What voltage to start balancing?

[wopachop]

Im on an RV forum and people are saying their batteries dont start balancing until 14.2v for a 12v battery. At that high of voltage, doesnt that mean the battery will spend less time balancing? Is there a reason the BMS doesnt start balancing at 13.8v or 14.0v?

 

[hwy17]

This is the meat and potatoes of where we debate. Most facts about batteries are agreed and just need to be learned, but even the experienced enthusiasts will disagree when we get into the weeds of the 3.4-3.5 window.

I charge to, balance at, and never balance below 3.4375. That's 13.75 in 12v. And I use BMS that allow me to control their balancing parameters. You could be dealing with batteries where you have to work around their pre set parameters.

 

[Ampster]

.....their batteries dont start balancing until 14.2v.....

That is 3.55 per cell and much higher than the typical 3.4 volts in which most BMSs start balancing. My Orion BMS was user adjustable but because of the size of the 3P16S pack I disabled balanceing on the Orion and used a 1 Amp active balancer which used 3.4 volts per cell as the balancing start voltage. An active balancer was more efficient when only one or two cells were runners since it transferred the energy from the high cells to the lower ones.

 

[upnorthandpersonal]

Mine are around 3.45V, take it for what it's worth. I don't see the point of starting earlier, and rarely go to 3.55V per cell in the first place (3.5V is 'full' for all intends and purposes).

 

[wopachop]

Another thing that's kind of weird in the RV world is the charge voltage. A lot of the 12v batteries list 14.4-14.6v as the recommended charge voltage. Just seems so high. I was commenting that people could charge much lower and another member corrected me and said he owned 2 batteries where the BMS didn't start to balance until 14.2v.

Is it possible those batteries are expecting the user to charge with a common RV converter that outputs 14.4v? So they purposely set the BMS at 14.2v?