SOC, reserve %, and when to search for chargers

This is the floor you never want to cross on arrival at a charger. Highway surprises — traffic, AC load, a missed exit — eat margin. Keep 20% unless you know the leg well.

When your estimated SOC along the route hits this level, the planner looks for DC stops. Lower threshold = later stops (riskier). Higher = earlier stops (safer, more time charging).

Brochure range is optimistic. Enter your average Wh/km from past drives — presets pre-fill for Nexon, Punch, etc. — so arrival % on each stop card is trustworthy.

Suppose a 45 kWh pack and 165 Wh/km. Usable energy at 90% start with 20% reserve is 0.7 × 45 = 31.5 kWh, about 190 km of highway before you must be at a charger. Search threshold at 30% means EV Grids starts looking earlier than the floor — that gap is the closed-site buffer. If you set both to 10% to ‘skip a stop’, you have donated your margin to hope.

Raise reserve on ghats, monsoon, and when the next charger is a single gun. Lowering search threshold to 22% with reserve at 20% is almost the same as having no search margin. Keep at least 8–10 points between them.

The chart on EV Grids is a sketch along the Google polyline using your inputs. It is not your BMS, not a live telemetry stream, and not a promise if you then drive 115 km/h in 42°C. Believe the lower of the two numbers: the card and the dashboard.

Reserve is the floor you will not cross. Search threshold is when you start looking. The distance between them is your entire margin for error — traffic, a missed exit, a detour around roadworks, or a charger that turns out to be inside a gated complex.

Setting them close together, say 25% reserve and a 28% threshold, means the planner starts hunting when you have almost no room to be choosy. A wider gap costs you a slightly earlier stop and buys the ability to reject a bad site and continue to a better one.

Raise both for ghats, monsoon nights, sparse stretches, and unfamiliar roads. A 25–30% reserve on a Western Ghats descent is not timidity: regenerative braking may return less than you expect, and the nearest alternative can be an hour away.

Lower them only on corridors you know, where you have alternatives in sight and you are confident in your consumption figure. Never lower reserve to make an itinerary look cleaner — that is optimising the screen instead of the drive.