With the Built-in protection of the BMS, what happens if u completely drain the Lithium? Is there a process to kick the BMS to allow the battery to start receiving charge?
Re: Balanced Cells: - There's some manufacturers that quote in their specs that their Lithium batteries are a balanced cell system where others don't mention it. How does a BMS keep ALL the cells balanced? I knew the BMS is there for protection in regards to Charging and Discharging, but didn't know (or how) it keeps the cells balanced...
You should never completely drain the lithium unless sheer neglect, they give you a wide obvious warning by the lower knee.
Balancing is sadly one of the most misunderstood things with li-ion batteries it's pretty pathetic. Beware of the google armchair 2week researchers...It usually does so by "top balancing" when the voltage is 14.3ish plus volts. The amount of work it does per cycle is soo small. Lifepo4 take alongvtine to go outta balance, it can usually handle a fair amount of imbalance. If the cells in the upper knee are out by more than say 300mv thats when to worry, 150 is OK for moderate loads, 50mv is for hard cycling that will degrade the cells anyway. Before lifepo4 went mainstream the 'founding fathers' ran many setups with no balancing and got by for years and years. The tragedy of balancing is if you start off with shit your balancing wont do jack. Just like if you use a cheap agm staying above 50% wont do jack. There are diff grades of quality so without knowing talking of balancing is armchair talk. The internal cells drift in an uncontrollable way and can age differently no matter what. The internal balancing has often been described as a sick joke, cost effective all in one solution so the user is forced to keep going into the voltage knees which isnt healthy longterm. The reccomend charge rates are 0.5C partly coz of this, hitting the cells at high c rates with high voltages is bad, better to keep voltages low.
Here's a funny story, some batts have multi cells in parrelle at the node level, and if a cell is bad the other will hide it and no amount of balancing will address this problem.
It takes years to learn how batteries work, half by experiment. Funny how some who were asking for lithium advice recently are now telling you what's what. Good place to read is expedition portal. Aus forums are just sad.
If the alt is really supplying 14v plus make sure you dont burn out the solenoid, bms. The goldilocks voltage of straight alt charging is ~13.8-13.9V at terminals. Other issue is driving around all the time on full battery will have an impact on lifespan at that voltage, how much? Who knows. The cost of a quality solenoid is more than a dc dc. So I went a dc dc charger coz it was part of a portable setup and i wanted to avoid the mess down the line of smart alts. Also charging off alt direct is a bit like running the washing machine and shower at same time. I'm not a fan of joining a lead acid and lifepo4, coz the diff in voltages. A dc dc is just set and forget, but I understand their large size and required ventilation could be a problem.
A voltage of ~13.4v is usually enough to get a lifepo4 99% charged, albeit quite along time.
