Double Battery Design Ideas

Gentlemen,
I'm finishing the tail feathers and have reached a point where I could use some advice. Could some of you share your designs for a double battery framework?

Thanks in advance.

Are you asking for electrical system architecture or battery box construction?

The battery box construction. . .

Double PC680 Battery Box

This is what I did for two PC680 batteries in my RV7A.
http://www.flickr.com/photos/94930805@N04/8647230516/
It is reinforced on the cabin side with aluminum angle similar to what is called out in the plans, but added between the exisiting angles where the new battery box bolts through the firewall and into the new angle. The floor of the box is .090 aluminum with lightening holes in it. I designed it with +6/-3 g loading on the weight of 2 PC680s in mind. The batteries shown are there for spacing only.

I'm still plainly confused by inserting images

Mike, sent you a PM.

Here are some photo's of my set-up. I just built a new tray using some leftover aluminum sheet and I used aluminum angles to stiffen it up.

We used a PC680 as the aux battery and a PC925L as the main battery since it fit in the existing tray. The black box is a charging relay manufactured by Blue Seas Technology P/N 7610. It keeps the aux battery charged as long as the main battery voltage is over 13.5 volts.

i really like a double battery design

had same in my last Mooney and now in my rv7a. batteries are a common source of ignition for fires during a crash. while a 20+ g design might not be practical, I urge you to think about crash loads and impact on big writes as you design your installation.

Double battery upfront

Is there anybody that considered to install a second battery (only for avionics and EFII system) up front? I have a second generator taking the place of my vacuum pump location. If os, where, how large and what electrical installation was used?

If you plan on hauling four with baggage like we fly, then one 925 in the back and a 680 on the firewall will work better for your CG especially if you have a lighter prop.

I'm very similiar to David, with a pair of 680s. I modeled mine after Bill Watson. Both of us have Kitlog sites if you want to look up the details.

The only unusual part of my installation is that I'm using a VP/X Pro with dual batteries and dual alternators. Vertical Power recommends dual batteries or dual alternators. Some may think it's overkill, but I think I'm covering all my bases.

It's pretty easy to modify the battery tray to accomodate the additional space for the second 680. It's only a few inches larger than the tray provided in the kit.

bob

Here's how I did it for (2) 680s.
http://www.mykitlog.com/users/display_log.php?user=MauleDriver&project=224&category=2155&log=43554&row=26

Aux Avionics Battery

II have a PC680 main battery, and a 7.5AH aux battery for powering ALL the avionics during engine start. The two batteries (both lead acid) are tied together during normal operations So both are equally charged - no diode drops), but automatically separate (via an under-voltage sense circuit driving a contactor) if the main bus voltage goes below 12 VDC, and during the time the engine starter is being engaged. Both batteries are used separately to power the essential avionics. I ALWAYS turn ALL avionics on prior to engine start, and none reset during engine start. I have manual switch operation of both battery contactors as well (OFF,AUTO, ON).. Both batteries are above the rudder pedals inside the cockpit, accessible via inspection covers on the front deck. If anyone is interested in the circuit design, I can post a PDF file of the schematic....

lammers4699 said:

Is there anybody that considered to install a second battery (only for avionics and EFII system) up front? I have a second generator taking the place of my vacuum pump location. If os, where, how large and what electrical installation was used?

Click to expand...

Fred.Stucklen said:

II have a PC680 main battery, and a 7.5AH aux battery for powering ALL the avionics during engine start. The two batteries (both lead acid) are tied together during normal operations So both are equally charged - no diode drops), but automatically separate (via an under-voltage sense circuit driving a contactor) if the main bus voltage goes below 12 VDC, and during the time the engine starter is being engaged. Both batteries are used separately to power the essential avionics. I ALWAYS turn ALL avionics on prior to engine start, and none reset during engine start. I have manual switch operation of both battery contactors as well (OFF,AUTO, ON).. Both batteries are above the rudder pedals inside the cockpit, accessible via inspection covers on the front deck. If anyone is interested in the circuit design, I can post a PDF file of the schematic....

Click to expand...

That sounds just about ideal.