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Discussion Starter #1
Before the fires started I was making a block diagram of the cooling loops. Anybody who has better information on this please post info. Mainly I'm interested in if it's a single system that shares the radiator, or separated. If it's a common system, then they theoretically have the cool feature where the heat generated from the battery and motor could go heating the cabin, or some combination of this.

I'll refresh myself on the cooling loops and my attempt to figure it out, meanwhile does anybody happen to know anything about it?
 

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Discussion Starter #3
OK I was able to do some tracing, here's one loop

Starting at the left side of the engine compartment from the radiator and ending at right hand side

  1. Radiator Out
  2. SPIM In (Single Power Inverter Module - 3 phase inverter for motor?)
  3. SPIM Out
  4. APM In (Accessory Power Module - 12V inverter)
  5. APM Out
  6. OBCM In (On Board Charging Module)
  7. OBCM Out
  8. Engine In? (can't see, looks like it goes back to the engine or battery, correlating with above must be engine)
  9. Engine Out?
  10. SGT LH (going into the reservoir)
  11. Reservoir
  12. LH
  13. Pump In
  14. Pump Out
  15. Radiator In
So at this point it appears that the radiator is just used for taking heat from the power system. The pump is on the right hand side bottom

  • Power inversion and engine use the radiator to cool only, the right most reservoir and pump (underneath) are for this system
  • Battery temp control and pump is the one on the left hand side. It appears there is some sharing of heating/cooling of the battery with the cabin, possibly via a internal fluid switch
  • HVAC reservoir is on the left back (closer to the cabin)
 

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Discussion Starter #4
So for heating/cooling they could have gone with two features seen in other cars but not the Bolt

  • Share power train waste heat with cabin (Tesla I believe has this feature)
  • Heat Pump + resistive heating (Leaf has this I believe, Tesla does not)
The problem is that these add complication and cost for small benefit. However when you have a dinky battery it makes some difference perhaps, but at some point of the engineering process you simply say 'screw it' and just put a bigger battery in there, as battery costs come down, and don't mess around with trying to salvage bits of heat here and there.

From what I'm seeing with the Bolt they opted for simplicity. The engine is a simpler design than others (sealed oil cooled single system shared with the gearing), and the cooling is quite simple too (no heat pump, compressor/heater shared with cabin and the simple battery cooling plate which dissipates heat just fine on it's own as noted above.) This KISS perhaps allows also for a larger battery which is the most important parameter.
 

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Here are the parts for the three coolant loops.

https://www.gmpartscenter.net/auto-parts/2017/chevrolet/bolt-ev/lt-trim/electric-engine/cooling-system-cat/radiator-and-components-scat

It appears the cabin heater has its own pump and reservoir. Obviously, it doesn't use the radiator. It uses its heater core. The battery has its own heater, chiller, pump and reservoir. It doesn't use the radiator, but they are worried enough about the battery coolant to have a coolant level sensor for its reservoir. The motor/charger/DC-DC/power inverter all share a reservoir, pump, and the radiator and fan. The radiator is mounted directly behind the AC condensor. They share the air inlet, and outlet ducts, and the shutter for closing off airflow. I assume at high speed, or in cold temps, the louver shuts.
 

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Discussion Starter #6

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I did some poking around on the internet when I saw that. I believe it is a cooler for the compressor oil, not the motor oil. Apparently this is done to extend the life of AC compressors.
 
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