RTV silicone glue for lithium-ion cells? - RC Groups
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Jun 11, 2017, 01:56 PM
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Discussion

RTV silicone glue for lithium-ion cells?


hi..

i was wondering if anyone of you are familiar with a compound which can be both thermally conductive like an RTV silicone , non-corrosive , but can also act as a very strong adhesive to glue cells to each other.

i'm looking to something similar used here :
EM3EV battery factory tour - State of the art 18650 battery packs (34 min 39 sec)
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Jun 11, 2017, 02:56 PM
Bombs away! Err...landing
Ira NZ's Avatar
I thought RTV was a pretty good insulator, not a good thermal conductor? Hot glue is the traditional method, but something like neutral cure silicone, though acid cure should work too. It's not corrosive once cured...I'm making an assumption it's mildly acidic uncured, doesn't matter much for batteries though.
Jun 11, 2017, 03:21 PM
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MrEFlyer's Avatar
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Last edited by MrEFlyer; Jun 11, 2017 at 04:05 PM. Reason: Bad idea
Jun 11, 2017, 03:46 PM
Registered User
Use thermally conductive glue made for electronic assemblies. http://www.ebay.com/itm/Large-10g-Th...-/370872305451
Jun 11, 2017, 04:44 PM
Bombs away! Err...landing
Ira NZ's Avatar
Quote:
Originally Posted by kamcoman
Use thermally conductive glue made for electronic assemblies. http://www.ebay.com/itm/Large-10g-Th...-/370872305451
Would that work? That's for gluing heat sinks to CPUs etc. 10g isn't going to go far if you're using a thick bead to attach lion cells together. You might not even finish off a whole pack.
Jun 11, 2017, 05:07 PM
characters welcome!
Mark Wood's Avatar
Meh. Medium CA and kicker.

mw
Jun 11, 2017, 05:31 PM
Registered User
actually they have a 30g version http://www.ebay.com/itm/30g-Thermal-...384720080#rwid

the description also says
"Please Note: This is NOT thermal paste & must not be used with a CPU and heatsink fan.
This is silicone glue that provides permanent thermal, as well as mechanical bond between two devices.
It is rather difficult, although not entirely impossible, to separate the devices once the glue cures."

although i have to wonder from what PSI level is it considered hard to separate things by hand..

CA looks like normal glue to me...
Jun 12, 2017, 04:56 AM
Registered User
i'm starting to think that i should re-phrase my search ..and give out on the thermal transfer

what's a good compound that's resistant to thermal cycling, non-corrosive, has high tensile strength , flexible, vibration resistant , and insulating?
Jun 12, 2017, 08:56 AM
Registered User
not a recommendation but perhaps GC Electronics neutral silicon RTV. It can be purchased in squeeze tube and you can see if it meets your needs. Commercial stuff is usually in 2 part helical mixing tubes and requires a special gun or applicator.
Jun 12, 2017, 04:38 PM
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vollrathd's Avatar
Quote:
Originally Posted by emaayan
hi..

i was wondering if anyone of you are familiar with a compound which can be both thermally conductive like an RTV silicone , non-corrosive , but can also act as a very strong adhesive to glue cells to each other.

i'm looking to something similar used here :]
IMHO, be very careful when using these types of materials with electronic circuits. If the package doesn't say it is safe for electronic circuits, it probably isn't.

The company I worked for before retiring got into a very expensive recall when the silicon type material used for protecting against vibration started causing circuit failures around a year after shipment of the products. Seems that RTV dissolved the copper foil patterns on the circuit boards.
Jun 12, 2017, 04:56 PM
Registered User
yea i know, initially i thought about using permatex till someone told me i need to look something that is "neutral curing"
my main battery is still ok, entering it's 4th year, because i can no longer get a new one from the person in the original video (the one i want is over 5kg which cannot be shiped here), i've decided to try and build my own, because that's only way i'll be sure i got the quality parts i want.
the aim is to create triangle battery pack 14s8p
for months i've been gathering supplies, i have around 140 cells of Panasonic pf (i'll be using 112, because although they are from different batches they from the same supplier)
i've already charge tested and logged each one in excel worksheet , and they all range from 2843 to 3063 in capacity.
i've got 2 bms from best tech power (hcx-131) they came highly recommended.
i'm still debating on method of assembly

i also got 2 kits from http://vruzend.com/, but his bus bars are rated up to 3.5 and my pack is have 1500w, so that should be like 3.75 amps per group, (even though some tested it to reach 5 amps) , also making a triangle pack out of it may prove to be problematic if you want some groups lay out differently.
if i want to go the spot welding way i already have the https://malectrics.eu/ which has proven to better then the crappy sunkko 709 welders i've tried.. at least at welding 0.15 strips
i also have the plastic squire holders, they seem to be recommended more then gluing the cells, but they also present a possible issue if you're trying to lay nickel strips diagonally to increase the current flow and prevent "hot spots".
but i want to go glueing way, i need to make sure i find a rock solid hardcore glue that can withstand shocks, not damage the battery, insulating and be very strong.
i also thought about maybe trying to use triangle shape holder, perhaps print it using my tarantula from ePC, or finally assemble my open build cnc router i got several months ago.
Jun 12, 2017, 05:09 PM
pull up -- PULL UP!!!
Regular RTV contains acetic acid -- electronics grade is acid-free, but expensive.
Jun 12, 2017, 05:12 PM
Registered User
yes i know, when i asked permatex about it, they recommended Ultra Grey https://www.permatex.com/products/ga...asket-maker-2/

you'll notice it's sensor safe, however i'm not sure how strong that is, i have some trying it out.
Jun 12, 2017, 08:01 PM
Registered User
Quote:
Originally Posted by emaayan
if i want to go the spot welding way i already have the https://malectrics.eu/ which has proven to better then the crappy sunkko 709 welders i've tried.. at least at welding 0.15 strips
I got the same kit and built a second mosfet board up using 1 mO mosfets. Changed the arduino sketch to make the first pulse a little hotter and to also track the second pulse time linearly as it was inceased. Welds 0.3mm tabs with 500 CCA without any trouble set to 15ms.

GC also makes thermal conductive 2 part epoxy if you want a solid bond. I thought you wanted it flexible. I mentioned GC because it is somewhat reasonable priced in smaller quantity. The acetic silicon would probably be ok once it cures but it will definitely corrode any metal it comes into contact with while curing. A long time ago we used the wrong stuff to pot components and all of the air tight assemblies failed about 6 months later. Pulled them apart and the acetic acid had ate all the traces on the pcb.
Jun 13, 2017, 01:51 AM
Registered User
that's why i said i won't be using anything that has acetic acid,

can the ac seems to be in a 1kg containers only, right?


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