hogback
New Member
Thanks for the energypanda link. Do you think bmss get so hot that they need extra heat sinks? Mines going to be in an enclosed metal box. See my post in diy battery packs on sunpower 6.5kwh....
My jk 200amp bms didn’t come with bolts. What’s the size?
- Thread starter Azguy82
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Donkey
New Member
Enclosed box...I am going to say yes. That is probably in the top 5 reasons why BMS units and inverters fail...enclosed spaces. If that BMS is maxed out at 200 amps, it is running at 5000 + watts! ?
I think that their cooling ability is dramatically reduced once they are in a small, enclosed area and the ambient temperature surrounding them continues to rise.
I would go through the extra trouble of attaching an additional heatsink if I were you. At minimum, a cooling fan at least the size of a PC cooling fan blowing right on the unit (80mm or so).
If your BMS and inverter are both in tight space, then I would have an opening with a fan evacuating air and be sure that the intake opening for fresh air is at least of equal size. I would say at least 92mm on the fan size.
Every time I watch a YouTube video regarding a failed inverter, it is nearly always tucked away in an enclosed space with no air evacuation = a coffin for the inverter. Then they wonder why the manufacturer will not honor a warranty claim.
In my Travel Trailer, the inverter, batteries and BMS are in the same environment as me - inverter on the wall, batteries and BMS in the open air of my cabin.
BTW: If you do not already have an IR temp gun, I would get one ASAP. Harbor Freight has one for $25. I consider this an essential device. You want to be able to instantly point at your inverter, batteries and BMS and know the real temperature. I depend on my trusty Fluke IR gun and I would never be without it. You also want to be able to point at battery conductors and the AC input/output wiring (especially at the terminal) and see temps.
I melted the neutral input terminal of my 3000 watt inverter and had to replace it. The cause? Severe arcing at the 30 amp connector plugged into the pedestal. I hit the neutral side of the 30 amp plug with my temp gun and it was 200 F!!! That is crazy arcing and it will cause higher current draw for that conductor, along with rising heat. Plugs, sockets and terminal connection are so very critical and I think most people don't think about them much.
I think that their cooling ability is dramatically reduced once they are in a small, enclosed area and the ambient temperature surrounding them continues to rise.
I would go through the extra trouble of attaching an additional heatsink if I were you. At minimum, a cooling fan at least the size of a PC cooling fan blowing right on the unit (80mm or so).
If your BMS and inverter are both in tight space, then I would have an opening with a fan evacuating air and be sure that the intake opening for fresh air is at least of equal size. I would say at least 92mm on the fan size.
Every time I watch a YouTube video regarding a failed inverter, it is nearly always tucked away in an enclosed space with no air evacuation = a coffin for the inverter. Then they wonder why the manufacturer will not honor a warranty claim.
In my Travel Trailer, the inverter, batteries and BMS are in the same environment as me - inverter on the wall, batteries and BMS in the open air of my cabin.
BTW: If you do not already have an IR temp gun, I would get one ASAP. Harbor Freight has one for $25. I consider this an essential device. You want to be able to instantly point at your inverter, batteries and BMS and know the real temperature. I depend on my trusty Fluke IR gun and I would never be without it. You also want to be able to point at battery conductors and the AC input/output wiring (especially at the terminal) and see temps.
I melted the neutral input terminal of my 3000 watt inverter and had to replace it. The cause? Severe arcing at the 30 amp connector plugged into the pedestal. I hit the neutral side of the 30 amp plug with my temp gun and it was 200 F!!! That is crazy arcing and it will cause higher current draw for that conductor, along with rising heat. Plugs, sockets and terminal connection are so very critical and I think most people don't think about them much.
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Donkey
New Member
I am trying to think of a clever way to mount the heatsink. I am thinking thermal pad, and mounting that does not require any drilling of the cover plate or screws...maybe even something as simple as hot glue on the four corners of the heatsink underside.
Another thought is something as simple as Velcro straps wrapped around, or strips or Velcro tape - that is how I mounted my BMS.
This is tricky...it has to have even pressure against the cover plate...which is why most heatsink designs use springs of equal tension.
Maybe a mounting bracket of some sort that can be glued onto the cover plate, and it accepts screw/spring assemblies to create downforce on the heatsink - like a normal design.
Another thought is something as simple as Velcro straps wrapped around, or strips or Velcro tape - that is how I mounted my BMS.
This is tricky...it has to have even pressure against the cover plate...which is why most heatsink designs use springs of equal tension.
Maybe a mounting bracket of some sort that can be glued onto the cover plate, and it accepts screw/spring assemblies to create downforce on the heatsink - like a normal design.
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chrisski
Solar Boondocker
- Joined
- Aug 14, 2020
- Messages
- 5,203
For finding size of bolts, tap and die sets or thread and stud measuring tools are nice tools to have. These are different than the ones I own, but similar:
Some of the things I have, I find the tech data is not exactly accurate or from an older model and sizes have changed in the newer model, or something has been modded by a prior owner.
Some of the things I have, I find the tech data is not exactly accurate or from an older model and sizes have changed in the newer model, or something has been modded by a prior owner.
Donkey
New Member
Nice set chriskki...I might have to get one. I have been needing a tap and die set for a while now.
Heatsink mounting...I am starting to like the idea of using the four tabs with holes in them (on the JK BMS) and use a really large heatsink that is bigger than the BMS unit. Then, we can use screws/bolts that run through the center of tensioner springs (just like a CPU heatsink).
Heatsink mounting...I am starting to like the idea of using the four tabs with holes in them (on the JK BMS) and use a really large heatsink that is bigger than the BMS unit. Then, we can use screws/bolts that run through the center of tensioner springs (just like a CPU heatsink).
Donkey
New Member
hogback, if your BMS has the same dimensions as mine, I measure about 6" L x 4.25" W. Now...to find a heatsink slightly larger than that. ?
Donkey
New Member
I believe I have found the ultimate heatsink for the JK:
5.551" W and they cut it to length. I think I will go with 6.5" L. It will be slightly larger than the JK, and the mounting tabs will fit perfectly.
$22.44 ?
Look at those nice, tall fins - 2.165". We might not even need fans.
Now, to find the mounting bolts that fit the holes in the JK tabs and some springs for tensioners.
Update: I just ordered from there - 7" L x 5.551" W. This BMS is going to chill! MOSFETs should be real happy.
5.551" W and they cut it to length. I think I will go with 6.5" L. It will be slightly larger than the JK, and the mounting tabs will fit perfectly.
$22.44 ?
Look at those nice, tall fins - 2.165". We might not even need fans.
Now, to find the mounting bolts that fit the holes in the JK tabs and some springs for tensioners.
Update: I just ordered from there - 7" L x 5.551" W. This BMS is going to chill! MOSFETs should be real happy.
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