Two Batteries (for CG)

Jimd · #1 04-01-2009, 09:22 AM

Guys,

I have searched through the two battery threads and did not find exactly what I was looking for.

My ONLY reason for wanting to add a second battery is to improve my CG (move it forward on an RV6).

The question-

Can I simply add a second 680 in parallel and nothing more? Will it charge properly, or cause problems somewhere like too many amps for starter or load for alternator?

I guess I could replace the 12v with two 6v and wire them in series if that makes a difference.

I have a vac system/steam gauges and LASAR/Slick mags and no real need for redundant electrical systems. I thought "If I am going to add weight up front, why not increase the battery capacity?" Hard to find a heavier chunk of balast that would not be too hard to add.

Thanks for the help-

BikePilot · #2 04-01-2009, 09:27 AM

It is impossible to have too many amps, no worry there and alternator load will be unchanged so long as both batteries are keept somewhere near full charge. If both batteries are dead and you jumpstart the plane (terrible idea imho), then there will be a greater load on the alt than if you did the same with a single battery arrangement.

pierre smith · #3 04-01-2009, 09:29 AM

....You won't hurt your starter with two batteries in parallel since it determines how much current to draw, not the batteries.

I'm curious as to why you need a more forward CG. We're running a 680 on the firewall and a light Catto prop and the CG is fine. It's a lot of weight to add if it's not really necessary....??

Regards,

Mike S · #4 04-01-2009, 09:29 AM

Quote:

Originally Posted by Jimd

The question-

Can I simply add a second 680 in parallel and nothing more?

Thanks for the help-

Yes, you can.

But, I would not do it that way----I would put an extra main contactor on the second battery, and another batt switch on the panel for the second battery.

Reason, if one unit goes south, you can isolate it.

Problem is, if one unit has a problem, and they are both in circuit, it will be a bit hard to isolate which one is bad-----

Jimd · #5 04-01-2009, 10:13 AM

Pierre,

I also have the Catto 3-blade and the CG is what I think is typical. I am limited to about 60lbs of baggage. My wife and I are both 150# or less so the gross weight is not a big deal and I would gain a few pounds of baggages capacity.

I need to power up the CG spreadsheet before I do anything but I think it will help.

Jim D.