• Nissan Leaf 40 kWh #Rapidgate
    12 replies, posted
Not really news until Nissan actually do something so you guys can have an EV thread... As many of you know, the Nissan Leaf is one of the few EVs on the market today that doesn't actively cool the battery pack. With the release of the 40 kWh Leaf this has lead to a bit of an issue with rapid charging... the pack gets so hot and then limits charge rates to 22kW - 29kW as opposed to the usual ~50 kW. Nissan have repeatedly stated this is isolated to a few cars in Europe but so far everyone who has tested driving long distances they have encountered this issue. A 28kWh Ioniq or even a 30 kWh Leaf are currently able to beat the new Leaf by several hours on long distance trips (about 400 miles) by several hours. https://www.youtube.com/watch?v=Dpwyue9IiBE
I'm no expert but wouldn't there be a recall to add active cooling to the battery packs if it turns out to be a major issue? If not, this is a pretty bad situation.
Nissan could (and should) recall them and add proper cooling but it would cost them a lot. I don't think there's any legal basis for forcing them to do it.
You would think battery cooling would be easy and to implement. Off the top of my head pumping mineral oil through the pack and between the cells would be dead easy. Attaching oil or water cooled heat sinks to the connector leads would also be somewhat easy. It just reeks of pure laziness.
I don't think Tesla force air through the pack, it's sealed. There was a lot of speculation about them using it for the Model 3 to save on costs but I don't think they ever did. If you get the car into diagnostic mode it actually shows you a cool diagram of how all the heating and cooling loops are working (stolen from TMC): https://teslamotorsclub.com/tmc/attachments/tesla-thermal-screen-jpg.219794/ 1. Main coolant radiator. Does not have a fan apparently. When vehicle is in motion air passes through the fins cooling the liquid. Coolant enters from the right side. This radiator can be bypassed with device #10. 2. Coolant circulation mode selector. A device that switches between two modes: Series and Parallel. If series, coolant passes from #1 to #3 and then from B to #7. If is parallel, one loop passes from #1 to #7 and other loop from B to #3. 3. 12V coolant pump. Percents indicate pump running speed. Slower speed consumes less energy, prolongs pump life and slows the coolant flow.  4. Adjustable coolant redirection valve. Sends 100% of coolant from #3 to #5, 100% form #3 to #13 or anything in between. 5. Coolant heater. Apparently is rated for 6kW. Runs on high voltage. If activated, coolant will be heated up. This is used to heat the Battery fast. Heat generated by #6 #8 #9# can also be used to for pack heating. Cold pack will also cool down those devices. 6. DC-DC converter. Takes energy from high voltage pack, keeps 12V battery charged and all 12V devices powered up. Small part of coolant is directed into this device as heat generation is small. 7. 12V coolant pump. This pump is required to keep second loop of coolant flowing if #2 is in parallel mode. Acts as a backup to #3. In series mode both pumps run at equal speed. 8. On-board charger. Is used for vehicle charging. Converts AC grid electricity to suitable DC for main battery. Second charger is not available any more. There is a coolant bypass. Likely required due to single charger has up to half the coolant throughput. Number on the left indicates temperature of the electronics inside. 9. Drivetrain. Coolant enters the motor. Circulates in the stator. Also circulates in inverter (power electronics) and then exits (with temperature value shown). Transmission (reduction gear and differential) doesn't require cooling though it gets some heat as it is between warm motor and inverter. Which raises the temperature of the oil and makes vehicle slightly more efficient. Also rotor temperature is shown (most likely calculated estimation) and Inverter electronics temperature (PCB).  10. Adjustable coolant redirection valve. Same as #4. Either sends 100% of coolant through the radiator, bypasses 100% or anything in between. If coolant is not directed to the radiator it can be used to heat the Battery. 11. AC condenser. Required to cool down refrigerant. Does have a fan. Fan speed indicated in percents. There are two condensers each having a 12V fan. Are between fog lights and front wheel arches. Air enters through louvers and exits to the wheel arc. Louvers can be closed for better drag coefficient.  