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Discussion Starter #61
It's nothing. Glad to help:)
 

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2001 5S "Turbo"
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What is a "pain scraper"? Fingers getting slow?
 

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Discussion Starter #64
It's nothing. Glad to help:)
Since the "can" was ripped at the top, I was able to measure with a caliper. The terminal depth is about .250" with an error of maybe +/- .008. Seems to me to be useless for drilling, given the softness of the material. Included is the very slight (.005" +/- "pad") on top of the terminal.

I think that these terminals were designed specifically for spot welding and that nothing else is going to work. I can't actually envision how they even did that.

I would send you the "top" in an envelope but I suspect the battery is still active and could provide some nice sparks if treated roughly.

I think that if one wanted to reconfigure the basic wiring of the pack, the best hope would probably be to cut the bus bars in the middle, bend them upward somewhat and spot weld to the bar halves. JMO.

From terminal voltage, the cell, though ripped open, is still charged. I would discharge it, completely disassemble it, and provide an autopsy if I could figure and effective means of discharging it. I don't want to short the terminals because it seems to me that that could cause massive damage.

I wonder if pouring distilled water into the open cell would bleed off the charge? I might have a resistor which could perhaps be soldered to the terminals???
 

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I think that if one wanted to reconfigure the basic wiring of the pack, the best hope would probably be to cut the bus bars in the middle, bend them upward somewhat and spot weld to the bar halves. JMO.
My 1st attempt of such on 3-12-20 .. I'd like to get the cut a bit cleaner.
85800
 

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Discussion Starter #66
Hey, great minds;)

If one could bend the bus bar halves closer to the spot well, there would be more room for spot welding.
 

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My 1st attempt of such on 3-12-20 .. I'd like to get the cut a bit cleaner.
View attachment 85800
Something like this:


will give you a very clean cut.

Dremel tool are great. They also have all sorts of little grinders and cutting wheels that would help you debur those tabs quickly. I prefer the carbide stuff for metal work because it lasts longer than the hardware store stuff since that stuff is for wood mostly.
 

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Since the "can" was ripped at the top, I was able to measure with a caliper. The terminal depth is about .250" with an error of maybe +/- .008. Seems to me to be useless for drilling, given the softness of the material. Included is the very slight (.005" +/- "pad") on top of the terminal.

I think that these terminals were designed specifically for spot welding and that nothing else is going to work. I can't actually envision how they even did that.

I would send you the "top" in an envelope but I suspect the battery is still active and could provide some nice sparks if treated roughly.

I think that if one wanted to reconfigure the basic wiring of the pack, the best hope would probably be to cut the bus bars in the middle, bend them upward somewhat and spot weld to the bar halves. JMO.

From terminal voltage, the cell, though ripped open, is still charged. I would discharge it, completely disassemble it, and provide an autopsy if I could figure and effective means of discharging it. I don't want to short the terminals because it seems to me that that could cause massive damage.

I wonder if pouring distilled water into the open cell would bleed off the charge? I might have a resistor which could perhaps be soldered to the terminals???
Thank you so much! Looks like I can go slightly deeper than my current tapped packs but not much deeper (again my use is for solar so no vibration concern). When I order more packs I'll have to think about the spot welding route. I played with the tabs I have lying around weeks ago and nickel strips do spot weld to them fine. Since I had enough spare tabs lying around though I tried spot welding two together directly and at least for my spot welder which usually gets up to around 600 amps I had no luck. The tabs are .5mm thick so it just didn't get hot enough. doubling up thinner pure nickel strips was fine though.

Soldering a resistor to the tabs since they are nickel plated was doable but I'm not sure about the terminals. I thought insightbuyer tried that and was unsuccessful and could only to the tabs but maybe my memory is wrong.
 

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Dremel tool are great.
yup , I have one .. and I agree .. very useful tool .. and I had considered trying it on the next one .. but .. I had some concerns about using it when I did that 1st one:

Grinding (instead of cutting) will make a bunch of airborne fine (conductive) metal dust .. I could try to cover everything else while grinding .. but still a small con.

