Hi everyone, how are you? I really need your help since yesterday I try to model this battery but it is not easy for me I have problems with boolean and artefects everywhere. I then said to myself that it may be my approach that is not the right one so I ask for your help if someone has a better approach to help me move forward it will do me great good.
Thank you
What does your topology look like?
I can see an internal face in the middle of the model that has to be fixes, can’t help much without seeing the file.
OK I send you the file
untitled 4.blend (750.8 KB)
There are alot n-gons in your model. You will have to add more subdivisions on the middle section of the battery or the normals will give you a tough time when rendering.
You need to follow some tutorials in youtube, Because you need to understand how topology works. I can try to explain but there are very good tutorials there.
Good luck
You don’t need so many edge loops, some are completely useless, and some shapes could be made with much less edge loops. For example a round corner can be made of only 5 edge loops, same thing for a circular arc. Also as Ertyy says, you have ngons, it doesn’t cause any problem on flat surfaces, but here there is a Subsurf that bends the surface a bit, so you need to make sure that you only use quads. Here is a quick try (the “?” means “do you really need these edge loops” but it’s a rough just to make you understand):
ok I see but it is precisely the concern when I try to add the subdivision it gives me a bad result but try to open the file and you will see when you will try to subdivide
yeah i don’t quite understand could you open the file and try to explain it a little in a little video? Please
or also if you could through a short video show me how to get the same result without so much edge and ngon it will make me very happy
well it would be a bit tedious 
but look at the white lines I’ve drawn, it’s the way I would model your object*, less edge loops, try to only keep quads, you don’t have to use boolean in you case, maybe knife project tool for some holes
but in this case how to achieve the result on the image with very rounded edges if I do not use as much bevel?
ah great I see now you can send me the blend file at the end that I study more closely please
really thank you very much for this approach can you send me the file at the end that I look more closely to better reproduce this technique
here it is, not sure it will help you though https://pasteall.org/blend/4cd78bfc1b6d4c5380c7e0d28da34434
Sure. Here you go. Good luck. Don’t forget to return the favour to someone else who needs some help! 
PowerBattery3.blend (918.0 KB)
