Chevy Bolt EV Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
5,357 Posts
Discussion Starter #1 (Edited)
Has anybody found a simple schematic, or even a clear description of the way the high voltage systems are wired? I have done a little poking around and have some of it figured out, with help from this video,


but still have a few questions.

The high voltage distribution module, on the passenger's side is pretty interesting. The DC lines from the DCFC port run into the front of it. The lines to the inverter run out of the left side of it, down to the inverter. There are four plugs on the right side of it. They feed pack voltage to the AC compressor, the battery heater, the cabin heater, and (I think) the DC-DC converter for the accessory battery. It seems logical, although it is hard to see back there, that the lines in back go to the traction battery pack. I had assumed the relay you hear when connecting, and disconnecting the charge plug, was in the module. But I had my wife plug it in and out a few times, while I had the hood up. It sounds like the relay is somewhere else, like up near the firewall. I am also still puzzled about the onboard charger. I can't really see where the lines come into or out of it. I assume the AC line, from the charge port, goes through the same relay as the DC from the charge port? Does the DC out of the onboard charger have its own connection to the battery pack, or does it run into the distribution module, at the back, first?
 

·
Registered
Joined
·
592 Posts
Has anybody found a simple schematic, or even a clear description of the way the high voltage systems are wired?
Yes at least a block diagram would be interesting

It seems logical, although it is hard to see back there, that the lines in back go to the traction battery pack.
What's the traction battery pack? Is that the one under the back seats? I was wondering why there are two main battery packs with two separate cooling loops.
 

·
Registered
Joined
·
5,357 Posts
Discussion Starter #3
ProfessorBolta,

"What's the traction battery pack? Is that the one under the back seats? I was wondering why there are two main battery packs with two separate cooling loops."

Traction pack is just a term used to differentiate the drive battery from the accessory battery. The part under the seat is just the "second story" of the battery pack. It is wired and cooled with the same systems as the rest of the pack.

Watch that video. The engineer drops a huge amount of info.
 

·
Registered
Joined
·
989 Posts
Here is the HV system and the car has 3 coolant loops.
It's not called the traction pack. It's a single (60kWh) high voltage battery.
HVB is the acronym
 

·
Registered
Joined
·
592 Posts
Watch that video. The engineer drops a huge amount of info.
Yes I've seen it several times before.

The interesting thing to me is a pattern. In a different interview an engineer says that because they didn't know what DC power rating they'd spec at they oversized the system (and settled on 50kW). In this video he mentions that the 12V inverter is specced at 1.6 kW - that's a pretty serious amount of power for 12V! Further the resistance heating for the cabin is a 6kW system.

I think we see a trend here which is the engineers over engineered various systems, and probably more than that, as a margin of uncertainty. It's a new design, new market, they played it safe and gave themselves a lot of leeway, because they could. Later versions will get trimmed down to save costs/price, but at the moment they are losing money on every one and want it to be a success, so they made it chunky.

Want to guess how much the battery was over engineered? I've heard that there isn't any hidden reserve and they give it all to us, but I wonder.
 

·
Registered
Joined
·
5,357 Posts
Discussion Starter #6 (Edited)
Traction pack is not a GM term. It is a term of art that has been used in the electric vehicle industry forever, using one definition of traction: drawing, pulling, or propelling. Thanks for the correction on the cabin heater power. I just went out and tried it. It indeed can pull 6 kW. Thanks for the jpg. The full link has lots of neat information.

http://sandyblogs.com/techlink/?p=7070

It clears up several things. The ac voltage does appear to go directly to the onboard charger from the charge inlet. The dc voltage out of the onboard charger goes to the HV distribution module, as seems most logical. The HV contactor must be in the HV distribution module. The only lines to the battery appear to come from that module. The battery pack heater is at the front of the battery pack. I have read or heard elsewhere that there is also an inertial disconnect near the front of the pack.

I am certain they are not letting us use the whole battery. That would guarantee a short battery life.
 
1 - 6 of 6 Posts
Top