News
Special NEWS !
Special update on batteries.
As I'm setting here, I'm trying to think about how to break this information. I'm sure some of the "experts" know about this, and certainly the manufacturers do. And I'm trying to figure out how to say this in simple terms for the laymen. This article will be easy for those with electronics backgrounds. I might even get sued over this but the truth is the truth. So here we go.....
When I first got into solar powered living Lead acid batteries were still king. When LifePo4 or LFP batteries were introduced, there were a boon to the solar industry for many reasons. But, they also came with a 'new' system attached, to control the battery. It's called a bms, short for Battery Management System. And each LFP battery has one. What it does is prevent the user from over-charging and over-discharging the battery, along with temperuture and maximum current (power) output limits. This was to ensure a long life and safe operation for the battery. It's a great idea, and it works within limits.
But there's an underlying problem and it's in plain site ! The Cell Balancing System in the BMS. Why ? Because it's set too high in almost ALL batteries without bluetooth control. The dumb batteries without bluetooth control can't change the cell balance settings or the Max charge voltage settings.
Problem 1: Cell balancing doesn't start until battery is near full charge.
Problem 2: Charge settings are fixed and set too high for long life.
The above information is for dumb batteries that doe not have bluetooth or programmable BMS boards in them.
The repeat: Dumb batteries us a fixed setting BMS that typically sets the max charge voltage near 14.5 volts before it disconnects to prevent over-charging. And most BMS boards DON'T CELL BALANCE until the voltage reaches 14.1 or higher voltages. This is nearly a full charge, and batteries that are in use may only see voltage levels that high for short periods of time thus not allowing them to cell balance.
So you see, the manufacturers are forcing you to fully charge your batteries to even attempt to keep the cells balanced. And it may rarely happen on some systems that are always using the batteries.
Next problem is the TRUE LONG LIFE settings for LFP and other types batteries is the 80/20 rule. Max charge of 80% and Max discharge to 20%. Of coursse this does not fully utilize the batteries full capacity, but it WILL give you the longest life for your money. And there are other considerations for long life, like keeping them below 120 F., but this bms issue is going to kill a lot of batteries much faster. Number one, because it stresses the battery to fully charge it, and two, it fails to keep the cells balanced in many situations. And that alone is enough to cause battery failure. A failure I've seen all too often...
Fix:
Bluetooth bms boards, if you can, buy the battery with one, or replace it yourself.
Downside: The bluetooth bms uses more power to keep the bms alive and as such, if you store that battery too long it will run the battery down and you may not be able to charge it back up. But a long as your using it, there should be no problem.
And don't get me started on hacking potientials.
That's the news for now.. Oh one more thing, if you're using 12 volt dumb batteries for a 48 volt inverter, get a 48 volt smart bms and install one of those on each set of 4 batteries to eliminate this issue. Contact me if you have questions.