PowerPaul batteries are supplied with SEMS assembly bolts (bolt, spring washer and flat washer as one assembly) of appropriate length depending on the terminal thread depth. However the supplied bolts may not be suitable for every setup, so the installer MUST ensure it’s done correctly.
In some instances, customers use very thin lugs (often supplied with cheaper brand products), and this could mean the bolt could be too long, leading to it bottoming out in the terminal hole before you have appropriate torque applied to the lug. This may not be visible to the naked eye and can cause a high resistance joint and excessive heat. You should always check how secure the lugs are by trying to turn them anticlockwise by hand, put a good amount of pressure on and if it turns, you know it’s not tight enough. You can use a washer ON TOP of the lug (never under the lug) if you need to space it out a small amount.
Similarly the supplied bolts may be too short in some situations. If you’re using multiple lugs on a terminal (NEVER use more than 4), then you may need a longer bolt. This needs to be checked by the installer and if need be, purchase longer bolts from your local supplier. You should always have as much thread engagement as possible, and NEVER less than 3 threads. Having too little thread engagement can result in stripped/damaged threads or the chance of the bolt coming loose during use.
If you are stacking a few lugs, ALWAYS have the parallel lugs against the battery terminal, then the next highest to lowest current drain lugs above that. This helps ensure identical current sharing between batteries, and reduced terminal heat.
Hint: Our M8 battery terminal thread pitch is 1.25mm, so you need about 5mm MINIMUM thread engagement.
You should always have a small gap between the bottom of the bolt, and the bottom of the terminal hole. Keep in mind that not all terminal holes are tapped to full depth, so you may feel the screw bind up before it hits the bottom.
If you want to use a torque wrench to secure your battery terminals, we suggest about 15Nm (10-20Nm is normally ok). We use a stubby ratchet driver here and make it “pretty tight by hand” on the test bench. One side has a 13mm socket for the M8 battery bolts, and the other has a 17mm for the M10 shunt bolts. The handle is also insulated to help prevent shorting. If you’re unsure of your own ability to gauge torque, get a torque wrench or get it checked by someone with one.
An Infra Red camera is also a good tool to have on hand for those of you doing this regularly.
We also promote the use of a conductive anti corrosive compound to assist in ensuring the connection maintains its integrity long term. The main function is to keep air and moisture away from the connection faces. We use Alminox here at PowerPaul however there are various products that perform similar functions.
Lastly, remember to check these connections periodically. You can do this yourself or you can engage a professional installer to go over your system and correct anything that may need attention. If you had your system professionally installed, always check with the installer first, and they may even have a maintenance plan to ensure peace of mind before you hit the road.
Enjoyed this article, from California! Thanks for writing it and providing photos and diagrams, much appreciated.