CALB CA series cell performances

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mikethebike3
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Re: CALB CA series cell performances

Postby mikethebike3 » Thu Jul 19, 2012 7:46 am

Andy Zhou replied as follows - I was waiting for his OK to post it, but I don't think it's that sensitive:
Hi
Thanks for your letter. attached pls see the quality claim file, including info we will need for cells replacing.
For the BMS needing, we ask for :
1. there should be BMS installed, collecting the current, voltage, and temperature data, carrying out protection function based on set up parameters.
2. active balancing will help in prolonging the battery cycle life;
I tried the link, I can't open it in China, sorry for that.
Peter, can you help deal with it?
BR,
andy

This morning I got a much more explicit email from Peter:
Hi Mike.

How the balancer work is not the thing.

Capacity one or a “heater” is equal.

You can pray to different god´s....

But a balancer is a must for the long life of the cells.
I know that some systems run without balancer long time.
But it is better to use them....

You know that a LiFePo4 cell will be destroyed real fast by under- or overvoltage.
And that is, why CALB want a highclass monitoring system.
If the system has no data logging, it is hard to decide what happen with the cells.
Also a OVP function by a contactor or the connection of the charger with CAN communication is necessary.
UVP must stop discharge., not only warrning.
If it is night, it rains and the system say stop, you will drive to your house on the hill 1 mile away.....If the system dont stop discharge....
And that could destroy cells....

Only left capacity and internal resist can be test direct.
If a cell case blow up, it can have diff. reason.
So the data of the last cycles will help.
And the user will get a new cell in short time.

The MSU ( most stupid user ) can destroy cells fast......

That is, why we connect the warranty with a high class BMS

I hope, it is clear now.

by the way......

Andy is a guy in the sales management in China.
But CALB want have a look on the deals in Europe.
That is the reason why they dont post the email of my company at their webside.
The address and phone number of my company is shown at the international marketing.

http://en.calb.cn/comm/?id-159.html

So if someone will contact me, he can do it direct

calb-europe@hotmail.de

And we work together with GWL, Lithiumbalance.DK and some other reseller in Europe
Our own stock volume will be high up soon.
And we also deliver complete solutions.

Best regards

Peter
(CEO)

Fahrzeugtechnik Jürgens
CALB Europe

and you can post it, if you want.

Helpful, but still not definitive. I sent a reply:
Hello again Peter
Thanks for that, very helpful and I understand much better now. And I will post your reply on the forum, I know many will be interested.
So if a UK (or any EU) purchaser buys through you, is their warranty agreement (like the sales agreement) with you, i.e. Fahrzeugtechnik Jürgens, and not with Calb-Cn?
So if we can convince you (rather than Calb-Cn) that a particular BMS is suitable, then the warranty will apply? If you go out of business (sorry to ask!), will Calb-Cn take over the warranty?
Calb's specification for a complex BMS, (in particular with data logging) as a requirement to keep the warranty valid is (I believe) a new development in battery supply. Of course those who have been looking after their cells responsibly can understand why (and do it anyway), but to make it a REQUIREMENT is new. Maybe Calb intend to release their own BMS, then at least satisfying their requirement would be clear, although I'm sure this would affect their sales.
As I am sure you know, there are a group of BVS members who have been building and operating their own design BMS's for many years, and who know their subject very well. You can see their postings on http://www.batteryvehiclesociety.org.uk/bvsorguk/forums/viewforum.php?f=53.
Although I am an engineer, I am quite new to all this - I just want to buy some batteries and know they are under warranty! My understanding is that top balancing while charging requires a distributed BMS (typically one per cell), whilst plain monitoring can be centralised, with balancing done occasionally if the monitoring indicates it is needed. Do you feel strongly about which (per cell balancing every charge, or monitoring with balancing when needed) you would/could accept? You say that OVP and UVP interlocks are essential (agreed), but otherwise, is the per-cell logging the most important thing, so either approach would be OK? Or will you insist on the installation of a particular BMS?
This really does need to be clarified Peter, I just want to buy my batteries and enjoy them!
Thanks again, and best wishes
Mike


I'll report back with any developments, but I would suggest that interested parties contact Peter directly (letting us know what happens). If I'm not the only one pushing (anyone there?), perhaps we'll reach a conclusion more quickly!

Mike

Beemer
Posts: 294
Joined: Sat Jun 04, 2011 12:10 pm

Re: CALB CA series cell performances

Postby Beemer » Thu Jul 19, 2012 8:52 am

You go buy your CANBUS linked "solution". To a non problem, girlfriend. :lol:
He's covering his ass and there's a ready sale for extra equipment.