12. Electric Air Conditioner Compressor. Runs on high voltage. It is used for two purposes. To cool the air for the cabin using #16 and/or to cool the glycol loop using #13. Percents indicate compressor running speed. If cooling requirements are very small compressor will be temporarily stopped to allow cabin air evaporator to stay above freezing point. Sensors before and after indicate temperature and pressure of the refrigerant before and after the compressor.  13. Refrigerant-coolant heat exchanger. Functions the same way as #11 #16 but instead of air it cools glycol coolant passing through it. While #16 is not allowed to get below 0*C/32*F chiller can go colder as coolant will freeze at much lower temperatures. Though it's more efficient to pass as much of coolant as possible. Chiller can be disabled with #14. To keep #16 functional (if user requested) #4 can redirect only some of the coolant. 14. Chiller activation valve. Is an on-off valve that either blocks the refrigerant from expanding into #13 or not. 15. Cabin evaporator activation valve. Is an on-off valve that either blocks the refrigerant from expanding into #16 or not. 16. Cabin air evaporator. Radiator inside HVAC system that cools the air that passes through. If climate control AC setting is "ON" or precooling is activated remotely this will cool and dry the air that passes it. Air gets here through cabin air filter and continues to #17.  17. Cabin air PTC heater element. Apparently is rated for 6kW maximum power. Runs on high voltage. Due to it being Positive Thermal Coefficient device, it can generate 6kW of heat only if air that enters is very cold and is moving very fast. If the element gets hot, it will reduce its draw even if it is activated to 100%. Usually air that exits doesn't get scalding hot no matter what. Temperatures between 55*C - 80*C can be expected at full requested power. B. Main traction high voltage battery. Some data is shown on the picture. Trend - Temp - Trend is coolant temperature that enters the battery. If it is hotter, battery will heat up. If is colder, it will cool the pack. Coolant temperature after the pack is to the left, below #7. Max/Min Cell Temp: extreme values of the sensors in the pack. There are lots of those all mostly being very close to each other.  Passive Cooling Target: this is the value system tries to bring the pack to passively. If B is below this value, heat that has been generated by #6 #8 #9 will bypass #1 and will be absorbed by the B. Active Cooling Target: this is the upper value for B temperature. If #1 is not capable to cool enough and trend is to go above that value, active cooling measures will increase. This means: #14 activates #13 and #4 selects a portion of coolant to be chilled. Depending on requirements #13 speeds up, as will fans on #11. At some point if cooling is not capable to cope other parameters can be limited (charging speed, vehicle power/regen limits). Active Heating Target: This is the lower value for B. Anything below that and vehicle will use active measures to heat the pack. Apparently #5. It appears that active heating to that limit can be disabled with range mode. This will compromise battery charging capability/regen a lot and also some of the power output.  Tesla Thermal Management System
Eh, I just found a diagram of one on a Tesla fansite.
A bit off topic but on the Model 3 to heat up the battery pack they actually make the motor more inefficient (and it even works while not moving) via software rather than having a resistive heater element just for the battery pack like in the Model S and X.
It makes you wonder if they had an idea this would happen as it's rumoured (or stated somewhere maybe?) that the 60kWh model is to be cooled.
Nissan USA responded saying it's a "safeguard" feature and working as intended, Nissan Europe have increased prices on the Leaf to try to "convince" people stop canceling orders.
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I mean, the software is working as intended. But this wouldn't be a thing if they had a proper thermal management system. Hell, even a fan blowing air over the cells would be better than nothing.
Why would you even use a electric car for a long trip anyway? Thats like using a gokart to cross the sahara desert.
A bit of a bump. I have a 40 kWh Leaf for a few days while mine has some minor work done, and I encountered rapid gate on my first charge. Was 30c yesterday, and the car had been sitting in the sun all day. I picked it up with 65% on it, ran it down to 20% and plugged into a rapid and only got 28kW from it, so it took ages to charge up. Nissan still haven't issued a proper response.
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