to buy the extras like the blocks and bus bars etc, - but the shipping cost is HALF what it would be from EV - HK - so that would cover the difference about 90% - i just figure it out today and put 8 cells in my cart - 10 blocks and 10 bus bars - just to see what the total cost would be - and guess what - its the same excat price i just paid for 8 Cells coming from HK - from EV - which it still has not shipped -

they offered me a disount on my next order and promised me that the shipping is resolved now and there are no more problems now - but mines was already sent to the shipper DHL and they cant get it back to reship with FEDEX now -

so i have to wait - now the only extra cost would be an extra 30 dollars for shipping if i purchased them from the above link compared to EV - in the end - its about the same and i get them fast from the US - no over sees shipping -
you can call and speak to someone in English - that along is worth 30 dollars if you ask me

so in the end - these 8 Cells i am waiting for - Cost me $212 total - and thats if i dont get hit with a extra fee later from UPS OR DHL Etc, - i have no idea -

if i would have ordered them from the above link - it would have cost me $242 - totals - shipped to my door - no problems - if you do the math - its really the same - its about $30 dollars difference - but if you get hit with a extra fee if coming from oversees - then its nothing different at all -

so anyone in the US thinking of ordering - you may want to check this link first - do the math - add it your cart - get the final cost to you and decide if its worth it or not - you dont have to purchase to know the final cost -

and you get a discount if you order 100 or more - i wish i knew before - i almost feel liking getting another 8 from them - and then another 8 later on when i do get them - its and idea - even though there is no rush really - i am inpatient once i decide i want to do it - and something like this is holding me up - but then again - i am still waiting for the BMS - so may not make much sense

[Burgerman]

for 16 cells you will need 24 bus bars.

[flagman1776]

Expresso:
You already have 8 cells, probably 8 buss bars, probably 8 orange blocks for your 8S pack because thats what EV Assemble ships.

To do a 16 cell 2P, 8S pack, you will need 16 cells, 23 buss bars total, 8 orange blocks total.

You ordered 8 cells, 10 blocks, 10 buss bars

Need List
You'll have enough cells.
You are going to be short 5 buss bars
You'll probably have 10 extra blocks

Check my numbers

[expresso]

i already have 8 Cells from EV - which ship with the orange blocks and bus bars -

So i would need another 8 Cells and 8 bus bar and 8 Blocks - i believe - i just added a few extra in the mix just to be safe - or am i missing something here ?

I am decided if i should Contact Paypal and start a case with them - this is not acceptable - EV - i hate the time difference also - but dont want to do that just yet in case this gets going in the next day or two - ? if its not shipped by then - i guess i have to start a dispute with Paypal - if thats the only way to get this either canceled or shipped -

you know i have to check the buss bars i have - i have to see if have enough now - i need 23 bus bars in total ? to make 16 Cell pack ?

i may actually be short now if thats the case - i didnt do the match correctly then -

[expresso]

Ok i checked - I have already - 11 Buss Bars and 12 orange blocks -

i suppose to get from EV if i get my order - another 8 Cells which already come with bars and blocks - so that would be another 8 blocks and 8 buss bars -

bringing the total to - 19 Buss bars and 20 orange blocks - which each block holds 2 Cells - so i have enough blocks to make a 16 Cell pack -

but do i have enough Buss bars ??

i though i needed - 15 buss bars to make this pack - like this - and if i want to add another 8 Cells to make it a 36ah pack - instead of two rolls - 3 rolls of Cells - then i would need 23 buss bars -

is that correct - ? because i may just have to place another order if i need more buss bars -


i am confused now - how do i need more than 15 buss bars ?

[expresso]

i decided to just open a dispute with Paypal - done - now we see whats the deal - ship it or refund it -

its a month since i ordered them - Dec. 11 2015 - now a month later and not shipped yet - they gave me a DHL tracking number - i called DHL - they dont have anything in here hands yet - someone has my package but its not DHL -

[flagman1776]

You are missing some of the bars on the other end of the pack pictured.

