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Re: Refueling time is the biggest hurdle for BEVs
bk11   12/17/2013 1:00:22 PM

What type of heat pump are you referring to?  I thought most larger systems used a compressor, and are essentially just "reversable" AC units.  Did you mean Peltier devices?  I wouldn't think they are nearly as efficient for cooling, but I could see them being used for heat (more efficient than resistive heating.)  I would think they would be pricey in that size, though.

Interesting idea about ammonia cycle for ICE-based cars, though.  I wonder what the roadblocks would be?

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Re: Refueling time is the biggest hurdle for BEVs
AZskibum   12/17/2013 10:09:37 AM
Excellent points Bert, and especially your tongue in cheek comment about recharging stations requiring their own nuclear power plant to deliver all the current that would be required to quickly recharge multiple BEVs.

Battery R&D will soon lead to commercialization of new anodes that can dramatically increase the capacity of Li ion batteries, but quick charging will require chargers that can deliver currents approaching the "C" rating of the battery. As battery C ratings increase, so does the need for chargers with incredibly high current capability.

Hyperbole aside ("gigamps" is a word you don't hear often!), rapid charging of next-generation EV batteries will require chargers capable of providing tens of kilowatts to each EV. A station that can accommodate a dozen vehicles at a time would easily exceed 100 kW. Nobody is making EV chargers anywhere close to those kinds of numbers, nor are grid infrastructure improvements being made to deliver that level of power to large numbers of charging stations.

The BEV recharging model seems hopelessly stuck in the mindset of 4-6 hours or longer charging times, and the power available from chargers will continue to be the limiting factor, far more so than the batteries. 

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Battery power is limited
prabhakar_deosthali   12/17/2013 1:28:55 AM
The passenger car industry is some centuries old and there are many hydraulic , pneumatic and mechanical systems which are proven systems for their simplicity, reliability ,durability and ease of maintenance.

If we are to replace all these systems by electrical systems , first question arise is how reliable they will be compared to the conventional solutions.

Secondly just to replace the engine with electrical motor and the associated batteries, we get only a limited range in one charge. Imagine if all the axillary systems are also to run on battery - what will happen to the range?

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Refueling time is the biggest hurdle for BEVs
Bert22306   12/16/2013 9:33:31 PM
Interesting thoughts. But I don't entirely agree.

On heating and cooling. The air conditioning compressor is a heavy load. The car designer will use whatever the most abundant source of power there is, to run such a heavy load. In EVs, especially battery powered EVs, it makes sense to install a heat pump, both for cooling and for heating. What better choice is there? You have no large excess of waste heat for winter heating, nor do you have any rotating motor with a large excess of unused power for running a compressor-based air conditioning system.

But does it make any sense to install a heat pump in a normal ICE car? I doubt it. In winter, it seems to me that there's enough waste heat in most ICE cars that you don't want to burden the electrical system. Coolness factor or not, I would think. And in summer, my question has always been, why don't regular ICE cars use the ammonia cycle for air conditioning? Using the waste heat from the exhaust system? Makes more sense than electrification, in an ICE car, doesn't it? My guess is cost. Either way, though, I don't see that electrifying the heating system makes a lot of sense in an ICE car.

One real problem I have with BEVs is, it takes longer to refuel them than the time you can drive them. Think about it. Drive a car, say, one hour, then you're forced to wait anywhere from 4 to 12 hours to get it refueled. Doesn't sound like something you can brainwash anyone to love, other than the true fanatic. At best, this might work for that second "commuter car," but it hardly supports a model of complete electrification. So we need something better, but also something that doesn't require recharging stations to have their own nuclear power plant, to supply that gigamps recharge current capacity that would be needed, to refuel all those hungry BEVs in a couple of minutes.

Seems to me that a hybrid approach will work best in the foreseeable future, although I would hope the hybrid is not with an ICE. My favorite being, a hybrid EV where the main energy supply is still a hydrocarbon fuel, sent to a hydrogen reformer, then to a fuel cell. And a hybrid-sized battery to take care of those short spurts of power cars need, and also to use regenerative braking for better urban fuel economy.

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