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Battery on firewall out there?

Space Cadet

Space Cadet

Well Known Member
Think I remember someone in RV-10-land who had to move their battery up to the front of the firewall. If so, where did you end up putting it? My c.g. is too far aft and moving the battery appears to be about perfect swap to fix. Will not do it until first annual, at the earliest if ever, but still pondering it.

Thanks,
Dwight
 
We did a RV10 with a firewall mounted 680 odyssey last year. The installation saved quite a bit of weight and complexity. The main mission for the plane was to be a cross country family airplane thus moving the weight forward meant that it was virtually impossible to exceed the aft centre of gravity and stay within Van's gross weight for the aircraft. Solo, the aircraft was placarded for a requirement of 50 pounds in the baggage compartment.
I flew the plane solo and fully loaded and it handled well in both configurations.
It had a six pack IFR panel and came in, I think, at 1625 empty weight. I would recommend this installation to others that have a similar mission.
 
It was probably us you are refering to. Transport Canada would not issue a C of A without correcting our aft c of g. We , like you had planned in moving our batteries forward during the next winter and wanted our C of A approved with the aft c of g, but that did not fly. We lost flying weather as I believe it was June when this took place. I have no regrets with the two 680 batteries mounted in their mounting trays, mounted directly on the firewall. We reinforced the firewall to accept the trays. Like Tom Martin says it reduced the total install weight by a bit, can't rember exactly but I could look up the ammendments. Our C of G is within limites solo with a 150lb pilot and no additional ballast and with all fuel levels. We still don't know why ours turned out so much different than most others. Our ac was complete and painted when we were doing our weight and balance.
Very pleased with the results.
Ron
PS Top cowling is off now I could take a photo and try and post it if needed.
 
Would like to see photos of this install, I am thinking about a 925 in plans location and a 680 on the firewall for dual elect ignition, anyone ever done this before?

Dave Ford
Cadillac, mi
 
Dave,

It's been done multiple times. Use the PC-680 battery box kit from Van's, add a couple of angles to the aft side of the firewall for the mount bolts and you're good to go. There are at least a half dozen that I'm aware of with a PC-925 in back and PC-680 up front (including my first RV-10 and the one I'm currently building).

For those considering this, the "normal", perfectly stock RV-10 will have a CG near the forward limit. Passengers and baggage will move the CG aft. Front passengers and fuel are close to the empty CG. Because of this, many people put a few pounds on the baggage compartment so there's isn't a heavy stick feel in the flair because of the forward CG.

Now, if you're swapping out mags for electronic ignition, have something lighter weight than the alternator and/or starter, have an O2 cylinder in the back, have a lighter prop than the Hartzell, etc. you'll have a CG that is aft of the forward limit. Since it really isn't possible to load "stuff" into the plane and move the CG forward, having the empty CG at or near the forward limit is desireable.

Bob
 
Battery Box for Firewall Forward

I have a battery box for an Odyessey PC680 that is designed to mount to the firewall. I personally would drill this out significantly with lightening holes. This is what I would use to mount it. I'll try to find some pics of an install on an RV-10, or at least of the space where you could install it and post those later.

RV10BatteryBox1.jpg


RV10BatteryBox2.jpg
 
I'm a bit confused - easily done :confused:

I thought the whole point of fitting the battery at the rear ( and having the subsequent extra weight of the #2 wire all the way for the starter) was because there was an issue of the CG being too far forward.......
 
This will give you an example Paul.

I built per plans...no A/C, no lightweight prop, no electronic ign, no heavy interior, cloth seats, elt just behind baggage bulkhead.

The extra heavy items added aft of cg are: pc680 aux beside 925, 10 ga wire to front, 6 space hot bat fuse block, extra contactor/#2 wire to interconnect to main bat, baggage led's/switch, two cig lighter accy ports, 6 spare 18 ga wires from panel to rear for future use(ads-b, etc).

My ewcg is 1/2" aft of Van's fwd limit. When loaded with family and 100 lbs of baggage I am at full gross with cg 1 1/4" fwd of aft limit. As the kids grow up a little more we will have to leave some baggage off. If I want to haul two normal people in the back then no baggage.

