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Connectors on hi power battery pack

Posted: Sat Mar 14, 2009 6:05 pm
by audia2ev
Two simple questions really:

1. Looking at the connectors delivered with my Hi Power batteries (look like 1mm steel) I see two problems: wrong material, way to flimsy. I've calculated that I need 50mm2 (copper) cable to connect battery pack to controller (100A cruise, 150A peak) so a 20mm wide aluminium (60% of conductivity cf. copper) connector would be equivalent if it was 50 / 20 / 0.6 = 4mm thick. Sound right? Anybody else used similar or has other advice?

2. Replacing the bolts: the fasteners will be too short, so I need a UK online source for these - M6/1 - anyone know where to get aluminum threaded bar? or alternatively is passivated steel OK? I tried RS but too long.

(Sorry I searched for "connector" but didn't find anything on this.)

Posted: Sat Mar 14, 2009 7:32 pm
by retepsnikrep
If you scrape the Highpower supplied connections it's copper underneath or was on mine, so some sort of plated copper alloy, as it was too hard to be just copper IMHO.

I used them and they work fine with my 40ah cells max drain 100A.

I used plated threaded steel rod and cut it to length to suit height of nuts etc. Bought from my local fastner supplier, you can buy it online from screwfix i think.

Make sure you screw studding into cells as far as possible, the cell terminals are quite soft material so you need all the thread length you can get.

I also power file'd all the tops of my cell terminals so they were perfectly flat. If you look at them you will see they are not all flat and inner sticks up on some and sits lower on others. This also means they are perfectly clean as should everything else be about your connections.

Assemble straight away and use some sort of locking nut. Torque down as much as you dare, more pressure = less resistance.

Thicker wire the better within reason for other interconnects.

Lots of discussion about soldering and crimping and relative merits.

I always crimp then solder and seal with heat shrink. Others may differ :wink:

Every connector or terminal should be like new, clean, dry free from grease/gunk etc. You want maximum contact area and maximum pressure.

Time spent getting this right is IMHO one of the most important considerations in the whole project !

I spent hours on mine. 8)


I also used heatshrink on the exposed sections of the cell interconnect plates, and plastic dome nut covers on all the terminal nuts.

All to minimise the risk with dropped tools and careless hands.

I also used the flexible corrugated plastic conduit from battery blocks to IMA controller for all high current wires.

The neater and more professional it looks then generally the better it will be. :D

Posted: Sat Mar 14, 2009 8:19 pm
by audia2ev
Now I searched on "interconnects" and found the older thread.

I'll go for the threaded rod. Must say I am not very convinced by the interconnects themselves, even if they are copper they are half the theoretical size they should be?

If I can't get the interconnects made up here easily (I'm planning to use 3mm Al sheet) then I'll just monitor how they go at first very carefully. After Greg's 126 accident the first installation will be provisional inside a custom case inside the car, where I can get good access to monitor everything anyway.

Posted: Sat Mar 14, 2009 8:46 pm
by audia2ev
For the record: just went and power-filed the edge of one of my connectors - copper, plated.

Still, 1mm seems real thin... I'll be keeping an eye on the temps.