The International Cessna^® 170 Association

Does anyone no of an STC to relocate the battery from the firewall to aft of the cabin on a Cessna 170B, I am installing an Airwolf oil filter on the firewall and need the room.

Ken,
Try Harry Dellicker at DEL-AIR, in Porterville, CA.
559-784-9440

Keep in mind that you are also adding at least 20 lbs of wire to bring the power back up to the firewall.

Unless you're hanging more weight on the nose- big engine, c/s prop, etc- I'd be concerned about what's gonna happen to your CG when you relocate the battery aft. Can't help but cause the CG to move aft, perhaps enough to affect load-carrying ability. I'd want to keep the empty CG pretty much as far forward as possible.
Seems like mine has enough room on the firewall to mount a filter or chip detector somewhere without getting rid of the battery. Those devices are plumbed with hoses, so just where on the firewall shouldn't be too critical, eh?

Eric

KENDRURY wrote:Does anyone no of an STC...

no. But I have some comments:

- you should be able to find room on your firewall without relocating the battery. It's been done many times before.

- moving the battery to the back adds several pounds of heavy gage wire to your airframe and will probably degrade your cranking power. That's why it's a popular mod on 180/185's to move the battery up to the firewall.

- IMO the Airwolf is a poor choice. You're adding 2 hoses and 4 connections to possibly fail on a critical system. Why not use a case mounted unit like the F&M?

- paul

I moved my battery back behind the baggage compartment and changed it from a 25 series to a 35 series for the extra capacity. The one positive power cable running forward to the starter doesn't add that much weight and the CG hasn't been a problem. In view of the fact that most of my flying is solo, I find that it is most helpful to have the extra weight in the rear. The airplane flys better and lands better. I used to carry a sand bag in the rear, when I was otherwise running empty, to improve the flight characteristics and landing CG.
I used the Del Air STC which cost $100, at that time, which included the plans.

I relocated my battery with Harry Delickers STC. You only add about 14ft of 00 wire. This does not add up to 20 lbs. I have a B&C light weight starter on my 0360 and it spins the hell out of the engine. There is no power loss by putting the battery back behind the passenger compartment. It also cleans up the engine compartment. Jon

You're right that figure is too high, I added the same amount of wire so all we need to determine is the weight per foot of this wire to get an exact amount. Also include all the clamps, screws,nuts,and firewall shields. I put the battery back there for weight and balance purposes.

BL, are you talking about having relocated the battery on a stock-engined 170, or on your IO-360 powered airplane?

Eric

I did move the battery back when I installed the IO-360 in that airplane. I needed it to get the CG within the envelope. In the stock airplane I moved it back to make it handle better. And it does.

blueldr wrote:I did move the battery back when I installed the IO-360 in that airplane. I needed it to get the CG within the envelope. In the stock airplane I moved it back to make it handle better. And it does.

My stock B-model bumps up close to the forward limit when solo. It DEFINITELY lands better with someone in the back seat! I haven't run the numbers, but even with the battery in the back, as long as you don't load the back seat without loading both front seats, I don't think you'd run into an aft CG problem.

Miles

There actually IS power lost thru the longer battery cables, but it's not likely to be significant if the connections are good and the battery is charged up. But a cold engine, and arctic night, and a hesitant start or two could prove troublesome.
I'd prefer and recommend the FM Enterprises filter over the Air Wolf, and avoid the problem and save a bunch of money also.

Good to see Gahorn is still around to refute any advise I put on the site. Yes there is minimal loss in a longer cable, but if you have trouble starting with the longer cable, it will most likely be in the connections, the battery, or the starter itself. This is exactly why alot of people don't give any advise or help on this site! Good luck, Jon

I have never been able to detect any line loss in my battery aft installation. I have only one long cable for the positive line and it is a piece of very,very fine stranded copper welding cable.
Iknow! I know! But it works better and is very flexible.

I am confused Why would anyone even remotely consider putting a bag of sand or other ballast in their rear seat or baggage compartment to aid in landing a C-170 "To aid in landing" If a C-170 lands better with something/someone in the back seat, so be it, but I sure can't see why you competent pilots would need any help with our easy to land aircraft. I used to have a '64 C-182 and it, admittedly, was easier to land with two folks in the rear seat and/or baggage, but with the application of elevator trim it landed just fine with me or me and one front seat passenger. And this was with a Cont O-470 & CS Prop. just forward of the firewall. Just curious