- Sep 14, 2012
Hi Leeleesafur said:tylerwatts said:Agniusm that looks like energy storage though, not high current. Would 2 8p modules in parallel be comfortable with 400A output? I am wondering about a pack similar size also.
Hi Tyler, The answer to your question is it depends. It depends on what battery and BMS you are using. The above picture of the green batteries is mine and I was surprised to see it when it showed up in a google search lol. What you see there is 9-15s8p 63v batteries. Soon to be 15 batteries.. I paused building them last year as it was just to hot on the boat coming into summer (I'm a fulltime liveaboard) to keep printing them. Each battery has its own 40 amp BMS that's tied to a huge busbar that you cant see. Each 18650 cell that I'm using has a standard discharge rating of 0.2c which works out to be 590mA. That works out to be .59amps X 8=4.72amps X the 9 batteries = 42.48amps standard discharge. That's 2,676 watts of power without anything breaking a sweat. The maximum output is a totally different story! Maximum discharge current is (2c 5900mA) 5.9amps X 8=47.2amps X 9=424.8amps X 60volts =25,488 watts! The most my system has peaked is 414amps and the BMS's will peak to 540amps for 5s. The system is fully automatic and will simply start the generator if we are pulling more than 5,000 watts for more than 2 minutes. So... yeah.. I guess you could call it both, a energy storage system with high current. Short of spending 10 times as much and buying Battle Born Batteries this was the safest solution for me. The N.E.S.E system is a sound product that has changed everything todo with boating for us.
Thanks for the background and fascinating use case. I was actually asking about the rating of the NESE hardware over the cells. I.e. if I built 8-10-12p modules of high output cells what max current could the NESE hardware handle comfortably before melting housings or seeing significant voltage drop. Particularly I'm considering how scalable the modules are for say building large motorcycle or small car packs of 20-30kwh and 100kw continuous or higher 5min rated outputs. And would I have to run a 400v system @250A to keep current down or could I run 160v say demanding 625A and possibly 30s bursts to 800A. Therefore rather than cells being the max discharge bottleneck would the NESE hardware start to be a concern?
I am aware that the hardware was improved not too long ago and rated to handle higher currents so I guess what is real world experience now showing? Does having lots of uncooled cells with potentially high current output in a densely packed battery assembly present a significant problem for the NESE system? And has anybody found a practical way for cooling potentially? Air channels in the modules or even interconnected water galleries that lock together when you stack modules maybe?
I apologise, I'm thinking aloud about the practicalities and challenges I'm likely to face on my desired builds, hypothetically.