Lithium Build for Magic Mobility X4

[ex-Gooserider]

Ring terminals. Cable. Solder. Heatshrink. Anything else is a bad idea.

What is the best size for the cable? 8 AWG?

BM uses 10mm^2 - which is theoretically equivalent to AWG 7, but while they have size specs for it, odd number AWG sizes are not normally available... AWG 8 is a bit smaller, and probably adequate... AWG 6 is larger, and on the 'overkill' side... Take your pick... Worth noting that the most commonly available pins for Anderson SB-50 / PP-75 connectors are sized for AWG 6, so it takes a bit of extra crimping or stuffing with filler wire to use smaller wire sizes.

I would look at the wiring used as stock on your chair and go for AT LEAST that large, and consider larger as IMHO many manufacturers seem to undersize their wiring, especially on a chair like yours which sounds like you may be more likely to use in high current load conditions...

I like welding cable more than the tinned marine wire - it seems more flexible, but either will work.

ex-Gooserider

[swalker]

I am starting to get excited:

[swalker]

The 176AH battery cells have arrived. They apparently spent most of the day traveling around in the UPS truck. While it was below freezing when they were delivered, the batteries appeared to be a bit warmer than freezing (but not much). I plan to let them slowly warm up overnight and then start charging the cells tomorrow.

I ordered 7 copper connectors. They appear to be tinned, which I was not expecting. I did not order any terminal bolts, as they said the don't stock them and would have to charge a significant amount for them. But, they included 16 of them anyway;).

The terminals have a plastic ring around them - black for positive and gray for negative. Those rings are embossed with a polarity symbol (black +, gray -).

Each cell is wrapped with what appears to be PVC shrink wrap as insulation. On at least one of the cells, that shink wrap has already worn through on one corner. I plan to add additional insulation as I build up the battery pack.

Here are some pictures.

[swalker]

Here are some more pictures.

Steve

[swalker]

The connectors and terminal bolts.

Steve

[expresso]

nice connectors - those screws look very short to me - you may want to change them anyway and use some allen head kind

now the fun begins -

[terry2]

The connectors and terminal bolts.

Steve

Are those 6 Mm by 10 mm long?

Thanks

[Burgerman]

Those connectors bars look far too stiff, and are not flat, and will give bad connections and come loose with vibrasion. If it was me I would definitely use ring terminals and flexible cable in place.

Those threads look a little rough. And the plastig grey part looks dirty as if its used? Maybe just the photo. Definitely throw away the screws. Use allen head bolts, and be sure they do not bottom in the holes when the terminals or bus bars are fitted.

And best test a cell or all cells before making a pack as they are unknown.

[flagman1776]

I would test fit the bus bars and see how they fit. If they are accurate, you should be good. If they need tweaking, do it off the cells. Make sure the contact area is clean & bright when you assemble.
Absolutely, replace those Philips head screws with internal hex head... the Phillips heads were originally designed for production assembly... and to slip rather than stripping the threads. You need a more positive drive & careful tightening for your connections.

[swalker]

Results of charging the first cell.

[swalker]

I have been debating what to use to connect the cells together. I had initially planned on using copper bus bars and ordered some with the battery. The are tinned, insulated in the middle, and quite malleable. They seemed like they would do the job.

Then, as I inspected each battery, I noticed that the large broad sides are not flat. They are slightly bulged. The bulge is the same on each of the large faces on each cell. I suspect this is from manufacturing, but would appreciate any opinions about whether or not the batteries are defective.

To my eye, they show no signs of prior use. The initial charge of the first cell put just under 175 Ah into it. The second cell is almost finished charging and looks like it will take 175 Ah as well.

With that slight bulge in the large side of the battery, the batteries are a bit more that the specified 54mm thick. It is hard to measure, but I am guessing the bulge adds about 3 to 4 millimeters to the thickness of each cell. I have plenty of room in my battery box to accommodate this extra size.

