Battery life has dropped substantially

Can you provide stat's. What range on full charge. What is the drop when fully charged vs from factory. Age of car and model. Anything particular that your friend has done that may have caused this ?

You gotta charge 100% at least once every month for batt calibration.

Without any details and stats given, what is even the point of your post?

"Battery life has dropped substantially" this statement has no value, no information and is unusable for anything. It has dropped from what to what? Did he measure the batteries charge/discharge capacity? At which temperature? Did the just use the range indicator? In which mode? Default or dynamic? Was he comparing what he got in warm weather with cold weather performance? At which speed was he driving before, at which speed is he driving now? What other variables might have changed (BMS calibration, excessive DC charging) etc. If the battery has suffered a noticeable degradation he might be eligible for BYDs warranty. But to answer in general terms: No, after just 2-3 years you should not see any degradation that would impact real world usage.

Battery capacity or real-world range?!?

It’s hard to know how many kms you used to get vs what you get now. Trips can vary so wildly it’s not funny. There are times I’ve got 420kms and times I’ve got 280kms depending on time of day, speed limit, ascent etc. best way to test is to actually get the battery checked. Deg for these cars is extremely low generally

* WLTP range is optimistic, CLTC even more. you have to minus between 15% to 25% to get real-world range. * make sure you try to calibrate your battery every chance you get. drive until it's below 10%, then charge to 100% at one go (best is to slow charge). * use a mileage log app to track your usage and running costs (charging, services, maintenance, etc.). my 2024 Atto 3 has advertised 420km worth of range, but i'm getting an average of 5.5km/kWh, so for a 60.3kW battery that's only \~330km range.

What is the battery SOH?

It’s not the battery, their driving style or circumstances probably changed.

Do you compare the range from winter to summer ? If yes thats very bad :))

It does not respect the battery cycle for its

Nah, it hasn’t dropped. They always had 480 km at 100%, which was the NEDC figure at launch. Later, the WLTP range was confirmed at about 420 km. WLTP is still a lab test (no A/C, lights, music, etc.), so in the real world you typically get 80-90% of WLTP. That puts the 60 kWh Atto 3 at around 350 km. My 2023 Atto 3 still does the same ~350 km. That's a realistic highway range, if you only drive slow at 60km/h it will consume less and the range will be more than that. My battery degradation is about 4%. I check it with an OBD dongle. Plug it in under the steering wheel, connect my phone, and I can read the state of health and other diagnostics.

Additionally, it should be under 10% and the charging process to 100% should be "in one go". (At least, that is written in my BYD Seal manual)

1. calibrate battery. 2. its because he is running the AC all the time because summer.

430 ish range for 100% of the battery bs 350 ish with 20% leftover, is not that far off??

No I mean the amount of kilometers he had initially on a full charge was 430 ish now it dropped to 350ish

What's a good combination of AC setting? Low temp+low fan speed Or higher temp+high fan speed?