The 40KWH Battery Topic

[danrjones]

Actually I was thinking a quick manufacturing change could itself he related to rapidgate.

But I have no idea really

[SageBrush]

I saw that post, but I don't really believe it. It is true that I see my Plus battery pack heat up much less than my 30 or 40kWh packs did, even with multiple long fast charging sessions, but I have mostly attributed that to the lower C rate. On my last long trip, our second charge lasted 55 minutes and we gained over 40kWh to a 94% SoC, which suggests that we were getting close to the full 44kW rate of the charger up to ~90% SoC. Even then, we only had 8 temperature bars. I'm afraid I neglected to get a LeafSpy reading at that point. Still, I didn't hear any sort of fan noise coming from the car, so if there is a fan, I can't imagine it's doing much.

Agreed that a lack of fan noise says a lot. I have heard Teslas at Superchargers that sound like little airplanes with propellers.

[SageBrush]

Yes, but some part of the battery (or whatever is monitored) heats up much faster than the rest.

No doubt. And the cells towards the perimeter cool off first. Such is the life of a passive cooling design

[DaveinOlyWA]

A bombshell comment made by a VERY reputable person from Nissan stating 62 kwh packs now have circulation fan. Still waiting on more details on that.

I saw that post, but I don't really believe it. It is true that I see my Plus battery pack heat up much less than my 30 or 40kWh packs did, even with multiple long fast charging sessions, but I have mostly attributed that to the lower C rate. On my last long trip, our second charge lasted 55 minutes and we gained over 40kWh to a 94% SoC, which suggests that we were getting close to the full 44kW rate of the charger up to ~90% SoC. Even then, we only had 8 temperature bars. I'm afraid I neglected to get a LeafSpy reading at that point. Still, I didn't hear any sort of fan noise coming from the car, so if there is a fan, I can't imagine it's doing much.

I only consider it newsworthy because of the source who I trust A LOT. Remember he just returned from the Corporate awards ceremony where exposure to the upper echelons of LEAF design is not only possible but expected so the timing of his reveal is not a surprise.

As far as testing heat dissipation; charging to high SOC is not the way to do it. The ramp down is designed to mitigate the heat issues. If you want to do a real test; Only charge to the knee where the current starts to drop. Do that repeatedly and you should gain much more heat over the same distance traveled (and spend a lot less time charging)

FYI; the full rate on "most" chargers around here at 90% SOC would be higher than 44 KW. That is only 366 volts. Do you have a charge curve you can post?

[DaveinOlyWA]

Maybe a dumb question, but could one of the three temp sensors (I only see three), could it be on the motor?

Most things are possible, but I doubt that this one is true.

Yes, but some part of the battery (or whatever is monitored) heats up much faster than the rest.

I'm not sure if leafspy arranges so Temp1 is always the hottest, or if temp1 is always sensor 1?
in my case Temp1 (left reading in leafspy) seems to always be the hottest.

In settings you can change order you see temp sensors so yeah, you can arrange them from high, average and low. FYI; even if using sensors, the last one will still be lower than the first two but at least you will see situations where the 2nd one is higher than the first one. I tried both and the info varies so little that its an "either or" preference.

[danrjones]

Thanks

There is definitely some thermal mass there. We were 56 this morning and my temps were 78 and 72, max and min. I would "assume" the bigger pack on the plus would have an even bigger thermal mass, but if its packaged into the same space, maybe not. Is it physically bigger?

[frontrangeleaf]

Not bigger but several hundred pounds heavier. Definitely more thermal mass. More mass period. Same surface area.

[lorenfb]

Not bigger but several hundred pounds heavier. Definitely more thermal mass. More mass period. Same surface area.

Correct, which implies a longer thermal time constant to heat/cool.

[danrjones]

Not bigger but several hundred pounds heavier. Definitely more thermal mass. More mass period. Same surface area.

Correct, which implies a longer thermal time constant to heat/cool.

Which with rapid-gate could mean they needed a fan......... maybe

[DougWantsALeaf]

If they had just build a couple head sinks and a fan into the 62kw design, it would have killed most of the whining about the car battery.