2nd Battery Placement

[Capflyer]

My Rv is a 7A with an I/O 360 engine. I'm going with 2 Odyssey batteries and one alternator for my electical system. The first has an obvious location on the firewall but not sure the best placement of the second. Anyone have some experience and/or pictures to help out with another firewall location that will not conflict with other stuff?

 

[DGlaeser]

2 batteries

I put both batteries behind the baggage area. I can't post a picture at the moment (firewalls at work), but my installation is very similar to this one:
http://cddevelopment.com/tcm/aftbatt.htm
(I will be installing an Eggenfeller Subaru soon...)

Since you have a 360, your CG may be quite forward with the batteries up front, so you might want to consider putting both of them aft (depending on how far along you are)

 

[jclark]

2nd Battery Placement ...

I put two batteries on the firewall of the 6A I am building. They are PC680's.

There is one on each side, down low enough so that they can be lifted out of the steel battery box. The boxes are mounted so they are attached as much as possible to the braces (angle) on the aft side of the firewall. It is snug but it all works.

The contactors are near the battery boxes on each side and the regulators are each **ON** the battery box. I am building to Aeroelectric Connection Z-14 (dual battery, dual alternator, crossfeed)

James

p.s. If you really need pictures, I will try to get some later.

 

[mike newall]

I am curious as to why you would want to lug another 20lbs of ballast around the sky with you ?

What possible occurance would need two batteries to be installed ?

 

[jclark]

Peace of mind ... if nothing else

I am curious as to why you would want to lug another 20lbs of ballast around the sky with you ?

What possible occurance would need two batteries to be installed ?

Two batteries ...

Allows for total independence of systems that I will depend upon a lot. All glass, electronic ignition (but all this with belt and suspenders).

Extra cranking power if I need it. (Shouldn't though ... no actually I **DID** need it once when the plane was on a trip and was left out in the COLD).

Peac of mind knowing that if one half of my dual electricl system dies, the other half SHOULD be there powering enough stuff to get me home or to the next airport with little or NO stress.

When the time comes, I will just have to work on saving the "20 lbs" by going on a diet.

To each his/her own.

James

 

[MCA]

Batteries on firewall

Here's a link to the two PC680's I mounted on the firewall. The contactors are mounted on the battery boxes, which are mounted a bit lower than the plans specify. 80 hours on the plane so far and it's working out well. In this case, the two batteries are for two independent electrical systems.

http://www.io-390.com/IO-390 electrical.htm

Marc

 

[Capflyer]

Thanks

Thank you for your responses and Marc, thank you for the picture.

Mike, the reason I need two batteries is because I have an all electric airplane with dual electronic ignitions. My options were two batteries and one alternator (which is what I'm doing) based on Z-19 or the two batteries & two alternators based on Z-14. I could not justify the extra $1000 expense of the SD-20 alternator and regulator so Z-19 it is. These are refering to the Aero-Electric Connection diagrams.

If I was flying with mags and a vacume system, I would only go with one battery. There is something to be said for not having the airplane drop out of the sky if one side of my electrical system fails.

 

[mike newall]

Ah, to be able to have all electric aeroplanes !

We are Mag on at leats one side, no IFR, no Night, so I guess I got confused.

Enjoy !

 

[N941WR]

Mike, the reason I need two batteries is because I have an all electric airplane with dual electronic ignitions.

Why not go with duel P-Mags? Then get the electronic ignition you want and you won't have to worry about becoming a glider in the event of an electrical problem and you won't need the 2nd battery.

Just another $.02.

 

[gmcjetpilot]

Here is an idea? Use a small battery

Mike, the reason I need two batteries is because I have an all electric airplane with dual electronic ignitions.

I am not sure what size 2nd battery you had in mind but a little 4 to 5 Ah battery is plenty to run one EI. You did not mention the ignition brand but Plasmas run on low voltage and they have some suggested wiring. I find "Z" drawings to be excellent and OVERKILL. Here are some links are references.:

Simple battery wiring for electronic ignition only (not the whole plane)
http://www.lightspeedengineering.com/Manuals/PS_Diagram.htm

Notice the builders picture, right, Aux battery tray on back (cool side) of firewall
http://home.bellsouth.net/p/s/community.dll?ep=87&subpageid=110104&ck=
http://home.bellsouth.net/p/s/community.dll?ep=87&subpageid=110105&ck=


Look what is going to fail? The alternator. How long will the main battery drive both ignitions even if you did not have a second battery? About 5 hours or more. At least more time than 1 tank full's worth of endurance. Consider one small 4.5 Ah AUX battery to just drive ONE ignition for more than sufficient time to get on the ground. ONe little 4.5 Ah battery should last at least the endurance of full tanks. The LS Plasma's use little current and run on low voltage.

I would not install TWO PC680's, it is just more weight. First the chance your main battery will fail is small. If you replace the main battery proactively every few years and maintain its charge, not over or under charging, it will be very reliable. The second battery is there more for a wire falling off, than the battery itself failing. Here are some small batteries from 4 Ah to 7 Ah (weights 3.9 to 5.5. lbs):

http://www.batteryweb.com/panasonic-detail.cfm?Model=LC-R124P
http://www.batteryweb.com/panasonic-detail.cfm?Model=LC-R125P
http://www.batteryweb.com/panasonic-detail.cfm?Model=LC-RB126R5P
http://www.batteryweb.com/panasonic-detail.cfm?Model=LC-R127R2P

You might get by with a 3.4 Ah (2.7 lb) battery if you have a Lightspeed. (Electroair uses more current and needs more voltage)
http://www.batteryweb.com/panasonic-detail.cfm?Model=LC-R123R4P

If your plan is only to back up one ignition you don't need a large battery. I suppose if you are EFIS and IFR than the second large battery makes more sense, but for EI electrical redundancy you only need to drive one of them for a few hours from an independant power source. A small battery is plenty.