Feature requests/input for MUXSAN 45kWh replacement LEAF battery

[mux]

Great information and really admire your work on all the developments, I'm building an EV Land Rover, based on a 2019 40Kwh Leaf, the battery pack and charging using a Resolve_EV controller's a challenge, as then I discover later Leaf won't run Chademo with that controller, may have to use an older PDM, but the info above regarding the cooling on the rear section of the battery pack is interesting. In this EV conversion, it would be necessary to split the cells up and position around the vehicle, so my guess is, this would help to some degree, but significantly so?

Yeah, it seems like you can somewhat safely depend on stacks of 3-4 modules at a time, but more and you'll run into thermal and end-of-life mechanical issues (cells swelling up and popping your constraints)

My second dream idea would be to design an extender pack that fits into the empty space where a spare tire goes in some.markets (not in the US or EU I think). It's just wasted space.right now, and if you could get a design with 8-10 kWh into that space it would be a nearly no trade offs way of expanding range.

We tried that, in fact I've done a few 3D scans back in the day (with a kinect, before we had a proper 3D scanner) to see how it would fit. You can get 20+ kWh in there, but it's a terrible position for a battery. There's little protection against the elements, the space is very irregularly shaped and the battery space interferes with a bunch of optional elements like the electric parking brake on gen1 and tow hitches. It's a challenge to get a battery underneath there.

 

[DougWantsALeaf]

Yeah, it seems like you can somewhat safely depend on stacks of 3-4 modules at a time, but more and you'll run into thermal and end-of-life mechanical issues (cells swelling up and popping your constraints)


We tried that, in fact I've done a few 3D scans back in the day (with a kinect, before we had a proper 3D scanner) to see how it would fit. You can get 20+ kWh in there, but it's a terrible position for a battery. There's little protection against the elements, the space is very irregularly shaped and the battery space interferes with a bunch of optional elements like the electric parking brake on gen1 and tow hitches. It's a challenge to get a battery underneath there.

Incredible! Thank you again for taking the time to answer. While 20kWh would be amazing, even 10 carefully jammed in there would make the Leaf Plus a doable long ranger. Didn't think about the tow hitch delima though.

Guessing market for a 10K USD upgrade for the Leaf extender spare tire pack might be limited.

 

[Joey21]

I don't have an in-depth understanding of the engineering required or the capabilities of a design like this but have you considered using a heat pipe design to remove heat from the Leaf pack? Or piggy back that with the car's air conditioner? Wondering if flat plates (1/16 inch thick) of copper could be sandwiched between the modules in the rear pack and a heat pipe run past those copper plate tabs to transfer heat to a heat pipe circuit - which then moves heat to the air conditioner and then outside. Could also be used to warm the pack using the heat pump function. Perhaps Nissan's winter heaters for the pack are already a better solution for the battery heating needs. I believe I've read somewhere that some Leafs in cold parts of the world are equipped with heaters.

Possibly use freon or even helium to wick heat away inside the heat pipe. I'm imagining a larger version of what my chunky old laptop uses to cool itself.

 

[cornbinder89]

The Leaf pack is already compressed together with through bolts across the entire rear module (64k pack is different) how you can incorporate more space into something that is compressed right now, I don't know?
It seams to me the way to attack the already mfg and installed packs is to look to cooling the shell in some meaningful way. Still not going to evenly cool the cells. Then may be you could open the shell and provide some thermal bonding to the shell (while still being electrically isolated from it). Big undertaking for limited gain.

 

[DougWantsALeaf]

With my eco tires and low.weight rims, I only needs just a few more degrees of cooling between DC charging. Even a small improvement would be a great help at least psychologically.

 

[nismoboy34]

Ive started down this road and its a tough one but to build the leaf battery with Active cooling or heating requires a redesign from the ground up . Its a workable solution but when you consider the cost of the new Alu case ( as aluminium is very heat conductive ) the question is are consumers willing to pay for the cooling ? Then comes the next question how to manufacture it safely and then how to make sure its crash tested ? and safe for passenger vehicles .? see the below idea we had the design consideration is that the total pack would have to sit at least 20mm lower to clear the rear passenger foot depression area . This means the overall pack can still be made in the same plane but with a lower height ? in saying this the 62Kwh pack sits 40mm lower so this isnt bad ? maybe some people can comment and give their thoughts . Many ways to achieving this but @mux would need to Chime in Heating and cooling are Every leaf owners concern .
It goes with out saying that a battery kept at 25Deg c is a battery in its happy place . It will give exponentially more cycles than a battery that is not heated or cooled . This means including some form of a heat pump or heater chamber into the coolant line to allow heating of the liquid that will flow through the belly of the battery ?Dividing compartments means no water and moisture ingress which we dont want happening on the leaf , And Fundamentally the NMC cells which are more modern would go a long way to increasing the lifespan of the leaf batteries over the previous Gen 1 LMO batteries .

