Hi Bryan,

 

While I do not fly with the EXP2V bus, I do have some knowledge of it as I helped an RV-6A owner with an electrical problem who had one.

 

   It turns out the EXP2V  electrical problem was not due to the EXP2V solely – it had considerable help from  someone who had screwed up and fried the on-board relay and then attempted to Jump the relay position rather than replacing the on-board relay.  The results were that without the relay and with the non-factory jumper (there is a factory jumper apparently with a diode embedded in it which can be used to replace the relay – but a piece of wire won’t work) – the battery stayed connected to the board load and more importantly to the alternator continuously.  That was fine in that it kept the battery connected and charged while the engine was running, however, upon engine shut down, This connection would drain the battery overnight and next day - no power to start the aircraft.  With the relay in place when the master switch is turned off the relay opens removing the battery from the alternator circuit, but that could not happen with this self made jumper in place.

 

Upon examination it was apparent that very high currents had been applied to some of the traces on the board, the copper traces had gotten hot enough to cause the solder coating to flow – undoubtedly this current also was responsible for frying the relay.

 

Initially, I was not highly impressed with the EXP2V but the more I examined the circuit  the more I became convinced that particularly for those “electrically challenged” this might not be a bad way to go.  The only downside I have heard is that trying to wire in later electrical additions to the board can be frustrating as you only have so many switches and circuits on the board.  The polyfuses (automatically reset) have gotten a lot of attention (not all favorable) but I do not personally know of anyone who has had any bad experiences with them.  I wired my own panel and therefore know it intimately, so changes are no problem.  However, as I indicated, this might be a better choice than trying to wire your own if you do not feel knowledgeable or comfortable about doing so.

 

I did come to one conclusion about the high current flow.  In looking at the circuit diagram, it became clear that if someone had been messing with the alternator AND had left the EXP2V master switch ON and then permitted the “B” lead of the alternator to become grounded – even temporarily – that would ground the battery through the board and the on-board relay.  I strongly suspect that this is what happened and with the resulting high current flow which fried the relay and melted the solder – so one could surmise that the board withstood the abuse about as well as any circuit could have.

 

I have no vested interest one way or the other, just passing on my observations and opinion.

 

Ed

 

 

Anyone out there using this bus?  Would welcome pros and cons with regard to the Renesis going into a RV-7.

Bryan

Just starting to think about electrical

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