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

Posted: Fri Apr 13, 2018 11:34 pm
by mux
As a rule, you will not get genuine brand-name cells from Chinese suppliers. They're either rejects, rebadges or bait-and-switches (where they sell you a couple genuine cells at first, and then when you buy a whole lot they're rebadges). Not because Chinese suppliers aren't to be trusted, they generally are, but because they generally can't get direct stock from US or Japanese suppliers at good prices. There are some import tariffs and protectionist things going on that make cells from China a lot more expensive than ones shipped directly from Japan to the EU.

So generally, you'll be better off buying at a reputable importer. NKON is (one of) the largest 18650 resellers in Europe and usually has good prices. Note that Norway is not in the EU, so you will possibly have to deal with import fees depending on what kind of treaties Norway has with the EU regarding lithium ion batteries.

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

Posted: Mon Apr 16, 2018 8:49 am
by Lylou2
Thanks for help I will be looking foward to this project:)

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

Posted: Mon Apr 16, 2018 12:53 pm
by jkenny23
I've been trying to hunt down the best 18650 or similar form factor batteries for the range extender pack, it looks so far like the following are the only good options able to handle quick charge (hardest requirement to meet):

Requirements (for small range extenders, e.g. 2-5kWH):
Discharge: >= 4.1C
Charge (in regen): >= 1.4C
Charge (DCQC): >= 1.9C

Requirements (for medium to large range extenders, e.g. 10kWH+):
Discharge: >= 3C
Charge (in regen): >= 1C
Charge (DCQC): >= 1.4C

So far the only cells I've found that meet this criteria are the following:
Boston Power Swing 5300:
http://liionbms.com/pdf/bostonpower/swing5300.pdf
Capacity: 5300mAH nominal
Discharge: 2.5C
Charge: 2C
Pros/cons: Good cycle life (1000 cycles quoted at full DoD, since in a Leaf with 4.12V max voltage, should last considerably longer), not in a typical cylindrical form factor
Price: ~$335/kWH with shipping from China (3.9kWH order)

Samsung INR18650-25R:
https://www.powerstream.com/p/INR18650- ... asheet.pdf
Capacity: 2500mAH nominal
Discharge: 8C
Charge: 1.6C
Pros/cons: Standard cell, may have better availability.
Price: ~$329/kWH with shipping from China (3.7kWH order)

LG HE2/HE4:
https://www.powerstream.com/p/LG-ICR18650HE2-REV0.pdf
Capacity: 2500mAH nominal
Discharge: 8C
Charge: 1.6C
Pros/cons: Standard cell, good availability, cheaper than Samsung above on Aliexpress
Price: ~$327/kWH with shipping from China (3.7kWH order)

Sony VTC5/VTC5A:
http://www.accushop.at/images/products_ ... 0VTC5A.pdf
Capacity: 2600mAH nominal
Discharge: 14C
Charge: 2.4C
Pros/cons: Amazing specs, worst availability/price of the ones above
Price: ~$415/kWH with shipping from China (3.8kWH order)

Sony VTC6/VTC6A:
http://queenbattery.com.cn/index.php?co ... achment=38
Capacity: 3120mAH nominal
Discharge: 5C
Charge: 1.7C
Pros/cons: Similar to VTC5/A with slightly higher capacity

A note of warning on the super high capacity cells (e.g. 3400/3500mAH), they typically do not like being fast charged (>1C), lucky if you find one that allows 1C charging in the datasheet. Not sure how much of an issue this is in the real world, but I've read a report on endless sphere of an NCR18650B failing at around 30-50 cycles at only 1C charge rate (3.4A). This doesn't bode well if you want your pack to hold up to DCQC, which, if you're considering an extender in the first place, I'm guessing you would.

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

Posted: Tue Apr 17, 2018 1:23 am
by mux
If you're looking at cells with that high of a price, it's much better to just source lower spec cells (pretty much any cell will do) and go with a larger pack. Low quality cells (e.g. INR18650-26J/H) go for about $150/kWh with shipping, less than half of your quoted prices, so you can simply put in twice as many. Decent quality cells (e.g. INR18650-29E, -35E) are closer to $200/KWh, which is still not too far off half the cost.

Considering a larger pack really isn't that heavy anyway, that seems like a much more palatable option. Also nets you a nicer capacity boost.

Also keep in mind that recyclers do exist, they just don't advertise very well. I got my packs from ecarACCU.nl, who sells entire modules for €100/kWh (~$130/kWh). The packs I bought have 10C charge/discharge ratings and you can have 8 of them (9kWH) for a grand. They're basically not degraded at all, still at full capacity.

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

Posted: Tue Apr 17, 2018 7:32 am
by jkenny23
Yeah I think your approach does make the most sense. Hybrids beat up on their battery with very heavy regen/discharge rates for the size of the battery. Can you provide more detail on the battery modules you are using, what vehicle they are from, voltage, and what others you know of that would be an easy retrofit to 96s?

