Batteries

JDA_BTR · #1 03-14-2023, 10:03 AM

I’m planning to put my battery aft in my Rv8. I have a small odyssey PC680 on my RV14 firewall and it’s okay except when things get really cold. Because an IO390 is my plan I could use a little extra weight aft (more weight - heresy). I was wondering when the RV8 was new many moons ago what battery was typically used and what did it weigh?

rv8ch · #2 03-14-2023, 12:19 PM

Quote:

Originally Posted by JDA_BTR

I’m planning to put my battery aft in my Rv8. I have a small odyssey PC680 on my RV14 firewall and it’s okay except when things get really cold. Because an IO390 is my plan I could use a little extra weight aft (more weight - heresy). I was wondering when the RV8 was new many moons ago what battery was typically used and what did it weigh?

In the early 2000s, it was the PC680 and about 15lbs, plus the mounting tray, and the heavy fat cables run between the battery and the starter.

Carl Froehlich · #3 03-14-2023, 12:32 PM

I think people used a PC-925 - and it fit the standard RV-8 aft battery mount. I recommend some careful measurements to verify.

If you decide to forgo the IO-390 for the standard IO-360-M1B I can offer how I mounted one PC-625 aft and one PC-625 in the forward battery well. I did this to hit my W&B target (and it came out just as I calculated).

Carl

moespeeds · #4 03-14-2023, 12:39 PM

2 GA welding cable is about 0.27 lb per foot.

An alternative to the PC680 is an Earthx 900 at about 4 lbs. Use the certified/vented version in the rear cabin. Cranks way way better than the 680 I used to have.

gnuse · #5 03-14-2023, 12:43 PM

I use the PC925 in the back of my RV8.......both for W&B and extra starting power. I previously used the PC680. The PC925 fits in the stock battery holder by laying on its side. They make the battery with the negative post on either side. I needed the PC925L due to the short ground cable I have installed. Hope this helps.

JDA_BTR · #6 03-14-2023, 02:24 PM

George that looks about right for me same reasoning.

RV8RIVETER · #7 03-16-2023, 06:32 PM

Originally used pc680 in back. After a few years changed to earthx 900. Much better cranking and big increase in rear passenger weight allowable.

barneylocke · #8 03-17-2023, 09:25 AM

Have owned both an RV8 with Concorde Battery in back and with PC680 on the firewall. First RV had a PC 680 in back and the plane would hardly crank (9.5:1 pistons Superior IO360) Changed to the Concorde and life was good. Also better balance during aerobatics. This plane also had an external battery access plug. Highly recomended!
Latest RV8 has the PC680 on the firewall (a 9.5:1 Superior Engine IO375) Not as impressive during start and cg is too far forward especially with smoke machine installed and filled. I need to put ballast in the rear seat to keep cg within forward limits.
would go with the Concorde in the rear.

rv8ch · #9 03-17-2023, 01:23 PM

Two cents incoming.

I have a very light EarthX on the FW. Cranks great, short cable runs, less total weight. If you need something in the back for W&B, just put your little travel tool bag back there. Also, consider a composite prop, and aluminum gear legs.

With my PV IO-360 (yes, I know it's not a 390), Hartzell metal prop, Grove gear legs, EarthX on the FW, I can stay in CG from totally empty to MTOW (501KG - 816KG).