Pack module nut installation, preferred tool?

Thanks to a friend with a really old Sears Craftsmen mini torque wrench I was able to establish that the lowest possible clutch setting on my screwdriver gun was equal to 48-inch pounds. Not sure those clutch settings are the same with all screwdriver guns, but that was an easy way to do it for me.

 

It's a clutch... It slips and won't tighten more when it reaches the designated Torque... It's a cheap Harbor Freight Screwdriver gun I bought for $50 about 8 years ago.

And while it is true you can't tighten torque by feel on larger torque settings. It's not that hard to do accurately on torque settings so low, especially because I've done it so many times working on packs for 5 years.

 

My buddy who was in millwright for RJ Reynolds tobacco company who likes to build batteries as a hobby go figure He uses a Milwaukee 1/4-in drive impact gun like I screw in deck screws with and use a yellow gun versus his red I'm not sure what he has it set on to do the nuts I'll check tonight but that's what he uses me personally I couldn't trust that there's no way in the world I have to do these by hand not necessarily with a torque wrench but by hand I have to feel the nut squeeze to the copper or silver metal bus bar and that's it I could not trust some electric gun blasting that thing down I know I should be able to but I don't think so and I don't do these very often to be even worrying about any of it. When you're screwing something on to a metal stud that's manufactured into cheap Asian plastic so on and so forth I just don't think I'd personally want to risk it then you're all together and ripping the mess out for one slip yuck.

 

Get a 1/4” drive torque wrench, decent quality Chinese? They’re not bad quality.

You can crude test them: clamp horizontally in a vice, dangle a dumbbell or what have you at a measured distance from fulcrum with it set accordingly; it should just click.

Verify the weight with a digital scale too; cheap dumbbell weight may not be that accurate.

 

On the space station during space walks when they put in bolts they have employees watching the video on the ground who's primary job as they work is to count rotations of the tool spinning the bolt and the person using the tool is told multiple times the number of rotations to get the proper torque. So you got a whole team of people ensuring proper torque based on exact rotations, as well as likely variability.

I once used this method by putting some tape on the chuck of my cordless drill to remove a headlight adjustment bolt when removing and reinstalling a replacement ballast in a Gen2 Prius headlight and no complaints from the car owner about headlight issues. The cheap after market replacement headlights on the other hand are quite the opposite and I won't bother you with how many complaints about the beams pointing in the wrong direction.

 

A moderately strong person can achieve 48 inch- pounds with a screw or nut driver by hand.

A ratchet or power tool might be "good enough", unless it's not. I prefer a decent quality torque wrench for the battery pack connections.

Posted via the PriusChat mobile app.

 

I got one of these (attached) a few years back; did a rough test (per post #6) and it seems accurate, working well. $44 CDN currently, think I got it on sale for around $39.

 

A super short stubby socket wrench is what I use to double-check all the bolts after I use the clutch on the lowest setting of my screwdriver gun. Double-checking is essential because you can heat up the pack real quick if you forget to put on a bolt or don't get it tight enough. Once you do it enough times with a stuby socket your wrist will know what 3-4 ft. lbs. feels like.

Also on Project Lithium packs they use higher conducting terminal bolts that are not as strong and this advancement in their design has led to a people snapping them when they over-tighten them. Fortunately their packs are designed to be easy to repair so you just swap out the terminal with a little bit of soldering.