I don’t have my EC3 yet, so I guess I don’t have a good feel for what circuits I need.  I have a chance to get a good deal on a unit never used from an abandoned project.  I think I can easily get my money back plus some if it is unsuitable.  The seller did say that they(control vision) don’t recommend wiring fuel pumps through the unit.  I can’t find that verbiage on their website though.

This unit has the battery back up option which seems attractive, but I’m so uninitiated.

BW

 

 

 

Well, Bryan, that’s a question that can probably only be completely answered by someone taking that step.

 

 

It appeared to me that while the EXP2 bus could handle the basic job of providing power distribution to the EC2/3, there are other electrical aspects such as your injector power switches, the ignition check switch not to mention the switches associate with the Program Controller.  Naturally, any “special” switches would have to be provided whether using the EXP2 or not.

 

IF I were to consider using the EXP2, I would go to their web site and get the schematic of the unit.  Study that to see what it would accommodate as for as meeting your needs, then look at what special needs you might have to address and see what portion of those the EXP2 might be adapted to meeting – and then there are perhaps a few things that the EXP2 simply can not handle and you would have to provide the means.  If its use reduces your workload a worthwhile amount on the basic power buss then you have more time to work on the “special’ needs of your system. 

 

But, as best I recall the unit cost around $300 and had (as best I recall) around 10-12 switches and circuits.  It also had a configuration whereby you could use external Contactors or relays instead of the on-board relay.  So that might not be a bad starting point.  But, as I said check out the schematic first.

 

I have never found the EC2 to be the least bit cranky about its hook up.  However, have not had an EM2/3 so can’t address how “finicky” they might be.  However, I think good electrical design and wiring practices can do much to ensuring these are kept to a minimum.  Anytime you try a different approach, you are the pioneer – you know that guy with all the arrows in his butt – so just try to assess what its going to take and see if that is where you are willing and capable of going.

 

Good luck in your decision.

 

 

I guess my main concern is if there is anything about the EXP Bus that might make the EM/EC3 not function as advertised.  We’ve all seen the posts lately regarding gremlins creating funky behavior in these critical components.  So, while there seems to be simplicity in the installation of the bus, there are internal components that add complexity and more potential sources of problems.

BW

 

 

Welcome, Bryan

 

As I indicated the EXP2 may not be a bad choice, the only downside I could see is making later additions.  Let me forewarn you -  as an alternative engine experimenter, there is a strong likelihood  that you will make changes {:>)

 

Ed

 

 

Thanks Ed,

I actually stumbled on your account on the aeroelectric website.

 

 

 

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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