There are two issues.
1. The copper bus bars I bought with the cells will not fit. They are too short, as shown in the picture. I now plan to use 6 AWG stranded connectors
2. I was planning to use fish paper to insulate each cell and then wrap each cell in PVC shrinkwrap. I still plan to do that, but now will need some compressible foam that can conform to the cells' curved sides between the cells. Fortunately, I have plenty of space in the battery compartment so that will not be a problem.

Steve

[Gnomatic]

Good info about those cells - I believe you're the first one here to use those in particular. Using 6awg for the connectors will work well, custom sized connectors for your pack.

[swalker]

I am glad I am able to share the knowledge I am gaining with these cells. I was kind of hoping somebody else would be the guinea pig, but I ran out of patience:).

The middle, insulated part of the bus bar is quite flexible. I tried straightening one out completely and found that when it is completely flat it is 1 to 2 millimeters too short to connect the cells, even with no extra insulation between the cells.

I am ordering 6 AWG tinned copper silicone sheathed wire along with tinned copper lugs.

Steve

[expresso]

i done one small ADD On with wiring and worked fine - maybe even better less there to begin with once bolted down -

the size of the Cells - just goes to show - hard to believe what they print or show in there websites - its best to confirm it again with them before ordering and then even still you found it a bit larger than expected - your lucky you can still use them in your space - but if someone was barely making it with the specs - they might have been stuck with them and not able to fit them.

175ah back in - good start

thin doubled sided tape and silicone sheet was what i used between the cells --

[Burgerman]

The bulge in the cells would worry me. Lithium cells bulge if over discharged, overcharged or used over current. Or if stored full.

You say you got 176Ah back into the cells. But that means that they either shipped them 100% discharged, which is rather unusual... Or that you discharged them.

Questions.
What was the exact voltage when they arrived?
What did you do first, top them up, then discharge to 2.9V?
Or just charge and got 176Ah back in?

They should be shipped at around 35 to 50% charged.
And...
You can only measure capacity on a controlled discharge, not a charge.

Next step, a controlled DISCHARGE on 1 cell to 2.90V to measure capacity.

[swalker]

Exact voltage as received: 2.98 for some cells, 2.99 for other cells.

When I received the cells I did the following:
1. Visually inspected the cells
2. Confirmed the marked polarity was correct
3. Checked the initial voltage, which was either 2.98 or 2.99, depending on the cell.
4. Charged the cells, without discharging first.

I have charged 2 cells and am in the process of charging the 3rd cell now. The graphs look similar for all 3 cells (see my post above for the charging graph of the first cell).

I did not write down the voltage before charging the cells. I will start doing that. They were at least 2.98 or 2.99. None were 3 or higher and none were 2.7 or lower.

I recognize that capacity can only be measured with a discharge. I plan to discharge the first cell to 2.9 volts tonight.

The amount I was reporting was that recorded in the "Capacity IN" field of the Cells tab of the PL8v2 software, which was 174943 mAh for the first cell I charged.

Thanks for your insights. Feel very free to point out anything I might be doing wrong or that I could do better!

Steve

[Burgerman]

Maybe shipping 99% empty is some air freight rule? But its very odd. A week or two delay could see them dropping to lower than allowed. And discharging to that level isnt really a good idea regardless other than testing.

The bulge part worries me. Shirley may be more helpful. He has used these style of cells, I have not yet.

[swalker]

The shipping was delayed by the Chinese New Year.

They were sent to shipper on January 23th. They arrived here on February 27th.

So, it was 5 weeks total since they left the factory. It does not seem like they would discharge by 20 or 30 percent in that amount of time.

Steve

[Burgerman]

Nope.

[Gnomatic]

The cells snaker got for his 150Ah pack also arrived 99% discharged. The PL8 refused to charge a few of them initially because the voltage was so low. Fortunately, once assembled etc his pack turned out okay. In fact I believe he holds the record here for longest distance traveled in a day.

[shirley_hkg]

The bulge in the cells would worry me. Lithium cells bulge if over discharged, overcharged or used over current. .

That's true . They are NOT manufacturing defect , but result from having been heavily used. Can't find any cells that are rated @176Ah actually .