 

[danielsantos]

First I'll ask your forgiveness for posting without first reading the entire thread! I'm a little over worked at this moment, but I would really like to have a bit of input on this.

I'm slowly working on a LiFePO₄ adjunct battery system (for the trunk or such) that works in parallel with the main battery (what ever that may be) but has it's own BMS including charger and current-limiting discharge circuit. This concurrent discharge w/o unintentionally ever charging the main battery pack (resulting in additional battery wear) while also keeping losses low is the bit I'm working out right now. But I'm also working on a thermal management system.

I live in Texas where bringing the batteries down to the outside ambient air temperature would be great, but will still kill them kind of quickly when it reaches 100°F (38°C) every day for 45 days in a row every summer . When I bought mine in 2013, I was going to modify the thermal management system until I realized that it didn't have one, then I was bummed.

So I would ask you to consider liquid thermal management and some insulation on the casing -- heating via the liquid coolant when it's cold and running it through a little radiator with a fan somewhere when it's hot. If it has that in place, then it can later be kitted to make it hot-weather friendly.

I don't have metrics yet (will need to install some sensors to get them), but my plan has been to tap the coolant system (add T connectors) in three places:

1. straight out of the pump,
2. immediately after exiting the motor, and
3. before going back in to the radiator.

The purpose is to 1 use freshly cooled coolant for cooling batteries, 2 to use waste heat from the chopper and motor when it's cold, and 3. to return the coolant. Hoses 1 and 2 would need to have some insulation.

Next, I'll replace that damn, uninsulated low-pressure refrigerant return tubing (coming out of the evaporator after it's already cooled the air) with a little counter-flow heat exchanger so I can run fluid from hose #1 through it in order to shed additional heat and bring batteries below outside temperature. (Also, insulate the full length of it so we're not wasting energy.)

Of course, a lot needs to be tested and worked out. Such a system will need to monitor compressor temperature and bypass the heat exchanger once the compressor temperature reaches a threshold that's still well below it's normal cutoff temperature.

It's possible that testing may not reveal a great benefit from trying to reuse the waste heat, in which case the system will only bother with cooling.

PS: If you aren't keeping up with the latest SiC power MOSFETs, they are amazing! e.g., Qorvo UJ4SC075008L8S is an N-channel 750V 106A MOSFET with 8mΩ Rds(on)! I was surprised! I could use that to switch the main BMS connection on and off and only loose 0.8% to waste heat. But I've found a diode that might actually work better.

PSS: During the summer, it's not uncommon for my compressor to shut off due to over-heating if I'm stuck in traffic where air isn't moving through enough and it's 110°F (43°C) outside.

 

[Ianlighting]

It's been a fair number of years since multiple announcements of aftermarket LEAF replacement batteries and, simply put, you still can't buy one. The best option you have right now to replace your Leaf's battery is to get a second hand 40 or 62kWh battery and use Dala's/my CAN bridge firmware to pair it to the car. As arguably the tech originator for a bunch of this stuff, we've been waiting for other parties to come with a good replacement battery option, but it seems like production and financing problems have plagued all the other options. DIY options are now slowly becoming possible from parties like Chooship, but are still reusing the old Leaf BMS and don't have any pack cooling. I don't think that is a workable long-term solution, a lot of the issues with the Leaf packs are down to the BMS and cooling.

So at MUXSAN we've been working on a replacement battery and we'll be announcing this publically soon. It's 45kWh (NMC) and has air cooling, and we offer CCS/CHAdeMO 2.0 charging at up to 100kW as an optional extra. It'll launch in the Netherlands to start, but we're aiming for worldwide shipping (with some liability asterisks). It won't be as cheap as the DIY kits, but not as expensive as our 45kWh extenders. You'll be able to buy one in the 4th quarter of this year and prototypes are going to be on the road and doing publicity 'soon'.

I think I kind of know what Leaf owners want in a hypothetical new battery - a bit more capacity, faster charging, cooling and Leaf Spy Pro support. But of course I'm in my bubble of colleagues in this space, what do YOU want in a replacement battery? This can be hardware or software.

Note that any Leaf Spy Pro feature is going to be dependent on the willingness of Turbo3 to work with us on that (don't get me wrong, he's awesome and really responsive to bugreports etc.).

Big hardware things are probably not going to be feasible, as we're aiming for production in the low hundreds of units per our current businessplan.

