From my experience, people usually just buy used or new direct from Chinese suppliers. The big companies (Sony, LG, Samsung, Panasonic...) don't like dealing with small quantity orders, so you always have to go through a 3rd party. Thanks to the vaping industry there are websites that sell individual cells, but they're at a premium. Not sure yet where to find that middle ground for quantities in the ~1-40kWH range.
Extra Battery, How to Integrate with 24kWh Traction Battery?
- Thread starter TonyWilliams
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Help Support My Nissan Leaf Forum:
IssacZachary
Well-known member
Do you think the Chinese suppliers are trustworthy? For an example, if I order a bunch of new, $1 per Wh LG 18650's from Alibaba.com, will I get new, real, LG cells or counterfits?jkenny23 said:
Also I've been following Jehú García on YouTube. Looks like he once did a group bulk buy. Maybe if several of us want cells we could get together and order some 100kWh of cells and then distribute them accordingly.
The electric bike and scooter people can tell you which suppliers are good, but a lot of them just buy a small number of cells from an Ebay seller, then buy more if they are good.
IssacZachary
Well-known member
It's hard finding a good eBay seller that can supply 10 to 60 kWh of Li ION cells that doesn't charge $300 or more per kWh. For smaller packs for bikes and scooters you can find sufficient quantities, but for a car is a whole other animal. There were a few, good, verified sales in bulk sizes by the dozens of kWh's a while back on eBay. But alas, they're all sold out at the time being.LeftieBiker said:
I suggest you sign up for a free membership at endlessphere.com and ask there. Lots and lots of people doing larger scale projects as well as smaller ones.
arnis
Well-known member
jkenny23 said:
Shouldn't be possible get better regen than with new vehicle.
Maximum regen Leaf supports (with brake pedal) is exactly 50kW.
Without brake pedal, around 30-35kW in B mode and high speed.
Regen is limited by software. Input for calculations are (at least): Hx value, battery temperature, SOC and maximum cell voltage.
When vehicle is started, regen limit is estimated by latest battery resistance value (Hx), temperature and SOC. Sometimes this limit is too pessimistic and during first regen event, regen can change a lot. Example, I charge vehicle to 90%, temperature around +10C, regen shows 2 bubbles. The first time I decelerate (or accelerate hard) regen adds 1-2 bubbles. It can be felt as well. It starts with 10kW regen and within 1-2 seconds it grows to 20-25kW. Clearly, voltage doesn't spike enough and more is allowed. Up to ~4.12V max cellpair.
The easiest way to fix regen is to find somebody who can access vehicle module software and remaps that regen capability.
Hx value is likely measured indirectly. It takes discharge/charge current (hall sensor), battery temperature (must be above +15C) and finds out, how voltage spikes/dips at those loads. If two batteries are in parallel, computer doesn't know that. As voltage dips/spikes are extremely small, regen capability map will adjust regen accordingly. But not more than 50kW with brake pedal and likely up to 30-35kW without (brake lights requirement).
My Hx on 4yo Leaf is jumping between 92% and 98%, depending on the season. Regen is almost always fully available (down to 4 Temp bars, aka +5C).
Easiest (cheapest) way to prolong range on a Leaf with worn battery is to find another worn 24kWh pack, connect them in parallel.
I bet safest connection point would be BEFORE contactors. So two batteries are ALWAYS in parallel. So there will never be arcing. Cable between two packs must be routed safely and reliably and also protected from possible damage. Secondary Leaf pack (in the trunk) must have DIY BMS that will balance out those 48 modules. Maybe original BMS inside secondary battery will work on it's own, but that must be manually verified. Balancing between two batteries will happen on its own.
I have just finished my first trip on a tiny (8.7kWh nominal) trunk extender battery. For the first time this winter, even though I had a lot of headwind and rain on the way, I've broken 100km (60mi) with the Leaf, which is a decent feat in itself. But as a reply to the above: I've also gained back all of my regen. From about 4-5 bars down, I was able to brake at more than 20kW again, which was not possible on the worn stock battery.
So yes, you pretty much immediately gain back added regen with an extender battery. I guess the only thing the VCM cares about when mapping regen is internal resistance (Hx).
Edit: just published my video
https://www.youtube.com/watch?v=Z9knihRoyo4
Edit 2: thanks! does indeed work better than the ostensibly obvious [youtube] tag...
So yes, you pretty much immediately gain back added regen with an extender battery. I guess the only thing the VCM cares about when mapping regen is internal resistance (Hx).
