diy solar

diy solar

Who has experience with (blue) aluminum cells in a mobile system?

sduser said:
I am considering using 8 of these 105Ah cells from @mkpieters in a 2P4S configuration. Normal usage would be low (0.1 C) charge/discharge rates. I would like to be able to use as a vehicle starting battery in an emergency though (bypassing the BMS and connecting jumper cables directly to the battery terminals. Any thoughts on the quality of these cells? Specs look good but my biggest concern is the M4 terminals with max torque of 8Nm. Thoughts on these securing larger busbars and pushing 2C-3C?

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135Ah LifePO4 cells for sale

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Looking for input regarding the M4 terminals with 6mm insertion depth and max 8Nm torque in a 4wd vehicle application. I would probably attach a SS stud with loctite first, then attach busbar and BMS connections with a nylock nut. I did read of one (or more) stripping out, but if they are not over-torqued should be ok? Is that enough clamping force for say 1/8" or 3/16" busbar pushing 300A? Thanks in advance.
 
Zil said:
Using a stud and nut is safer than over tightening a bolt.
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sduser said:
Looking for input regarding the M4 terminals with 6mm insertion depth and max 8Nm torque in a 4wd vehicle application. I would probably attach a SS stud with loctite first, then attach busbar and BMS connections with a nylock nut. I did read of one (or more) stripping out, but if they are not over-torqued should be ok? Is that enough clamping force for say 1/8" or 3/16" busbar pushing 300A? Thanks in advance.
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I am doing 4 cells but I feel like if the cells are effectively bound together with vhb in the middle and outside fixation, either hoseclamp style or tightened nylon straps, and then the 4 cells are in a container that's prevents having any individual cell movement(tight fitting), I feel like the it would be pretty secure or am I missing something. I'm not an engineer lol.
 
I was talking about tightening the bolt, machine screw, into the terminals on those particular cells. They are aluminum and easily stripped of threads, or cross threaded while in work. If a stud is threaded into the terminal, a nut can be tightened onto the stud with not as much chance of cross threading, or stripping from over-tightening.
 
Thanks. I read through this thread again and a few others a few and feel I should be ok if careful. Three of the busbars will be spanning 4 cells and the main + and - busbars will be spanning 2 cells so that should help distribute forces better
 
Hi,

I have these cells and the studs have an allen wrench top to tighten. I just snugged them in good and then use the allen key wrench to hold the stud while I tightened the nut down. If you don’t hold the stud from turning with the nut while tightening the nut you could possibly turn the stud in too tight and strip it.

B
 
I permanantly glued my 4 cells together with 3M 5200 marine adhesive and they are now one solid unit impossible to separate. The alum cases are not straight and I doubt VBN tape would have much surface contact on the warped surfaces but the 5200 oozed out and was full contact.
 
redmessengerbag said:
I am doing 4 cells but I feel like if the cells are effectively bound together with vhb in the middle and outside fixation, either hoseclamp style or tightened nylon straps, and then the 4 cells are in a container that's prevents having any individual cell movement(tight fitting), I feel like the it would be pretty secure or am I missing something. I'm not an engineer lol.
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I wish I still had access to fiber banding equipment. We had plastic corner protectors and ours used heat to permanently seal the fiber together. I would use 2 straps per battery pack.
 
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Directshort said:
I permanantly glued my 4 cells together with 3M 5200 marine adhesive and they are now one solid unit impossible to separate. The alum cases are not straight and I doubt VBN tape would have much surface contact on the warped surfaces but the 5200 oozed out and was full contact.
Click to expand...
I used 2 strips of 1" wide Gorilla HD double sided tape. Two strips per battery. Used the table and fence of my table saw to line them up next to each other and slid them together. You could used your work bench and a board clamped to it, to do the same thing. It will keep the cells in the same plane, top-bottom and side-side. Then used some plywood and clamps to squeeze them together and make sure the tape had good adhesion. Wiped them down with a lint free cloth and rubbing alcohol first.
 