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

Posted: Tue Apr 17, 2018 9:33 am
by mux
Mine are from the various electric/hybrid VWs - they all use the same or very, very similar modules. They are simply the easiest for me to get a hold of for this project, so I used them. They're not particularly easy to work with; I reverse engineered the BMS for the supplier, but this isn't open (I did this as paid work under NDA). So you'll have to add your own BMS to make this work. They're 12S modules, so you need 8 in series to get to 96S.

It's probably easier to go for Mitsubishi Outlander PHEV modules or GM Volt modules. They've been documented and are a bit easier to work with, especially the Volt modules. I believe those are 12 or 16S as well, so an easy multiple up to 96S. And people crank a kiloamp out of those as well, with very little wear.

On top of all of this you also need to add some BMS magic to make the GoM say useful things. I'm working on that, but it'll take about a month before that will be anywhere near done. This involves interrupting the EV-CAN from the main battery and modifying the GID packages to reflect the capacity in all batteries. Once I have that figured out, I'm making a bit tutorial on how to mod the '11-12 Leaf with extender packs.

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

Posted: Wed Apr 18, 2018 1:43 pm
by IssacZachary
mux wrote:Mine are from the various electric/hybrid VWs - they all use the same or very, very similar modules. They are simply the easiest for me to get a hold of for this project, so I used them. They're not particularly easy to work with; I reverse engineered the BMS for the supplier, but this isn't open (I did this as paid work under NDA). So you'll have to add your own BMS to make this work. They're 12S modules, so you need 8 in series to get to 96S.

It's probably easier to go for Mitsubishi Outlander PHEV modules or GM Volt modules. They've been documented and are a bit easier to work with, especially the Volt modules. I believe those are 12 or 16S as well, so an easy multiple up to 96S. And people crank a kiloamp out of those as well, with very little wear.

On top of all of this you also need to add some BMS magic to make the GoM say useful things. I'm working on that, but it'll take about a month before that will be anywhere near done. This involves interrupting the EV-CAN from the main battery and modifying the GID packages to reflect the capacity in all batteries. Once I have that figured out, I'm making a bit tutorial on how to mod the '11-12 Leaf with extender packs.

Thank you so much MUX!!!! I so anticipate your work!!!! (I'm actually writing this as I charge from a charging station that's so far from my next destination I'm going to have to go 30mph down the highway for this next leg!)

Also, while we're on the subject of where to get cells I'm looking at getting some of those Boston Power 5300's for about $25 per 100Wh used. I might get about $200 of them per month since that's about what my ICEV fuel bill is and with the better weather I can start to use just my Leaf so I won't be buying any fuel (I also get lots of free charging, but even paying for the electricity at home is very cheap compared to gasoline or diesel.) I'm trying to figure out a way to make a buildable battery, one that I can add in cells as I buy them so that I don't have to be bogged down with one big payment. If I can't I'll just put them on my credit card and pay them off as I go.

Another option I was also thinking of were these:

Tesla Modules

The only thing is you need $20,000 of them to make a 96s 74p 80kWh battery. Great for a battery trailer I guess. But otherwise I wonder if a guy could "cut them in half" and make a 37p 40kWh battery with them for half the price. Still, I'm short that kind of money though.

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

Posted: Wed Apr 18, 2018 2:47 pm
by jkenny23
IssacZachary wrote:Thank you so much MUX!!!! I so anticipate your work!!!! (I'm actually writing this as I charge from a charging station that's so far from my next destination I'm going to have to go 30mph down the highway for this next leg!)

Also, while we're on the subject of where to get cells I'm looking at getting some of those Boston Power 5300's for about $25 per 100Wh used. I might get about $200 of them per month since that's about what my ICEV fuel bill is and with the better weather I can start to use just my Leaf so I won't be buying any fuel (I also get lots of free charging, but even paying for the electricity at home is very cheap compared to gasoline or diesel.) I'm trying to figure out a way to make a buildable battery, one that I can add in cells as I buy them so that I don't have to be bogged down with one big payment. If I can't I'll just put them on my credit card and pay them off as I go.

Another option I was also thinking of were these:

Tesla Modules

The only thing is you need $20,000 of them to make a 96s 74p 80kWh battery. Great for a battery trailer I guess. But otherwise I wonder if a guy could "cut them in half" and make a 37p 40kWh battery with them for half the price. Still, I'm short that kind of money though.


For your money, the Chevy Volt batteries are the cheapest by far from what I've seen, as low as $130/kWH from eBay, and even lower if you search locally on salvage parts websites. Problem is they are pretty large. Smallest 96s configuration you could get is 3 16s2p groups (from a 2016 Volt or newer aka Gen 2) rewired for 32s1p, and that takes up most of the trunk volume, with ~9kWH capacity. Plus, rewiring them as series would be very challenging from what I've read. I'm probably going to go with a small modular pack approach using cells like the ones I posted earlier that can handle 2C charge rate. Smallest pack I would make is probably around 96s4p, with 8 12s4p modules wired in series.

