I was just going through Ebay searching for vex v5 batteries since my team only has one. I came by a vex 7.2 volt battery and was being sold as a vex v5 edr peice and I was just wondering if i can use that to power my vex v5 electronics like motors and brains?
No. First of all, it would not be compatible because the VEX V5 Robot Battery has a nominal voltage of 12.8V, meaning the 7.2V battery will not provide enough power. The cable additionally does not plug into the V5 Robot Brain. Even if you could make some kind of cable that would connect it, the odds of it being safe to use are incredibly slim, not to mention the lack of voltage it has. If you tried to use the battery to power other electronics, I would think it’d be incredibly difficult to establish communication with something like a V5 Smart Motor because of the nature of the RS485 cables necessary for it.
unfortunate that eBay seller would say this is V5 compatible - flag it as fraudulent on eBay.
This may not apply perfectly here, but this i think this image pretty well shows how dangerous batteries can be if you use them wrong.