Li+ 42Ah cell swap. How to proceed??

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mpregal
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Li+ 42Ah cell swap. How to proceed??

Hi,

During last months I have experienced a severe range loss and some unpredictable behaviour in my Vectrix Li+.
After many tests and theories, I found that cell 3 in block 0 is conditioning all the pack.
While riding uphill, this cell drops from 2,97v to 2,65v (all other 39 remain 3,12-3,20v).

I have decided to swap this cell with another fresh one.

The question is "how to proceed??"
I know how to reach the battery pack and BMS, but no further.
My idea is to take BMS-0 out, unscrew connectors from cell 3 and "push up".
Is it so easy?
Has anybody swapped Li cells?

Any advice (pictures) will be welcome!

Thanks!

Kocho
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Re: Li+ 42Ah cell swap. How to proceed??

I don't know how to take that one cell out as I have not seen the Li packs. However, what I can say is that you need to manually balance the replacement cell to the voltage of the rest of the cells, so that you do not have to go through tedious and long balancing through the stock BMS.

I would also suggest you troubleshoot the BMS itself - was the cell bad to begin with (good, as replacing the cell will solve your issue) or is the BMS killing it over time (bad - you'd need to fix the BMS or it will kill the new cell too)?

mpregal
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Re: Li+ 42Ah cell swap. How to proceed??

Hello Kocho,

Thank you for your advice.

Regarding the BMS, I only had 1 board working properly. The other 3 boards were replaced because they didn't read voltages right.
As soon as I replaced the BMS boards many cells I thought were "weak" began to charge and discharge properly.
There is only one cell that rejects to charge over 3,310v.
This makes eq process eternal.

Thanks again.
Manuel

Jorge Rocha
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Re: Li+ 42Ah cell swap. How to proceed??

Hello,
I know that a lot of work, remove one of the interior of the cells together, and I know a lot more work to put everything in place.
The cells may already be slightly swollen, and this can make it more difficult this process.
I would first few screening tests in order to verify that it is actually happening this, or if this reading is caused by some other defect in the BMS.
The first test would put no load the damaged cell with a charger for a cell the maximum 3,60V. Then a discharge test in conjunction with a neighboring cell also precharged. Thus we can be certain that there differences between cells.

Electrifying greetings,
Jorge Rocha

All for a more ecological world!

mpregal
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Re: Li+ 42Ah cell swap. How to proceed??

Hello Jorge Rocha!

Thanks for your advice! I have seen your job in Jasmim's bike: excelent!

Regarding my battery, I also think that swapping one single cell will be hard, so I will try to charge the lazy cell with a single charger and see what happens.

Thanks again for your opinion.

Manuel Pregal
Vigo-Galicia-Spain

mpregal
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Re: Li+ 42Ah cell swap. How to proceed??

Hello again Jorge Rocha!

I have made some tests, and charged the weak cell alone up to 3,6v.
The problem is that as soon as I unplug the charger voltage drops to 3,2v (while other cells in pack remain at 3,4v). This cell only takes charge if I apply 2Amps or more.
So when equalizing this cell drops and equalization never ends.

I have decided to replace it.
If you have pictures of the dismantling procedure they will be welcome.

Regards!
Manuel Pregal

Jorge Rocha
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Re: Li+ 42Ah cell swap. How to proceed??

Hello,
Also it happened to me the same when I tried to load the cells with the inserted BMS. I never did, by having the BMS to do the bleeding when it should not.
When I removed the céluals and its BMS can confirm that that was it, the BMS bleeding without the need to do so.
So you'll know if it's defective cell when the off loading up the BMS.

Electrifying greetings,
Jorge Rocha

All for a more ecological world!

mpregal
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Re: Li+ 42Ah cell swap. How to proceed??

Thanks Jorge Rocha!

I will continue with tests following your advice.
If I don'f find the problem may be I take the bike to Aveiro for a "restyling" ;-)

Thanks!

zeuz
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Re: Li+ 42Ah cell swap. How to proceed??

Hi,

There's a person in Portugal selling a complete Li+ pack (it is an original kit to upgrade from NiMh to LiPo). If you want I can pass is contact to you.

You also have the option to buy from Vectrix Parts: http://shop.vectrixparts.com/category/batteries-

Oh! And Jorge Rocha is a very capable technician!
Luckily for Vectrixians in Portugal there are 3 very capable technicians to help us keep it on the road.

mpregal
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Re: Li+ 42Ah cell swap. How to proceed??

Hello Zeuz,

Please send me by MP the contact of the seller.

I have also thought to visit Jorge Rocha (I live in Vigo, only 230km from Aveiro).

Thanks!

zeuz
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Re: Li+ 42Ah cell swap. How to proceed??

Done!

mpregal
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Re: Li+ 42Ah cell swap. How to proceed??

Thanks!!!

MEroller
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Re: Li+ 42Ah cell swap. How to proceed??

(I live in Vigo, only 230km from Aveiro).

I was on business in Vigo two months ago, and actually was on the lookout for electric two-wheelers, but sadly saw none. Good to know there actually IS a VX1 at home there :-)

My rides:
2017 Zero S ZF6.5 11kW, erider Thunder 5kW

mpregal
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Re: Li+ 42Ah cell swap. How to proceed??

Hi MEroller!

Here in Vigo I have seen one Vectrix NiMH (acid gren) and during last month two BMW's Evolution-C (one of them is a demo unit from a local dealer).

There are also some cars:
I-ons and C-zeros for rent, others from the local authorities and two or three from individual owners.
There is also one Nissan Leaf I see every day at my son's school.

Not a very big electric team, but it grows year by year.

Whatever you need here in Vigo, please let me know.

Regards,
Manuel Pregal

Jorge Rocha
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Re: Li+ 42Ah cell swap. How to proceed??

I have also thought to visit Jorge Rocha (I live in Vigo, only 230km from Aveiro).

Thanks!

It is always a pleasure to receive friends this electric mobility. And Aveiro is a very beautiful city to meet and visit! Everyone is invited!

To disconnect the BMS must be made in a way that a cell is turned off at a time, from highest to lowest. Thus, the last connection to do will be the GND.

All for a more ecological world!

mpregal
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Re: Li+ 42Ah cell swap. How to proceed??

Good point Jorge Rocha!

I didn't know that about BMS's

Thanks for sharing!

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