Ending Amps / Tail Current on or off?

[googdot]

I've read through quite a few posts and am wondering what the consensus is for this setting?

Have seen some posts saying switch it off, and others stating to use it at .05C.

I will be using the LF304 in an 8S config using the JK BMS w/ 2A active balancing. Planning to set float to 3.35Vpc (26.8V) and absorb to 3.45Vpc (27.6V) for 60 minutes (initially at least and go from there). Also start balance on the BMS to 3.45vpc as well (or a bit lower as per Steve_S's recommendations ?)

Should I set my ending amps to 15.2A or just leave it turned off?

I guess I'm wondering if these settings will be giving the cells enough balance time.

 

[sunshine_eggo]

0.05C only applies when charge voltage is 3.55-3.65V. At 0.05C/3.45V, you're not fully charged. If charging at high rates, i.e., near 0.5C and charging to 3.55-3.65V/cell, yeah, tail current is more useful.

The bigger issue with 3.45V is balance time. 0.05C @ 3.45V will mean you get only a few minutes of balance time w/each charge.

IMHO, with 3.45, set fixed absorption time to 2 hours, disable tail current/end amps.

3.35V float is going to allow some consumption. IMHO, 3.375V is better and more commonly used.

 

[googdot]

0.05C only applies when charge voltage is 3.55-3.65V. At 0.05C/3.45V, you're not fully charged. If charging at high rates, i.e., near 0.5C and charging to 3.55-3.65V/cell, yeah, tail current is more useful.

The bigger issue with 3.45V is balance time. 0.05C @ 3.45V will mean you get only a few minutes of balance time w/each charge.

IMHO, with 3.45, set fixed absorption time to 2 hours, disable tail current/end amps.

3.35V float is going to allow some consumption. IMHO, 3.375V is better and more commonly used.

Thanks very much for the reply. You are a wealth of knowledge on this forum and I appreciate the explanation.

What are your thoughts on those who go aggressive with their settings? Just trying to wrap my head around the different routes and why people choose one over the other.

 

[sunshine_eggo]

Thanks very much for the reply. You are a wealth of knowledge on this forum and I appreciate the explanation.

What are your thoughts on those who go aggressive with their settings? Just trying to wrap my head around the different routes and why people choose one over the other.

What do you mean by aggressive? If folks are operating their batteries outside of ratings, that's dumb.

"Aggressive" should be nothing more than 3.55-3.65V/cell @ 0.5C and 0.05C cut-off, i.e., cell ratings.

Mostly from information on this forum, the 3.45V peak number seems to be pretty effective at further reducing wear during charging and improving cycle life.

 

[googdot]

What do you mean by aggressive? If folks are operating their batteries outside of ratings, that's dumb.

"Aggressive" should be nothing more than 3.55-3.65V/cell @ 0.5C and 0.05C cut-off, i.e., cell ratings.

Mostly from information on this forum, the 3.45V peak number seems to be pretty effective at further reducing wear during charging and improving cycle life.

I guess I'm meaning these two general options:

3.55V, shorter absorb time and/or 0.05C cut-off
vs
3.45V, longer absorb time and no cut-off

I am running a pretty small system, and it's been great for the last 8-10 years using AGMs. Would the size of my system / usage mean I should go one way or the other when I make the switch to lithium?

 

[sunshine_eggo]

I guess I'm meaning these two general options:

3.55V, shorter absorb time and/or 0.05C cut-off
vs
3.45V, longer absorb time and no cut-off

Gotcha.

I am running a pretty small system, and it's been great for the last 8-10 years using AGMs. Would the size of my system / usage mean I should go one way or the other when I make the switch to lithium?

Actual use case drives it more than anything. If you're AGMs have lasted 8-10 years. That hints that the utilization is low, and the batteries are fully charged most of the time. With low utilization, I would shoot for 3.45V.

 

[googdot]

Actual use case drives it more than anything. If you're AGMs have lasted 8-10 years. That hints that the utilization is low, and the batteries are fully charged most of the time. With low utilization, I would shoot for 3.45V.

Thanks again for the advice and explanation. We used a smaller system in the first two years we were off-grid while setting things up, so the current AGMs we have are in their 8th year now. We do have pretty low usage...usually around 2-3kWh per day.

 

[Ampster]

Should I set my ending amps to 15.2A or just leave it turned off?

If you are using a timed stage for CV (Absorb) that current setting may not work. At least my former system only let me chose one vs the other. My SolArk doen't give me a choice.

 

[googdot]

If you are using a timed stage for CV (Absorb) that current setting may not work. At least my former system only let me chose one vs the other. My SolArk doen't give me a choice.

My controller has the ability to set a both a timed absorb and ending amps, and it will switch to float when one or the other occurs.