Battery Upgrades are very possible

[coleafrado]

Obviously I'd love to engineer and sell something that you can just slap on and it works, but - pending internal design efforts being done right now - I don't think that will be worth it.

But if you did figure out a supplier for internally cooled batteries, surely you'd try out a man-in-the-middle heat exchange attack on the HVAC high-pressure loop, right? It'd be ridiculous to mount another 400V compressor and refrigerant/water cooling loops below the trunk.

[mux]

Correct, we're hijacking the existing HVAC water loop for our battery cooling efforts. This does mean there's some weirdness the user has to do - we're not installing switch valves so while the car is instructed to turn on the HVAC to cool or heat the battery, the cabin will also be cooled/heated. In practice this means the user will have to either close the vents or change the airflow mode in the vehicle to redirect undesired heating/cooling.

This is, sadly enough, exactly how the e-NV200 already operates.

[coleafrado]

Correct, we're hijacking the existing HVAC water loop for our battery cooling efforts. This does mean there's some weirdness the user has to do - we're not installing switch valves so while the car is instructed to turn on the HVAC to cool or heat the battery, the cabin will also be cooled/heated. In practice this means the user will have to either close the vents or change the airflow mode in the vehicle to redirect undesired heating/cooling.

I was under the impression the water loop was just for PTC heating in the ZE0 cars and was completely absent from AZE0 and onward... without airflow, meaning the vents can't really be closed, there won't be any substantial heat exchange between the heater water/air exchanger and the cooling air/refrigerant loop. I must not have read the HVAC diagram clearly enough.

This is, sadly enough, exactly how the e-NV200 already operates.

I guess they did what they had to do in 2012: ship the product!

[mux]

There's still water in the air con loop! That being said, there have been more than 2 revisions of the loop over the course of the Leaf's lifespan, so there may be a generation without a water circuit. But it's on the gen1 and gen2 at least.

[Marktm]

mux;
Again thanks for sharing lots of hard-earned learnings. I put my few $$'s down on Fenix Power's first offerings - knowing it was likely only going to promote more knowledge about the Leaf's battery, with a good chance of failing in their expected offerings/results. Have you been able to obtain, analyze, use any of their work - if only what not to do?
Mark

[DougWantsALeaf]

Mux,

Thank you as well. Do you think there is any value in opening the hump in the back seat and trying to direct the AC output from the cabin into the hole? Or is that just futile? Anecdotally, it also seemed that by opening the front hood (the bonnet) while Quick Charging, it would mildly reduce the rate of battery heating. But again, that seemed mild at best.

In most of my driving, its local or within a 150-200 mile round trip, so this would only be used for a once a year cross country sort of trip where a little bit of "extra fun" would be completely acceptable to manage down battery temperature to keep the battery in good health and facilitate additional QC stops.

You can always use the Quick charge as a way to keep your battery heated in winter, so I don't care so much about heating the battery via the HVAC.

[mux]

mux;
Again thanks for sharing lots of hard-earned learnings. I put my few $$'s down on Fenix Power's first offerings - knowing it was likely only going to promote more knowledge about the Leaf's battery, with a good chance of failing in their expected offerings/results. Have you been able to obtain, analyze, use any of their work - if only what not to do?
Mark

The big issue with Fenix isn't necessarily technical (I don't know anything about their technology and don't think we'll be able to get anything), it's just the financial aspect. They are not charging enough money to run a sustainable business. As a small company in a pretty small niche, you can't sell quality new batteries for $6k. You're losing money on that deal, and you're not getting enough of it back on subscriptions.

But that said, I do have quite commie ideas about how you should run a sustainable and responsible company, so don't take this as gospel.

Thank you as well. Do you think there is any value in opening the hump in the back seat and trying to direct the AC output from the cabin into the hole? Or is that just futile? Anecdotally, it also seemed that by opening the front hood (the bonnet) while Quick Charging, it would mildly reduce the rate of battery heating. But again, that seemed mild at best.

Some people have done that and report good results, a customer of ours has done this and swears it's made a big difference. I'm less convinced.

You're blowing ever so slightly colder air over a battery case with poor thermal conductivity. There's not enough delta-T and not enough thermal conductivity to get much heat out of the battery that way. During a QC session the battery is producing between 1-2.5kW of heat, and the best you can do with 10C colder air is remove in the order of 100W or so. It's going to delay thermal throttling a little bit, but not much.

[Dala]

Wow, this thread is really starting to contain some quality information on how to make better batteries.

I don't have much to add to this cooling discussion, I've been thinking about increasing the thermal mass of the battery by installing heatsinks all over the bottom of the battery. But a few kg of aluminium wont do much for so many kW's of heat being generated, along with poor contact with the actual cells. So adding passive heatsinks might not help enough.

This thread now has swaps, upgrades, rebuilds, re-packaged and cooling of batteries Maybe we could start a separate Battery Cooling thread soon?

To further add to the diverse discussion, I've created a technical deep dive video on how the BatteryID works on the Leaf. I'll release this to the public soon, but if you want to watch it straight away you can get early access via my Patreon https://www.patreon.com/dala

I'll post the video for the public soon!

[DougWantsALeaf]

Mux,

If you remove the bolts and the underlying panel, doesn't that directly expose the battery interior (Only guessing from what I have seen on youtube videos. Even if you could only slow the heating a bit, and also apply cooling in the driving (where let's say you are pulling about 12KW of continuous power while driving vs 50-78 at a QC) you could maybe gain back enough thermal delta for a second long quick charge during the day.


I thought of the cooling fin idea, like a microchip or something, but the challenge is that you would need the fins to go through the case to have any ability to work effectively, and that seems like you would be risking water issues, and the like. I did once go through a car wash after a very long drive on a very hot day and it did seem to help a bit with the hot battery (maybe 5 C reduction in the 5-10 minutes).

[coleafrado]

If you remove the bolts and the underlying panel, doesn't that directly expose the battery interior (Only guessing from what I have seen on youtube videos.

The battery interior is only accessible by taking off the entire top of the case. The 'underlying panel' exposed in the back seat is just an opening that exposes the interior of the car to the outside.