Originally Posted by
gigaplex
If you look at the discharge voltage curve for current gen LiPo vs LiHV when charged to 8.4V, their graphs look the same. Both LiHV and LiPo have the same recommended storage voltage of ~7.6V. If you're only charging your HV pack to 8.4V then you're not starting at 100% capacity, so your effective nominal voltage will be lower.
SMC regularly get asked why they don't offer LiHV packs for racing. Here's their response.
https://www.smc-racing.com/Regular%20vs%20LiHV
Feel free to take it with a pinch of salt since it's from one of the battery manufacturers, but if there actually was a benefit to LiHV packs, they'd sell them.
You're kidding, right? The rules allow HV packs. They don't allow charging higher than 8.4V. They need to be on an approval list (eg ROAR, BRCA etc). I buy the batteries available at our local hobby shop. Are you suggesting I'm doing something wrong here?
That is just not true. You can set your storage voltage to 7.6v and it will charge a non-HV pack to 7.6v, which will happen above 50% capacity (nominal) where the voltage starts to climb for the last bit of the charge. The charger doesn't care and the non-HV battery is not hurt by sitting at 7.6v because it is still much lower than the 8.4v limit of a full non-HV pack. I don't know how else to make you understand that which voltage you tell the charger for storage mode doesn't mean anything. Storage mode is just something to trick uneducated people into leaving the pack close to nominal voltage. I don't use storage mode and never will. I understand to leave the packs close to nominal if I am not using the pack for a while.
Go run your car for 1.5x the length of a normal race. Bring the car into the pits and put the pack on the charger. BEFORE you start charging your pack will be at either 7.4v or 7.6v. If you charge an HV pack to 8.4 it will still rest at 7.6v at 50% charge. If it is a non-HV pack it will rest at 7.4v.
^ Ignore the part of the red or green line above 4.2v (charging an HV pack to 8.4v) and the HV pack still holds a higher average voltage than a non-HV pack. If your packs are HV cells labeled as 7.4v cells then they have an advantage over anyone running true non-HV cells. There is a difference in chemistry between LiHV and LiPo and that manifests as a difference in nominal voltage.