I am very interested in what you are trailing here. I just sent a comment in via your website to join any mailing list you may have for updates to this story.

You asked for requests. In my case, although I have a Leaf, it currently has good range. My requirement is for another vehicle which is an EV conversion based on a salvage Leaf, using Resolve-EV VCU, so needs a Leaf compatible BMS.

Ideally:
50 - 70kWh
Trusted supplier
Does not require metal case
Decent instructions
Warranty

Option for faster charging - if that’s something that can be added at a later date when funds allow, that would be great as an option.

I look forward to hearing more.
Thanks.

 

[mux]

I don't have an in-depth understanding of the engineering required or the capabilities of a design like this but have you considered using a heat pipe design to remove heat from the Leaf pack? Or piggy back that with the car's air conditioner?

Well yes, there will be a heat exchanger that can be tied into the A/C system. It's not a heat pipe, rather just a branch off the existing piping that drops into the pack. A sealed battery pack without any dedicated way of deliberately moving heat into/out of the pack is never a good idea.

Ive started down this road and its a tough one but to build the leaf battery with Active cooling or heating requires a redesign from the ground up . Its a workable solution but when you consider the cost of the new Alu case ( as aluminium is very heat conductive ) the question is are consumers willing to pay for the cooling ?

We're working within the constraints of the original pack for two big reasons: one is that it allows for relatively easy engineering of the most safety-critical parts, the other is that it saves a lot of cost. That does mean thermal management is going to be somewhat suboptimal, but really... it's not that bad. As soon as you have just any airflow inside the pack, the few hundred watts you're dissipating are very easily transported around.

Then comes the next question how to manufacture it safely and then how to make sure its crash tested ? and safe for passenger vehicles .?

Realistically, for a near EOL vehicle, you're not going to get a new battery shell design approved. Now, fortunately, the battery isn't part of the safety rating (it's not a structural component, crash testing is done with dummy masses instead of the battery) so you could probably get out of this without a bunch of expensive crash testing, but it's much easier to take what's been approved and build on top of that.

To be clear, we're still doing all the appropriate testing and validation to ensure the pack complies with relevant safety regulations - ECE R10, R100, etc.

see the below idea we had the design consideration is that the total pack would have to sit at least 20mm lower to clear the rear passenger foot depression area . This means the overall pack can still be made in the same plane but with a lower height ? in saying this the 62Kwh pack sits 40mm lower so this isnt bad ? maybe some people can comment and give their thoughts . Many ways to achieving this but @mux would need to Chime in Heating and cooling are Every leaf owners concern .

The lowest point on the leaf is already a bit lower than the battery itself, you can move the floor of the battery down exactly 40mm without needing new certification (that's what Nissan did on the same environmental/safety certificate number with the 62kWh battery - i.e. no need to retest).

So I would ask you to consider liquid thermal management and some insulation on the casing -- heating via the liquid coolant when it's cold and running it through a little radiator with a fan somewhere when it's hot. If it has that in place, then it can later be kitted to make it hot-weather friendly.

Yes we have thermal management as an option*, but you'll still have this problem when the car is sitting idle. No matter how much you insulate the battery, it's eventually going to heat up to whatever the ambient temp is. The only solution to that is letting the car sit in an insulated, air conditioned garage.

I don't have metrics yet (will need to install some sensors to get them), but my plan has been to tap the coolant system (add T connectors) in three places:

1. straight out of the pump,
2. immediately after exiting the motor, and
3. before going back in to the radiator.

The purpose is to 1 use freshly cooled coolant for cooling batteries, 2 to use waste heat from the chopper and motor when it's cold, and 3. to return the coolant. Hoses 1 and 2 would need to have some insulation.

If you're making a custom solution anyway, it's much easier from a pressure management perspective to put a T-valve in front of and after the existing interior evaporator and switch them both over to your own heat exchanger, insulating both lines. Then you have the same performance and pressure drop characteristics (so no problems with the AC Auto Amp throwing errors) and only two cuts/4 joints to worry about.

PS: If you aren't keeping up with the latest SiC power MOSFETs, they are amazing! e.g., Qorvo UJ4SC075008L8S is an N-channel 750V 106A MOSFET with 8mΩ Rds(on)! I was surprised! I could use that to switch the main BMS connection on and off and only loose 0.8% to waste heat. But I've found a diode that might actually work better.

On this entire project: don't consider what happens if things go right, but consider what happens when things go wrong. If that MOSFET fails, it will fail closed and thus explosively. MOSFETs are not a usable high energy contactor. You HAVE to use a mechanical contactor with arc extinguishing features, e.g. TE LEV200.

