terry82517
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Where did you get the box please mate?
280ah Lifepo4 Leisure Battery - Build Thread
- Thread starter Mrdanielmh
- Start date
Where did you get the box please mate?
Mrdanielmh
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Hey @terry82517 It was from Ebay UK, just search for M27 Battery Box
terry82517
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great thanks. Any chance you could screen shot the settings you used in the app for the bms? If you have done that yet?
Mrdanielmh
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Hey @terry82517 - All I did on the BMS was change the temperate to 2 to help with charging below freezing. I didn't change anything else!
Thanks for documenting this, it is helpful.
Are those M4 threaded terminals? Any issues connecting busbars and the BMS? I have my cells in parallel at the moment while waiting for the power supply to arrive to top balance. I am planning on using some 1/8" x 3/4" copper to make the busbars and to be honest the tiny M4 threads have me a little worried. I am using some studs with purple loctite so that should help.
Are those M4 threaded terminals? Any issues connecting busbars and the BMS? I have my cells in parallel at the moment while waiting for the power supply to arrive to top balance. I am planning on using some 1/8" x 3/4" copper to make the busbars and to be honest the tiny M4 threads have me a little worried. I am using some studs with purple loctite so that should help.
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Ampster
Renewable Energy Hobbyist
The studs will not carry much current. The biggest issue is getting the buss bar completely flush with the surface of the battery terminal. 1/8 copper is not very flexible so the cells need to be on a smooth level surface.. Make sure you clean both surfaces so any oxidation is gone.
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The studs don't need to carry any current, they are strictly mechanical. The busbar to terminal connection is what is carrying the current. I want to make sure there is adequate clamping force to carry 200A without stripping out the aluminum threads. I am planning on using "NO-OX-ID A-Special" on the busbar/terminal interface, and will clean the surfaces well.
Note that the spec calls out maxium 8Nm (5.9 ft-lbs) torque. That's not a lot. I used my small 1/4" drive torque wrench to tighten the nuts to the studs I used in the terminals.
Yeah that's not much. I can't use a torque wrench as I am using an hex key to keep the stud from turning while tightening the nut. I am using a nylock nut which would probably mess up the torque reading anyway. The cells will be in a wooden box preventing movement in any direction, and under compression from the end of the pack.
Sorry for posting in this thread, but I feel it is relevant to @Mrdanielmh installation if his cells have M4 terminals, especially in vehicle usage.
Sorry for posting in this thread, but I feel it is relevant to @Mrdanielmh installation if his cells have M4 terminals, especially in vehicle usage.
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Ampster
Renewable Energy Hobbyist
For that reason I am using Permatex Red to secure the studs. I back the studs out 1/2 turn from the bottom. I still use a a hex key to make sure they don't move and hand tighten them using an insulated end wrench. Then I check the torque using my torque wrench It never takes more than an 1/8 turn to get the torque right. I use Nordlock washers.
You can buy a box end wrench attachment for the torque wrench. You need to adjust the torque by the supplied multiplier. You could also Loctite the stud into the battery first and then once that it's cured torque down the bolt.
I haven't looking into the contact force specs, but a sufficient spring washer, and two nuts jammed together would also work. On long rigid assembles where it isn't practical to float one element, A slotted hole, using a carefully chosen spring, and a lock/jam nut to tension the spring, can be effective. Obviously correct lubrication of the contact face and occasional inspections are suggested.
Another question. Is that 5ft-lb the max allowed twisting torque on the terminal? Or is that the max pull-out torque of the threads?
I am inclined to believe its the torque on the terminal. So if you counterhold the stud, you can go to the max safe torque for pure aluminum threads of that size (would need to pulled from the relevant tables). Off the top of my head M6x1 is probably only safe to 4lb-ft in soft aluminum. M8 would be around 10lb-ft.
Another question. Is that 5ft-lb the max allowed twisting torque on the terminal? Or is that the max pull-out torque of the threads?
I am inclined to believe its the torque on the terminal. So if you counterhold the stud, you can go to the max safe torque for pure aluminum threads of that size (would need to pulled from the relevant tables). Off the top of my head M6x1 is probably only safe to 4lb-ft in soft aluminum. M8 would be around 10lb-ft.
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Would that be the same for 6063 alloy bolts?
60in/lbs is actually a fair amount of torque on an M6. With some blue Loctite, I wouldn't worry about them at all.
Mrdanielmh, which charger/converter are you going with? Victron has a number of chargers that say they are smart.
Prefersdirt
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@Mrdanielmh did the busbars come with the batteries? Or did you get them elsewhere? Thanks
Rogerb
Knows just enough to be dangerous to himself
I have the same BMS, thanks for the great idea!
Not sure about that, it's hard to find the specs, but one thing is sure is that 6063 is very weak. Any reason to not use 6061? Also, why use aluminium bolts in the first place?
Well at least if you break something it's the bolt, not the terminal. I guess it's a good reason for using 6063 bolts ?
