BMS? or no BMS?

[Ron]

I think I remember Will talking about not using one. My BYD 4.5 Batteries will be connected(two) as a 48-volt system. I am wondering about just hooking them up in series after I first check their voltage. I ran into this, wheelchairdriver.com/BMS.htm The article mentions the BMS as a wonderful lithium battery killer. All this trying to connect a generic Chinese BMS makes me wonder. Are our Expensive battery banks depending on Chinese BMS? It almost appears as a guessing game from the posts here. This is all just a thought, I hope someone here will show us all a nice step by step article on a really good BMS setup for these 4.5 batteries everyone is buying.

 

[Phil Orton]

BMS discussions are making my head hurt(lol) and I have the same concerns with sub-standard hardware and sketchy product information. Think my approach is just going to use my high quality charge controller(midnite solar that also has temp control) to control input voltages, add a cell balancer and set up a reliable low voltage disconnect on the load and hope for the best. Am also wondering about testing the setup(minus the balancer) using the 12v lead acid now in place to check that all voltages, disconnects, etc. work before putting LiFePO4 bats in. I'm trying to get comfortable with managing this smaller system before moving on to a larger, more expensive, 48v lead acid replacement.

 

[Steve_S]

Phil, the battery temp monitor on a classic won't help youu, they also do not support LFP/LiIon directly, it's abit of a kludge but workable because the controller IS programmable. The Midnites focussed on Lead Acid variants and are slow to update their firmware to support LFP/LiIOn profiles, as well as communicating with a BMS. They are still hacking about with their Inverters (over 2 years now) and never even considered a power pack line for themselves. This is discussion on the Midnite Forum on this and some of what's coming out from a "few in the know" leaves me wondering. I use Rule of three, they are on Strike 2 and quickly headed to strike 3.

 

[Phil Orton]

Thanks Steve, this complicates my decision process even more but really good information. If you had to make a decision today on a charge controller for a 1000w solar panel layout to support the Lifepo4 batteries which one would you choose. I'm willing to get a new one and 'mothball' the midnite until they get sorted out. i've also been disappointed with the lack of upgrades they have implemented. It's a shame that they don't move forward because they have some nice features.

 

[Steve_S]

I bought mine back in 2015 and back then (my gosh, just 4 years) they were literally the Cat's Meow with their extras... they stayed put, more or less BUT they are not some big massive company like Schneider though, so it's understandable. Now that Victron is available in Canada & USA I would go that route myself but NOT the wee small stuff when it comes to the MPPT controller... I'd get a bigger one so I buy it once... With Victron you have a whole family of gear which all works together interactively. Once Midnite has their inverter out and eventually their batter packs too, it may come close to the full house offered by Victron. It is a bit more but not when you add it all up. Additionally, with the management & control capabilities and supporting extras make it a winner IMO.

https://www.victronenergy.com/solar-charge-controllers <--- there is a sizing tool there too.