This is the second battery I've built from SFK, and it was MUCH easier than the first time. The prepackaged cells and heaters saved so much time and effort! WELL DONE!!!
Great update , good explaination. Ive got the DIY kit without the cells and installed the EVE LF280K cells that i buyed seperatly at my region. But i will keep mension it that main double cable 6AWG (13.5mm2 x2 = 27mm2) size are to small for the 200amp BMS. My draw test of 199amps for 30 min with original cables get to hot and BMS was getting 69C celsius. . The BMS kept working fine and only got error shut down at beginning of test when the draw was a few seconds to long above 200A (205-210) because i dont have a lab draw tester and use real devices with an inverter to get the draw to the 200amp Ive changed the cables to : 50mm2 (1 AWG) single cable on the B- 50mm2 (1 AWG) single cable on the positive 35mm2 (2 AWG) single cable on the C- With this cables the 30 min test with 199amps draw the BMS get max 58C celsius and the 50mm2 get just warm and the 35mm2 was getting hot but not burning hot as the original cables. On the DIY page there is no mention of 200A max short burst so i expected the DIY to work fine with the 200A draw Lucky i used common sense and tested everything out . Yes its less easyer to fit but still works fine and should not be an big problem for a good diyer . Type of cable i used is Flex cable category 6 , 70c nominal and 160c shorted. Another thing i could advice is to find away for the thermal probe fit closer to the bottom (middle would be fine too) and not on top , like true the side isolation that press the cells together . Keep up the good work and updating the SFK kit.
Really looking forward to the data port integration with victron! I am planning a multi battery implementation on a sailboat where this feature would greatly improve the robustness of the install.
While getting a BMS designed, it is a 100% MUST that it can cross communicate with a amp flow meter so you can run 1 to 20 batteries in parallel easy. It baffles me why I can not find something like the equalizer Buss Bar system I made being a factory option! My design takes a re-active percentage from each battery, so if I am using 10 batteries the draw is 10% max on each. If I am using 4 its 25% on each. This way, the BMS is only seeing a max percentage being called for based on your build. If I can fund it to be made in mass and compact it, I would be a billionaire!
High Temp industrial PLA at 100% infill. PLA is more dimensionally accurate than ABS and works well for keeping things in place. The BMS is placed on a 3mm thick fiberglass plate as its the main component that generates heat in the battery.
@@sfkenergy ok. I was thinking PLA would warp at high temperatures, but not if you’re using the high temperature stuff with annealing. It’s so much easier to print than ABS.
@@jmpattillo the fiberglass plate that holds the BMS is 3mm thick and takes care of any heat issues, the PLA will not become "soft" until in reaches 155F / 70 C. The battery will go to thermal shut down at 140 F / 60 C so essentially the battery will shut it down well before any heat related issues that could affect the structural integrity come into play.
@@sfkenergy thank you. I was thinking more about how it might have a problem in an RV stored in a hot place. However, it’s hard to imagine it getting that hot in any reasonable circumstances.
REQUEST: I have a travel trailer and my battery is on the tongue of the trailer and not protected from the elements. How about making a cover that snaps on that protects the cables from rain.
This is the second battery I've built from SFK, and it was MUCH easier than the first time. The prepackaged cells and heaters saved so much time and effort! WELL DONE!!!
Great update , good explaination.
Ive got the DIY kit without the cells and installed the EVE LF280K cells that i buyed seperatly at my region.
But i will keep mension it that main double cable 6AWG (13.5mm2 x2 = 27mm2) size are to small for the 200amp BMS.
My draw test of 199amps for 30 min with original cables get to hot and BMS was getting 69C celsius. .
The BMS kept working fine and only got error shut down at beginning of test when the draw was a few seconds to long above 200A (205-210) because i dont have a lab draw tester and use real devices with an inverter to get the draw to the 200amp
Ive changed the cables to :
50mm2 (1 AWG) single cable on the B-
50mm2 (1 AWG) single cable on the positive
35mm2 (2 AWG) single cable on the C-
With this cables the 30 min test with 199amps draw the BMS get max 58C celsius and the 50mm2 get just warm and the 35mm2 was getting hot but not burning hot as the original cables.
On the DIY page there is no mention of 200A max short burst so i expected the DIY to work fine with the 200A draw
Lucky i used common sense and tested everything out .
Yes its less easyer to fit but still works fine and should not be an big problem for a good diyer .
Type of cable i used is Flex cable category 6 , 70c nominal and 160c shorted.
Another thing i could advice is to find away for the thermal probe fit closer to the bottom (middle would be fine too) and not on top , like true the side isolation that press the cells together .
Keep up the good work and updating the SFK kit.
Excellent Progression I see a lot of improvements from version 3.5😁
Great progress, keep it up, looking forward to more upgrades and improvements.
Really looking forward to the data port integration with victron! I am planning a multi battery implementation on a sailboat where this feature would greatly improve the robustness of the install.
They use the same BMS as the JBD so it already work with solar assistant and victron.
Nice work
Very Nice!
While getting a BMS designed, it is a 100% MUST that it can cross communicate with a amp flow meter so you can run 1 to 20 batteries in parallel easy. It baffles me why I can not find something like the equalizer Buss Bar system I made being a factory option! My design takes a re-active percentage from each battery, so if I am using 10 batteries the draw is 10% max on each. If I am using 4 its 25% on each. This way, the BMS is only seeing a max percentage being called for based on your build. If I can fund it to be made in mass and compact it, I would be a billionaire!
Hi John, we can send one of these kits to for review, please check your email. Thanks
@@sfkenergy Yes, absolutely. It's a pinnacle of your work this V5.
how could someone help you with this? id love to utilize this in an rv
Will your new BMS be able to communicate with victron inverters?
All bms will be able to including current ones (with the SFK hub, we are just waiting for VIctron to let us use the Victron Connect logo on our hub).
Good info.
I’m curious as to what sort of plastic you use for your 3D printed parts.
High Temp industrial PLA at 100% infill. PLA is more dimensionally accurate than ABS and works well for keeping things in place. The BMS is placed on a 3mm thick fiberglass plate as its the main component that generates heat in the battery.
@@sfkenergy ok. I was thinking PLA would warp at high temperatures, but not if you’re using the high temperature stuff with annealing. It’s so much easier to print than ABS.
@@jmpattillo the fiberglass plate that holds the BMS is 3mm thick and takes care of any heat issues, the PLA will not become "soft" until in reaches 155F / 70 C. The battery will go to thermal shut down at 140 F / 60 C so essentially the battery will shut it down well before any heat related issues that could affect the structural integrity come into play.
@@sfkenergy thank you. I was thinking more about how it might have a problem in an RV stored in a hot place. However, it’s hard to imagine it getting that hot in any reasonable circumstances.
REQUEST: I have a travel trailer and my battery is on the tongue of the trailer and not protected from the elements. How about making a cover that snaps on that protects the cables from rain.
Please check our accessories on our site we have an insulated bag that can protect these batteries.