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?
This morning I got a much more explicit email from Peter:
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.
So if someone will contact me, he can do it direct
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.
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
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!