Re: Volt, TMS, and battery temp
EdmondLeaf wrote:I am not Volt specialist but what I know Volt allow battery temp to be from 18 to 90F and if not plugged or charged TMS will be off on hot day or cold day.
I'm certainly not an expert here, either. If 18F is really the lowest target for the Volt TMS, then I am wrong here. But I though it was 50F. If 50F and with a thermal time constant measured in hours, I would expect Volt batteries to live at a much higher average temperature than LEAF batteries in cold climates.
From this article:
http://www.caranddriver.com/reviews/201 ... -road-test
... requires its own coolant circuit in order to heat or cool the 288 cells to keep them in the optimal temperature range (32° to 90°F).
Temperature extremes can diminish a battery’s efficiency and rapidly accelerate battery aging, noted Frank Weber, Volt’s enthusiastic and laser-focused Global Chief Engineer who departed the program last year for Opel.
“For example, the delta between 70°F (21°C) and 90°F (32°C) can be critical to battery life,” he asserted. The battery is designed to work while plugged in, at temperatures from -13°F (-25°C) to +122°F (+50°C). The permitted temperature gradient within a battery cell, and from cell to cell, is 5 to 10 K.
A 50:50 glycol mixture is actively circulated through 144 metal “fins” between each of the Volt’s 288 cells. The fins are 1-mm-thick (0.04-in) stamped aluminum plates that conduct heat. The Volt’s pack has five thermal management circuits to handle the multiple subsystems. The system uses multiple electric coolant pumps (12- and 50-W) supplied by Buehler Motor of Germany. The pumps feature brushless dc motors and integrated electronics, and are designed to run extremely quietly, explained Robert Riedford, President of Buehler Motor Inc.
And a very interesting post in the past few days from SH on gm-volt
This morning I drove rather aggressively, and so I was showing 2.4kWh used for my 10.1 mile commute and a battery temp of 82F (outside gauge said 83F) when I parked. When I got in the car after nine hours of high temps increasing to triple digits (car said 106F when I finally started it,) it showed a battery temp of 90F; I'm not positive if the TMS hit the battery - if so it didn't use much power (there's a 1-200 Wh discrepancy with some of the numbers that could be TMS activity,) and the 16 degree delta could be the result of thermal mass and insulation.
The remote start hit the fan hard pretty quickly - for the majority of it the remote start was drawing around 5 kW while it ran, with momentary drops to 2.8/3.0 and an instantaneous peak of 5.4 kW. I could also hear the radiator fan running.
It seemed to prioritize the cabin - the battery didn't change from 90 for the first few minutes - but by the end of the ten minutes the battery showed 84F, clearly showing the battery was being cooled effectively. From the changes to the "battery remaining" calculation off of the reported SoC in the DashDAQ, the remote start used ~650Wh - but when I started the car, is showed 3.2 kWh used (the discrepancy I mentioned; the SoC often has a slight mismatch to the overall use for some reason - it always starts showing 10.2-10.4, but it;ll show zero when the engine kicks on and the car will say 9.9 used.)
When I turned it on, the car was soon hitting the same 5kW in Park; by the end of my drive home even though the fan was at the same speed and the air blowing cold, the draw was down to around 2kW (colder recycled air means less work for the compressor causing the reduced draw?) and the battery average temp was down to 75F.