lithium battery power on lifestand LSC?

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lithium battery power on lifestand LSC?

Postby funkykeyboard » 20 Mar 2012, 13:08

Given the way these bolt together, and given the confines of space on my wheelchair, couldn't this be the best solution?
http://www.wheelchairdriver.com/BM-MK3- ... rchair.htm

At the end of the day I'm going to have to look for somebody to do this for me [an electrician]. So is it feasible?
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Re: lithium battery power on lifestand LSC?

Postby Burgerman » 20 Mar 2012, 13:20

How feasable it is depends on your depth of understanding. To me its not only feasable but probably the only option you have since the manufacturers forgot that the battery was the very heart of all electric vehicles and used up the space for other things!

You need to ask many questions, until you grasp everything. And start here: http://www.wheelchairdriver.com/convert ... ithium.htm

And rather than 2x 12v packs you need to make either 4x 6v packs, 4x 12v packs, 4x 24v packs, as you prefer/whatever is easiest to fit in the space.
And connect up either in series, or parallel, or parrallel/series as yours is already to end at 24v.

Remember that 8 cells in series is 24v.
4 is 12v
2 is 6v

And any sets of these can connect up in parallel. So connecting two 12Ah cells in parallel gives same volts, double the Ah.

The only complex bit is making up a charger balance cable. Thats fiddly! Buy relatively simple.
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Re: lithium battery power on lifestand LSC?

Postby funkykeyboard » 14 Oct 2012, 17:34

I have been in this forum several times about the problems with this viewtopic.php?f=6&t=194 wheelchair charging. I have also thought about the idea of building a burger man chair. At last, it seems I have somebody capable of doing this kind of work.

The guy is a Texan trained electrician [house electrics I guess]. And so what I thought I would do first is use the F 55 I have got hold of as a temporary wheelchair, whilst I upgrade to lithium batteries on the life stand wheelchair.

I'm getting the Texan to write up a shopping list from the directions on how to convert, on this website. I suppose my first question is, what are the dimensions of these lithium battery packs. Will I be able to fit them into the current 2 battery housings, which hold at present 4 x C5004XXXFO Batteries 12Volt 18AH? here is a pretty poor video of the battery housings. http://s627.photobucket.com/albums/tt35 ... EO0006.mp4 I will take better lit pictures on Monday.



[[[[[[[[[it is a few years old this wheelchair now, so any suggestions on upgrading, improving it are welcome.for example, I am at least going to service the drive motors, which produce a reasonable 6 mph, but if people think it may be better replacing the drive motors I'm interested in people starts.]]]]]]]]]
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Re: lithium battery power on lifestand LSC?

Postby Burgerman » 14 Oct 2012, 19:50

The video didnt help much!

You just need to replace the lead, with as many Ah of high rate lithium (headway cells most likely) that will fit into the space. There isnt much space so you will struggle. The chair is designed to do standing at the expense of battery power. As you found out already.

So its a matter of looking at how many 8, 10, 12, or 15 Ah lithium cells you can physically get in your restrictive battery compartment.

As an eg, a pair of greoup 24 batteries (70Ah) can be replaced with 72 12Ah cells. Giving 108Ah. This should allow around double the range, or more, due to the lack of Peukert affect on lithium cells, as well as a very long service life. (around 2000 cycles at 80 percent compared to 3 to 5 hundred from lead.

So if your guy gets things right you should be looking at about a 50 percent increase in Ah. If he can only fit the same Ah as stock you are only looking at a minor improvement. It depends on HOW you convert to lithium not just converting for the sake of it. Cell measurements are here: www.evassemble.com
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Re: lithium battery power on lifestand LSC?

Postby funkykeyboard » 29 Oct 2012, 23:27

pictures of under the hood added here.
http://s627.photobucket.com/albums/tt35 ... and%20LSC/

Present battery compartment measuring H9W3L15.