I counted again. The double row is 2P, 8S. Each of 8 Parrallel pairs requires 2 buss bars (one on each end)... That's 16. Assembling the series requires 7 more buss bars additional. Which means 23 buss bars total for the double row. The double row will require 8 orange blocks.
(Double row 2P, 8S requires a total of 16 cells, 23 buss bars, 8 orange blocks)

To build a 3 row 3P, 8S. That will require 8 more cells, 16 more buss bars, 4 more orange blocks. You reuse the 7 series bars from above.
(Total 24 cells, 39 buss bars, 12 orange blocks)

You are hung up in shipping limbo. I think it's right to open a complaint. You can't do anything until the second EV Assemble shipment is straightened out. If you order it someplace else, you could get stuck paying for both shippments.

[scitech]

Sorry if this post is a bit off-piste ..... I was very interested in what the long term experience of the Headway cells in the Powerchair has been? It must be a few years since I first came across this very interesting site and I wondered if the battery had lived up to the high expectations of cycle life?

Scitech

[expresso]

OH - I think i get it now - both rolls of Cells top and bottom get connected with the buss bars - thats 16 bars - - then in series 3 extra bars on top and 4 on the bottom - Red marks in the picture show -

making it 24 buss bars - so i am short buss bars even if i get the shipment from EV - which means i have to place an order for just buss bars from the other site here in the states - but should wait to see if EV ships it out or refunds me -

then i would re order everything else from the states - Cells - etc, all this time - i figured i had enough of what i needed - oh well - better i know it before i started at least -

[Burgerman]

Well some of mine have been in a chair 4 years, and balance and work as good as new. And capacity testing shows no loss of capacity over about 7 cycles. But they are not used heavily. Its an experimental chair so spend time parked while I make changes, or lenny writes new code, etc. Right now its got a bad motor. I also have some 108Ah in another old chair than gets fair use, no problem either.

That's a 45V 13S 72Ah 78 cell pack. And a 108Ah pack 72 cells. My new chair (just being rebuilt rather than new) has a 120Ah pack. As yet brand new.

I fitted a friends off road tramper (a kind of scooter) with 108Ah 24v 8S setup 3 years back, and its used severely almost every day if its warm enough. Also as good as new. Perfect cell balance and no capacity change.
I have also built some 24v packs - but smaller - for local users that have them in over powered E-Bikes. Again years old not one issue.

But remember that these do NOT have a BMS on them. They are all using super accurate PC controlled and logged Hobby chargers that treat cells perfectly. And all these are LARGE packs so discharge rates, and discharge levels are low. And so is heat. BMS are the cause of almost every cell or lithium battery problem for a bunch of complex reasons. Non of these cells for eg has ever seen more than 3.650V even for an instant other than the first few initial charges. Most are charged to 3.550 or 3.600 per cell say every few days only with no overshoot and to an accuracy of 0.003V plus/minus. And never stored full. Discharge to 70% or less.

A BMS equipped pack can last a long while if luck is with you and cells have a good equal self discharge rate, or it can die in a week due to balance or dead cells. All depends on a lot of things like what peak voltage the BMS allows the cells (the full ones) to reach over and over while the weak balance circuits attempt to drag a cell down for eg. And if they try and (incorrectly) balance all the time rather than only above 3.4 to 3.45V. And so on.

From my experience problems come from bad connections, loose screws on most packs! Or BMS induced issues. Cells themselves IF TREATED CORRECTLY seem fine.

[flagman1776]

Squeeze a 150ah in there.

Lots a motors Besides the charger, I don't know what else is in that rear "box".

[Burgerman]

>>>Squeeze a 150ah in there.

And then some.

If it was mine it would get jet washed, stripped, rebuilt clean and checked out, and I would be looking at Prismatic cells. Because scooters draw lass peak amps, less big amps while turning etc. So lower C rate prismatic cells, and easy to find space for large capacities make sense. Less connections etc.

