[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

(ET) Charger failure with very interesting data....

This morning I was using the "newer" E15 tractor and putting it on charge between runs. No biggie, runs fine.
However after about 30 minutes I noticed that the transformer was humming when I walked by it. Odd, but didn't make the connection that things were "wrong"
A short time later I was sitting in the hammock, looked over, and saw a wisp of smoke coming from the charger (lid was open). Ran over, AC cord was hot, unplugged it, pulled the cage over the charger and yep, the transformer windings were smoking on the primary side.
Bad. Drove it over to the hose, hosed it down to cool it off, took a picture, still hot even with water on it. Very odd. 

WHAT HAPPENED?
The good news is I have it plugged into a Third Reality outlet which logs all data to my Home Assistant. So I was able to pull up the charge profile to see what the heck happened. It's.... interesting and kind of explains what went bad.
Normally when charging the charger goes to 11 amps/1000 watts/PF 90% then quickly drops to around 8a, 800 watts, PF 92% as it bulk charges. Then as the battery voltage hits 42.5 or so the AC power input drops, power factor stays about the same. Ok.
Not this time. As the charge current tapered down the power factor began to drop 80%, 70%, 60% then it dropped like a rock to 20%. At the same time the wattage went up sharply from 116 watts (fully chargedish) to 600 then 700 watts then 480 and was climbing back to 600. The power factor was 23% and the amperage went from 1.4 to *19* amps. (all at the AC plug values) 

WOW!
This was not good. While the watts drawn was within specs, the current had skyrocketed and would probably have popped the breaker in a few more minutes. And while it was only pulling 400 "watts" it was probably pulling 2000+ volt/amps. 

So what happened?
Not sure yet, but I'll bet the capacitor went to a dead short. I'm wondering if that was the winding that was smoking; if so is quite possible the transformer is toast. Oddly enough the wires to the capacitor (pretty light ones) were not smoked, so what I may have seen in the graphs was the capacitor failing, then the PFC windings heating up and shorting then all hell breaking loose.
Very interesting. I THINK I have a spare transformer; but I don't think this was a diode failure. Diode bridge was cool and batteries are charged and working. 

Interesting data point.