Teslita
The headline feature: raw signals, not estimates
5 featuresA charge-curve estimate of state-of-health is one data point taken from one slice of behaviour. The BMS itself uses dozens — cell voltages, pack imbalance, module temperatures, isolation resistance, fault flags. Teslita streams those numbers straight from Tesla's telemetry the moment they change, surfaces the ones that matter, and trends them over 90 days. When the pack is healthy, you see why. When something's drifting, you see what.
Overall verdict, plain English Live
One headline line at the top of the Health page summarises every sub-signal: green when everything looks fine, amber when a value is drifting, red when something is outside the healthy range. Saves you reading ten charts to answer "is the car OK right now?".
Cell-level voltage spread BMS
The millivolt difference between your strongest and weakest cell group, sampled directly from the BMS. Healthy packs sit under 80 mV most of the time; a slow upward drift is normal with age. A widening spread is the earliest warning sign of an imbalanced or failing module — months before you'd notice it as range loss.
HV isolation resistance BMS
The insulation between the high-voltage system and the chassis, measured in kΩ. Higher is better — a steady multi-megohm reading is a healthy pack. A gradually falling value is a classic early sign of moisture ingress and is worth a service check before it turns into a fault code.
Module temperature spread BMS
The difference between your hottest and coldest pack module at the same moment. Under 5 °C is a sign the cooling loop is balancing flow well across the pack; a widening spread can indicate a blocked coolant channel or a degrading pump — caught early via the data, before the warning light.
Live system-state chips Live
Small coloured chips show the current state of the high-voltage interlock loop, the battery management system and the four drive inverters. Green means running normally, red means an active fault worth investigating. Updates in real time over the telemetry stream.
90-day trends, not just a snapshot
3 featuresCell imbalance trend line
A 90-day chart of your cell-group voltage spread. The trend matters more than any single sample — a stable line above the healthy threshold is just an older pack; a line that's climbing week-over-week is something to investigate. Teslita draws both so the difference is obvious at a glance.
Isolation resistance trend
The HV-to-chassis isolation reading plotted across the same 90 days. A flat line in the megohms is what you want to see; a slow downward slope is the kind of evidence a service tech actually appreciates because it tells them where to look.
Fault count, 90 days
A running count of HVIL, BMS and inverter fault events from the last quarter. Click through and you get the exact events with timestamps — so you walk into a service visit with "the BMS posted 14 events on these specific dates" instead of "it feels off."
Buying a used Tesla? Run the diagnostic first.
3 featuresReal numbers in 24 hours
Connect the seller's Tesla account (or your own, after the test drive) and Teslita pulls the same BMS signals the manufacturer's technicians use. Within a day of connection you have cell-group imbalance, isolation resistance, module temperature spread and a 90-day fault history — for free, before money changes hands.
Spot a hidden module problem
A pack with one underperforming module looks normal on the dashboard until you read the cell-group spread. Teslita surfaces that number directly — so if a seller has been hiding a warranty conversation, the data shows it before the test drive ends.
Warranty-claim-ready evidence
If your pack is degrading inside the warranty window, Teslita's trend lines and fault count are the kind of evidence that turns a "we'll take a look" appointment into an actionable claim. Plain charts, real numbers, dated.
The context around the pack
3 featuresPhantom drain tracking
Any overnight battery loss while the car is parked is tracked and charted. A few percent a day is normal; sharp spikes can indicate Sentry mode, cabin overheat protection or a car simply failing to sleep — all of which read as "range loss" but are nothing to do with pack health.
Sleep timeline
A 30-day timeline, one row per day coloured by what the car was doing (sleeping, idling online, driving, charging). Makes it obvious whether the car is actually sleeping at night or staying awake and burning kWh — the most common cause of "my range is dropping" worry.
Anomaly flags on charging
DC fast-charging sessions where peak kW fell well below the same site's baseline get flagged automatically — sometimes a sign of pack thermal management, sometimes a bad stall. Either way you have a list of which sessions to look at instead of a vague sense that "Supercharging seems slower lately."
Trust & audit
3 featuresStreams from the official Tesla telemetry
Every number on the Health page comes from Tesla's own telemetry stream — the same channel Tesla's mobile app reads. Nothing extrapolated, nothing made up, nothing scraped. If the BMS reports it, Teslita shows it.
Official OAuth, never your password
Teslita connects to your Tesla account via the official OAuth flow, with the minimum scopes needed to read vehicle state and telemetry. Your Tesla password never touches Teslita. Revoke the connection from your Tesla account at any time — data already collected stays in your archive.
Delete everything in one click
Want out? A single confirmation in Settings wipes your Teslita account and every reading from our servers, and revokes the OAuth token so Teslita disappears from your Tesla account too. No retention period, no email chain to start.
How to read your pack's vital signs
Two minutes from signup to a full diagnostic — and a 90-day trend by next week.
Connect your Tesla account
Sign up with email, click "Connect Tesla", approve the OAuth scopes on Tesla's own login screen. There's no app to install on your phone or in the car — the whole setup runs in the browser.
Diagnostics fill in within hours
Teslita immediately starts streaming the BMS, HVIL and inverter telemetry. The verdict chip, cell-imbalance number, HV isolation and module temperature spread all populate as soon as the car reports them — usually within minutes of connecting.
Trends build over the next 90 days
Single readings tell you the present; trends tell you the direction. The 90-day charts fill in gradually as data accumulates, so by next quarter you have an actual evidence base — not a single dot, not an estimate.
Why people pick Teslita for this
The paid battery-report tools mostly estimate state-of-health from charging behaviour. We read the BMS directly, surface the raw signals, and don't charge for it.
Paid battery-report tools
- Subscription per month or annual report
- State-of-health estimated from charging curves
- A single number, no underlying readings
- No HV isolation, no module-temp spread, no live state
Teslita
- Free — no card on file
- Cell-group mV, HV isolation kΩ, module temp °C — raw
- 90-day trend on every signal, not a single dot
- Plus invoices, driving log, sleep tracking and ~50 more
What it costs
Free
No card · no trial · no paywall
Battery health comes with Teslita
There's no paid tier for battery health, and no paid tier for anything else either. Teslita is a single free product — battery diagnostics are one of about sixty features in your account from day one.
- Every Tesla on your account
- Cell-group voltage spread (mV)
- HV isolation resistance (kΩ)
- Module temperature spread (°C)
- 90-day trend on every signal
- Live HVIL / BMS / inverter chips