Lost / shortened tab .. Cutting (snips) does not reduce the length of the metal tab .. but grinding will reduce / shorten the metal by a little more than the thickness of the grinding wheel .. I guessed it would loose around ~1/8" .. might not matter , but , a small con.

if I don't think of a cleaner cutting method I'm happier with .. I might try to dremel grinding eventually.
 

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Discussion Starter #71
I would use some sort of Dremel saw, not the grinding tools. The saws will produce metal debris, but not nearly as dusty. Most of the saws are thin, like 1/32, but check as you shop. You could carefully blow away the debris between steps.
 

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20 inch pounds (1.75 ft lbs) is well short of the typical 8 ft lbs that most automotive batteries recommend so I would assume tapping is a no go in a car but you guys would know better than me at what you need for all that vibration.
Yeah, that would seem pretty shaky for an automotive application. I got the cell fully discharged so, give some off time, I'll do a tear down with pictures.
 

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Yeah, that would seem pretty shaky for an automotive application. I got the cell fully discharged so, give some off time, I'll do a tear down with pictures.
Something seems to have gone wrong with a moderator edit, when I get time later today I'll try and put my original data back.
 

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Discussion Starter #74
Sorry, nothing is wrong with the system, I screwed up your data by hitting the wrong button. Gotta be more careful or they might take my buttons away. Repost what you can of it:oops:
 

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Sorry, nothing is wrong with the system, I screwed up your data by hitting the wrong button. Gotta be more careful or they might take my buttons away. Repost what you can of it:oops:
No worries it happens. Tapping data below:

I messed around with a 6061 aluminum bar and the fit pack terminals yesterday. I'm using 10-24 threaded rods so for a 1/4 inch terminal that's a max of 6 threads if perfect (so most times you have 4 or 5 threads to torque against). On the practice bar the highest torque before the underlying terminal stripped was 26 inch pounds (just over 2 ft lbs) and was using steel threaded rods. Whether it was 6 threads (.25" deep), 5 threads, or 4 threads (.16" deep) had very little difference on stripping torque value so it's best to not worry about puncturing through the battery terminals and give yourself a little leeway and go a bit more shallow than .25".

When I moved over to the fit packs I could feel on my beam torque wrench that ever so slightly the terminals seemed very slightly softer than the 6061 practice bar so the terminal is likely 6101 highly conductive aluminum. As far as torque though it had little impact. Since even with steel the torque values aren't very high, I switched over to aluminum rods so that corrosion isn't a concern and so that if you ever do make a mistake its the rod that strips and not the battery terminal. With an aluminum rod on the battery 20 inch pounds of torque is the max before stripping the rod (1.75 ft lbs). For a stationary application the difference is so slight vs steel that I would recommend using aluminum rods and being ok with 4 threads of grab with using nylock nuts.

In an automotive application though 1.75 ft lbs of torque is shaky with all the vibration in the car. Tapping is likely not recommended for the car, only for something stationary like solar. You could probably increase the stripping torque a bit by using 10-32 threads or going larger like 12-24 but based on everything I saw it's not going to get you close to the 8 ft lbs of torque most automotive batteries recommend. The weak link is the soft battery terminal and since the terminal is 7mm long x 14mm wide you can't go anywhere near large enough to get close to 8 ft lbs. Leaving the tabs in place and either spot welding nickel strips to them or bolting to the tabs is likely the correct course of action if you are rearranging the pack in a car like for the starting battery Jime did.
 

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Discussion Starter #76
Ok, just a quick summary update on performance. The 5 cell LTO has been installed for about a month now and is working quite well. With the DVCT wire cut, the battery is operating at about 13.85-14V when the car is running. Since the operating point is right on the steep part of the charge curve, then the voltage changes fairly rapidly under operation, i.e. at around 2.8V/cell, it only takes a small amount of current to make a big change in battery voltage. Again, it doesn't take much parasitic load from two days of parking to drag the battery down to 13.2-13.4V, or the much more linear part of the charge curve.

I have no idea if I'm shortening battery life by operating the cells at this voltage point. I do have the 6 cell version on the bench, but have not tested that yet. I think I would want to find a way to somehow approximate the battery current before installing the 6 cell. With 6 cells, the operating point will be well within the linear part of the charge curve and the low internal resistance cells can adsorb considerable current over long periods, relative to what the lead acid battery does.
 
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