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0 pointsbaybal24y ago0 comments

Aren't you are mistaking galvanic isolation with insulation?

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3 comments · 1 top-level

aetherspawn4y ago· 2 in thread

Galvanic isolation is useful because it means that you have to touch 2 specific points on the affected unit simultaneously to die, rather than 1 point. Galvanically isolated systems can detect leaks on both the positive and negative sides by using a dual channel IMD. Any insulation issue is bad, but this method of detection can usually detect it before it's able to instantly kill someone per-se. Electric vehicles are an example of a galvanically isolated system (from earth) with dual channel IMD, hence you can have massive leaks such as 8-20mA before it becomes a safety issue.

baybal2OP4y ago

Yes..., but what difference it makes to this fire?

Are you working in EE?

aetherspawn4y ago

Galvanic isolation probably wouldn't have prevented this fire, it sounds like the cells just shorted together. They would have had to short over several cells, since a non-trivial voltage is required to break down coolant, so having maintenance contactors to break the pack up into 20V or so segments may have prevented this fire.

Using a mineral oil type coolant that is not electrically conductive (such as used in Tesla vehicles) would have also helped to prevent this fire.

The batteries should be galvanically isolated from the casing so that if liquid causes a current flow from any point in the pack, then the maintenance contactors can be opened and the opposite side current path for the leak is interrupted. We can only assume that they are already (galvanically isolated) since anything else would be bizarre.

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