How to check your Mustang Mach-E's battery health
Your Mach-E calculates its own battery health every day. Here's how to read it in about a minute, what the numbers mean, and what normal aging looks like.
The number that matters: state of health (SOH)
State of health is the battery management system's own estimate of how much capacity your pack has left compared to new. A Mach-E showing 96% SOH has lost about 4% of its original capacity. This is the same figure that drives warranty conversations — Ford's EV battery warranty (8 years / 100,000 miles) kicks in if capacity falls below 70%.
The dash never shows SOH. The only ways to see it are a dealer visit (FDRS), a laptop running FORScan, or an app like Mach-E & Lightning Companion that reads it over a Bluetooth OBD adapter.
How to read it yourself
- Get an ELM327-compatible Bluetooth LE adapter — the vLinker FS (~$36) or OBDLink CX (~$40) both work great. Adapter guide here.
- Plug it into the OBD-II port under the dash, left of the steering column.
- Open the app with the car on, tap Connect, and pick your adapter. Your SOH, true charge level, cell balance, and pack temperatures appear in under a minute.
What's normal Mach-E degradation?
Most lithium packs lose capacity fastest in their first year, then settle into a slow, steady decline. Rough rules of thumb owners report:
- Year 1: 2–4% is common and not a concern
- Years 2–4: roughly 1–2% per year
- High DC-fast-charging use, frequent 100% charges, and hot climates age packs faster
What deserves attention isn't the level — it's the trend. A pack dropping a point every month is telling you something. A pack that lost 3% in three years is doing great.
Cell balance: the early-warning number
Your pack is built from cell groups that should all sit at nearly the same voltage. The difference between the highest and lowest group — the spread — should stay under about 30 millivolts in a healthy pack. A growing spread is the earliest sign of a weak group, often visible years before any warning light. The app shows highest, lowest, average, and the spread on the Battery tab.
Don't forget the 12V battery
The most common Mach-E "breakdown" isn't the big battery — it's the ordinary 12-volt battery that runs the computers. When it gets weak, the car can refuse to start or throw a storm of warnings. Healthy resting voltage is above 12.4 V. The app watches it on every connection and can warn you below a threshold you set.
Why this is the only way left
Ford revoked API access for third-party apps and bans FordPass accounts that use unofficial workarounds. Cloud-based EV apps for Fords are gone. Reading the car directly over the OBD port is the one approach Ford can't switch off — and it's more private, too: nothing ever leaves your phone.