How low can you go? SOC that is.

i've gone as low as 30% due to my canview telling me so. I got greedy in ev mode, so when my acceleration popped the engine alive, it was still taking energy away from the battery for stage 1. By the time the fuel enrichment mode was done with, my SOC was 30%, and boy I've never seen the engine worked so hard but at the same time your speed increases very slow.

Also when working on the prius in the dealership, we have to turn it on IG2 (power button twice without brakes) to put it in neutral so that we can put it up on the hoist. And up in the air if you forget to power it off, the battery will drain too, mine was down to one pink bar when I was done my oil change and inspection... and it wasn't even on READY MODE Wth!!?!

 

I think I've seen as low as 26% on my trip through the Rockies. I'll check CAN-View tomorrow.

 

When your ScanGauge read 27.5%, what did the MFD traction battery SOC gauge show?

Is it possible that the ScanGauge is incorrectly calibrated with respect to this parameter?

 

Hmm, if the traction battery gauge was basically showing zero bars, maybe the ScanGauge is reading correctly. (Sorry, I now see that your initial post provided this info.)

I am not aware that the ScanGauge is user-programmable. My thought was maybe that parameter was not being correctly read, i.e., a flaw in the product.

 

Some of the numeric sub-fields of all those digits you enter for an XGauge constitute scaling and offset instructions--so in a sense provide an opportunity for mis-calibration.

But the overwhelming majority of mistakes you could have made in those entries would give completely nonsensical results, not ones that are slightly off. Still, no harm in checking it.

I think it far more likely that your ScanGaugeII is displaying what your vehicle is reporting on the CAN bus, and that the "folk wisdom" on this forum for the allowed range of State of Charge is wrong. I suspect that too few SG2 and CANView owners who travel up long hills may have reported their SOC observations. I suspect a true flatlander may not see as broad a range of SOC in a year as we folk with some hills see daily.

I've already seen well below 40% myself, while operating only for a couple of hundred miles with an SG2 on a Prius, and with a maximum elevation change in the area I drove those miles of only about a thousand feet.

 

While it's true the statement "the lowest the Prius will let the battery SOC get is 30%" is not absolutely accurate, 27% SOC is pretty close! The Prius is not a lab accurate electronic machine!

While 27% SOC may seem low, you still have almost 1/3 of full charge in there. Damage to the battery will occur if any cell has 27% less capacity than the others (the cell goes to 0 charge at 27% battery charge and reverse charges). This is unlikely except in a very old battery. The cells are matched to at least 5% when new. The battery is never discharged below 30% (27 in your case), or above about 80%, so it's unlikely any electrolyte is lost (unless there is a physical seal failure). Electrolyte loss is the most common cause of cell capacity loss.

I still marvel at owners expecting better than 10% accuracy in any parameter in cars!

Oh, and seeing 27% at the top of a mountain pass is a -good thing- (tm). Lots of room for the coming regen charging! I hate it when Pearl shows five blue bars at the top of the pass! I know I'm going to have to "waste" energy on the way down.

 

It's been posted by those who measure such things that under "normal operation" the car will run in the range from 40% to 80% SOC, generally trying to stay around 60%. If you push it you can get down to about 30% SOC (run it out of fuel for example). You can then get it even lower if you repeatedly try to start the system without adding fuel. It will eventually stop trying, requiring a reset. Perhaps that would be at or around the 25% level. I'm surprised your car went down to 27%, but when you think about it, the 3% difference isn't much energy - .03 X 6.5 A-hrs X 201 V or 39 W-hrs. Leave the doors open for an hour and it's about the same (though that wouldn't impact the traction battery, but it's a good comparison on how much energy we're talking about).