Check Out The Chevy Bolt EV High Voltage Components In Detail


We bring you the fifth video in an ongoing, in-depth study of the Chevrolet Bolt EV battery and electrical systems.

There’s arguably no one better than John D. Kelly at Weber University when it comes to deep dives into batteries and electrical components of today’s EVs. This is, of course, barring our own George Bower and Keith Ritter, who love to work their models and help us decipher the facts. For those highly interested in the subject, this video series is a must. In the fifth video from Kelly’s ongoing analysis, he takes a more detailed look at the high voltage system in the Chevy Bolt and how its nine individual components work together.

Yes, not unlike Kelly’s previous videos, this is a long one likely geared toward those with specific knowledge of the subject and the need to get into the nitty gritty. Still, it’s not as lengthy as some of his previous shares. Grab the popcorn and carve out about a half an hour to take it all in.

Do you pride yourself on extensive knowledge of EV and battery tech? Please share your wisdom with us in the comment section below.

Video Description via WeberAuto on YouTube:

Chevrolet Bolt EV High Voltage Components

Finally, the Chevrolet Bolt EV high voltage system broken down into its nine individual components. See how they are all connected.

Video Timeline:
Video introduction at 0:12
See the under hood view with everything removed at 1:04
See the traction motor Drive Unit (DU) at 3:56
See the under hood cross-car beam at 7:28
See the Single Power Inverter Module (SPIM) at 8:32
See the High Power Distribution Module (HPDM) without fast charge at 10:10
See the High Power Distribution Module (HPDM) with fast charge at 11:29
See the on-Board Charger Module (OBCM) at 13:35
See the Accessory Power Module (APM) at 15:26
See the Air Conditioning Compressor Module (ACCM) at 17:39
See the High Voltage Battery Coolant Heater at 19:20
See the 3-Phase cable connections at 20:27
See the HPDM to SPIM harness connection at 22:25
See the HV battery to HPDM harness connections at 23:08
See the HPDM to APM and OBCM connections at 25:33
See the DC Fast Charge receptacle to HPDM connection at 26:57
Video review at 32:28

2017-2019 Chevrolet Bolt EV high voltage electrical system components – A Youtube first!

Weber State University (WSU) – Department of Automotive Technology – Ardell Brown Technology Wing – Transmission Lab.

This is the fifth in a series of videos on the 2017 Chevrolet Bolt EV

This video helps cover content related to the 2017 National Automotive Technicians Education Foundation (NATEF) Master Automobile Service Technology (MAST) Standard task 1.A.9 “Identify service precautions related to service of the internal combustion engine of a hybrid vehicle.”

W.S.U is a leader in Hybrid and Electric Vehicle education. This topic is taught as part of our 4-year bachelor’s degree program.

This video was created and edited by Professor John D. Kelly at WSU.


Chevrolet Bolt EVs - finding more US driveways every month!
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The introduction (and US reception) of the Chevy Bolt EV has pulled forward GM's 200,000th sale by at least a year (now expected in Q2 2018) Chevrolet Bolt at the recent GM Official autocross event near Detroit. Chevrolet Bolt EV (wallpaper 2,560x) Chevrolet Bolt EV Chevrolet Bolt EV (wallpaper 2,560x) Chevrolet Bolt EV (wallpaper 2,560x) 2017 Chevrolet Bolt EV Chevrolet Bolt EV The best option overall is generally to drive at normal speed Chevrolet Bolt Chevrolet Bolt Chevrolet Bolt EV Interior Chevrolet Bolt EV:  Lots of useful room inside...and a fair about of standard finishes Bolt Interior Chevy Bolt Chevrolet Bolt EV - right-hand-drive?! Chevy Bolt rear seats The rear seating area offers plenty of room for passengers Inside the 2017 Chevrolet Bolt

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26 Comments on "Check Out The Chevy Bolt EV High Voltage Components In Detail"

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Wow, this is a really, really good video. Would love to see the equivalent video for the Tesla Model 3 and compare/contrast the differences.

Engineerix and Jack Rickard have done breakdowns of the 3.

Great video. Now I Just need one to show me how to make a trike out of those components.

The Bolt cannot use a DC fast charger in cold weather? Well that is certainly a drawback.

It can! It is common for any EVs to throttle back the charging speed when the battery is below certain temperature threshold. EVs with proper heating control can warm up the battery before charging. It takes time for it do so.

He said in the video it has no provision to heat the battery during DC charging so it cannot do it, with the owners manual confirming this.

Yes, but the Bolt ev (like other GM PHEV products) can heat the battery while the car is driving. So presuming you drive the car for a bit before actually getting to the fast charger and then plugging it in, everything should be fine. At that point it becomes a problem of too much heat.

He’s wrong.

Multiple Bolt owners with OBD readers have seen the battery heater active during DC charging. In fact, one of the important jobs of a battery heater is to help raise cold battery temperatures to enable higher-powered DC charging. On batteries much under 68F the charging power has to be reduced in order to avoid possible damage to the battery anode.

