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Crimped Copper Lug Size, BMS, Battery Terminal and Inverter

Oldtoad

New Member
Joined
Jun 22, 2020
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201
Location
ME to AZ
Going to order a BMS from Chargery. They offer 1/4", 5/16" and 3/8" crimped copper lugs.
Also re building the board for my solar setup.
Would like to make it really sanitary, guess I should do all the 12v power supply stuff the same size?
 
Good luck standardizing. I have 3/8, 5/16 and 1/4 in mine. My T class fuse and the shunt are both 3/8. Bus bars, Blue Sea circuit breakers are 5/16. Battery posts? M6 for my batteries but I think the 1/4 worked there. I may have fudged some of the sizes, meaning the post was 5/16 but a 3/8 lug was used.

I ordered my BMS with no lugs. In retrospect, what I should have done was ordered it with the lugs, but uncrimped.
 
Thanks.
Did a dig deeper survey and concluded 5/16".
That is what was ordered on the Chargery BMS.
Tried to find out the Inverter but went to the 4/0 cable, those had 5/16" lugs, that was enough for me.
A drill will turn 5/16 into 3/8 and a flat washer will pin a 5/16 on to a 1/4" post, close enough...
 
I'm not familiar with the Chargery BMS. Does it have three cables each for the load and battery sides? That's how the Overkill Solar BMS is. I felt the best connector in that case was a single 2 awg lug with all three cables crammed into it. I later found out that 4 awg lugs would have also worked. I tried putting a long on each lead and it just didn't work out as well on the battery post, and it sure didn't look tidy.
 
Made a mistake, purchased a Overkill Solar BMS, 4s, 5/16" lugs, 8 ga wires.
Don't know where the Chargery came from.
Chargery is mostly for ebikes.
 
Made a mistake, purchased a Overkill Solar BMS, 4s, 5/16" lugs, 8 ga wires.
Don't know where the Chargery came from.
Chargery is mostly for ebikes.

Chargery may have been for e-bikes originally, but it is actually one of the more popular BMS' used on this site (as is your JBD smart BMS from Overkill Solar).
 
I got sick & tired of playiing with different sized LUGS with different hole sizes, so I bought 50 Selterm 4/0 with 5/16 holes and open them up to 3/8's when needed with the drill press, the 1/16 slack for a 1/4" hole is tolerable.
 
I have the same BMS, sans lugs. Below is my first attempt at connecting the BMS leads to the battery. Bleh.

View attachment 22158
That is one rugged battery encasement.......(a newbie askin) is it necessary? How serious should I get to secure my LiFePor 120Ah in something as stout?
 
That is one rugged battery encasement.......(a newbie askin) is it necessary? How serious should I get to secure my LiFePor 120Ah in something as stout?
With inflexible buss bars, it is very important to solidly secure the cells... they WILL try to expand, and the soft aluminum of the lugs will give way and destroy themselves if not secured.
 
Adding to what was said in the post above, the "rack" I made compresses the battery cells, which the manufacturer recommends for more life cycle of the cells. Further, the racking also provides a great way to secure the cells in place so they aren't moving. It's hard to see but I have angle aluminum holding the racking on three sides.
 
With inflexible buss bars, it is very important to solidly secure the cells... they WILL try to expand, and the soft aluminum of the lugs will give way and destroy themselves if not secured.
I am impressed with HRTKD's encasement.
Had not thought about expansion.
Lots to consider, thank you.
 
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