AIM EVO 4 question

I could call Veracity or AIM, but also this group may know off the top of their collective heads.

I use my EVO 4 as a dashboard and rarely download the data, like not for several seasons, but I wanted the data from my last session this time. According to the manual it records to a circular buffer, deleting oldest data as new data comes in, but when I look in the data logger download all the data is old. Any explanation?

Also, given that the GPS knows the time to a nanosecond, why does the time in the logger drift? My Garmin and TomTom never need their time set.

Dave, I do not know this for a fact but it depends on what level of firmare the manual is referring to and what level is installed in the unit.

If you have not download or uploaded to the unit the firmware you are using may not be overwriting while the manual may indicate it does.

Regarding the GPS antenna and time - even with my new EVO4S this year I have notices a lag on time update when I turn on the unit first thing in the day. After the first initialization it seems pretty accurate.

The internal battery is small on those units. I had a similar problem (dates back to manufacturer date) and sent it to AIM.
All was well, but if it doesn't get external battery power every few weeks you need to reset the time.

Just yesterday, I worked remotely with a customer with an EVO4 where he had never downloaded the data. I found the most recent test at the bottom of the list, even though all the dates were "today". His clock was not set. We did set it, and calibrate his throttle.

Data was useful to discover why the car ran badly in the last race. Alternator stopped charging resulting in low battery voltage, electric fuel pump was then losing pressure. Not sure the root cause, but he knows what to test and/or replace.