Edit: just published my video
https://www.youtube.com/watch?v=Z9knihRoyo4
Edit 2: thanks! does indeed work better than the ostensibly obvious [youtube] tag...
IssacZachary
Well-known member
mux said:
Congrats! Now I really want to jump into this same solution, instead of giving away my Leaf for dirt cheap so that I can buy an ICE that will cost me much more than a 10kWh worth of cells just so I can make it 65 miles between charging stations. It looks like I've found a source for getting 10kWh's of name brand 18650's for as little as $1,500 or less.
mux said:
R = E/I
The question is where the current is being measured? It sounds like the Leaf judges battery resistance measuring current from the motor controller. In that case, the more you add to the main bus in batteries the less resistance the Leaf will sense and the more regen it will have. But if it measures current from inside the battery case and before the bus then it's only measuring the Leaf's own traction battery's resistance, and wouldn't include the auxiliary traction battery's resistance in the equation.
Try putting your YouTube videos in url brackets:mux said:
[ url ] YouTube Video [ /url ]
First of all: IsaacZachary: Yeah man, you seem to be chomping at the bit to build an extender in your Leaf. I consider what I did to be 100% doable and, as long as you know what you're doing, safe and durable. Make sure to bolt down and fully immobilize the wiring, batteries and contactors, use locking nuts, loctite, whatever everywhere. Don't cheap out on the contactors. If you wish to work on it before I make a guide, we can collab on one.
I do recommend putting in more than I did for now. I have another 8.7kWh currently balancing, ready to install. That will increase the range to about 160km/100mi real-world in winter. I feel like your 10kWh figure is a bit on the low side. Take into account that the car only charges up to 4.05V/cell and down to like 3.5V, so a lot of capacity is left untouched. That 10kWh only translates into maybe 7-8kWh usable, which is 40km/25mi in hilly terrain or at high-ish highway speeds. Of course, once you have the wiring and contactors, you can essentially keep expanding every time you find a good deal on batteries.
Re: regen. If you look at the battery itself (plenty of youtube videos of people pulling them open): there is no current shunt anywhere internally. Well, in the pyrofuse (or whatever kind of active fuse that is), but not something that the BMS interfaces. So the motor HAS to be the primary point where current is being measured. This also explains why the car has to guess instead of properly measure auxiliary system power use. It literally has no way to sense it, it HAS to guess. So it also makes sense that engine power and regen power is regulated from the motor controller.
I will be *trying* to get a hold of a high-current CAN-connected current sensor. These things are ludicrously expensive (think: as expensive as 5kWh of batteries), so I have to find some second hand source, but wish me luck.
I do recommend putting in more than I did for now. I have another 8.7kWh currently balancing, ready to install. That will increase the range to about 160km/100mi real-world in winter. I feel like your 10kWh figure is a bit on the low side. Take into account that the car only charges up to 4.05V/cell and down to like 3.5V, so a lot of capacity is left untouched. That 10kWh only translates into maybe 7-8kWh usable, which is 40km/25mi in hilly terrain or at high-ish highway speeds. Of course, once you have the wiring and contactors, you can essentially keep expanding every time you find a good deal on batteries.
Re: regen. If you look at the battery itself (plenty of youtube videos of people pulling them open): there is no current shunt anywhere internally. Well, in the pyrofuse (or whatever kind of active fuse that is), but not something that the BMS interfaces. So the motor HAS to be the primary point where current is being measured. This also explains why the car has to guess instead of properly measure auxiliary system power use. It literally has no way to sense it, it HAS to guess. So it also makes sense that engine power and regen power is regulated from the motor controller.
I will be *trying* to get a hold of a high-current CAN-connected current sensor. These things are ludicrously expensive (think: as expensive as 5kWh of batteries), so I have to find some second hand source, but wish me luck.
IssacZachary
Well-known member
mux said:
Thanks for the tips and encouragement!
Yes, 10kWh total isn't much. The 24kWh battery of mine with 11 bars only puts out around 17kWh of actual energy. And yet I have made it 65 miles climbing 6,000ft and descending only 4,000ft with that battery capacity. It's just nerve racking to make it home with less than 10% after driving at 35mpg down a 60mph highway for two hours in fair weather. If I add even just 2kWh of actual usable energy that alone would be a big help. But like you said, this could grow and grow. Ideally I'd like to build up to close to double the actual range. But even 1.5 times the current range would make a world of difference for me.
