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Bolt EV - a resistive element or heat pump?

41K views 65 replies 27 participants last post by  Steverino 
#1 · (Edited)
Does anyone know what is gonna cool/warm the cabin of a Bolt ? A resistive element or a heat pump ?
 
#38 ·
Just using it as a real-world example. Considering heat pumps aren't effective in temperatures much cooler than that, and they definitely are not effective in high-humidity conditions. The coldest conditions I've driven my Bolt EV in were mid-20s, but that was only 55-60 mph driving for 30 to 40 miles. Not really a test of the Bolt EV's capabilities.

Other examples include the Bolt EV that got into an accident during the test drive where the driver was on track to hit 200 miles on a charge in 17*F temperatures. Still not amazingly cold, but it does demonstrate that resistance heating isn't much of a liability.
 
#41 ·
Again with your Cali orientation. Yes, comfort is relative. When it gets into the 40's here in the spring I sometimes go with just a long sleeve shirt because it feels so warm (no sun either and a good wind) - however, none of this is relevant to the issue at hand, trust me! And maybe you never have to use near the full charge of your Bolt in more severe conditions. California isn't where the height of the bar is set for everyone on earth. I know that may come as a surprise, but still.

https://www.slashgear.com/5-things-...bolt-winter-road-trip-19485525/#disqus_thread
 
#44 ·
And thus, ignorance is born. I'm sorry you disagree with me, but ignoring someone solely because they present you with an alternative argument is a surefire way to close yourself off to new information.

For those who are interested in an alternative point of view. The time of heat pumps for electric vehicles has passed. They were effective and necessary in small battery vehicles operating in mild climates. However, it is now cheaper and simpler to add more batteries than it is to pay for the cost and complexity of a heat pump, especially when you account for the fact that most heat pump equipped EVs still require a resistance heater in addition (i.e., Nissan and Tesla).
 
#46 ·
To me, the Prius Prime is the perfect example of a short-range/small-battery EV, and California is one of the primary markets. So a heat pump makes sense.

The other area where I feel heat pumps make sense are in clothes dryers.

Ultimately, though, the core argument in favor of heat pumps is decreasing energy consumption to save money. With a home heating/clothes dryers, the ROI is very fast (a few years). For a vehicle, it might not be seen in the life of the car.
 
#47 ·
I'm going to guess the return on investment would be many, many multiples of the extra cost and effectively increase the range of the vehicle and owner convenience. As I understand it the more efficient set up could also apply to the battery conditioning loop during cold weather not just cabin comfort.
 
#48 ·
I'm going to guess the return on investment would be many, many multiples of the extra cost
At this stage in automotive heat pump cost, reliability and effectiveness, I'll guess the opposite. Now what? :)
 
#50 ·
Beats me, like you I'm just guessing. The Prius having a heat pump doesn't tell you how reliable they will be over the life of the car, the extra cost, how much they actually save in real dollars. For all we know, Toyota (or the Japanese government) is subsidizing the extra cost like they are with the FC cars. What's the actual cost of adding the system to the resistance heating system? How expensive will they be to repair? Would I actually save more money than it costs?
 
#53 ·
The EV1 had a heat pump 20+ years ago, so GM certainly knows how to do one. Since ECO mode seems fairly efficient compared to MAX, I am guessing the extra cost of the heat pump wasn't worth it?
 
#57 ·
... if the Japanese can do the heat pump in lesser cars that GM can do it also...
It is a more complex system. Maybe the cost for the added complexity is not too much in a production car.
But 'more complex' could mean more things to go wrong.

How much difference is there in efficiency in terms of $$ to drive in 20-40° weather? (there is that certain range)
And add in the fact that some/most of the time the car can be 'Pre-conditioned' while plugged in.


Since a resistance heating system is always needed , maybe I can see GM's reasoning to just go with the one simple heat source on a 238 mile EV.
 
#58 ·
Yeah, I know, I'm digging up an old thread .....

Having lived in the south my whole life (Texas and Georgia) where heat pumps work great, I'm a major heatpump fanboy.

But no one on this thread so far has mentioned that heat pumps MUST have a "defrost" cycle to melt the ice that will form on the outside coil in low temp/high humidity conditions. In those conditions, the coil must periodically be heated to above 32F.

On a stationary system like in our homes, during this defrost cycle the the system actually becomes an airconditioner ..... yep, the inside coil gets cold and typically a bunch of resistive strips come on to heat the air so we puny humans don't complain about the blast of cold air. Also, the massive fan on the outside coil turns off during the defrost cycle.

So, on the Prius Prime, is there some sort of "air valve vent" on the front of the car to prevent airflow through the condenser during the defrost cycle while driving down the road?

I'm also a big fan of efficiency, but I'm an even bigger fan of reliability. I bet heatpumps will prove to be too unreliable in modern EVs.
 
#59 ·
Not sure if this was mentioned yet, but the Bolt has a 8 kW resistance heater. It can suck down the juice, but you won't be cold for long! After a few minutes, the heater draw will back down to 2-3 kW....as long as you don't have it cranked to the max.
 
#60 ·
Yeah, that was pointed out in one of the early posts in this thread. Many folks are disappointed that it ONLY has resistance heating and no heat pump. Any design has trade-offs, and my bet is GM decided it was not worth the expense and reliability hit.

Love your blog, BTW. I don't own a Bolt .... yet. I'm just a wanna be.
 
#61 ·
Going to get my first test of really cold today in my Bolt. It's 17 f out. So far aside from using a lot of battery I like the Bolt heat. It flat works, unlike the Volts heat which is a mystery to me on how to keep the car warm.
On the Bolt I can set the heat at a reasonable setting 68-72 and am comfortable. Sitting at a light I see a drain of 1-2 kw.
 
#63 ·
So far aside from using a lot of battery I like the Bolt heat. It flat works, unlike the Volts heat which is a mystery to me on how to keep the car warm.
On the Bolt I can set the heat at a reasonable setting 68-72 and am comfortable. Sitting at a light I see a drain of 1-2 kw.
Agree the bolt heater is definitely better than my gen1 volt. Will get its test next week when an arctic air mass descends on me.
 
#62 ·



HEATER - GM (42539734)

FWIW: Seems the Bolt is equipped w/the 2nd Gen version of Eberspaecher heater pictured above...



Bolt PTC Heater



Chevy Volt Gen2 Heater




Eberspaecher starting production of new high-voltage heater

Comparison between 2nd Gen heater used in Volt Gen2 & Bolt with 3rd Gen above...



Finally pictured above from left to right Eberspaecher PTC heaters 1st Gen (Volt Gen1), 2nd Gen (Volt Gen2/Bolt), then 3rd Gen (?Future Vehicle?).
 
#64 · (Edited)
The Bolt heater heats and it heats FAST.Really, with the heated seats and steering wheel there is an abundance of heat. Yes, it uses some range, that's expected. I'm not worried, but I'll be interested to see how it does this winter in Chicago.

I just asked my wife how the Bolt's heater use has been affecting her drive. Her answer: "Who the hell cares? (laughing) I don't pay attention to gas stations or battery range anymore. I always arrive home with at least 90 miles to spare."

So there you have my scientific poll results, :)
 
#65 ·
Her answer: "Who the hell cares? (laughing) I don't pay attention to gas stations or battery range anymore. I always arrive home with at least 90 miles to spare."
Good for her. I fail to understand how anyone would buy a BEV (or EREV for pure EV duty) that doesn't meet their driving needs. If you are constantly running at the bitter end of your daily battery range (including HVAC), then you have the wrong car.
 
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