Flying with 8 batteries

[assiegordon]

For all you that fly with more than the standard 4 batteries.

I see most mount the bottom batteries vertical (as per Glydrfreak’s excellent method). I’m thinking of doing the same as it is obviously better for keeping the wire lengths as short as possible.

Just one thing that keeps nagging me. With all the weight of the batteries hanging off the side of the batteries, there will be a moment on the connection points. Have any of you experience cutting or marking of the zip ties into the battery casings? Or is there some foam support between the printed part and the battery?

Or would it better to have an angle at the bottom to support the weight of the batteries on their ends?

Or a box like Grassyellow’s installation?

Thanks.

[glydrfreak]

Credit for that printed track method goes to my dad (@GliderPilot). He will be able to answer your question better, but I don’t think there has been any damage caused by the zip ties. I wondered the same thing at first, but they seemed to have held up for a long time now. I even flight tested it to 3.5 G’s.

[GliderPilot]

The batteries have a thin aluminum plate under the
heat shrink that keep the zip ties from damaging the pack. I use foam tape on the printed part just to help hold them in position so they stay lined up.

[assiegordon]

How about when the batteries are turned on their side (to allow for 4 down there). That would put the plate perpendicular to the ties.

I noticed that you rotated batteries 2 and 3 when you went from the velcro to the slide. Is this the reason why?

Thanks.

[GliderPilot]

The aluminum plate would still protect the corners the same. The pressure of the ties are on the corners not the surface.

Do you really think you will be able to fit 4 batteries at the bottom?

The way I arrange my batteries makes the wires as short as possible both inside the motor as well as the leads from the batteries which are cut approximately in half.

[assiegordon]

8 does not look to be a problem. Although I want the connection side of the batteries to be facing up, which means I need a little more support at the top of the bottom frame (just below the hinge) as the frame isn’t wide enough for 4 batteries.

From a wire length point of view, 8 is just as short as 6 (maybe even an inch or so shorter).

I’m thinking of using angle aluminum to support the batteries both top and bottom, with velcro back and straps (similar to the original four batteries) to hold them. I think the batteries will almost be hanging from the straps in flight because of the angle of the bottom frame and hang angle. We’ll see.

[GliderPilot]

@assiegordon

From a wire length point of view, 8 is just as short as 6 (maybe even an inch or so shorter).

We keep the total wire length short to reduce induction spikes. It’s the total length of all wires including the leads that matter. How could 8 be shorter than 6 if you have two more sets of leads?

[assiegordon]

My apology, forgot total wire length.

So it adds another 4" of wire and the associated battery leads for batteries 7 and 8. I think the extra batteries would out weigh the issues of the extra wires.

[assiegordon]

So wired for 6 or 8. Comments welcome. I think the wires are about as short as they can be without too much physical stress on the wires.

[GliderPilot]

That looks really good! I like that you are putting my 3D print designs to use too.

Did you add capacitors to the ESCs? Even though your wires are as short as possible they are still longer than intended for the ESCs we use.

[assiegordon]

I did add the capacitors, and the precharge. It has all the little upgrades now.

Really like your 3D parts. They have a very nice fit and finish, especially compared to some other parts. Thank you so much.

I did print your lower battery connection. But it didn’t work because the sides of the bottom hinge does not have the bottom slots. The slots are also slightly narrower. So designed my own two part connector for the bottom. Always fun to swap colours halfway through a print

[bartremes]

@assiegordon

So designed my own two part connector for the bottom

nice
can you share the 3D files?

[assiegordon]

Here you go. I mirror it in the slicer to get the left and right versions.

Lower Battery Plug_Bottom.stl (52.7 KB) Lower Battery Plug_top.stl (69.2 KB)

[assiegordon]

Brackets made and installed. First flight, 33 minutes long. I don’t like to push my batteries. They barely warmed up at all.

Not difficult to do, but I wouldn’t want to blow too many take-offs with the set-up. You do know there are 4 more when you have to carry it around. Not cumbersome, but noticeable.

Brackets

Installed on unit.

Batteries installed, ready for flight.