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

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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.
 
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/INR18650-25R-datasheet.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_images/apdf/Sony_US18650VTC5A.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?controller=attachment&id_attachment=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.
 
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.
 
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?
 
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.
 
mux said:
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.
 
IssacZachary said:
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):
0kMU4tX.png


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):
UgDZUTc.png


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:
DPY5nIL.jpg


About 5 of these would fit in this orientation, but you could get creative with it. Each pack is ~3.6 kWH.
 
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!
 
IssacZachary said:
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).
 
jkenny23 said:
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).

Here in Colorado my electric rate is much cheaper than California's (around 10 cents per kWh). And I also can charge for free at work and some other places. (Of course good things don't last forever.)

I've seriously considered buying a hybrid. In fact with both the Colorado and Federal tax cuts I could get $9500 off of a new Prius Prime. And after driving a 1985 VW Golf for several years that consistently gets over 55mpg, a hybrid would likely be the only kind of car that would make me feel good about the fuel mileage. But the numbers don't crunch because, like you said, the high initial cost. Even a used Prius would be more expensive to own and operate than a cheap used ICEV, at least according to Edmunds TCO. And this may just be coincidence, but I keep finding lots of hybrids around here with dead traction batteries. I don't know if it's the cold or the steep terrain around here or just coincidence. I also understand that the cold offsets the fuel mileage quite a bit (well I guess it does in an all-electric too). The coldest I've seen it is -52°F. The second coldest record in Colorado was set not too far from here at -60°F. Most winters it gets down below -30°F for a few days.

Just yesterday I drove over 150 miles in the Leaf and went up more than 10,000 ft and down more than 10,000ft, starting at 7°F in the morning and getting back at 25°F at night with a peak ambient temperature of around 58°F. Battery temp bars ranged from 3 to 5. Charging off of level 2 with about 65 miles between charging stations, I got all my work done with time to spare. The total cost of electricity was $0 for the entire trip. Not bad for a 24kWh, 11-bar Leaf! :mrgreen:

It just feels like the Leaf just barely makes it though. I pulled up to my house with only 9% left on the battery.
 
IssacZachary said:
Any recommendations on what contactors to use?

Not that easy of a question to answer, because I've run into a couple issues.

Ideal choice: buy a Leaf contactor assembly and use those (e.g. https://www.ebay.com/itm/CONTACTOR-...278965?hash=item3d3bae3a35:g:rscAAOSwfRdZH4oE).

Second good choice: get a salvage set of contactors from a recycler, ebay, etc. Any contactor from any plug-in hybrid or fully electric car will do, and I've seen them come by pretty cheap (like $40 for a set).

Nonideal, but what I did initially: get a couple of cheap contactors from China. I purchased https://www.ebay.com/itm/200A-12V-2...hash=item4d70a2d882:m:mmbBymiKdBTKti955Pjmeiw.

The contactors will usually run fairly warm at 12V (12V x 0.4A ea = 10W for a set). I made a little circuit that engages the relays at 12V and drops down to ~5V after a second. Secondly, you HAVE to use two relays, don't skimp and only implement one. You'll get HV isolation warnings and your car won't start once in a while. Lastly, it's good practice to use a separate relay driver and not drive the relays directly from the RLY P/N lines on the VCM. Some people have had trouble with the relay drivers not managing the extra current and/or throwing errors. So treat the RLY P/N lines as 'digital' inputs to a separate relay driver circuit.
 
mux said:
Not that easy of a question to answer, because I've run into a couple issues.

Ideal choice...
Thanks again! (This forum needs a thanks or thumbs up button for each post. Just imagine I put a thumbs up on nearly every one of your posts in this forum.)
 
IssacZachary said:
Any recommendations on what contactors to use?
If you want a set of original Leaf contactors (including the pre-charge) then let me know, I have several contactor boxes from the Leaf packs that I disassembled. I am using twin Leaf packs in parallel, each with its own BMS, in my electric truck.
Since it already had its own contactors, I do not need the Leaf contactors that I removed.
 
Another video update on my car, posting it here for those who are interested:

https://www.youtube.com/watch?v=0i6VcZXXQyY

In short: Swapped tires out for 51PSI capable ones and immediately saw a decent efficiency increase. Should be able to (just about) hit 250km (155 mi) of range if I'd run it all the way dry. Aeromods so far have not meaningfully contributed, and I'm working further towards making a hardware kit to upgrade the Leaf with an extender.
 
mux said:
Another video update on my car, posting it here for those who are interested:

In short: Swapped tires out for 51PSI capable ones and immediately saw a decent efficiency increase. Should be able to (just about) hit 250km (155 mi) of range if I'd run it all the way dry. Aeromods so far have not meaningfully contributed, and I'm working further towards making a hardware kit to upgrade the Leaf with an extender.

You mention in the video that you've reduced (~ 50%) the coil currents of the main power relays of the add-on battery.
Are you concerned that the contact resistance of the relay will increase to a point where the relay life may shortened or
that a problematic relay contact voltage drop, e.g. at 100+ amps, may occur?
 
lorenfb said:
mux said:
Another video update on my car, posting it here for those who are interested:

In short: Swapped tires out for 51PSI capable ones and immediately saw a decent efficiency increase. Should be able to (just about) hit 250km (155 mi) of range if I'd run it all the way dry. Aeromods so far have not meaningfully contributed, and I'm working further towards making a hardware kit to upgrade the Leaf with an extender.

You mention in the video that you've reduced (~ 50%) the coil currents of the main power relays of the add-on battery.
Are you concerned that the contact resistance of the relay will increase to a point where the relay life may shortened or
that a problematic relay contact voltage drop, e.g. at 100+ amps, may occur?

These particular relays are supposed to be rated to full engagement down to 80mA, and I've tested this before on the bench. So far I've kept an eye on it and it doesn't seem to be an issue, nothing is getting warm even when pounding the car. Obviously a relay fail-open or fail-closed scenario would be pretty devastating, so you have to check these things.
 
Good work mux!

I also wouldn't think that blocking the grill would do much. According to >>HERE<< those that have done a grill block have seen between a 1% and 6% improvement (which I'm personally skeptical even about those numbers.)

I do want to do a tail like on this car though as well as wheel skirts:

https://aerocivic.com/
 
mux said:
lorenfb said:
mux said:
Another video update on my car, posting it here for those who are interested:

In short: Swapped tires out for 51PSI capable ones and immediately saw a decent efficiency increase. Should be able to (just about) hit 250km (155 mi) of range if I'd run it all the way dry. Aeromods so far have not meaningfully contributed, and I'm working further towards making a hardware kit to upgrade the Leaf with an extender.

You mention in the video that you've reduced (~ 50%) the coil currents of the main power relays of the add-on battery.
Are you concerned that the contact resistance of the relay will increase to a point where the relay life may shortened or
that a problematic relay contact voltage drop, e.g. at 100+ amps, may occur?

These particular relays are supposed to be rated to full engagement down to 80mA, and I've tested this before on the bench. So far I've kept an eye on it and it doesn't seem to be an issue, nothing is getting warm even when pounding the car. Obviously a relay fail-open or fail-closed scenario would be pretty devastating, so you have to check these things.

Thanks for your feedback. Keep-up the great project. It's impressive.
 
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