jkenny23
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Thu Apr 26, 2018 7:10 pm

Just thought I'd update with the discharge test results of the Boston Power Swing 5300 batteries I bought (just 4 samples from a US supplier on eBay) since they're the leading candidate for a small range extender pack:

Image

They fare average, keeping 90.9% of the 4.2V discharge capacity, with a discharge characteristic similar to LCO, though from what I read it's a Li-Manganese battery (NMC?). Will be interested to see the 2C charge tests once I get my 10A battery tester in a couple weeks. A 96s2p pack built with these cells should have a capacity of ~3.2kWH usable.

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IssacZachary
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Thu Apr 26, 2018 7:57 pm

jkenny23 wrote:Just thought I'd update with the discharge test results of the Boston Power Swing 5300 batteries I bought (just 4 samples from a US supplier on eBay) since they're the leading candidate for a small range extender pack:

Image

They fare average, keeping 90.9% of the 4.2V discharge capacity, with a discharge characteristic similar to LCO, though from what I read it's a Li-Manganese battery (NMC?). Will be interested to see the 2C charge tests once I get my 10A battery tester in a couple weeks. A 96s2p pack built with these cells should have a capacity of ~3.2kWH usable.


Nice! Here's some more data from Endless-Sphere:

https://endless-sphere.com/forums/viewtopic.php?t=90938

Image

What do we know about Queen Battery? Can they be trusted?

http://queenbattery.com.cn/our-products/286-boston-swing-5300mah-low-temperature-fuel-battery-cell-37v-13a-discharge.html?search_query=boston&results=8
2013 SL 50,000 miles.
12 bars until 44,300 miles on June 2, 2017. :D
11 bars current. :)
The Nissan Leaf is the fourth best long distance car for highway driving. >>Best Long Distance Cars<<

mux
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Fri Apr 27, 2018 12:07 am

Note that if you want to make an extender with NMCs and mix them with the NCA-lite modern Leaf battery or LMO old Leaf battery, it needs to be a really large pack. As you can see, a significant amount of charge, even more than with NCA, is in the bottom end, so as the main battery discharges, the extender almost entirely takes over. NMCs are typically a bit lower rated (this one is rated for 0.7C charge/2.5C discharge) than NCA and LMO, so you either need to make sure never to use DCQC with an empty extender and to make the pack large enough that it can deliver your typical discharge current. If you make sure to drive the car gently, that means your minimum extender size is probably around 10kWh, so a 96S6P configuration.

jkenny23
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Fri Apr 27, 2018 6:34 am

mux wrote:Note that if you want to make an extender with NMCs and mix them with the NCA-lite modern Leaf battery or LMO old Leaf battery, it needs to be a really large pack. As you can see, a significant amount of charge, even more than with NCA, is in the bottom end, so as the main battery discharges, the extender almost entirely takes over. NMCs are typically a bit lower rated (this one is rated for 0.7C charge/2.5C discharge) than NCA and LMO, so you either need to make sure never to use DCQC with an empty extender and to make the pack large enough that it can deliver your typical discharge current. If you make sure to drive the car gently, that means your minimum extender size is probably around 10kWh, so a 96S6P configuration.


Do you happen to know of any 18650s with a similar LMO chemistry/discharge curve? I'd like to bench test in my parallel cell setup to see the current sharing across the discharge/charge curve. I may just buy a real Leaf cell but at 64AH it's going to be a very long and very low C-rate test :)

mux
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Fri Apr 27, 2018 8:20 am

There are basically no commercial LMO 18650s anymore. I know of none that are still sold.

jkenny23
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Fri Apr 27, 2018 8:36 am

Thanks, Leaf cell it is. I've got a 30A electronic load which I guess will be about 0.5C which isn't too bad, no way of charging at high rate though, my biggest power supply is ~20A.

jkenny23
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Tue May 01, 2018 12:56 pm

Just got an updated price list of cells from the Chinese supplier (Queen Battery), here's the breakdown of best options for a Leaf extender pack, taking the most pessemistic assumption that the extender pack will need to provide 100% of the discharge current, and take 100% of the max charge current:

Image

The Boston power cells still come out as the best option for minimum investment, which would be a ~39.5 kWH pack at $6,628 for full power.

alozzy
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Tue May 01, 2018 3:04 pm

That price makes the LEAF replacement pack deal offered by Nissan seem not so bad after all. Unless prices drop considerably, the DIY doesn't look to provide any savings, nor is there any warranty. Thanks for doing the leg work!
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jkenny23
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Joined: Sat Aug 19, 2017 12:49 pm
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Tue May 01, 2018 3:32 pm

Yes, especially with their new replacement program (not yet rolled out in the US as far as I know), their pack prices are very cheap. This is only for those wanting to extend the range; which you can't do by buying a pack from Nissan as they take the old one back to refurbish/repurpose. Otherwise, if you can get a very large amount of cells, say from salvage laptop packs at free or low cost, an extender can definitely be done on the cheap, but you would need a very large capacity (around 96s40p or ~34kWH) to keep the per cell currents for quick charging/regen and discharge down, not to mention a much more capable BMS to handle larger balancing current.

I'm trying to get a Leaf module from Cor (also a member of these forums) to start doing some parallel charge/discharge tests between a Leaf cell and various common 18650 and the Boston power cells, to see what percentage of power is coming from the Leaf vs. extender pack at different points during the SoC curve.

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IssacZachary
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Tue May 01, 2018 4:56 pm

alozzy wrote:That price makes the LEAF replacement pack deal offered by Nissan seem not so bad after all. Unless prices drop considerably, the DIY doesn't look to provide any savings, nor is there any warranty. Thanks for doing the leg work!

But you do realize that for around the price of a new Leaf battery you are more than doubling the capacity! (39.5 + 24 = 63.5kWh!)

Plus, even if you're gutting your old Leaf battery and making a new one you not only could sell the used Leaf cells on eBay for up to some $4,000 (so you end up paying less than $3,000 for a 40kWh battery) you can also add whatever TMS system you so desire, in some cases improving both performance and longevity.
2013 SL 50,000 miles.
12 bars until 44,300 miles on June 2, 2017. :D
11 bars current. :)
The Nissan Leaf is the fourth best long distance car for highway driving. >>Best Long Distance Cars<<

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