Formula Hybrid forums

Does the protection circuit stated in B11.4.5b need to be commercially manufactured? or can it be student made? does this rule imply that the protection circuit for the HV battery packs also need to be commercially manufactured?

This has been answered in the the announcements forum but I'll post the information here as well for your convenience.

As previously posted, consistent with Formula SAE rules:

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B11.4.5 Battery packs based on Lithium Chemistry other than LiFePo:
a. must be commercially manufactured items
b. must have over voltage, under voltage, short circuit and over
temperature cell protection
B11.4.6 All batteries using chemistry other than lead acid must be
presented at technical inspection with markings identifying it for
comparison to a datasheet or other documentation proving the pack and
supporting electronics meet all rules requirements
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However, for Formula Hybrid, the rules committee will consider providing waivers to teams on a case-by-case basis to allow them to build their own packs with lithium batteries other than LiFePo, including, if they wish, designing and building their own protection circuits. To obtain approval for such a pack, you would need to document the electrical and mechanical design of the pack, including the implementation of the protection functions above and submit those documents as an electrical rules query. The rules committee would evaluate the design, including making sure that the enclosure provides similar fire protection to that required for the HV acccumulator, does not have risks of short circuits (e.g., due to inadequate insulation or poor mechanical design), etc. The committee could then opt to grant a waiver.

No such waiver is required for a LiFePo battery, or for a commercially manufactured pack of a different lithium chemistry. You of course still need to design a robust and safe system, and with other lithium chemistry, it still needs all the protection built in. A LiFePo battery (or lead-acid or NiMH) requires only over-current protection (fusing) and does not required a waiver, so those are the simplest way to go.

We also strongly recommend that all LV batteries be separated from the cockpit by a firewall (e.g., that they be behind the main firewall). This may become a requirement in future years.

--FHRC