Jonathan1981
100 W
- Joined
- Mar 29, 2011
- Messages
- 180
Tried to search the forum for something similar to what I'm doing but couldn't find anything that relevant.
Just starting to research, learn and get into DIY pack building. My first DIY pack will definitely not be this big but I think it's something I'd like to do eventually, to have for vehicle applications AND as a spare energy backup for household use.
Right now, I'm mostly trying to figure out the basic principles to battery pack building and energy system setups...bare with me as some of my questions will probably be noobish for experienced builders.
I've attached some images of a proposed 18S42P pack.... Samsung 30Q 3ah 15A cells.....so 72V system...Peaks of 300A. Noticing that for that high draw most BMS's come with a huge @ss relay...
1. Why is a relay required for 300A draw and not 200A? how exactly are they connected? does the BMS provide the 12V power to power them?
2. On my cad mock-ups, I've used a laser cut nickel plate(to be spot welded).....from further research, it seems like I will need to add buss bars to these connections I assume? Are there any preferred methods for connecting up such a high draw capable batt pack? What sort of thicknesses are generally required? I notice Tesla uses thicker bus plate and small "fuse" type wire......does the fuse wire need to be specked to the max output of each individual cell (for 30Q, is it 3ah or 15A discharge capable?) or the overall output of the grouping of parallel cells?
3. From the images, is my general connection logic sound?
Many other questions but I guess that gets the ball rolling...
Just starting to research, learn and get into DIY pack building. My first DIY pack will definitely not be this big but I think it's something I'd like to do eventually, to have for vehicle applications AND as a spare energy backup for household use.
Right now, I'm mostly trying to figure out the basic principles to battery pack building and energy system setups...bare with me as some of my questions will probably be noobish for experienced builders.
I've attached some images of a proposed 18S42P pack.... Samsung 30Q 3ah 15A cells.....so 72V system...Peaks of 300A. Noticing that for that high draw most BMS's come with a huge @ss relay...
1. Why is a relay required for 300A draw and not 200A? how exactly are they connected? does the BMS provide the 12V power to power them?
2. On my cad mock-ups, I've used a laser cut nickel plate(to be spot welded).....from further research, it seems like I will need to add buss bars to these connections I assume? Are there any preferred methods for connecting up such a high draw capable batt pack? What sort of thicknesses are generally required? I notice Tesla uses thicker bus plate and small "fuse" type wire......does the fuse wire need to be specked to the max output of each individual cell (for 30Q, is it 3ah or 15A discharge capable?) or the overall output of the grouping of parallel cells?
3. From the images, is my general connection logic sound?
Many other questions but I guess that gets the ball rolling...