Electrical isolating plastic


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gpn

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Jan 21, 2018
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I need to mount some cell groups close to some metal surfaces but I don't want the bus bars to arc off the metal. They will be vibrationally isolated with rubber strips but I want a little reassurance. Is ABS a good material to use? Sheets of 1/16" thick ABS are cheap and readily available as well as lightweight. This is for a portable setup that will be housed in a pelican box. The cells are in a 7s40p battery that is broken into a 4s and 3s segments and will be secured to a metal sled that everything will secure to inside the case.


I was planning on using this material to keep the cells separated from the coated metal surface: https://www.mcmaster.com/#1142a34/=1e8t2ef
 

Crimp Daddy

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Feb 21, 2018
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ABS sheet, plexy, lexan... I would consider using any of those myself. I've even used scrap wood board before only because I had it handy.

I think the only concern that I really though about was thermals. If your packs get crazy hot a lot of these plastics may start to loose their structural ability or cause fire. Everything I have done so far is generally pretty low drain so I haven't seen it be a real concern with my portables.
 

gpn

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Jan 21, 2018
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Max load should be around 80 amps. And that is pretty high use... It won't last long at that rate!

It is built with Samsung inr18650-25r cells. All are new. Should be a little over 2kwh once you factor the limited range of use (3.0-4.1v).

I'll order some ABS then. If that is getting soft I've got some serious issues somewhere and all of my fail safes have failed.
 
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Another option, very cheap, is to use old, used rubber inner tubes. Go to the local garage and ask for the old used ones and use a couple of layers, bit flexible, helps absorb movement and free....
 

daromer

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Oct 8, 2016
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Many commercial have hard plastic cases but they also have a sticky or almost glue like thing between to make sure that the cells doesnt rub or move against the surface. this is what I have used as well to make sure they dont create any issues in long run where vibration exist
 

gpn

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Jan 21, 2018
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250
Here is a better picture of how the cells will be in the "sled" that connects to the pelican case. All the elctronics (inverter, bms, dc stuff, etc) will also connect to this frame. And yes, I will be adding gussets across the top to stiffen it up.

image_vwumqd.jpg
 

Crimp Daddy

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Feb 21, 2018
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gpn said:
Here is a better picture of how the cells will be in the "sled" that connects to the pelican case. All the elctronics (inverter, bms, dc stuff, etc) will also connect to this frame. And yes, I will be adding gussets across the top to stiffen it up.

That'sa nice rendering, I wish I had some CAD skills. What size / model # Pelican case are you using to fit all that stuff?

I have a few cases I collected over the yearsI want to use for some projects but its a little hard deciding which one.
 

gpn

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Jan 21, 2018
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Pelican 1550 in black.

It will fit the 7s40p as you see it plus a victron phoenix 24/100 ve.direct, victron mppt 100/15, Victron BP 24/100, and a generic chinese bluetooth smart bms with room to spare. I still need to buy a 60w 4-port QC usb board and a 24v -> 12v converter to run the 12v stuff.

Eventually I'll add a small wifi router with vzw card and a Victron Venus GX ethernet monitor. But I'm going to make it work before I worry about the fancy wireless stuff.


I'm building the sled in CAD because it will be laser cut from 14ga mild steel and cnc bent to perfection so I want to figure out where most of the holes will go and have the laser cut those out. Much easier than drilling! If I leave it solid it will weigh just under 11#. Plan to skeletonize it and drop at least half that weight. Plan to bolt the sled to the bottom of the pelican with 5 bolts and minimize the number of holes I'm punch in the pelican. Once I figure out some interface issues I'll probably cut a large hole in one of the panels and mount a permanent external interface plate so I don't have to open the case to use it. I am curious to see how hot things get when it is being used to see what I need for ventilation.
 

Crimp Daddy

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Feb 21, 2018
Messages
970
Very nice. I have a 1520 and a 1600 laying around.

I generally use them without the foam for random things... camping, to keep things weather protected but I kind of want to do some type of battery build like yours but I am afraid I won't get to use it much.

Nice choice on all the Victron gear, can't go wrong with that stuff. They have become me go-to for various items including DC-DC converters.
 
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