We cannot see a way that removing the battery compartment provides any more space for batteries.
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Re: lithium battery power on lifestand LSC?

Postby Dannyboy » 30 Oct 2012, 01:12

Hey, Danny here and I'm the one that is working on the chair so I guess I will just throw out my rough calculations to get some input.

So far we have 4 12v 18Ah batteries that equal 36Ah@24v

From what I can gather on the size of cells it looks like we will be able to squeeze 40 of the headway 10Ah cells into this space (10 per cell).
So, that is if I am not mistaken 100Ah@24v. If that is right that's a massive increase! Well worth the time and effort to convert..

~Danny
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Re: lithium battery power on lifestand LSC?

Postby Burgerman » 30 Oct 2012, 01:34

40?

You need 8 cells for 10 Ah so 5 x 8 cells gives 50Ah.

That would be 5 in parallel giving 50Ah and 8 of these sets connected in series for 24 volts.

So you would have 50 USABLE lithium Ah.

When using such small lead batteries the following is also true, and gains are better than expected.

The LEAD batteries are 36Ah of which only 80 percent is actually usable, in theory (or they will last just months). And because of the resistance/peukets of such small batteries and high C rate loading, only HALF of this 80 percent is actually accessible and usable. So in reality your 36Ah lead is just 80 percent of 18Ah. Not very pretty.

So you will get 3x the range, at approx 1500 cycles or 5 years use. Since Peukert affect is missing in lithium, resistance is low.
Or 7 to 10 years at double the range.

Or at the same AVERAGE daily range as a full set of lead gives to 100 percent, you should get 10 to 20 years life if charged CORRECTLY.
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Re: lithium battery power on lifestand LSC?

Postby Dannyboy » 30 Oct 2012, 01:57

Your right sorry, for some reason I was thinking 4 cell not 8.

Where can I find the exact width of the plastic battery holders? All I have to go off of is the battery diameter?
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Re: lithium battery power on lifestand LSC?

Postby Dannyboy » 30 Oct 2012, 02:08

Do the dimensions sound right? Box is 3wX9hX15l and cells are 1.4 so thats how I figured the 40. I think we will also be able to go up to the 12Ah cells since they are just taller giving us a total of 60Ah.

Where can I find the exact width of the plastic battery holders? All I have to go off of is the battery diameter?

Danny
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Re: lithium battery power on lifestand LSC?

Postby Burgerman » 30 Oct 2012, 02:33

All the plastic blocks on 10 or 12Ah cells are 40mm square. So each block that interlocks is 80 x 40 or multiples of this.

So each cell is 40 x 40 x its length plus screw heads and a 3mm clearance.

So 5 cells in a block is 5x 40mm or 200mm exactly. 4 is 160mm. etc.

My 13 rows x 6 cells is 13x 40mm long, 6 x 40mm cells. See my BM3 page.

As for length the TOTAL including blocks is 172mm for 12Ah cells. And deduct the 20mm difference for 10Ah cells as these are shorter.

http://www.evassemble.com has measurements.
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Re: lithium battery power on lifestand LSC?

Postby Dannyboy » 30 Oct 2012, 09:23

Great thanks for your help!
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Re: lithium battery power on lifestand LSC?

Postby funkykeyboard » 11 Nov 2012, 22:15

so when I am ordering 34 of these from here http://www.ebay.co.uk/itm/2x-JST-XH-con ... 35bb6866f1
do I need to include any forms about VAT etc, and disability? With it being America? Not used to ordering from abroad and 'claiming' the VAT relief

thanks in anticipation for any help.
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Re: lithium battery power on lifestand LSC?

Postby Burgerman » 11 Nov 2012, 23:12

Ordering from china, europ etc not usually any problem.

Ordering from the US you will likely be stung by the UK customs, for charges, VAT, then again by the damned Royal Mail for yet more charges. And they wond deliver your parcel until you pay them online / other.

I hate the customs/mail scam.

