Best way to do this?

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ebike11

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Hi guys..
I have 2 x 72V packs. One was already in series so I decided just to put the second pack in series and then to parallel to double the Ah.
What you recommend as the best way to connect + to + and - to - and then the final leads?
Just solder or crimp in a "T" form for the positive and then the negative?
Im mainly using xt90s for connectors and i also have copper tubes to use as crimps.
Thanks
 
As long as the connection is mechanically strong and can deliver as much amps as the batteries can without overheating, it's a good connection.
You can crimp, solder or use connectors. If you solder, make sure you use enough solder, and if you use connectors just make sure the connectors can deliver enough current like I said.
Maybe parallel the ground terminals into one xt90, do the same for the positives and then put xt90s on the controllers terminals to match.
No matter what you choose, make sure to use equal lengths of cabling. If current from 1 battery needs to travel across a longer cable until it parallels with the other battery, then the two batteries won't deliver equal amounts of current. This will cause them to wear unevenly or in worse cases even over-current one of them.
 
They are going to wear unevenly in any case.

Make sure to do occasional cap tests maybe ESIR at the cell level if possible

to determine EoL proactively
 
From my 72v paralleling experience, a small mismatch in lengths and uneven wearing never turned out to be issues, esp if not used at crazy amp levels and super deep discharges.

One thing to consider if using XT90 type is if you make it to where the system can run with one battery unplugged, the metal prongs on the unoccupied plug are going to be energized and might need to be capped off or something.

Here some 6x36v into 3x72v craziness for ya 🤘
KIMG0054-640x360 (1).JPG
I could split it all back down to 36v modules for fast recharging with 6 cheap 36v chargers at once too!
 
There are JST plugs on each pack so i can monitor occassinally. The wires are 8awg so i wont be able to put them in an xt90...i guess solder 2 into 1 and have the end of the wire fit into the xt90
 
Are you planning on leaving them parallel for a while? If so use screw down terminal for a better connection and security. Then, solder or from battery or make a wire lead for charging.


Sent from my iPhone using Tapatalk
 
Cdub said:
Are you planning on leaving them parallel for a while? If so use screw down terminal for a better connection and security. Then, solder or from battery or make a wire lead for charging.


Sent from my iPhone using Tapatalk
Click to expand...

Yes I plan to keep them in parallel
Do you have a link for those connectors as an example?
 
They are basic crimp on round terminals ranging in size depending upon application demands. Use a terminal block or some small nuts and bolts. You can solder after crimping for a better connection.


Sent from my iPhone using Tapatalk
 
Just goggle screw terminals. Some are solid copper and big enough to supply welding current.


Sent from my iPhone using Tapatalk
 
I would only use a xt90 or any other quick connection for a charging lead. Everything else should be solid.


Sent from my iPhone using Tapatalk
 
ebike11 said:
There are JST plugs on each pack so i can monitor occassinally. The wires are 8awg so i wont be able to put them in an xt90...i guess solder 2 into 1 and have the end of the wire fit into the xt90
Click to expand...
8AWG fits into XT90.
 
serious_sam said:
ebike11 said:
There are JST plugs on each pack so i can monitor occassinally. The wires are 8awg so i wont be able to put them in an xt90...i guess solder 2 into 1 and have the end of the wire fit into the xt90
Click to expand...
8AWG fits into XT90.
Click to expand...

Yes but not if i solder 2 ends of 8awg together coz it would be too thick to fit in the xt90 cylinder
 
ebike11 said:
serious_sam said:
ebike11 said:
There are JST plugs on each pack so i can monitor occassinally. The wires are 8awg so i wont be able to put them in an xt90...i guess solder 2 into 1 and have the end of the wire fit into the xt90
Click to expand...
8AWG fits into XT90.
Click to expand...
Yes but not if i solder 2 ends of 8awg together coz it would be too thick to fit in the xt90 cylinder
Click to expand...
Ah yes, I stand corrected.
 
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