Overkill BMS Heat Sink & Mounting

[WA5IDX]

I searched the forum & may have missed the info but here's the question(s) I need to answer.

I have two Overkill 12v 120A BMS units to build my RV Battery Packs with. I'm struggling with the mounting of these since there are no mounting tabs, etc.

I would also like to add heat sinks to them as part of the mounting arrangement.

Anybody know what pitch the M3 screws are? They will need to be replaced with much longer ones since the 6 screws go thru one AL plate and thread into nuts embedded in the opposite side AL plate.

Has anyone else added additional heat sinks to the units?

Thanks

 

[snoobler]

Have you reached out to Steve? His support is excellent.

 

[WA5IDX]

No I have not contacted Steve (yet). I did read one post to indicate he was "working on mounting" system for the units.

Small "L" brackets would work for mounting but that still requires replacing the screws.

Thanks


I sent an e-mail to Steve with the question about size.......

 

[HRTKD]

Before you add cooling, have you tracked the internal BMS temperature to see if it's warranted? I did some tests on mine when I first installed them and there wasn't much heat. Not enough for me to even write it down for posterity.

 

[WA5IDX]

That would make to much sense!!!! No, I have not even placed them in service as yet. Too be honest, the "Heat Sink" was to be a way to mount the BMS units in the RV effectively. I have some 10 mm thick Aluminum plate and could just "sandwich" the units between two pieces and end up with a big heat sink as well as some "excess" real-estate on any or all sides to mount them .

I can see a few times when I might be pulling the full 120A across them ( both as the same time) for periods of 15 to 20 minutes.....

I'm a bit (subjectively) anal about over-engineering solutions especially when the parts come out of my junk box......

 

[Sojourner]

I searched the forum & may have missed the info but here's the question(s) I need to answer.

I have two Overkill 12v 120A BMS units to build my RV Battery Packs with. I'm struggling with the mounting of these since there are no mounting tabs, etc.

Anybody know what pitch the M3 screws are? They will need to be replaced with much longer ones since the 6 screws go thru one AL plate and thread into nuts embedded in the opposite side AL plate.

Yeah, the screw thread is M3-0.5. I have that type of 12mm long screws added to the topside of the screw holes (did not remove the original screws from the bottom side, wasn't necessary for my mounting needs). There are 6 holes as you can see, but I'm only using the four corner ones to hold the unit in place. Better/cleaner than zip ties, tape, etc IMO. Home Depot had these screws in their hardware section in the sliding drawer cabinet, not the stock hanging on the walls. Cheers.

 

[Kennedyma]

I have used double sided 3m tape for my personal builds with great success.
Here is the tape I use: https://amzn.to/3aj76Kj


I also know that Steve has a 3d printer model of a mounting plate on his site as well.

OverKill 120a LifePo4 BMS braket for 4s 60ah Fortune cells by LuckyC

Quick way to attach a 4s Overkill BMS to the threaded rods you can use on a 4s 60ah Fortune lithium Iron phosphate bank, has holes in bracket for cable managemnent Remove the corner screws in the BMS and run a longer 20mm M3 from the back of the model to secure the BMS in place Attach the...

www.thingiverse.com

 

[John Frum]

I used

#8 x 1" flat head wood screws
#8 x .5" round nylon spacers

mounted to 3/4" plywood.

 

[MrNatural22]

VHB tape. ?

 

[Gould]

VHB tape. ?

View attachment 35328

Your setup has me intrigued, very interested in your tensioning. I think I know they answer but are your end plates 3D printed?

I’m prepping for my battery build and have a seen a lot of simple yet affective approaches using plywood and threaded rod but I’m looking for something a little more streamlined as space will be an issue and my OCD usually gets the best of me.

Apologies for the hijack

 

[MrNatural22]

Your setup has me intrigued, very interested in your tensioning. I think I know they answer but are your end plates 3D printed?

I’m prepping for my battery build and have a seen a lot of simple yet affective approaches using plywood and threaded rod but I’m looking for something a little more streamlined as space will be an issue and my OCD usually gets the best of me.

Apologies for the hijack

The battery is an A123 24v from Bigbattery.
I didn’t assemble the pack. I just added an Overkill 8s 100a BMS

 

[Gould]

Haha, thanks.

 

[WA5IDX]

I ordered a bunch of M3 50 mm long cap screws with nuts and washers. I'm going to sandwich the Overkill BMS units (via the existing holes) in two pieces of 10mm thick Aluminum plate I have. My junk box has all sorts of stuff I've collected over the years.

That is very much "Overkill" (forgive the pun) as a requirement but I have it already. By making the plates "oversize", I have room for mounting on all four sides as may be needed. My Pack is square (8 each- 272 Lishens) with AL compression plates on the ends (usual threaded rod).