Better to order from anywhere but the US if possible and accept that you will pay vat for small stuff.
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Re: lithium battery power on lifestand LSC?

Postby funkykeyboard » 12 Nov 2012, 17:09

sorry just to clarify, ordering from China http://www.ebike-bmsbattery.com , I just place the order on the website, I don't offer them any paperwork or anything? Don't sort anything out with the VAT

This is the proper link to what I will be ordering http://www.evassemble.com/index.php?mai ... ucts_id=21
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Re: lithium battery power on lifestand LSC?

Postby Burgerman » 12 Nov 2012, 17:18

I just ordered and that was it. No customs issues. You may or may not be lucky. Not sure if you could get them shipped as wheelchair batteries direct from EVASSEMBLE.

You need to stick a label on outside saying tax relief claimed and also on the postage declaration. They are chinese so probably get it wrong.
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Re: lithium battery power on lifestand LSC?

Postby funkykeyboard » 12 Nov 2012, 22:29

might try here, going to contact them today.
http://eclipsebikes.com/headwaylifepo4- ... -1012.html

£16.50, fully featured the VAT off, £13.20. $18 equals £11.33. So about 70 quid dearer, but should be easier.
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Re: lithium battery power on lifestand LSC?

Postby funkykeyboard » 16 Nov 2012, 17:54

sales@eclipsebikes.com
We could offer 8.5% off the price of the 12Ah Headway cells and also include the plastic cell holders & metal connectors free with your order.
The 12Ah cells are normally priced at £16.50 so minus 8.5% discount would be £15.10 each.

34 x 12Ah Headway LifePo4 cells (£15.10) = £513.40
34 x Headway Cell Holder 38120S / 38140S = £0.00
34 x 2 Hole Cell Connectors 38120S / 38140S = £0.00
1 x Tracked UPS delivery (mainland UK excl. extended postcode areas) = £10.95

Total £524.35


-------------------------------------------------------------------------------
G-Power helen sales02@ebike-bmsbattery.com.cn
thanks for the link,the price is:USD:18/set(include 1pcs 38140 cell+1pcs hoder+1pcs connector),such as the picture.


the cost as below:
1. cell cost:$18*34=$612
2.shipping cost:$146
----------------------------

I have asked the English one if they can do it for £500, but to be honest I will probably play the extra 50 quid, and get them from the UK.
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Re: lithium battery power on lifestand LSC?

Postby funkykeyboard » 14 Dec 2012, 16:35

Okay, everything is up and running.

Had a few teething problems. There was a burning smell at one point, but we put that down to the newness of the charger transformer. Then there was the connection. The connection method was far too complicated for live PAs, so we've switched it to a new method, which just involves 3 straight plugs in. I'm hoping my electrician will come on and do a brief explanation as to how we changed the charger connection method.

Thanks for everybody's help.
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Re: lithium battery power on lifestand LSC?

Postby funkykeyboard » 14 Dec 2012, 17:35

Another question has popped into mind.

Is there a way to calibrate the battery charge indicator on the Dynamic DX controller, with the new lithium batteries. It would be handy if I could have a clue when I'm getting down to around 50%. The Hyperion charger told me the batteries were about 70% discharged when I charge them last time, but there was no indication at all on the indicator.

Is this even possible?
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Re: lithium battery power on lifestand LSC?

Postby Burgerman » 14 Dec 2012, 18:02

No.

The graph below is a discharge curve.

Volts drop from 3.6v or (3.450 here) fast in the first hundred yards. After that each cell group settles at a slightly different voltage, where it stays for the first 17Ah with hardly any drop at all. The same happens right up to about 1/3rd discharged, where it suddenly drops by about .05 volts. It then stays constant all the way to about 80 perecent discharged.

So you cant tell state of charge by voltage. Especially as the lowest group of cells are lower than the highest group (13 lines there!). After 17Ah removed, the highest line is still lower than the lower cells were after 1Ah...