He likely saw a statement around page 135 in the 2017 Bolt EV owners manual that said:

This message displays during
extremely cold temperatures, when the vehicle will not start until the high voltage battery is warm enough.
Plug the vehicle in to an AC charging station and make sure
POWER is off to allow the charging system to warm the high voltage battery, then the vehicle can be started. DC charging cannot be used to recover a cold high voltage battery.”

This is referring to batteries that are getting down below to -40F or -40C. Pretty much by definition, if you drive to a DC charger to start a charge your battery will not be that cold.

WRONG. The Bolt definitely can heat the battery while fast charging. I’ve witnessed it myself with the TorquePro app and the relevant PIDs. The battery heater uses 2-3 kW of power when active.

I understood it to mean that you couldn’t fast charge if the battery was cold, but when would that happen? If you drive to a fast charger in cold weather the battery will be fine for charging. It would only be a problem if for some reason you parked at a fast charger not plugged in for several hours then didn’t run the car and tried to fast charge. That’s probably why it can’t heat the battery when fast charging because it wouldn’t ever need to.

Yeah if you ever ran into the problem the owner’s manual states – there is no real problem if you have a bit of battery capacity left. Simply turn on the car and the battery heater will start using the juice remaining in the battery to warm itself, unless the battery is very dead.

John Kelly and Weber State are to be commended for producing and making available these outstanding videos. Makes me wish car makers made a lot more of the technical details available to the public.

I think GM cancelled the Volt because they’re losing the tax credit and predicted that sales would plummet. Makes me wonder what they really have planned for the Bolt.

Also, losing the tax credit, brings up the question of price. Did GM include the tax credit in the Volt list price? Inflating the price of the Volt? We won’t know now, because it won’t be on sale after the loss of the credit.
Very Convenient. Because the used car market simply assumed the Volt list price was inflated by the credit.

Interesting that the Bolt isn’t cancelled too.

Give them time. If the Hyundai products eat their lunch and BOLT ev sales tank, then I’m sure they’ll have no problem discontinuing their LAST electric car, since they had no problem discontinuing 2 of their 3 current ev products, without announcing any replacements, including of course the VOLT which is the Most Popular EV currently in the US and Canada (until the M3 catches up of course).

GM is discontinuing production of all the other cars that are assembled in the plant where the Volt assembled… Hamtramck.

Why does it have a liquid heater coolant heater???
It should be using an Electrical Resistant Heater, situated IN the car body.

Having an external heater element outside the interior means heat loss to the world, an inefficient heat loss to the world, and liquid heater core? Pulling components from the Spark again?
Very disappointing.

Additionally: If the electrical components get hot enough, you could scavenge that heat and put it in the cabin, with liquid cooling, but, they’re not doing that.

GOOD POINT on the motor CV joints being equal length, and should have NO Torque Steer.
That should have been a selling point.

This way they use the same resistance heater to heat the battery and/or the car interior. There may be some advantage to that.
All FWD GM cars have no torque steering. But you are wrong in assuming that all it takes is equal length CV joints. In fact I have a hard time understanding how equal length CV joints actually have anything to do with torque steer. Torque to each front wheel has to be controlled with some mechanism like limited slip differential so power goes fairly equally to each wheel. Without this control a simple differential will effectively deliver the most power to the outside wheel because it rotates faster than the inner wheel, nothing to do with length of CV joints. Think of it has each wheel having a different gear ratio and the outer wheel is in low gear and the inner in high. More torque in low gear.

The amount of BTU/Hour loss in the piping is miniscule compared to the heat released in the cabin, and allows them to use a standard heater core with gradually modulating temperatures.

Those portable ‘roll-’em’ around electric radiator space heaters are proof of concept as far as even heat goes.

Professor Kelly and Weber University should be given Awards for his succinct, detailed, and easily digested videos. Now I know what all the boxes are doing under my hood. I knew they were all there, just didn’t know which was which.

I thought the comments he made on torque steer were interesting because I see many reviews complain that the Bolt has bad torque steer, but I don’t experience it at all. Seems to track straight as an arrow for me under hard acceleration. But maybe I’m just numb to it from driving Saab’s for the past 20 years, which supposedly have a fair amount of torque steer.

I see those too. I think they are mistaking losing traction on one wheel or another, and the traction control trying to compensate, with actual torque steer.

The Bolt has two tankless hot water heaters. One on the firewall for cabin heat, and one just in front of the battery pack for battery heat. I suspect they didn’t want a resistance heater in the cab for safety reasons.

I still maintain, the smartest way to heat an EV would be a small ethanol burner. I remember the gas heater in my girlfriend’s Corvair. The size of a gallon paint can. it would melt the rubber soles of your galoshes in 30 seconds, in the frigid north. Best heater ever!!

A far better use of corn ethanol than inefficient ICE combustion.

I think you are referring to the early 1960-63 Corvairs. My 1966 Corvair used engine heat. In fact, after it finally warmed up, it tended to have a faint oil smell due to gaining heat from the air-cooled engine block. (Warming up the air-cooled engine was an exercise in patience with Michigan winters.)

I do believe the early Corvair gas heaters were pretty dangerous because of possible carbon monoxide issues.

Is there some actual reason why they have all these non-standard acronyms, or just being fancy?…

Nice video – did you ever tear down the inverter? I am interested in understanding the power module choices or discrete IGBT designs.