HV battery module busbar nut torque value

Did you get the number from YouTube?
I torqued my nuts to 5,5 Nm (48" lbs).
It seems about right. Just make sure that you are using a real torque wrench and not some el-bozo cheapo POS.
Are you only cleaning the busbars, or also reshuffling the cells?

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You're replacing modules. How many miles you got?
I reshuffled the modules at 80k miles. I've got less than 1/10th of a volt difference between the individual modules. I urge you to use a torque wrench.
Even in winter I still get 51mpg calculated.
I had the transaxle oil changed at 70k miles even though it is not mandated by Toyota here in Germany.

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On 6mm bolts, full contact resistance and 60-90 degrees angular torque is often specified for aircraft-spacecraft assembly, instead of a frictional torque value.

That's around 48-60 inch pounds.

The angular torque method has been found to be more reliable in multiple industry studies, where the bolt tension has been measured from each method.

 

yes....Toyota states 48 inch pounds for the module fasteners, which includes the positive/negative terminals and the mounting fasteners that thread into the bottom of the module. If you really want documentation, I can hunt it down in the repair manual, or you can just google torque requirements for that size fastener (M5)

 

Just to eliminate any doubt....here you go...

 

I tend to regard the generic torque charts by fastener size to be a distant second in preference order to getting a specific torque for a specific fastener out of the repair manual.

(Also, while on the subject of the repair manual, it also has a chart of generic torques by fastener size, up in the front matter, for reference in case there is no specific number given for a particular fastener. And that chart has different columns according to the strength of the fastener, and pictures explaining Toyota's markings that tell you the strength of each bolt or nut. That's an important detail to keep in mind when using the generic chart!)

But the manual does give specific torques for nearly everything, so the generic chart is more of a last resort. The generic chart can't take into account all the variables: is this a stud threaded into a block of iron, or molded into a plastic battery module? What kind of washer is on it? Domed spring washers are not intended to be completely mashed into pale flattened versions of themselves. Etc.

 

Third gen Repair Manual excerpt (...Hybrid Battery Removal) has removal/install instruction, but maybe not bus bar nut torque. However, second gen RM excerpt (Hybrid Battery) has the bys bar nut torque values:

 

If I may clarify for my own piece of mind... the manual excerpt @Mendel Leisk posted which looks very similar to the page @TMR-JWAP photographed is labeled "2006 Prius Repair Manual". Are the torque specs the same for a 2010, Gen3?

Like @iskoos, I've seen a couple of other numbers online, but none specific to a Gen3 original battery.

Thanks

 

If I search my 3rd gen repair manual copy for:

5.4 (55, 48 in.*lbf)

or various portions of it, I'm getting no results.

Maybe some of the battery pros will weigh in, but my hunch is you can't go wrong with 48 inch pounds. IIRC I've heard that mentioned here, for second or third gen. That's 4 foot pounds, very low torque. Do use a 1/4" drive torque wrench.

I think there's even some sort of T-Wrench you can get, tuned to slip once torque reaches a value, say 48 inch pounds.

 

48 inch pounds is in between 5 and 6 newton meters, advertised here:

(likely need to turn off ad-blocker)

And here's a 48 inch pound one, pricey though:

TW:BT-1R-1/4-48.0 THX:BT-1/4-4MM, Torque Wrench with Hex Bit Socket | Ruland

 

One of the videos I saw from a non-specialist said 60 in lbs for the Gen2 and one of the battery reconditioners said 44 in their video, which is why I wanted to ask. Don't want to snap one off, that's for sure.

Thanks

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I've experimented with this. With only a nut on the terminal stud (no busbar linking to the next stud), it took about 110 inch pounds to damage the terminal stud. The stud actually twisted inside the module. 48 or 60, either will be just fine. Personally, I would not go less than 48.

 

110 inch pounds is not that much, divide by 12 to get (almost) 10 foot pounds. You did this on a defunct cell?

 

Yes, sometimes I used failed modules for fun experiments when I get bored.....
I think it would take more torque to cause damage if the busbar were installed linking it to an adjacent module. As it was, the torque applied to the nut was effectively applied to base of the stud and the mechanical linkage behind it that attaches it to the internal busbars.

 

Please forgive me for extending this thread with the dumbest follow-up ever, but I'm trying to baby the battery. (I saw the post about the battery fire, when I was searching for an answer this afternoon)

What size socket are the 56 specialty nuts holding the bus bars in place?

While looking for the size, I tried a 5/16th in both a socket and a nut driver, but both had just a hair of play and because they are torqued on there, I wouldn't want to risk rounding them off, if that's not the right size. I've also tried a 9/32" but that was too small. Mathematically, the 7 and 8mm sockets missing from my set should be too small and too large, respectively. I went to a couple of stores this afternoon looking for a 19/64th or a 7.5mm to no avail.

If I may ask, what size socket has everyone else used?

Again, thanks! I appreciate the help.