So you can only see when it drops off a cliff at the end at about 90 percent used up. Or count Ah out. Buy 2 of those Ah/watt meters by turnigy. Connect in parallel.
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Re: lithium battery power on lifestand LSC?

Postby funkykeyboard » 23 Dec 2012, 22:57

Burgerman wrote:With lithium you are batter never topping them up fully...

Keep them between empty and full.

I charge mine to 3.450v per cell, not 3.600v It takes a little longer, but they are still 99 percent charged but will live longer.

First time you do this it will take a while to balance, at this lower voltage. After that no problem.

What capacity did you remove (lead) and what do you have now?

How did it affect performance and range?

okay, to save confusion, I am going to to the relevant thread.
I think the questions about capacity et cetera are answered above, aren't they?

I will see my electrician about changing the amounts of charge.
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Re: lithium battery power on lifestand LSC?

Postby Burgerman » 24 Dec 2012, 00:25

?? Elrectrician?

You just change the charger settings?
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Re: lithium battery power on lifestand LSC?

Postby funkykeyboard » 07 Jan 2013, 21:51

okay, this is the discussion between me and the electrician guy who has done my wheelchair.


adjust the charger according to this from the website;
With lithium you are batter never topping them up fully...

Keep them between empty and full.

I charge mine to 3.450v per cell, not 3.600v It takes a little longer, but they are still 99 percent charged but will live longer.

First time you do this it will take a while to balance, at this lower voltage. After that no problem



I am not sure if burgerman is using an updated firmware on his charger or not because I could only set it to -20mv so 3.580 so if you want I can research that if you want it all the way down to the same level.


so are you using updated firmware? Do you have a download link if you did, and update directions?
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Re: lithium battery power on lifestand LSC?

Postby Burgerman » 07 Jan 2013, 23:40

I am using an updated one, but the current official firmware is the same here. It allows LiFePO4 voltage settings to be from 3.450 upwards.

These are minor technicalities. The sort of thing you fine tune later as you wish at home. For now just use stock 3.600v setting for LiFe batteries. I cant decide if 3.450 or a little higher (since it charges and balances faster) is preferable. 3.500 seems a good compromise for Headways. The thing is that even at 3.600v it will likely outlive your chair! You will know the best setting when you look at the shape of the curve that the CALB batteries give. They may need to be at 3.5v or 3.6v If they shoot up high right at the end over a fraction of an Ah then dont need to charge that last bit.

See settings here:
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Re: lithium battery power on lifestand LSC?

Postby Burgerman » 07 Jan 2013, 23:54

This is 3.500v

It still shoots up fast at the end. And this happens in minutes so gives little significant extra Ah. Probably under .1 of an Ah extra to 3.600v Because this is higher than the full charged voltage, the balancing is easier and faster though.
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Re: lithium battery power on lifestand LSC?

Postby funkykeyboard » 15 Jan 2013, 22:24

okay considering what you have said there, about them probably outlasting the wheelchair anyway, I will just leave them charging to what he has set them on the charger now. Thanks anyway.
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Re: lithium battery power on lifestand LSC?

Postby funkykeyboard » 03 Mar 2013, 14:10

Been having problems with my wheelchair. The battery was completely flat The other day. I was gutted, because I thought these new batteries would be the end to them kind of problems.

Anyway, got all charged up again, and I thought I would try to gauge what I am getting out of these batteries. So I went out this morning from a full charge, having charged this morning, went out along the Marine Drive, and came back past the eco-centre.

Just checked out on Google maps, and it says that is 1.8 miles. So this is not full test, but I thought I could extrapolate from that figure.

It was a bit crazy. When I first plugged the charger in, it said it was 26,430V, but then it started fluctuating between that, and about 27,150. This chair normally charges up to about 27,670V. So;
27700
26400 -
01300

27700 / 1300 = 21.3
1.8 X 21 = 37.8 miles

So I can't really work out why the battery was nearly dead the other day. Strange.
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Re: lithium battery power on lifestand LSC?

