I've wondered why the GM team chose 30% to 80% SOC. Was this to improve battery life? The A123 web site seems to indicate that after 7000 cycles, 0-100% SOC each cycle, that the battery has degraded from 16kW to 13kW. This seems good enough for production. Maybe going 30%-80% improves battery life even more.
Or, maybe 30%-80% was chosen so that the battery doesn't go lower than 0% or higher than 100% SOC under extraordinary driving conditions. (i.e. climbing a mountain pass in Colorado, in which case the ICE may not be able to keep up with the power demands, or decending the auto road on Mt. Washington after plugging in at the top, in which case regen will put in about 15% SOC)
If 30%-80% was indeed chosen to handle these special situations, then maybe GPS could be used to calculate whether either situation is possible. All you would have to do is look at altitude. If you are near sea level, then it would be pretty safe to allow the battery to charge to near 100% SOC. You can't regen downhill under the ocean. Likewise, it should be possible (though not as easy) to say whether there are any mountains nearby to climb (with a car), and then let the battery maybe go lower before kicking in the generator.
My first instinct as an engineer was that using a GPS is too complicated - "Keep It Simple, Stupid". But if it means you could get 2x the range out of a given battery, or 1/2 the battery for the same range, then it seems worth a bit of complexity for the money saved! We're talking about the price of the 20 mile version, but the range of the 40 mile version.
Almost forgot - GO CELTICS
Or, maybe 30%-80% was chosen so that the battery doesn't go lower than 0% or higher than 100% SOC under extraordinary driving conditions. (i.e. climbing a mountain pass in Colorado, in which case the ICE may not be able to keep up with the power demands, or decending the auto road on Mt. Washington after plugging in at the top, in which case regen will put in about 15% SOC)
If 30%-80% was indeed chosen to handle these special situations, then maybe GPS could be used to calculate whether either situation is possible. All you would have to do is look at altitude. If you are near sea level, then it would be pretty safe to allow the battery to charge to near 100% SOC. You can't regen downhill under the ocean. Likewise, it should be possible (though not as easy) to say whether there are any mountains nearby to climb (with a car), and then let the battery maybe go lower before kicking in the generator.
My first instinct as an engineer was that using a GPS is too complicated - "Keep It Simple, Stupid". But if it means you could get 2x the range out of a given battery, or 1/2 the battery for the same range, then it seems worth a bit of complexity for the money saved! We're talking about the price of the 20 mile version, but the range of the 40 mile version.
Almost forgot - GO CELTICS
