Victron MPPT config query

[Nigel Crompton]

My original Victron MPPT 100/20 that charged my old lead-acids was reconfigured by my lithium installer.

I've now added a 75/15 to plug stand alone panels in.

Going thro' the 100/20 config a line at a time and setting the 75/15 to match.

When I got to the Absorption section the 100/20 is set for fixed duration, 2 hrs & tail current disabled. The 75/15 by default is set to adaptive, max 6hrs & tail current 1amp.

Looked at Victron bumf, adaptive sounds the better mode to me - but what duration, and what tail current is appropriate?
I don't know what a tail current is; is it the current applied to the battery in the Absorption phase?

Eleksol 300ah, which I believe contains 4x125ah cells.

 

[Raul]

Adaptive is for lead acid only. Lithium 2hrs and tail off is ok.
Change your new controller to lifepo4 preset, then go trough it to match the existing

 

[Lenny HB]

Lithium don't really need an absorption phase that is why it is best to set to a short fixed time of 1 to 2 hours.

The tail current, when the charging current drops below the set value the battery is considered charged and the charger stops charging again not really neccessary for Lithium, I've got mine turned off.

 

[Jo May]

My original Victron MPPT 100/20 that charged my old lead-acids was reconfigured by my lithium installer.

I've now added a 75/15 to plug stand alone panels in.

Going thro' the 100/20 config a line at a time and setting the 75/15 to match.

When I got to the Absorption section the 100/20 is set for fixed duration, 2 hrs & tail current disabled. The 75/15 by default is set to adaptive, max 6hrs & tail current 1amp.

Looked at Victron bumf, adaptive sounds the better mode to me - but what duration, and what tail current is appropriate?
I don't know what a tail current is; is it the current applied to the battery in the Absorption phase?

Eleksol 300ah, which I believe contains 4x125ah cells.

42

 

[autorouter]

42

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[Nigel Crompton]

42

Sorry Jo, what was the question?

 

[Kannon Fodda]

Fogstar suggest in their small print guidance 1/2 hour absorption per 100Ah of battery.

 

[Raul]

Fogstar suggest in their small print guidance 1/2 hour absorption per 100Ah of battery.

That is a good base line, the idea is to allow the pack time for balancing. If you know the cells are very close, in summer time you can get away with 30-40 mins absorb even on a 600ah up. In winter I still allow 1hr absorb on solar, but only 30mins on EHU if I ever plug in.