I am very interested in what you are trailing here. I just sent a comment in via your website to join any mailing list you may have for updates to this story.

You asked for requests. In my case, although I have a Leaf, it currently has good range. My requirement is for another vehicle which is an EV conversion based on a salvage Leaf, using Resolve-EV VCU, so needs a Leaf compatible BMS.

Ideally:
50 - 70kWh
Trusted supplier
Does not require metal case
Decent instructions
Warranty

Option for faster charging - if that’s something that can be added at a later date when funds allow, that would be great as an option.

I look forward to hearing more.
Thanks.

Thanks for the message, you're on the list now. Still working on that website and feature brief, but the kids take up much more time than you'd think!

*(option meaning: we're shipping these as kits, so you need to find somebody who has the equipment to pump out the HVAC system, connect new pipes onto our quick disconnect, test everything and pump refrigerant back in - the rest of the battery is plug and play, HVAC mods obviously arent)

 

[Ianlighting]

Well yes, there will be a heat exchanger that can be tied into the A/C system. It's not a heat pipe, rather just a branch off the existing piping that drops into the pack. A sealed battery pack without any dedicated way of deliberately moving heat into/out of the pack is never a good idea.


We're working within the constraints of the original pack for two big reasons: one is that it allows for relatively easy engineering of the most safety-critical parts, the other is that it saves a lot of cost. That does mean thermal management is going to be somewhat suboptimal, but really... it's not that bad. As soon as you have just any airflow inside the pack, the few hundred watts you're dissipating are very easily transported around.


Realistically, for a near EOL vehicle, you're not going to get a new battery shell design approved. Now, fortunately, the battery isn't part of the safety rating (it's not a structural component, crash testing is done with dummy masses instead of the battery) so you could probably get out of this without a bunch of expensive crash testing, but it's much easier to take what's been approved and build on top of that.

To be clear, we're still doing all the appropriate testing and validation to ensure the pack complies with relevant safety regulations - ECE R10, R100, etc.


The lowest point on the leaf is already a bit lower than the battery itself, you can move the floor of the battery down exactly 40mm without needing new certification (that's what Nissan did on the same environmental/safety certificate number with the 62kWh battery - i.e. no need to retest).


Yes we have thermal management as an option*, but you'll still have this problem when the car is sitting idle. No matter how much you insulate the battery, it's eventually going to heat up to whatever the ambient temp is. The only solution to that is letting the car sit in an insulated, air conditioned garage.

If you're making a custom solution anyway, it's much easier from a pressure management perspective to put a T-valve in front of and after the existing interior evaporator and switch them both over to your own heat exchanger, insulating both lines. Then you have the same performance and pressure drop characteristics (so no problems with the AC Auto Amp throwing errors) and only two cuts/4 joints to worry about.

On this entire project: don't consider what happens if things go right, but consider what happens when things go wrong. If that MOSFET fails, it will fail closed and thus explosively. MOSFETs are not a usable high energy contactor. You HAVE to use a mechanical contactor with arc extinguishing features, e.g. TE LEV200.


Thanks for the message, you're on the list now. Still working on that website and feature brief, but the kids take up much more time than you'd think!

*(option meaning: we're shipping these as kits, so you need to find somebody who has the equipment to pump out the HVAC system, connect new pipes onto our quick disconnect, test everything and pump refrigerant back in - the rest of the battery is plug and play, HVAC mods obviously arent)

Do you think using the HVAC cooling will be a necessity? Would it work without? I’m in the UK, most of the time we do t have Arizona temperatures which some of your other customers might be more concerned about

 

[mux]

Do you think using the HVAC cooling will be a necessity? Would it work without? I’m in the UK, most of the time we do t have Arizona temperatures which some of your other customers might be more concerned about

No, it's not necessary and not compulsory for installation - the pack can be installed like a regular Leaf pack. It will still actively circulate air within the pack to ensure even degradation and maximum passive heat exchange through the shell.

I don't think I have to say what the advantages and disadvantages are in this forum, y'all know what's wrong with the Leaf's original pack.

 

[Joey21]

Excellent discussion!

 

[DougWantsALeaf]

Even with internal circulation, pack will cool a fair bit faster.

 

[MikeinPA]

In case its not on the list already, lots of cheap NTC thermistors in wells between (or on top) of cells. Or at least make provisions for installing thermistors.

Will the shell be gasketed, or wet seal?

 

[Oostenrijker]

The best option you have right now to replace your Leaf's battery is to get a second hand 40 or 62kWh battery and use Dala's/my CAN bridge firmware to pair it to the car.

