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48V is good because a lot of safety standards have the cut off for 'extra-low voltage' at 60V DC, gives you a bit of margin (when battery charging it pushes up

48V is good because a lot of safety standards have the cut off for 'extra-low voltage' at 60V DC, gives you a bit of margin (when battery charging it pushes up to be in the 50s for example). Some battery systems I've seen at 56 volts nominal too. so sometimes people do have a bit higher-voltage ELV systems. 48V still lets you touch both conductors with dry hands and it's still very unlikely for you to be able to get any current to flow through you, you can't even feel it (although with safe working practices you'd only touch either positive or negative at one time, not both). Obviously it's very much not the case to be able to touch the 800V conductors safely in the traction systems in EVs, that side is extremely dangerous and requires extreme caution and safety procedures!

formerly_proven 3y ago
If you can't feel 48 V with your hands I'd recommend moisturizer, because you have very dry skin.
jeffrallen 3y ago
> requires extreme caution and safety procedures As long as the battery pack is still sealed and the interlock systems are undamaged and working correctly, it's no big deal. You follow the manufacturer's instructions to make it safe, then work on it like there's no voltage present. If the battery pack is broken or a prototype or whatever, yeah, then you need to think things through carefully before doing them. And have a plan for what you're going to do when things go wrong. Source: I work in electric aviation and work on battery packs.
- sokoloff 3y ago
  GP was talking about the low voltage system (the 12-volt system in most cars) and choosing a voltage for it, not anything about the traction battery.
  - carstenhag 3y ago
    No, they were comparing the difference in precautions between 12/48v accessory battery and the 400/800V traction battery.
    - sokoloff 3y ago
      You are correct; thanks; I missed the precise context of the snipped text.

formerly_proven 3y ago

If you can't feel 48 V with your hands I'd recommend moisturizer, because you have very dry skin.

jeffrallen 3y ago

> requires extreme caution and safety procedures As long as the battery pack is still sealed and the interlock systems are undamaged and working correctly, it's no big deal. You follow the manufacturer's instructions to make it safe, then work on it like there's no voltage present. If the battery pack is broken or a prototype or whatever, yeah, then you need to think things through carefully before doing them. And have a plan for what you're going to do when things go wrong. Source: I work in electric aviation and work on battery packs.

sokoloff 3y ago
GP was talking about the low voltage system (the 12-volt system in most cars) and choosing a voltage for it, not anything about the traction battery.
- carstenhag 3y ago
  No, they were comparing the difference in precautions between 12/48v accessory battery and the 400/800V traction battery.
  - sokoloff 3y ago
    You are correct; thanks; I missed the precise context of the snipped text.