Reliablity

So far the car has been very reliable, this page will outline the faults that have occured, and subsequent failure analysis.

2010-03-03
DC-DC converter failed.

This was my first major failure since the car went into service on 2009-02-15.
I was driving home at night, and the headlights started getting dim, this was a sure sign the DC-DC died. Luckily I still had a 12v battery installed in the car and was able to limp home. The DC-DC converter is made by IOTA, and it supplies 12v power to accessories like head lights, wipers, radio, ect. Upon opening the DC-DC converter, I noticed a burn mark on the internal fuse. It was mounted resting against a capacitor, and the fuse eventually wore a hole though the capacitors vinyl wrapper and caused a short circuit.


I bent the fuse away from the capacitor to show the burn mark



The DC-DC converter was replaced free under 2 year warranty, no questions asked. I opened the new unit and noticed the same issue with fuse placement, so I bent the fuse out of harms way. The new supply is slightly more ruggedized, with heavy components siliconed in place to prevent solder cracks due to vibration. Others have criticized this supply for not being ruggedized for automotive use, I have to agree. Hopefully the newer version will prove more reliable. I will say that IOTA stood behind their product and sent me a replacement without having to first send them my damaged unit.


2010-03-10
Main 300A fuse blown.

This was not a good week in terms of failures. My spare fuse blew as soon as I turned the ignition on. I saw my inverter had charged up to at least 250 volts and then lost power.

I traced the problem down to a stuck aux. contact on my main contactor. The aux. contact is not the high power contact, it is a smaller contact used for feedback. This contact being stuck bypassed my precharge circuitry (see red lines in circuit below). As soon as I turned the ignition on, the main contactor energized and connected my capacitor bank to the battery pack (without being pre-charged first). This caused a huge inrush of current which blew the fuse.



Kilovac replaced the contactor free of charge, no questions asked. I do not know what caused the aux. contacts to get welded.

The ignition switch energizes the coil and handles the coils inrush. The aux. contact on the main contactor is not subjected to inrush current because the coil is already energized when the aux. contact closes. The aux. contacts are only used to keep the coil energized.

The holding current of the coil is 0.13A which is above the min, and below the max rating of the aux. contact. The contactor also has an economizer which eliminates arcing when de-energizing the coil. I'll have to see if Kilovac is interested in doing a failure analysis.

I have since rewired my precharge circuitry so a single failure won't cause the fuse to blow.
New schematic