Sgt Raven said:
I used 2 strips of 1" wide Gorilla HD double sided tape. Two strips per battery. Used the table and fence of my table saw to line them up next to each other and slid them together. You could used your work bench and a board clamped to it, to do the same thing. It will keep the cells in the same plane, top-bottom and side-side. Then used some plywood and clamps to squeeze them together and make sure the tape had good adhesion. Wiped them down with a lint free cloth and rubbing alcohol first.
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I bought 8 fortune Aluminum cells from Overkill Solar (thumbs up) and am using the fuzzy electrical tape as padding and then hose clamps. Food for your and anybody else's thought. In the future you might want to take those cells apart to reconnect in a different way or to replace a faulty cell. I have lot's of experience with 3M 5200 and the only thing that will break the seal is heat.... not too good for cells. Just another perspective. Good luck to all of you with your builds. I am sure learning a lot on this forum and appreciate all the help that has been so freely and cheerfully given.
 
Mex Rider said:
I bought 8 fortune Aluminum cells from Overkill Solar (thumbs up) and am using the fuzzy electrical tape as padding and then hose clamps. Food for your and anybody else's thought. In the future you might want to take those cells apart to reconnect in a different way or to replace a faulty cell. I have lot's of experience with 3M 5200 and the only thing that will break the seal is heat.... not too good for cells. Just another perspective. Good luck to all of you with your builds. I am sure learning a lot on this forum and appreciate all the help that has been so freely and cheerfully given.
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Check out the case Overkill Solar just released. Its made for your cells
 
Dzl said:
Check out the case Overkill Solar just released. Its made for your cells
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Where did you see this? It's not on their website or Amazon storefront.

OK, I found the post.
 
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Just to update, I ditched the plastic box and the foam, (couldn't fit the BMS in).
Made a new tight fit plywood box with bubble wrap lining.200 Ah Van battery (1).jpg
 
Hey Tex, hows the cells holding up? Have you been able to give them a good workout out on the road since you started this thread?
 
Hi LoadToad,
No problems with cells, only managed one trip before lockdown, all worked great.
Bought a dual induction cooktop, boiled a big pot of water from cold for 30 mins, didn't break a sweat.
However, over the last couple of days I had an issue with the BMS not charging, no resolved in the positive. I suspect somehow the battery sync with the BMV-712 was off, (View this thread for details), and some other guff.
I have fitted a newer Victron MPPT regulator with built in BT (my dongle died), a BMV-712, a 250 Amp disconnect, and a few other bits.

I see there are some 280 amp cells available pretty commonly now. However, I note they still have 6mm. aluminium terminals which is ridiculous, I would not buy a battery with that size terminals again, and I would ALWAYS fit studs instead of bolts.

BTW I complained to the manufacturer and they offered to supply laser welded studs (to order), stating:
"free bolt is 12mm in length, and the maximum torque would be 18N*M, but 10N*M is enough".
 

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As mentioned before, not all blue aluminum cells are created equal. I have the Overkill version which has robust studs. My eight cells (200 AH) are in the Overkill stainless rack with Gorilla tape around them. I have been driving over washboard Mexican dirt roads weekly and have made several 800 mile trips to California since installing the batteries and have had no issues with the cells or the Overkill BMS's. They are very robust and well made.
 
I have the usual Aliexpress 280ah set-up and have put it through a torture test for a while now and it's the best purchase I ever made for the camper . In combo with the Overkillsolar bms probably have under $600. invested total compared to around $2700. for the Battleborn set-up. Of course money no object get the BB but I believe I get about the same functionality for a whole lot less.

I didn't have a problem with the studs but was careful and ended up using hex headed studs in the terminals which allowed me to torque them all tight between the other 2 bolts separately without taxing the battery threads. Basically locking the hexbolt to the post with a nut then using 2 more nuts separately and above that nut to tighten hard against each other with the terminal sandwiched (not against the battery post) so one bolt and 3 nuts per stud.
I absolutely Luv this set-up combined with the cheap $40. Ali meter the functionality of this is amazing. And I am a total newb electrical guy hence my avatar Directshort but it was all pretty easy to put together with some youtube watching.

 
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