[Scollard]

OH - I think i get it now - both rolls of Cells top and bottom get connected with the buss bars - thats 16 bars - - then in series 3 extra bars on top and 4 on the bottom - Red marks in the picture show -

making it 24 buss bars - so i am short buss bars even if i get the shipment from EV - which means i have to place an order for just buss bars from the other site here in the states - but should wait to see if EV ships it out or refunds me -

then i would re order everything else from the states - Cells - etc, all this time - i figured i had enough of what i needed - oh well - better i know it before i started at least -

Expresso, order 7 of these:

http://www.headway-headquarters.com/4-hole-bus-bar-38/

[flagman1776]

I tried laying out the 60 or 100ah Calib calls & so far have not found a successful layout for the group 27 footprint (12” L x 6.63” W x 9.06“ H {actually I'm allowing 10"H under the cover}) There's ~4" of space between the SLA batterys with a 2" seat pedistal toward the rear. The Headway layout has more hardware but can be laid out to fit.

[expresso]

OH - I think i get it now - both rolls of Cells top and bottom get connected with the buss bars - thats 16 bars - - then in series 3 extra bars on top and 4 on the bottom - Red marks in the picture show -

making it 24 buss bars - so i am short buss bars even if i get the shipment from EV - which means i have to place an order for just buss bars from the other site here in the states - but should wait to see if EV ships it out or refunds me -

then i would re order everything else from the states - Cells - etc, all this time - i figured i had enough of what i needed - oh well - better i know it before i started at least -

Expresso, order 7 of these:

http://www.headway-headquarters.com/4-hole-bus-bar-38/

Hi - thanks - Is there anything else i should get in case ? 7 of those and should i get a few more reg. buss bars ? right now i will have 16 Cells to make a pack - i may get another 8 Cells for later after this is done and i can confirm i have room to make a 3 Roll fit - but for right now just the 16 -

[Burgerman]

Those square bus bars are no longer made by headway for quite a while.
And there are many reports of them not fitting as they are made by other third party suppliers badly. Needing to be drilled out and enlarge holes. So be careful what you order. I have some here. Those didn't fit before drilling to 7mm.

[Scollard]

Those square bus bars are no longer made by headway for quite a while.
And there are many reports of them not fitting as they are made by other third party suppliers badly. Needing to be drilled out and enlarge holes. So be careful what you order. I have some here. Those didn't fit before drilling to 7mm.

I got my 4-hole bus bars from EV Assemble when I ordered my 15Ah cells and they definitely fit. But the 15Ah bus bars won't fit the 12Ah cells.

[expresso]

Oh ok - thanks for that - i didnt order yet -

you know what - i will just order the normal 2 hole buss bars - i have 19 - i need 24 ? i can order a few extra also - and a few orange blocks for the 15Ah Cell - i want to check my box with those just to double check - i will post pics later - i checked my chair last night -

Short story - 6 x 6 12ah cells - CAN Fit if you do some work and then NO ROOM for Wiring etc, - its very very tight - i will show the pics later - so i think best bet may be the 15Ah Cells - one large flat pack -like Scollard suggested -
giving me 90ah - a little less - but i have the room on top to connect wires and be able to slide the tray in and out easily - will sit in the same tray as the MK are now - and be neater i think than it is now -

i show the pics - i spend a few hours last night - checking and looking and trying - i am sure YOU BM would make it fit - cut this or remove that etc, - but i cant get too much into modifiying things that way - i am luck i can the ADD on done with help here - never mind the whole pack with work being done to the chair itself

but i show you in a few - thanks for the update on those plates - and EV is shipping it UPS now - i may get it next week - PayPal worked - they offered me $38 off the next order - its not alot - but well see - i will close the case with paypal once i see the tracking as shipping with a due date - till then i leave the case open - they got on it fast once i started the case with Paypal

also - BM i may get the PL 8 - if i make a decision on the whole chair project - looks like i have my work cut out for me - but hopefully with Scollard - you and others here can get me going for the summer -

[Burgerman]

>>>giving me 90ah - a little less

Compared to 108Ah its a huge 20% less.

That's a huge 20% better range, 20% less amp draw under load per cell so less damaging, 20% less average DOD level so less wear, 20% better service life approx, etc. And you will kick yourself if you don't do it! Would you rather your fuel tank held 4 gallons or 5? That's 20%!

That's why I am fitting 120Ah. I have 6 gallons...

The wires will fit. They can go in the gaps the orange block pins leave.