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SOLIDSTATE SWITCHES AND LOGIC IN THE SAFETY LOOP
· FH+E 2025 rules presently require mechanical latching relays for IMD and BMS faults.
"EV7.1.1 (9): Both IMD and AMS must use mechanical latching means as described in Appendix G."
· However, the new FSAE-2025 rules are more lenient, but still require "When the BMS, IMD or BSPD Open the Shutdown Circuit: … a. The Tractive System must stay disabled until manually reset". Relay logic is not required.
· In order to harmonize with FSAE this year, FH+E will allow solid-state devices such as SSRs and FETs in the safety loop, and also allow digital logic to be used for the latching function.
· We need to ensure that IMD and AMS trips are reliable and latched as they are the fundamental safety checks for participating vehicles. We also need a way to review the latching function. Thus, for 2025, we are not allowing software latching.
· This limitation is the same as FSAE who clarified: “We allow digital circuits in the shutdown circuit like discrete logic latches, and semiconductors to switch the shutdown circuit current for the AMS, IMD and BSPD. We do not allow software.”
· The trip and latching functions will be tested during tech testing. We may also perform spot checks at other times(including the rain test).
· IMD trips are easily tested using the TSMP connection. Make sure that you have a clear and simple way of testing AMS faults – and document it in your ESF2.
· If you planned to use software for latching IMD and AMS faults, we suggest that you first seek clarification and approval from FSAE. Then we may be open to variances based on their response.
Rob Wills
Chief of Electrical Tech Inspection
Due to a change in formatting of our end of competition program guide, team photo formatting has been dropped. A single group photo is now all that is needed.
Be advised that a correction has been made to Figure 37 from section EV7.1. Please refer to this updated version.
This is a friendly reminder to submit your structural equivalency spreadsheets by midnight UTC on November 15th. Late submissions are penalized 10 points per day, so be sure to get them in on time.
Please note that there have been a few changes to the warning light section of the rules. These changes can be found here.
Team numbers are posted here.
Please follow this document naming convention when uploading:
Document Submission Title:
Per Rule A9.2.2: All documents must be submitted using the following document title, unless otherwise noted in individual document requirements:
Car Number_University_Document_Competition Year
i.e. 000_Oxford University_SES_2025
Teams are responsible for submitting properly labeled documents and will accrue applicable penalty points if documents with corrected formatting are late.
Please follow the following steps for compressing submitted documents:
We are unable to accept Google Docs and suggest the following to compress pictures.
-Open original document in .docx format and open it in Word
- Go to File/Options/Advanced/Image Size and Quality. Set the Default Target Output to 96ppi and click on Discard Editing Data and then “OK.”
- Go to one of your pictures in the doc - Figure 1 will work. Click on the Figure and then at the top, click on Picture Tools/Format/Compress Pictures.
- Click on 96ppi and unclick Apply Only To This Picture. Click on “OK” and “Save As.”
- Check the size in File Explorer.
- If the doc is still over-size, save your biggest picture in .jpeg instead of .png. This will often save a lot of space.
FH+E would like to welcome you to the 2025 competition! We want to remind you to keep track of these rapidly approaching deadlines. There are bonus points available for teams who submit their documents before certain due dates!
With registration for the 2025 Formula Hybrid + Electric competition only days away, teams should take note that the latest edition of the amazing resource book "Learn and Compete Second Edition" (Vol 1 and 2) is available. The two volumes cover not only Formula Hybrid + Electric but also Formula SAE and Formula Student topics. Authored by long-time FH+E volunteers Michael Royce and the late Suzanne Royce.
Link to purchase is on the FSAE Online site here.