As a matter of fact: one hour ago, I have checked ANWB Koerslijst and AutoWeek Occasions. Trading in my current 40kWh to a 62kWh Leaf, would cost between € 5000 and € 7000 let say.

Picking a N-Connecta is ofcourse cheaper than a Tekna, but I have Tekna on the moment. So don't get me wrong: if I want to replace the battery pack of my Leaf for a bigger one, then I would just trade my 40kWh in for a 62kWh.

Because electric cars depreciating crazy currently, I would also not wanna invest any money expect new tires when needed. For example: put 3 phase charging in a Leaf, and one would either charge 11kW or 22kW. Who needs fast chargers? But you charge more than € 3000 for 11kW 3 phase charger, and more than € 5000 for 22kW charging.

That money can get me a used 62kWh: where I wouldn't need 3 phase charging at all, because I do an average of 12kWh/100km. So I should be able to do easily 400km on a single charge.

So would I be willing to pay for a 45kWh aftermarket replacement battery pack? Yes when you charge € 5000 for it, because if it's € 10.000 then it's not worth it. For that money, one can trade it's Leaf in for a used Tesla model 3. Which already does 3 phase charging, has more than 400km range etc.

Don't forget cheaper EV's are on the way: Citroen C3 Electric, Renault 5 Electric etc. When you put a aftermarket battery pack in a Leaf, still the rest of the technology is outdated.

So once I wanna sell my Leaf with
a aftermarket replacement battery pack, then it's going be difficult to earn that money back. Because Henk and Ingrid wanna buy Leaf's perhaps, who don't care that you spend € 15.000 at aftermarket upgrades. A Leaf isn't a Peugeot 205 GTi that keeps it value well.

For me fast charging isn't important: so any future EV, just needs to do 3 phase charging. CCS would be nice: again because of Tesla, as Tesla superchargers are way more affordable than Fastned and Co.

But more importantly: how will you deal with warranty? Selling a 45kWh aftermarket pack is one thing, but if something is wrong with it. Then it's not cool to read on Google maps, from customers that you don't provided them aftersales on the extender they got installed by you. That makes me skeptical, if you would not give home when there are issues.

Another thing I miss within the Leaf or any EV: I want to be able to do CHAdeMO charging at a speed of my choice. So 20kW max for example. That way the battery won't heat up so much, and I still gain more than 150km rang while charging for an hour.

The only way to achieve this now is: by purposely charging at CHAdeMO chargers, that only deliver 20kW. But they rare, and usually free. Which means they are usually taken.

 

[woeful]

As a 40 kWh e-NV200 owner, this is fascinating but it should be a while before I want a replacement battery. Does the e-NV200 original battery pack (which has an internal fan and a feeble connection to the air conditioning) have a generally longer working life than a LEAF battery? Or is it crippled by the battery firmware not operating that fan often enough?

I'm very pleased to see such battery upgrades being produced. It gives me hope that mine will be replaceable when it degrades too far to be useful. These are otherwise well-made vehicles and it seems wasteful not to run them until their mechanical parts fail, rather than when their range becomes uncomfortably short. Congratulations for producing a working product, and I hope it is a success.

 

[Joeaverage]

These are otherwise well-made vehicles and it seems wasteful not to run them until their mechanical parts fail, rather than when their range becomes uncomfortably short. Congratulations for producing a working product, and I hope it is a success.

This...

 

[Nightmare]

I think that a completely new interest in the properties of the battery should be added here. I had a Leaf G1 for a few months in 2012, so I thought about it for a long time, and now there is a great opportunity for cheap Leafs, where no one is sorry to rebuild it completely from scratch, my plan is to run a 160kW inverter at 500V and try to use parts with a JUKE 4x4 and back place the second engine, what is the biggest draw we can get from the biggest battery?

 

[mux]

The new battery isn't rated for that, the manufacturer's maximum rated draw is 96.6kW (continuous), 131kW (60s) and 180kW (peak, 10s).

I'd be a bit hesitant to run a 160kW inverter from a 45kWh battery. It's fine if all you do is off-the-line acceleration. Though be warned that the main battery connector is technically only rated for 400A peak.

 

[Nightmare]

The new battery isn't rated for that, the manufacturer's maximum rated draw is 96.6kW (continuous), 131kW (60s) and 180kW (peak, 10s).

I'd be a bit hesitant to run a 160kW inverter from a 45kWh battery. It's fine if all you do is off-the-line acceleration. Though be warned that the main battery connector is technically only rated for 400A peak.

180kW 10s on factory e+ battery or yust MUXSAN 45kWh replacement?