IssacZachary said:
Both LeafSpy and LeafDD read total battery charging & discharging current from the BMS ECU data. So the BMS by using the change in output
voltage divided by the change in output current, the internal resistance of the battery is determined. Both LeafDD and LeafSpy provide
a calculation of the Leaf''s battery's internal resistance. LeafSpy will indicate the accessory, e.g. fans, current draw with just the ignition
being on (not driving), so it has access to current data without using the motor controller's data.
mux said:
Excellent progress! Question, how are you (or aren't you) balancing/monitoring the second extender pack? My plan was using a second Leaf BMS with a dedicated phone and Leaf Spy to monitor it, and if WolfTronix ever sells his BMS MCU replacement use that for monitoring and cutoff control.
IssacZachary
Well-known member
Maybe regen current is limited to max voltage?? It only cuts back once it reaches near max voltage??lorenfb said:
If there's a hall effect sensor reading current on the battery to calculate battery resistance I don't see how it could indicate less resistance with the addition of an external battery.
jkenny23 said:
The packs I'm using as my temporary extender (which I just drove with) are VW GTE batteries, which have a CAN connection that I will just... directly connect to the vehicle CAN. Then I am planning to, at some point, build a little screen on top of my dash that shows me relevant vehicle information. The pack will then also self-balance. However, I need to still do some reverse engineering to get this to work.
Another progress update: the car just finished charging for 10 fucking hours. I did the math: the car was *just* at VLBW when I plugged it in (i.e. remaining range showing dashes), which means there should be about 5-6kWh left in it. The original pack is 24kWh, but its state of health is 70%, so there's really only 16.8kWh left. The new pack is 8.7 kWh nominal, so the total nominal capacity in the car right now should be 25.5kWh. I measured the total energy going in with a wall socket energy meter, that was 21.4kWh, so if you subtract ~8% conversion losses that's 20kWh of actual charge. And yep, that's 5.5kWh below the expected capacity of the pack. The math checks out! And also: the extender pack has performed nominally, it's not degraded. Awesome!
Just had another crazy idea this morning, but it would probably exceed the cost/effort threshold of saving up to buy a dual motor Model 3 or something equivalent;
What about adding another electric drive motor to the rear wheels? I'm not a mechanical guy, so this is probably way too much effort in itself, finding a suitable rear axle with differential to add to the rear of the car, but this would give some extra power on the drive (as opposed to approaching the weight limit of the Leaf's drive system and keeping the sluggish 80kW motor), and also give some extra regen to the second pack. This also frees up the second pack to be a different voltage (of course no longer in parallel) with the main pack, since it's got its own drive system. You would need a controller that would take the throttle input and maps it to appropriate values for the main motor and auxiliary motor to give the desired power output. You could modify these values as the packs discharge to maintain the 2 batteries at roughly the same level, kinda like a Hybrid maintains its battery at ~70% by changing the power from/to the electrical motor vs. the ICE.
What about adding another electric drive motor to the rear wheels? I'm not a mechanical guy, so this is probably way too much effort in itself, finding a suitable rear axle with differential to add to the rear of the car, but this would give some extra power on the drive (as opposed to approaching the weight limit of the Leaf's drive system and keeping the sluggish 80kW motor), and also give some extra regen to the second pack. This also frees up the second pack to be a different voltage (of course no longer in parallel) with the main pack, since it's got its own drive system. You would need a controller that would take the throttle input and maps it to appropriate values for the main motor and auxiliary motor to give the desired power output. You could modify these values as the packs discharge to maintain the 2 batteries at roughly the same level, kinda like a Hybrid maintains its battery at ~70% by changing the power from/to the electrical motor vs. the ICE.
First of all - I'm unsure whether you can really call the EM61 sluggish. I can reliably pull the motor into ESP, even on dry, cold roads, with stock (equivalent) tires. Sure, more grippy tires would help a lot, but what really is the value of an extra motor if the car is already at city driving speeds in about as much time as it takes you to push and then let off the throttle? How often do you really need more power? Seriously?
I've driven in eco cars a lot - the Mitsu Mirage most recently, and the Suzuki Alto before. Now those are cars that need more power. Those are cars that even with 2 people inside can't climb a steep slope at highway speeds. They're consistently slower even at maximum acceleration than anyone else pulling out from a traffic light. You're a hindrance in these cars.
The Leaf? If I floor it, I see cars standing still, quickly becoming smaller in my rear view mirror. It can climb a steep grade at highway speeds, fully loaded to 4k lbs. I just did that yesterday.
I'm aware that the EM57 (2013-17 Leaf) is quite a bit less torquey, so the 'feel' of the car may have changed a bit. Also, even though my Leaf accelerates well over three times quicker from a stop than the Mirage, the sheer lack of noise gives a false impression of slowness. Still, it's got plenty of power.
