whatever wrote:they are crazy not using iron phosphates, its a bomb waiting to go off
Except we've never seen a leaf burn, and we have seen a dozen or so 4x more expensive iron phosphate battery cars burn.
Remember, after $50million in GM's battery lab test program, an Iron phosphate cell by A123 was rejected over poor safety vs the NMC cells from LG.
Jeremy Harris wrote:One idea that's been adopted by at least one ASHP manufacturer is to use two parallel heat exchangers with an electronic valve to switch between them. When one ices up it is turned off so that the ice can melt and the other one is used.
That method would not work at all, even in Houston where the temperature rarely drops below freezing. On a 5 degree C with 95% RH, my "turned around" window air conditioning unit would ice up within 20mins. Turned it off and it took at least 40 minutes for the ice to completely melt.
You design your heatsink for the environment. If you're making an AC unit heatsink, icing isn't a design criteria, because it's always getting warmed. When you're designing something with the intent of being a heat pump heat sink for all humidity climates, you design it with avoiding icing as a key criteria, and you can achieve that need at the expense of additional heat sink size, wider thicker fin spacing, and a few other tricks.
The best part of putting the heat pump in the leaf, is the electrical components for it will all be in the cabin space as well, so even in some situation where it was so cold you couldn't overcome that outside delta-T to extract heat from the outside air, you still get every watt of power dumped into the pump system as heat for the cabin, so in your worst case scenario you still function as well as a small resistive heater.
Also, I would like to add that OEM's generally test the snot out of these systems before they put them in a car. It's not like they just add a heat pump and don't try it out before it goes into production. They test these systems in the coldest climate test facilities and hottest climate test facilities they can find for months of the most extreme use, continous freezing water spray in -30degC climate chambers until the cars suspension is sagging from all the ice accumulation, or test chambers with asphault heated to 70degC (160F) and radiators/heat exchangers all packed with dust in stagnant air running the AC continuously for weeks at a time. It's not like they just say, hey! Heat pump! And convert all the cars before trying it out in the worst possible conditions.