Here's a quick 3D mockup of the Volt modules in the Leaf trunk area (not sure if the Leaf model is scaled correctly, seems to be 0.3m short when I measure front to rear):
Image

Here's a table of the current best deals I've found for Leaf cells including minimum total price (i.e. minimum capacity to meet that cell's C rating):
Image

Best compromise for small initial investment and price/kWH is the Swing 5300 cells from Queen Battery (Chinese supplier).

For contrast to the Volt pack, here's what a 96s2p pack with the Swing 5300 cells would look like in the trunk:
Image

About 5 of these would fit in this orientation, but you could get creative with it. Each pack is ~3.6 kWH.

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

Posted: Thu Apr 19, 2018 3:10 pm
by IssacZachary
That's great info jkenny23!

I have to justify this before jumping into buying a bunch of expensive batteries and "hacking" into my car.

So far my Leaf is paid off. So I'm only paying for electricity, insurance, maintenance and any repairs. Using data from total cost to own calculators I should average out to around $3,179 per year or $264 per month for all car related expenditures with the Leaf by itself. However, I calculate that I'll actually paying closer to around $130 per month average including costs of original Michelin Energy Saver tires every 3 years as well as 12V batteries and windshield wipers and such. Of course I'm not calculating a new traction battery every so often in that figure.

Now if I sold my Leaf for as much as I possibly could and bought the most frugal car out there, like a used 2014 Mitsubishi Mirage I calculate I'd actually be paying as much as $200 more per month on average for the first 5 years! $200 in a year alone is $2,400 dollars! And by the time the 5 years are over I'd have saved as much as $12,000 by keeping the Leaf!!! So I guess what I'm saying is that I have $12,000 to invest in a better battery on the Leaf before it starts to become impractical. Or if I go by what online data says I could be paying in repairs and maintenance on the Leaf I still have as much as $6946 to spend on a better battery for the Leaf every 5 years.

So if I can spend that much every 5 years on battery technology then basically the Leaf would be cheaper from here on out than trading it in for even the most frugal ICEV available in the United States. Not that I have that $12,000 on hand right now, but it is a thought as to what makes the most sense. And that's not even comparing what I'd be spending if I traded in the Leaf for a Tesla, Bolt or newer Leaf!

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

Posted: Thu Apr 19, 2018 3:16 pm
by jkenny23
IssacZachary wrote:That's great info jkenny23!

I have to justify this before jumping into buying a bunch of expensive batteries and "hacking" into my car.

So far my Leaf is paid off. So I'm only paying for electricity, insurance, maintenance and any repairs. Using data from total cost to own calculators I should average out to around $3,179 per year or $264 per month for all car related expenditures with the Leaf by itself. However, I calculate that I'll actually paying closer to around $130 per month average including costs of original Michelin Energy Saver tires every 3 years as well as 12V batteries and windshield wipers and such. Of course I'm not calculating a new traction battery every so often in that figure.

Now if I sold my Leaf for as much as I possibly could and bought the most frugal car out there, like a used 2014 Mitsubishi Mirage I calculate I'd actually be paying as much as $200 more per month on average for the first 5 years! $200 in a year alone is $2,400 dollars! And by the time the 5 years are over I'd have saved as much as $12,000 by keeping the Leaf!!! So I guess what I'm saying is that I have $12,000 to invest in a better battery on the Leaf before it starts to become impractical. Or if I go by what online data says I could be paying in repairs and maintenance on the Leaf I still have as much as $6946 to spend on a better battery for the Leaf every 5 years.

So if I can spend that much every 5 years on battery technology then basically the Leaf would be cheaper from here on out than trading it in for even the most frugal ICEV available in the United States. Not that I have that $12,000 on hand right now, but it is a thought as to what makes the most sense. And that's not even comparing what I'd be spending if I traded in the Leaf for a Tesla, Bolt or newer Leaf!


Are you not considering hybrids for the larger initial cost? Priuses are dead on reliable from what I've read (and my personal experience with a 2011 as my second car), and with electricity prices as crazy as they are for me in California, it's cheaper per mile to drive the Prius, though I get free charging at work so all my commuting is with the Leaf. Sadly longer range EVs are still very much in a higher tier price bracket, and look like they're going to stay that way for at least a decade.

Since I've been keeping track in 2015, my total cost per mile including maintenence for my Prius is $0.066, and since I've bought it, is $0.044 for the Leaf (thankfully greatly offset by free charging, otherwise at $0.279/kWH would be $0.074/mi at 4.2mi/kWH).