I'd say they are 200-210Ah NEW , that I could find and match to their general specs .


Lost 15% during use/aged, and reach the swap out criteria , into hands of recycler. They pick out the survived ones and sell to non-demanding applications, so-called "secondary recycle / use " .

Shouldn't worry too much, as our wheelchair-draw is pretty gentle , relatively .

[Scooterman]

That's an astute analysis Shirley, and makes sense.

If what you say is correct, shouldn't the seller declare that in the listing, so buyers can make an 'informed purchase'?

[terry2]

I have been debating what to use to connect the cells together. I had initially planned on using copper bus bars and ordered some with the battery. The are tinned, insulated in the middle, and quite malleable. They seemed like they would do the job.

Then, as I inspected each battery, I noticed that the large broad sides are not flat. They are slightly bulged. The bulge is the same on each of the large faces on each cell. I suspect this is from manufacturing, but would appreciate any opinions about whether or not the batteries are defective.

To my eye, they show no signs of prior use. The initial charge of the first cell put just under 175 Ah into it. The second cell is almost finished charging and looks like it will take 175 Ah as well.

With that slight bulge in the large side of the battery, the batteries are a bit more that the specified 54mm thick. It is hard to measure, but I am guessing the bulge adds about 3 to 4 millimeters to the thickness of each cell. I have plenty of room in my battery box to accommodate this extra size.

There are two issues.
1. The copper bus bars I bought with the cells will not fit. They are too short, as shown in the picture. I now plan to use 6 AWG stranded connectors
2. I was planning to use fish paper to insulate each cell and then wrap each cell in PVC shrinkwrap. I still plan to do that, but now will need some compressible foam that can conform to the cells' curved sides between the cells. Fortunately, I have plenty of space in the battery compartment so that will not be a problem.

Steve

I have got mine coming on Monday from the same company.
I'll let you know if my cells are the same.

[steves1977uk]

That's an astute analysis Shirley, and makes sense.

If what you say is correct, shouldn't the seller declare that in the listing, so buyers can make an 'informed purchase'?

I agree, also heavily used cells should be discounted by 30-50% since you won't get the full cycle life or capacity.

Steve

[expresso]

this seems to be common with many sellers from China etc, - they all claim its brand new etc, but we cant know that for sure and its not easy to deal with them once you got them in your home already - if in fact these are used of some sort or defective - it should have been disclosed as such and discounted of course -

the only recourse we have is - either return the whole thing - and have to pay for shipping back - which i dont think will be Cheap - or try to work out a deal with them and get a partial refund at the very least - so far the only brand new cells were the headways and they proved themselves over the years - but of course there time is up now .

at least have to ask about the bulging of the cells - and try to get a some refund based on that alone - if all the rest check out fine at 175ah cap. you did get what they say they are - 176ah - its always a hit and miss with these things - till we find a GOOD Seller that delivers on its promise - From now on i guess we have to tell who ever we buy from to please check the cells physically also before shipping them out -

if they are new - they shouldnt have to do that really - but we have to be very very specific with them.

https://www.ev-power.eu/LiFePO4-small-c ... ro21i3stu7

i feel this site is honest with there cells - they all look brand spanking new to me - but very limited with there sizes and Cap. so not much use to us

[elryko1992]

this seems to be common with many sellers from China etc, - they all claim its brand new etc, but we cant know that for sure and its not easy to deal with them once you got them in your home already - if in fact these are used of some sort or defective - it should have been disclosed as such and discounted of course -

the only recourse we have is - either return the whole thing - and have to pay for shipping back - which i dont think will be Cheap - or try to work out a deal with them and get a partial refund at the very least - so far the only brand new cells were the headways and they proved themselves over the years - but of course there time is up now .

at least have to ask about the bulging of the cells - and try to get a some refund based on that alone - if all the rest check out fine at 175ah cap. you did get what they say they are - 176ah - its always a hit and miss with these things - till we find a GOOD Seller that delivers on its promise - From now on i guess we have to tell who ever we buy from to please check the cells physically also before shipping them out -

if they are new - they shouldnt have to do that really - but we have to be very very specific with them.

https://www.ev-power.eu/LiFePO4-small-c ... ro21i3stu7

i feel this site is honest with there cells - they all look brand spanking new to me - but very limited with there sizes and Cap. so not much use to us

Yes is a trust company from Czech Europe.