My thoughts on the firewall mounted pc680 battery. If you are going to have lightweight prop/starter/ignition then I would install aux bat up front. If you are going to have A/C then install it up front. Otherwise as you can see I would be over gross before I went past my aft limit and will never go past my fwd limit. If one decides to go with all of the heavy stuff up front incl pc680 and A/C, plus heavy interior then you will probably be fine with cg but will just be limiting your useful load. Plan accordingly.
 
What about 2 people??

Wayne Gillispie said:
This will give you an example Paul.

I built per plans...no A/C, no lightweight prop, no electronic ign, no heavy interior, cloth seats, elt just behind baggage bulkhead.
Click to expand...

Wayne,

What about when you carry only 2 adults up front? Do you have to carry ballast? If so, how much and where?
 
Wayne's approach is a good one.
The cg range of the -10 is not as generous as, say, a 182.
If you can start out with the cg a little forward at light weights, just front seats occupied, you can always add ballast in the back. Then when the cg wants to go aft with heavy loadings in the back of the plane, you've got some room on the cg chart.
But you do have to be careful. For some configurations it may be necessary to place the bags at the passengers' feet.
Also, note that with aft cg loadings, the cg will move further aft as you burn fuel. Be sure to check the cg with the minimum fuel, too.
 
Wayne Gillispie said:
The extra heavy items added aft of cg are: pc680 aux beside 925, 10 ga wire to front, 6 space hot bat fuse block, extra contactor/#2 wire to interconnect to main bat, baggage led's/switch, two cig lighter accy ports, 6 spare 18 ga wires from panel to rear for future use(ads-b, etc).
Click to expand...

The reason no ballast is needed on mine solo or two up front is the above items which probably weigh 25-28 lbs, plus I always have oil, tools, covers, tiedown kit, first aide kit and survival kit in baggage area(another 25 lbs). If I did not have these very useful items then one would definitely have to put 50 lbs of something in the baggage area.

I really like the way it flies fully loaded better than solo...stable, responsive, and very little trim adjustments between takeoff, cruise, landing or go arounds.
 
tfarrell839 said:
I have a battery box for an Odyessey PC680 that is designed to mount to the firewall. I personally would drill this out significantly with lightening holes. This is what I would use to mount it. I'll try to find some pics of an install on an RV-10, or at least of the space where you could install it and post those later.

RV10BatteryBox1.jpg


RV10BatteryBox2.jpg
Click to expand...

Is this the battery mount kit that Van sells for the PC680 ?
 
Batt Box

Wesael,

Honestly I can't remember. I think it came from Odyssey directly , but I don't think they offer it any more. It is made from 3/32. I don't know what Van's offers exactly, maybe someone has a pic of a vans tray.

Good luck.
 
tfarrell839 said:
Wesael,

Honestly I can't remember. I think it came from Odyssey directly , but I don't think they offer it any more. It is made from 3/32. I don't know what Van's offers exactly, maybe someone has a pic of a vans tray.

Good luck.
Click to expand...

Thanks for your help. I could not find specific information on it so I just ordered the one that van offers for the 680.

I hope it is the same....I like that set-up
 
I took three photos of our firewall battery installation today. I've tried inserting photos before and it a pain for me. If someone would like to give me their e-mail , I can send them and you can post them for me.
Ron
 
Wesael said:
Thanks for your help. I could not find specific information on it so I just ordered the one that van offers for the 680.

I hope it is the same....I like that set-up
Click to expand...

So is the vans 680 battery mount the same as the prior photo?
 
Battery temps?

I think with the amount heat up there, and the CofG differences.....put them where they should be. I know the 2 seat RV's have them up front, but this is not a two seater.
 
Battery up front.

Well I like the idea of a Odyesse 925 in the back for the main battery, and a 680 up on the firewall to help the weight and balance, and extra battery capacity for the unforeseen electrical emergency.

I will have a all electric instrumentation and in think having several layers of redundancy it a very important. IE Backup Alternator, backup Battery, and emergency battery's on all efis panels.

Just my 2 cents worth.
 
David
For us, it was a C of G issue that had Transport Canada concerned , and is the reason for us moving them on the firewall. Hopefully battery heat /temperature will not be a problem for us. I'm keeping an eye on the battery casings for signs.
Ron
 
I've had a 680 on my firewall for 7+ years.
I'm replacing it this spring for reduced capacity.
It is starting to turn the prop slower if the oil is cold.
If it exhibits any heat damage, I'll post up.
Tom
 
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