Postby funkykeyboard » 03 Mar 2013, 14:21

The charger has peaked to say the battery is fully charged. It is still charging with a low level indication, and low-level of fan noise. At present it is saying 1.16a charging. But that is changing all the time. And the amount the batteries are at 27654V is also fluctuating all the time. Why does it do that? Is it going through the cells telling you what each cell is charged up to. Should I really leave it charging for ages and ages for all the cells to equalise? I did leave it on the other day for about 800 minutes. Does it need long charges to equalise on regular basis?

Leaving it on for ages is a problem, as I did it feel other night, my wife had to go in the other room to sleep, and the charger kept me awake all night. Will not be doing that soon.
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Re: lithium battery power on lifestand LSC?

Postby Burgerman » 03 Mar 2013, 15:11

funkykeyboard wrote:Been having problems with my wheelchair. The battery was completely flat The other day. I was gutted, because I thought these new batteries would be the end to them kind of problems.


Determined how? COMPLETELY means down to 2.5v per cell. Lower than this means damaged cells...

Anyway, got all charged up again, and I thought I would try to gauge what I am getting out of these batteries. So I went out this morning from a full charge, having charged this morning, went out along the Marine Drive, and came back past the eco-centre..


How are you determining full? 3.600v per cell (+ or - 0.003V) and completely balanced?

Just checked out on Google maps, and it says that is 1.8 miles. So this is not full test, but I thought I could extrapolate from that figure.
It was a bit crazy. When I first plugged the charger in, it said it was 26,430V, but then it started fluctuating between that, and about 27,150. .


Then you have a bad connection. Unless the batteries are either being charged or discharged by something voltage should be stable. It may climb smoothly by a few 10ths of a volt after use for say 20 mins only.

This chair normally charges up to about 27,670V.
So;
27700
26400 -
01300

27700 / 1300 = 21.3
1.8 X 21 = 37.8 miles
So I can't really work out why the battery was nearly dead the other day. Strange.


I am confused. Battery terminal voltage has little bearing on range and a totally discharged battery would be around 2.7v per cell.

You need to recharge after a run. And read Ah back. Dont look at volts, other than to see when it reaches 3.600v per cell and all cells within 0.003v of each other.
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Re: lithium battery power on lifestand LSC?

Postby Burgerman » 03 Mar 2013, 15:39

The charger has peaked to say the battery is fully charged. It is still charging with a low level indication, and low-level of fan noise. At present it is saying 1.16a charging. But that is changing all the time. And the amount the batteries are at 27654V is also fluctuating all the time. Why does it do that? Is it going through the cells telling you what each cell is charged up to. Should I really leave it charging for ages and ages for all the cells to equalise? I did leave it on the other day for about 800 minutes. Does it need long charges to equalise on regular basis?

Leaving it on for ages is a problem, as I did it feel other night, my wife had to go in the other room to sleep, and the charger kept me awake all night. Will not be doing that soon.


When FULLY charged it will read 0.00Amps. And each cell will read between 3.698 and 3.602 and the charger will be holding them there. Then disconnect in the morning.

Its fluctuating because the charger sees the voltage correct under charge, but when it "lets go" the voltage falls. So it starts again. If batteries had no internal resistance and if charge and balance cables wer infinitely fat and short then it would just end. But they are not. So this will continue untill the battery becomes full and amps drop to zero. During the pulses it sees cell voltage or terminal voltage is lower than a full battery. Leave it till morning.

Remember you are chargeing a 200Ah battery at around 16Amps. So that means that it will take 12.5 hours! If you REALLY ran it dead. But the time taken for the last 2 percent is about 2 hours no matter how much you need to put back, plus balancing.

Balancing a very well made pack is almost instant. But if cells vary in resistance or self discharge, Ah, resting voltage etc then it takes a variable amount of time. That part was down to whoever you had build the pack.
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