CC Doing SHV

[johnrobholmes]

Kinda what I figured, but the talking heads in the light electric vehicle community are sold on the legged package so hard that there is no convincing them that SMD FETs can perform at higher power levels.

So far we have found that the HV160 is good for about 6000 to 7000 watts burst on 12s with a low inductance and resistance motor like a hot 3210 Astro. Above that and the ripple voltage starts to get out of hand and things go south after about 200 miles. Things never get warm externally, but the system just doesn't like it.


Regarding the safety issues above 12s- Above 50v electricity will start to arc across dry skin. The amount of wattage available if a battery short happens becomes very dangerous. One of the members here had a bullet plug incident, I think it was 18s.

This is from one small mistake, Thanks for the pic Metallover



There are other instances of burned skin and melted systems. My buddy had an incident on 18s that destroyed his connectors, but luckily didn't spot weld them together and cause further damage. It happened in his car, he is lucky a fire didn't start.

[Pdelcast]

Originally Posted by johnrobholmes

Regarding the safety issues above 12s- Above 50v electricity will start to arc across dry skin. The amount of wattage available if a battery short happens becomes very dangerous. One of the members here had a bullet plug incident, I think it was 18s.

This is from one small mistake, Thanks for the pic Metallover

That's not caused by arcing -- 50V won't arc through skin -- but it's caused by vaporized copper. When an ESC fails and the connectors vaporize, the vapor flash burns the skin.

One of our engineers here had a 6.5mm bullet vaporize in his hand, and he got 3rd degree burns over about half of his hand.

It's not really the VOLTAGE that's the issue at 50V, it's the current availability. A typical lightweight wiring harness (like for a 1/10th scale car) is about 5 milliohms -- so at 10V, the current through a short circuit is about 2000 amps -- gets things HOT QUICK, but doesn't vaporize metals instantly. A heavy duty wiring harness used with high power equipment is usually sub milliohm -- and at 70V the instantaneous current can be 50,000-100,000 amps. That will vaporize most connectors and wires almost instantly.

That's one of the "safety concerns" I'm talking about in the high voltage systems...

Thanx!

Patrick