Electrical systems

[Bob Brown]

I'm in the throes of making decisions on the electrical system. I'm considering an Odyssey 925 battery, what would you suggest as a backup and do you have any photos of that setup (bracket, mount, etc). The electrical system of the plane will include a 70 amp Plane Power and an SD-20. Other items under consideration, Essential bus? Architecture? (We're installing a Garmin G900), etc, etc. Feel free to shoot me some wiring plans if you have something similar so I can noodle through them.

 

[RV10Pilot]

Here is William Curtis' 925 mount

Or Tim Olson's

 

[w1curtis]

.. Other items under consideration, Essential bus? Architecture? (We're installing a Garmin G900), etc, etc. Feel free to shoot me some wiring plans if you have something similar so I can noodle through them.

You do realize that the G900X is a 28 volt system right? If you don't have a 28 volt electrical system, you will have to plan for the required 14 to 28 volt converters.

Here are some
http://nerv10.com/wcurtis/90Electrical/indexEL1.html

Wiring Overview
http://nerv10.com/wcurtis/90Electrical/RV10WireBookPage1.pdf

Wiring Schematic
http://nerv10.com/wcurtis/90Electrical/RV10WireBookPage2.pdf

 

[tx_jayhawk]

Actually, I heard only the 16 Watt COM in the G900X requires 28 volt. Everything else runs on 14V. I suspect you could address the COM power needs by using a small 14 to 28 convertor, or your could get creative and use a couple of 14V batteries that were serially connected.

 

[Bob Brown]

Stein's the man doing the panel

He knows we have a 12V system, and has a handle on the required electrogizmoids required to run the G900 video game. He's put something like 24 of these together and I'm hopeful he's worked through the worst of the gremlins, I'm challenged by changing flashlight batteries...

 

[RV10inOz]

We are using a 680 as our backup battery! Mounted near the main one.

DB

 

[GTWreck]

Actually, I heard only the 16 Watt COM in the G900X requires 28 volt. Everything else runs on 14V. I suspect you could address the COM power needs by using a small 14 to 28 convertor, or your could get creative and use a couple of 14V batteries that were serially connected.

This is correct. I just went through the entire G900X installation manual. There is only one LRU(GIA63W) that requries a 28V input, and it is the COM power input. The remainder of this LRU is powered by 14V or 28V.

All other LRUs in the G900X system can run either 14V or 28V.

 

[johngoodman]

I'm in the throes of making decisions on the electrical system. I'm considering an Odyssey 925 battery, what would you suggest as a backup and do you have any photos of that setup (bracket, mount, etc). The electrical system of the plane will include a 70 amp Plane Power and an SD-20. Other items under consideration, Essential bus? Architecture? (We're installing a Garmin G900), etc, etc. Feel free to shoot me some wiring plans if you have something similar so I can noodle through them.

The thread has sequed to the G900 requirements and not the question - what would you suggest as a backup.
I'd like to see some discussion on this part. Also, I would like to ask why the PC925 seems to be the battery of choice. If you are looking for more juice, why not a PC1200 instead?
John

 

[Mike S]

A little food for thought here---------

Use two batteries that are the same-----680 or whatever.

That way, you can setup a regular rotation of changing out one batt, (2 years or whatever you feel to be adequate), new batt is the main, and moving the remaining one to the aux position.

 

[Bob Brown]

The thread has sequed to the G900 requirements and not the question - what would you suggest as a backup.
I'd like to see some discussion on this part. Also, I would like to ask why the PC925 seems to be the battery of choice. If you are looking for more juice, why not a PC1200 instead?
John

Thanks for bringing us back around John, I am not hung up on having a backup battery, I wanted a 925 so I can have more juice. I'm not against having a backup battery, but I don't want to run another big honkin ground cable all the way forward to the single point firewall ground (I'm already running one 2ga cable up there). The other consideration of the PC925 is that I think it fits in the stock Van's battery box (on its side) with little to no modification. I'll do a little more investigating, then probably will just go with the PC925, they're 150 bucks locally.

 

[Mike S]

but I don't want to run another big honkin ground cable all the way forward to the single point firewall ground (I'm already running one 2ga cable up there).

The ground cable is not needed.

Just make sure you have good engine to airframe ground for the starter load, and it is a good idea to have a single point ground for the avionics that ties to the airframe, such as one of these from B and C.

 

[Bob Brown]

I ve already got that single point ground (on both RV's), but in my experience, I always grounded the negative battery cable to it to avoid electrogremlins like strobe pops and "cable quality" music in the intercom system. I have flown in a 10 that had strobe pops and its battery was grounded locally instead of to the single point ground, so it's a 10 ton (actually 10 pound) gorilla I'm going to put up with. Can I run a backup battery without running two ground cables, ie, an intertie in the back with only one ground cable running fwd?

 

[Mike S]

Can I run a backup battery without running two ground cables, ie, an intertie in the back with only one ground cable running fwd?

Yep, just hook both neg terminals together.-----

If you are going to use the forward running gorilla wire, I suspect that you do not want to ground the batt locally also.

I suspect the plane with the strobe issue was something else besides using an airframe ground.

But, you have to build to your own set of standards.

Carry on.

 

[johngoodman]

Thanks for bringing us back around John, I am not hung up on having a backup battery, I wanted a 925 so I can have more juice. I'm not against having a backup battery, but I don't want to run another big honkin ground cable all the way forward to the single point firewall ground (I'm already running one 2ga cable up there). The other consideration of the PC925 is that I think it fits in the stock Van's battery box (on its side) with little to no modification. I'll do a little more investigating, then probably will just go with the PC925, they're 150 bucks locally.

Bob, you bring up a valid question - ground wires. I've been looking at the discussions out there and there seems to be a "primer war" over using the aluminum airframe versus a cable from the "forest of tabs" back to the battery. I lean towards the folks suggesting a real ground wire, but does it have to be a 2ga? Wouldn't an 8 be enough? After all, the aluminum body is still there (I can't remember which hotel I stayed in but I must be an expert in something)

 

[Bob Brown]

Equality of flow? Let's treat all the electrons the same.

Heck John, I'm no electrician, but I think all that comes out of the positive side of the battery flows back in, minus what's used up in the "doing of work", such as turning the starter. That's why I've always used the same diameter ground wire as the positive side. Seems that by using the same size cables, the resistance in the circuit is optimized. Besides, I've already installed the 2ga wires...its too late for me to reform! Perhaps someone more knowing than me can weigh in on the appropriateness of this decision.