I have been working on a similar project. PCBs are on the way.
http://dirtypcbs.com/store/designer/details/8265/6262/top-zip
http://dirtypcbs.com/store/designer/details/8265/6261/bottom-zip
I have a 3d printed canister that they fit in that uses M3 screws to hold it all together.
These are the springs I am using: https://www.mouser.co.za/ProductDetail/Keystone-Electronics/211-D?qs=%2Fha2pyFadui9q4JttDHta7ui%252B%2FLDVmbiwU8jRQ1OBRE=
looks pretty much the same as mine.
PCBs are also being printed. Let me know how it works 
Would it be possible to sleeve two cells inline and eliminate contact pins in middle? With spring contacts on ends this would be very economical.
Vibration and contact is the bulk of the problem. This is why the springs are necessary.
I am getting sample pogo pins to make some tests, would need to order 5000 for it to be economical…
Ok so with the expensive price of the pogo pins and the machining of all the parts. I can sell this harness for about 500USD.
Not sure if anyone will be interested at that price but I will make a couple for myself…
Cheers,
E.
Received my parts today and went ahead with the pogo pins as I cannot get current rating for the springs.
Missing the PCB but will rig something up for testing.
First prototype completed and tested. The only downside is it needs to be fitted in the longer 298mm acrylic tube. But considering the benefits of being able to power the ROV while travelling, I think this is a win.
After running a few charger cycles at 20A the unit is not overly heating up. This appears to be a success.
Will run more tests in the tank.this week.
That is looking great. What is the expected max current draw from the ROV?
Depends what you have got installed, at what % your running etc.
BR uses 90a cable from the battery housing and I think a 100a current sensor off the top of my head.
In reality, this high current draw is mostly in bursts.
I think 20a on average with the charger is higher than reality which is why I thought it was a good test.
My batteries last me between 2 and 4 hours depending on what I’m doing. that’s about 4.5 to 9a average…
Hi,
This looks awesome. Is the project viable for selling? kits? pcbs? i’m interested
It’s too expensive to make to be a viable product.
I have one I can sell for 500usd.
Let me know.
Cheers
E
That’s a shame, when there is no alternative it is never too expensive.
Hi Eloi,
I have had zero interest in this product in the last 2 years…
Works great though
I would need to mass produce in order to get the price down and since I’ve had no interest it would be a bad idea…
Cheers,
E.
The bullet connectors are super expensive, i’m starting out on my 3D CAD journey, linux user so that’s FreeCAD.
I’ve bought a welder for batteries but that’s not for everyone. I really think with some redesign to reduce the costs you could be onto something.
Do they all need to be spring loaded for example? are the lengths of the cells so wide tollerance you couldn’t use solid copper for example? and then the tie bolts you show already?
From my experience they need to all have spring loaded Pogo pins or else they arc from vibration.
I tried to make full copper plates with a small cylinder shape under each cell and it was an epic fail.
Looked into using springs and they would get too hot they would melt the solder.
Pogo pins were the only proper way to do this project.
Maybe you can figure out another way.
hahahaha, no, i doubt it!
No offense meant
None taken.
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