Li batteries at 48vdc
After much deliberation and questions, I'll likely be purchasing the 48v Lithium battery pack instead of 4-12v. I liked the idea of 12v batteries for weight and ease of handling, but the possible cel...
Forum Discussion
2oldman wrote:Searching_Ut wrote:The BMS is internal to each battery.
whats missing here is an understanding of how the different folks are planning to put together your battery management system. If it has the charge control electronics incorporated then I don't see where there is any issue.
As explained to me, as long as the DOD does not exceed 80%, balancing issues should be rare. If I went below 80, I don't know. It's difficult to get the same answer from any 2 techs, which is why I think the 48v pack would *have* to have internal balancing for the entire pack.
It sounds like the BMS doesn't include an active balancing function. With a well designed BMS you shouldn't have to worry about DOD as the BMS would simply shut off the battery if the state of charge got too low, or any individual cell was at risk for getting to low. It should also limit charging and discharging currents if needed, help in maintaining cell balancing, and prevent overcharging of either the pack as a whole, or any individual cell. Sounds like they aren't providing any cell balancing and want the 80 percent DOD limit as a buffer to prevent possible cell damage or reversal.
I'm afraid everything I've worked with hands on in the Lithium battery arena was for high end military applications where some of the battery systems cost more than most RVers could afford. For the money though the do get excellent BMS systems that account for and respond to just about every charge, discharge, and temperature scenario you could think of. Until batteries designed more specifically for RV type use become more widespread and thus mass produced I think the systems available to us will be less than optimal.