Interestingly GWL powers' old BMS was dropped like a brick for the new one. No further support, blah, blah.. There was a reason for that. They had a nice piece on how to de-balloon your cells in a vice. I cannot help but put 2+2 together but hey.

Still off subject but as we have to suffer the ignominy about BMS's, here's john Hardy experimenting on cell drift to see if he can find any throughout the life of the cells. I linked a video of him before.
http://tovey-books.co.uk/testing.php

mikethebike3
Posts: 27
Joined: Wed Sep 17, 2008 3:19 pm
Location: NE Norfolk, UK

Re: CALB CA series cell performances

Postby mikethebike3 » Thu Jul 19, 2012 11:42 am

OK, some good (i.e. clear) news in an email from Peter:
Again....

first look in the pdf:
Expl 1.jpg
Expl 1.jpg (42.52 KiB) Viewed 13233 times

selfmade BMS can be accept, if the system has the functions.

CALB will provide the warranty also if i will lay in future only at a sandy beach........
But first the reseller must controll the cells.
If you buy from CALB direct, you must send it back to china.
Much cost in front for you and need also a lot of time.

BMS are from all provider continuous under develop.
So they will be better over the time.
And for different use of the cells, you need different BMS.

I hope, now it is clear

Best regards

Peter

Very interesting I think:

1. The European agent Fahrzeugtechnik Jürgens will honour the warranty. If for any reason FJ aren't there, Calb Cn will take this over (although I'd like this verified by Calb Cn)
2. BMS can be homemade, so long as it has some basic functions:
2.1 Individual cell monitoring is a must
2.2 If any cell goes over 3.7V, the charger must be disconnected
2.3 If any cell goes less than 2.5V, further discharge must be disabled
3. Balancing should be included in the BMS, but it's not essential
4. If balancing is included, it can be mounted on the cells or in a centralised monitoring unit
5. (mentioned in a previous email...) Datalogging during charge and discharge is not essential, but if recent data can be provided with a suspected faulty cell(s), it will speed up its (their) replacement

Mike

GregsGarage
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Re: CALB CA series cell performances

Postby GregsGarage » Thu Jul 19, 2012 4:14 pm

Mike,

Looking at the responses from CALB, they are recommending balancing but not requiring it. The only thing I would have to disagree with is the statement that "if you don't use balancing unit the cells will lost capacity". I think this isn't being translated well and what I think they mean to say is "if you don't use balancing the pack will lose capacity". As long as you are monitoring on a per cell basis and you bms prevents any cell going over or under voltage the cells will be fine. You will not have any damaging cell reversals or any cells getting overcharged, the bms sees to that. What you won't be able to use is all of the packs capacity. Lets imagine a 3 cell pack, cells A, B and C are all at 100%SOC. You can discharge and recharge and use all the capacity of the cells. Now lets say cell A is 100%, cell B is 75% and cell C is 50% SOC. When you discharge 50% out of the pack you then have 50, 25 and 0% in the three cells. Your bms stops the discharge because of cell C and when you recharge it will stop when cell A gets back to 100%. Your pack has lost 50% of its capacity, but the cells still have 100%, you just can't use it until you bring them all back into balance. This is a very simplified example and the other main thing it doesn't address is capacity variations in the cells. Lets say the the 3 cells are 100ah nominal but actual capacities are 110, 100 and 90 ah. How do you balance those 3 cells. You can top balance, get all cells to 100%. then when you take 90ah out you have 20ah left in cell A, 10 in B and 0 in C. As long as you have individual cell monitoring this isn't a problem, bms stops discharge when cell C gets to 0. If you are running a pack without a bms and keep discharging, cell C gets reverse charged and destroyed. The bottom balance idea is to balance all cells at near 0% SOC. Then you reduce the risk of a reverse charge on the cells, all cells get to 0 at the same time. But in both cases you still only have 90ah of capacity in the pack. What really matters in this simple pack is that we can use all of cell C's 90 ah capacity. Any further balancing towards the top or bottom gains you no extra range.

