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Best battery and location?

R

Ross7A-builder

Member
There are multiple batteries out there (KITPLANES reviewed several small ones last year). Would anyone like to make a recommendation and say something about the basis for your decision?

And is the best location on the front of the firewall (short cables but a hot environment), or the baggage compartment, or elsewhere?
 
Im in a 9A so not sure if the W&B are similar. But if I mounted my battery in the back I would have to strap any passenger on the cowl to keep it in the box. I do have a Catto and 0-320 and you probably have an 0-360 so it may work.

One other consideration is cold weather starting. When it is cold, I heat my engine and that heats the battery. It would be difficult to heat the battery if it were behind the bulkhead. I really hate taking that bulkhead out too. On the firewall it is easy to access with just the top cowl being removed.
 
There are tradeoff for this decision. My RV8 kit has a place below the rear baggage compartment to house a heavy acid battery. I elected to use the smaller PC680 and mounted it at the front using the Vans mounting kit. The positive about the large rear battery is its large cold cranking amp at the expense of using heavier gauge cables and increased weight. Another benefit for the RV8 is the heavy battery serves as a rear ballast for optimum CG when flying solo. My firewall mounted battery is small and it suffers when starting the engine below 40degF. The advantage is that you use less cable and hence lower the aircraft empty weight. Due to the front weight bias of my setup, I need to add ballast in the rear seat or the rear baggage compartment when flying solo.
 
As another data point, I currently have an Odyssey PC680 in the baggage area of my RV-3. Since purchasing the plane a little over 5 years ago, I’ve swapped out to a much lighter constant speed prop. My CG is a little more aft than I’d like with the prop change and a little baggage, so my plan is an EarthX vented battery mounted on the cool side of the firewall on top of the tunnel between the rudder pedals. I’ll fabricate an airtight box with venting to the underside of the plane in case of battery malfunction. In my mind, this will remove the weight of the PC680 and about 4 feet of heavy wire and will add just a few pounds forward of the CG. I’m estimating it should save about 15 pounds in total weight.

For what it’s worth, I’m also installing an EarthX battery in my Glasair 1RG as part of a big avionics upgrade. It’ll go on the hot side of the firewall and will be contained within the heat shield battery box that EarthX sells. I’m pretty sure the model number on the Glasair battery is 680C. It’s their compact battery.

Both planes have B&C 40 amp alternators and B&C voltage regulators.

Battery choice has almost become the equivalent of the Primer Wars of days past, so I’m actually a little hesitant to post!
 
RV-9A with CS prop, I have two PC680s in series, mounted on the firewall (one is avionics backup). I've had no concerning issues with the PC680's. On my particular airplane, my empty CG is at 80.8 inches, generally in the middle of the CG range (77.95 to 84.84 in) .


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