I just added an SOC reading to my ScanGauge II and was surprised to see that shortly after a full charge the SOC only read 84.7% The starting level was 24.3% and the EV miles read 0.1 miles, that is, just above where it would automatically switch to HV. It took 2.94 kWh reach do "full charge". Is this normal, incorrect or what?
Yes 84.7% is good. The battery doesn't charge to 100% Toyota believes the battery lasts longer if it's not charged to full or depleted to 0% SCH-R530M ? 2
That makes sense. Also, for the record, the display SOC was full and the EV miles (computer guess) was at 14.6.
That's about on par for the non-PiP Prius as well. My Gen 2 Prius will not charge the HV battery beyond 80% if it can help it (although I've seen it rise to 81.5% before due to its recalibrating after hitting 80%-- I wasn't moving while it was climbing the last 1.5%). It also tries to stay above 40% if possible, and tries desperately not to drop below 30% ever, although I've seen it drop to 27.5% while climbing a very long 10% grade once. I don't remember the exact technical reasons for it, but rechargeable batteries do last a lot longer if you avoid using the top and bottom little bit of capacity (some laptops will even allow you to do this automatically). Since the HV battery is considered part of the emissions system, Toyota has to warranty them for 10 years, 100,000 miles in the U.S., and even longer in CARB states, so they're relatively conservative so that they don't have to swap batteries at their expense except very rarely.