You know about Lithium Titanate?

https://www.youtube.com/watch?v=eAUYbSDEy6I

[Burgerman]

But they have a few issues for our use.

[swalker]

Here is some information for a single cell.

Initial voltage out of the box: 2.99
Capacity IN for initial charge: 173862 mAh
Cap. OUT for the subsequent discharge: 167184 mAh

Charge and discharge were done with the preset BM posted for "LiFe Charge ONE 90 to 200Ah Cell". This charges to 3.6 volts and discharges to 2.9 volts. I changed the charging current from 40 amps to 25 amps to keep wires a bit cooler.

Here are the graphs of the charge and discharge.

Steve

[swalker]

I really appreciate the contributions everyone has made. Your honest opinions of the cells has been most welcome, even if that information is a big disheartening.

Here is my dilemma.

The cells are clearly not what they were described to be. They were described as being new. They were described with a certain size, which turns out to be invalid because of the bulging. They were described as having a 5 year guarantee with a life of 6000 charge/discharge cycles.

After a more careful visual inspection, I find indications that these ARE NOT new cells. There is enough debris around the terminals and a fine wear pattern on the terminals (visible with a magnifying glass) to indicate that they are very likely used cells. The bulging of the cells indicate that they are most likely well used. The various mars in the PVC shrink wrap reinforces this opinion.

Now, what do I do about it?

I will take whatever steps I can through the vendor, paypal, and my credit card company to get financial relief. Returning them to China will certainly be expensive, and very well may not be cost-effective.

What I am pondering is whether or not the cells are good enough to keep and use if there is sufficient financial compensation.

The one cell I have tested for discharge shows it will has a bit over 165 Ah of capacity when drained to 2.9 Volts from a full charge to 3.6 Volts. Assuming the other 7 cells have similar behavior, is this a set of cells I can use?

While I have not yet test fitted them, I am convinced from measuring them that they will fit in my wheelchair's battery compartments.

I think from an energy capacity standpoint, they may work. But, what about from a safety standpoint? Are these well-used, bulged cells going to be safe to sit on top of while they power my wheelchair?

I am certainly interested in your thoughts on this.

Steve

[expresso]

Paypal will be very helpful i believe - you can take pictures of the cells to prove they are what you believe to be used - etc, i filed a claim also with them and they agreed and told me to send them back to get all my money back - but i didnt want to do that - i just needed one cell replaced - because of paypal stopping the payment - seller sent me an extra cell -

you may have better luck with your seller - at least you have to contact them and let them know and see what can be done - with twice i ordered from china - what ever they stated as there Ah - it usually comes out to be a bit less - more or less between 5ah and 10ah less than stated - since we stop at 2.9V and charge to 3.6v

they will say to go to 3.65v and down to 2.5v to get the rated Ah they state - i kept both my orders in the end and i got a little refund on one of the orders because i did complain that it wasnt a 80ah cell rather more like a 70ah - but they seem fine to me - in your case - its tough - i would call them - contact them and start there -

call your credit card also to ask what can they do in this case - maybe they can reimburse your shipping it back IF you wanted to do that - Paypal gives you 90 days i believe to open a case - in the meantime - just for you to know - call DHL or UPS etc, who ever delivered it to you and ask how much would it cost to return it - you have the return info on your label ? size of the box and weight etc, - see if you can get a ball park figure on return shipping just to know - we know it wont be cheap - but maybe if you had to - and credit card can help etc, - never know - at least get your facts together on what can be done and what it would cost - this way you can try to get a refund and keep them if they offer a good enough refund - that would be the easiest solution - or replaced with new ones ? if they want to replace with new ones for real - and you pay shipping back - if a few hundred maybe it may be worth it that way - only if you really get NEW ONES -

sorry to hear -