Extra Battery, How to Integrate with 24kWh Traction Battery?

[jkenny23]

Had to buy a second one actually, fried one of the ASICs on the first after bad wiring...

Wow!

How well does it work as a balancer?

Well since I fried my first one, and it doesn't balance any less than a full 96s pack, I haven't really tried it yet. There's lots of detail on how it works here: http://www.mynissanleaf.com/viewtopic.p ... d75c110590

It has a 430 ohm shunt resistor, which means less than 10mA balancing current at max charge. I do have a 1.8kWH pack made of salvage cells, and a Chinese BMS with about 30mA balancing current, and it has been plugged in for about a week and is almost fully top balanced now. Each series component in the pack is within ~134mAH (0.38%) of balance across 14s (35AH total capacity). So you can assume with only 10mA balance current or less you need a pack within maybe 0.1% of capacity delta across the series sets of cells.

I have considered making an expansion board that could work with any of these type of balancers, and add a larger balancing current in parallel.

[Lylou2]

I made a colculation, the best option looks tu use space in baggage use 96s14p, 1344 cells, weight aprox 70kg, 14.3kw/h extra energy for 70/120 km, couse if connect 14p for discharge it can handle aprox 140A if it's ncr18650PF cells, so it's enought then you have stock battery instead. For charging its only 19A (1350mAh for 1 cell) and I got max 7,6kw/400v, (max 15kw for 2 batteries) the question is that it's possible use fast charging?

[jkenny23]

I made a colculation, the best option looks tu use space in baggage use 96s14p, 1344 cells, weight aprox 70kg, 14.3kw/h extra energy for 70/120 km, couse if connect 14p for discharge it can handle aprox 140A if it's ncr18650PF cells, so it's enought then you have stock battery instead. For charging its only 19A (1350mAh for 1 cell) and I got max 7,6kw/400v, (max 15kw for 2 batteries) the question is that it's possible use fast charging?

If you assume the 120A of the quick charger is split proportionally across the Leaf + extender battery pack, you would be getting ~45A into the extender, or 3.2A per cell. This is double their recommendation (max 0.5C). I would recommend finding a cell that can at least handle 1C charge, that said, you will still be exceeding the spec for a little while at the start of the QC session; most 18650s do not allow charging above 1C rate.

[jkenny23]

I did another discharge test from 4.2 vs. 4.1V with a different cell (different chemistry too I believe), and the result it the same. This time from 4.11 instead of 4.125V, but at a lower discharge rate of 0.4C:

[mux]

That looks a lot like either the same chemistry, or an NCA vs NMC. These two chemistries are very similar, with NCA a bit 'bumpier' than NMC.

The real differences are LMO/LCO vs NCA/NMC. Try getting one of those to see the impact of significant chemistry differences!

[jkenny23]

That looks a lot like either the same chemistry, or an NCA vs NMC. These two chemistries are very similar, with NCA a bit 'bumpier' than NMC.

The real differences are LMO/LCO vs NCA/NMC. Try getting one of those to see the impact of significant chemistry differences!

Looks like you're right, I didn't realize the Panasonic cell is NCA chemistry (makes sense, it's similar to the battery they make for Tesla). The first cell, Sony VTC-5A is NMC chemistry. I ran the test on an older Sony LCO battery, I'll try an LGABD11865 today since that's one of the ones for sale at ~$170/kWH from alarmhookups and I believe is also LCO chemistry:

[Lylou2]

Maybe somebody knows the best way to find and buy 18650?

[IssacZachary]

Maybe somebody knows the best way to find and buy 18650?

That depends in what country you live and what you are after (quality vs. price vs. availability).

[Lylou2]

Ok the new ones I can buy from victpower.com f.eg. I was looking for NCR18650PF best option for me price unit is aprox 1,85e plius sending 100euros to Norway it's good price? Some versions for used ones with good condition?

[IssacZachary]

Ok the new ones I can buy from victpower.com f.eg. I was looking for NCR18650PF best option for me price unit is aprox 1,85e plius sending 100euros to Norway it's good price? Some versions for used ones with good condition?

I don't know much about dealing with Chinese companies. I've been tempted to buy some from similar companies. But it could be a good deal or a type of fraud.

I don't know if you can get them to send to Norway but https://eu.nkon.nl seems to have a good reputation in Europe for selling 18650's.