Now that we understand that, how often do we need to balance. It turns out not very often. People from both camps, to bms or not to bms have found and proven that these cells don't drift. So daily balancing is not required. I was speaking to Evan Tuer recently, he has one of the Peugeot 106 electrics from the late 90's converted to CALB cells. He no longer bothers with balancing, just monitors cell voltages, after over a year they are all spot on. "I'll balance them once a year whether they need it or not" where his exact words. That is why I think a better solution is to move balancing off board of the car, make it part of a regular maintenance operation when you check cell connections, battery box mountings, etc. This makes the bms simpler and cheaper and gives you the option of having a balancer that can be used on multiple packs. :D
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191

GregsGarage
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Re: CALB CA series cell performances

Postby GregsGarage » Thu Jul 19, 2012 4:15 pm

Beemer wrote:here's john Hardy experimenting on cell drift to see if he can find any throughout the life of the cells. I linked a video of him before.
http://tovey-books.co.uk/testing.php

Looks like a good write up, I'll have a good look later. :)
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191

Beemer
Posts: 294
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Re: CALB CA series cell performances

Postby Beemer » Thu Jul 19, 2012 5:36 pm

GregsGarage wrote:
Beemer wrote:here's john Hardy experimenting on cell drift to see if he can find any throughout the life of the cells. I linked a video of him before.
http://tovey-books.co.uk/testing.php

Looks like a good write up, I'll have a good look later. :)


Yes, I like what he's doing. Thought it odd his test unit was interfering with his Arduino so had it mounted outside the steel shed. Lessons to be learned!
Anyway, here's a better link where the video actually starts:
http://youtu.be/jiBunCL_ywI?t=52m50s

JR said he is going to do 10C tests on a new 100AH CALB. I'll nick his graphs and in return possibly aid his market for the items he sells.
Like ya do :mrgreen:

Beemer
Posts: 294
Joined: Sat Jun 04, 2011 12:10 pm

Re: CALB CA series cell performances

Postby Beemer » Thu Jul 26, 2012 11:14 pm

Damien McGuire from down near Dublin has been experimenting with the new 180AH cell in mind to convert a BMW 5 series.
Here's his action packed video with lots of sparks, glowing steel bars and a melted, twisting BMW 18mm spanner as the single cell kicks out about 3KW.
http://youtu.be/xcuyfS7yybQ

On the other end of the coin and being totally off base, (like we do). Tom Hardy who has been (BMS free, lol) testing for bottom balance drift using Headway cells has stopped short his experiment at cycle 576 due to cell #8 failing on him. Bottom balance stayed good. 576 might not sound a lot but he was dis/charging at 2C. If this was a 100 mile car it would equate to a one in eight failure at 57500 miles. However, he did note this cell was a bit "off" from at outset but put it down to other factors.
http://tovey-books.co.uk/testing.php

GregsGarage
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Re: CALB CA series cell performances

Postby GregsGarage » Mon Jul 30, 2012 8:21 pm

From Tom's website, this caption on one of his charts caught my attention.
This chart records the difference in voltage between lowest cell voltage and the highest cell voltage (the horizontal axis is GMT time). As the test has concluded, this shows two weeks up to the death of cell 6. The increasing variance is the approaching death of cell 6, not cell drift. Note that the minimum variance on each cycle remains broadly unchanged.

To me this would appear as a good reason to have cell monitoring. Being able to see that a problem is developing 2 weeks before it actually dies is a nice warning. 8) This is also probably why CALB wants you to use a bms with data logging.
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191

Beemer
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Re: CALB CA series cell performances

Postby Beemer » Thu Aug 02, 2012 10:14 am

Odd, my last post hit the ether.

Note John's blog. That cell was remarked as being "odd" from the outset. He initially put it down to being cold. The test's effective mileage if 100 miles, doing 2C charge/discharges is over 54 thousand miles. Most home builders are happy with a 0.125C (8 hour for 100%) charge rate and a working 3 hour drive. The cell life/mileage will grow accordingly.

Same with Damiens Headways. He noted two were a little off before assembly so he placed them where he can easily swap them. Yes, they died. He has no BMS while being a self build electronics whizz-kid. http://youtu.be/q4EXAzl9HPI

The best monitor for safety and life is not voltage but temperature! I drive a Ford and a few times now, the ECU has thrown a dicky fit. These are made using CANBUS communication. Fully EMI protected in a metal case. You can dig your garden with it and use the thing as wheel chock in any weathers and in use it can still go cross-eyed. So why should I trust my vehicle to an excess of needless electronics with loose soldered wires all over the place that is not warrantable?

The fact all these CALB's outperform their capacity in all conditions and are so very closely matched and are proven highly consistent in quality against Headways simply precludes dangling delicate electronics all over the place.

We have drifted wildly off topic here.

GregsGarage
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Re: CALB CA series cell performances

Postby GregsGarage » Thu Aug 02, 2012 3:06 pm

Beemer wrote:The best monitor for safety and life is not voltage but temperature!

:?: Sorry, can't agree with you on this point. Temperature is important, but in most cases cell voltage readings will highlight a problem long before temperature does. For example, I couldn't find any mention of abnormal temperature readings during John's testing when the headway cell failed. Voltage readings are instant, waiting for a component to get too hot takes time depending on it's thermal mass.
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191


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