CALB CA series cell performances

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mattcarr
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Location: Hampshire

Re: CALB CA series cell performances

Postby mattcarr » Sun Jul 15, 2012 10:59 am

So that is just over £300 per kwh. I think that is a good price. Also, if you have got 20kwh in total I would think your range would be considerably more than 50 miles.

Beemer
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Re: CALB CA series cell performances

Postby Beemer » Sun Jul 15, 2012 12:38 pm

I agree with Matt,
As a rough guide find the weight in lbs then divide by ten. This will give you the approximate WH/mile.

So the theoretical max of a 20KW pack on a 2000lbs car is:-

2000(lbs)/10 = 200 WH/mile
20,000(WH)/200(WH/mile) = 100 miles range. Call it 80 miles for the ±10% safety all cells require.

People who have made the change have been blown away by how much better the car drives. There is far less voltage sag under load, especially after miles. They weigh half as much, carry 3x the charge and last longer than 6 months before they start to deteriorate.

Bottom balance, never over-volt them, so there is no need to use money on bms's either.

Grumpy-b
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Re: CALB CA series cell performances

Postby Grumpy-b » Sun Jul 15, 2012 4:54 pm

All of the Blingos I have had have used about 300wh/mile. Thats what power goes in to deliver the miles traveled, rather than what the cells can deliver.

Grumpy-b

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timpootle
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Re: CALB CA series cell performances

Postby timpootle » Sun Jul 15, 2012 5:05 pm

300Wh/mile matches what I found on my test journey in the long-ranger.

I will accept that balancing does not seem to be required on these cells, but I would never want to drive without some sort of per-cell voltage monitor. That's what the Guantuo BMS gives me. What do these Germans recommend for your CALB cells?
Tim Crumpton

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

Re: CALB CA series cell performances

Postby mikethebike3 » Sun Jul 15, 2012 10:15 pm

Thanks for the responses.

I guess my Seicento will weigh less than a Blingo and probably be a little more slippery so hopefully somewhere around 2-250 Wh/mile would be about right. Where I live in Norfolk is pretty flat and we're looking for at least 40 mile range, so anything more would be great.

Seems the consensus is that the FJ's quoted price for the CALbs is reasonable so I've sent some more questions to Peter Jürgens regarding warranty. I'll report back anything interesting I learn.

Mike

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

Re: CALB CA series cell performances

Postby Beemer » Sun Jul 15, 2012 10:54 pm

Hey did I not re-nick the latest graphs for cold running as promised?
Comparing CALB's old and new battery figures with EVTV's. He does not check down to such a deep voltage but matches the manufacturers claims I think quite reasonably.
Well, here they are:

Image
Image
Image
Image
Image
Image

Shows on any cold cell when load is applied they heat a little internally so become a little warmer.

What worries me when BMS's control the charge when they do not monitor the temperature. The cells are cold and do not charge well nor attain the voltages so end up overcharging. Having the mains power keep the cells at a reasonable temperature via a heated blanket or water pipes would go a long way on all counts; power, charging rate, running voltages, warm car when bum hits the seat, bms viability etc.

Hey Mike. We're all ears :)

mikethebike3
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Location: NE Norfolk, UK

Re: CALB CA series cell performances

Postby mikethebike3 » Mon Jul 16, 2012 1:34 pm

Well you can't fault Peter on the speediness of his replies!

Main warranty on the CA's is 18 months and would be handled by Peters company in Germany (any battery found to be faulty will be replaced FOC including carriage).

There's also a further 18 months with a 50% refund "if a high class battery monitoring and balance system is used".

Now this is a bit of a problem as "high class" is not exactly definitive, and no actual BMS's are proposed as suitable candidates. Previous postings imply that charge balancing is unlikely to be needed, yet Calb's "Warranty document" and section 2 of their "Manual for after sales service":
CalbWarranty Europe 1.pdf
(44.97 KiB) Downloaded 460 times

Section2.pdf
(163.72 KiB) Downloaded 1606 times

appear to be quite specific, although the full version of the latter document (I'm only allowed to upload 250Kb) only shows piccies of the earlier SE series which may have been more demanding during the charge cycle.

I would definitely incorporate a per-cell voltage display and alarm (I was thinking of a 3 x LTC6802-based system - perhaps a version of Gregs design - as I will only have a maximum of 36 cells), but IIUC, balancing would require at least basic charge control for every cell which ups the BMS complexity by at least an order of magnitude. I WAS hoping to use my 120V Zivan NG3 presently set to 72V LA's (but believed to be reconfigurable to LiFePo4) but it seems that this would not satisfy the warranty requirements.

Again, can the wise men of BVS advise whether I do understand this correctly? I want to do the right thing, but I thought we were starting to move away from active charge balancing on lithium.

Thanks as always

Mike

flaninacupboard
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Re: CALB CA series cell performances

Postby flaninacupboard » Mon Jul 16, 2012 2:35 pm

I've used the miniBMS system on my lithium pack for some time. It top balances, has high voltage and low voltage cell cutoffs, and is temperature compensated (per cell for the distributed system, or per block for the centralised system)

I don't have to look at anything, check anything or do anything, it just works.

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

Re: CALB CA series cell performances

Postby Beemer » Mon Jul 16, 2012 2:54 pm

Thanks for that Matt. There we have it.

Something to consider for the lovers of small packs
Standard (dis)charge rate is 0.3C

Limits
3.6V per cell/pack max.
Trickle to no less than 0.05C
Float charging to 3.4V.
Warning alert at 3V

Absolute max Voltages
Cut-off charger when the first cell hits 3.9V
Cut-off controller when the first cell hits 2.5V
2V or under is considered unrecoverable.

Temperature ranges
Cool the cells at 40°C
Reduce power at 50°C
Kill the pack at 55°C
Range 5°C to 45°C
Never charge at 0°C or below.

GregsGarage
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Location: Galashiels, Scottish Borders
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Re: CALB CA series cell performances

Postby GregsGarage » Mon Jul 16, 2012 10:15 pm

Hi Mike,

Daily balancing is not required on these cells which is why I am leaving off any balancing features for my 6802 based boards. Matter of fact my own cells seem to be behaving better now that I am not trying to balance them. I have an idea for a balancer that would be used only when required and would be separate from the car. But first I need to get the monitoring boards made. Nearly have a pcb layout done, but still lots to do, software to write for both slaves and master, testing to be done, etc, etc. We are always looking for more people to get involved in the project. :wink:

Regarding the stated warranty, their terms look reasonable. The problem with lithium cells is if you let them over or undercharge just once you will probably have ruined it permanently. I like the analogy of a china plate, it will last you a life time as long as you don't drop it. :shock: Even with the best care you do get some unexplained failures, you might consider buying an extra cell or 2 just in case. So with all that in mind if you do have a claim you will need to satisfy them that the cell hasn't been abused. I would think that a monitoring only system would be fine, but ask the question and see what they say.

One option you could consider if the cells arrive before a 6802 system is ready, would be a simple system like the miniBMS or Cedric's cell protectors available from Agni Motors and then add the 6802 system when it is ready.

Regarding the Zivan, I have been using my NG3 which is configured for sealed lead acid with my lithium pack for over a year now. The BMS switches it off when any cell gets to 3.66 volts. But my lead acid pack was 12 batteries and the lithium is a 48 cell pack so voltages are nearly the same. I do have a hole in the case so I can easily adjust the voltage pot, but I don't think you could go from 72 volts to 120 volts. Again warranty needs to be considered, you could sell the charger and buy a new one.

Hope that helps.
Greg Fordyce

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


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