All that aside: is it possible? Yes! In fact, there is plenty of room around the rear subframe to mount a rear motor. I'm pretty sure that with a lot of dedication, you can just put a Leaf drive unit flat instead of upright under the car, and it will fit just fine. Note that there is a sea of empty space behind the rear axle. All you have to find a new place for is the electric parking brake, which arguably you should just replace with a hand-operated one if you're making the car AWD. The car also has pretty good anti-dive, decent sideways stiffness and the original drive unit comes with a differential in the package, so no need to do funny stuff to it to make it work. It won't fit stock, don't get me wrong - you'll need to make a bunch of adapter brackets to fit it to the existing suspension points and hinges, not to mention grind off a whole lot of crap, but from a volume and size perspective, this is possible.
-----------------------
Another update: I've driven with the car fully loaded (max. GVW) by installing a second layer of batteries AND lugging around another battery, just sitting in the car doing nothing, and a bunch of other luggage, and a girlfriend. Also, we had very cold weather (couple degrees freezing) and a 6Bft head/sidewind. Despite all that and my 12V battery dying, I managed to drive 100km with 11km on the GoM, so a decent 7-8kWh still remaining. I'm thoroughly impressed with the range now. This car only needs some aeromods and it'll be an acceptable car!
I've driven in eco cars a lot - the Mitsu Mirage most recently, and the Suzuki Alto before. Now those are cars that need more power. Those are cars that even with 2 people inside can't climb a steep slope at highway speeds. They're consistently slower even at maximum acceleration than anyone else pulling out from a traffic light. You're a hindrance in these cars.
The Leaf? If I floor it, I see cars standing still, quickly becoming smaller in my rear view mirror. It can climb a steep grade at highway speeds, fully loaded to 4k lbs. I just did that yesterday.
I'm aware that the EM57 (2013-17 Leaf) is quite a bit less torquey, so the 'feel' of the car may have changed a bit. Also, even though my Leaf accelerates well over three times quicker from a stop than the Mirage, the sheer lack of noise gives a false impression of slowness. Still, it's got plenty of power.
All that aside: is it possible? Yes! In fact, there is plenty of room around the rear subframe to mount a rear motor. I'm pretty sure that with a lot of dedication, you can just put a Leaf drive unit flat instead of upright under the car, and it will fit just fine. Note that there is a sea of empty space behind the rear axle. All you have to find a new place for is the electric parking brake, which arguably you should just replace with a hand-operated one if you're making the car AWD. The car also has pretty good anti-dive, decent sideways stiffness and the original drive unit comes with a differential in the package, so no need to do funny stuff to it to make it work. It won't fit stock, don't get me wrong - you'll need to make a bunch of adapter brackets to fit it to the existing suspension points and hinges, not to mention grind off a whole lot of crap, but from a volume and size perspective, this is possible.
-----------------------
Another update: I've driven with the car fully loaded (max. GVW) by installing a second layer of batteries AND lugging around another battery, just sitting in the car doing nothing, and a bunch of other luggage, and a girlfriend. Also, we had very cold weather (couple degrees freezing) and a 6Bft head/sidewind. Despite all that and my 12V battery dying, I managed to drive 100km with 11km on the GoM, so a decent 7-8kWh still remaining. I'm thoroughly impressed with the range now. This car only needs some aeromods and it'll be an acceptable car!
IssacZachary
Well-known member
The ambiguous line between sluggish and sporty is defined by each driver's opinion. Personally I feel like a road warior driving my 1972 VW air cooled Beetle with its stock 1600cc engine, tiny stock single barrel carburetor and "pea shooter" tail pipes. Anyhow, it feels much more powerful than my 1985 non-turbo 1.6L diesel that died and I am fixing. I never ever use "full throttle" in the Leaf. (I'm not sure if "full throttle" is the correct term for both electric and diesel cars since neither have throttles.)
But as far as driving a second axle is concerned there also is the pusher trailer concept. I'm actually split between either adding more L-ion cells to my Leaf or converting the diesel into a natural gas powered pusher trailer. Each has it's own pros and cons.
But as far as driving a second axle is concerned there also is the pusher trailer concept. I'm actually split between either adding more L-ion cells to my Leaf or converting the diesel into a natural gas powered pusher trailer. Each has it's own pros and cons.
Back in the Eighties, one of the car magazines took a Honda Civic wagon, and added a second Civic drivetrain (automatic) in the rear, with the steering locked. It wasn't twice as fast, but it had quite a bit of Pep - and weight.
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