Victron Adaptive vs Fixed Absorption Charging

I was just wondering if any of you guys could tell me what absorption mode setting I should choose between adaptive or fixed on my Victron charge controller? I have a 300ah LiFePO4 battery, and I occasionally medium discharge the battery down to about 70% of capacity, but never lower than that. I've heard that an adaptive absorption mode setting will give your battery a longer lifetime. Any thoughts would greatly be appreciated, thanks.

I have two Victron solar charge controllers. I'm not familiar with there being two charge methods. If there are two methods, I suspect I'm using the fixed method. Mine charge to 14.4 in bulk and then float at 13.6. I'll be reducing the 14.4 to 14.2 eventually. The more conservative settings for charging, and not going below 10% State of Charge will provide a long cell life.

My cells have yet to go below about 60% (once) and rarely see below 90%. Without changing anything, I suspect that the cells will outlive the technology (something new will come along), will see ten years of use, or I'll sell the RV.

SolarBaby said:

I was just wondering if any of you guys could tell me what absorption mode setting I should choose between adaptive or fixed on my Victron charge controller? I have a 300ah LiFePO4 battery, and I occasionally medium discharge the battery down to about 70% of capacity, but never lower than that. I've heard that an adaptive absorption mode setting will give your battery a longer lifetime. Any thoughts would greatly be appreciated, thanks.

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@SolarBaby you have asked this question multiple times in multiple threads.
By adaptive absorption @Solar baby probably means tail current as opposed to timer based termination.

Victron document: Adaptive Charging - how it works. It appears to be an older document, but the idea is Adaptive is supposed to prevent over-Absorption.

My general take is that under-absorption is more of a problem for off-gridders than over-Absorption, but they are engineers and I am a random dude camping in a forest.

This setting is irrelevant for LiFePO4. When you select that battery type in the settings of your multi/quattro, it will select fixed for you. Adaptive won’t make these batteries last longer.

cinergi said:

This setting is irrelevant for LiFePO4. When you select that battery type in the settings of your multi/quattro, it will select fixed for you. Adaptive won’t make these batteries last longer.

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Thank you. Your post saved me from reading the Victron document.

Victron recommend 14.2 volts charge and 13.5 volts float and 15 minutes absorption time for their lithium batteries. On my own batteries I use 14 volts charge , 13.4 volts float and 15 minutes absorption.
If I am not using the batteries on my boat or RV, then the charger settings are reduces to 13.3 charge 13.2 float, this keeps the battery at around 60% capacity.

Mike

mikefitz said:

Victron recommend 14.2 volts charge and 13.5 volts float and 15 minutes absorption time for their lithium batteries. On my own batteries I use 14 volts charge , 13.4 volts float and 15 minutes absorption.

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It's too bad Victron only supports absorption times in 1-hour increments for the Multiplus. At least that's the case for my 24V/2000W Multiplus when setup via VictronConnect. My Victron 150/45 SCC supports much finer grained absorption times via VictronConnect.

Though I'm not sure if there is finer control for this setting via VEConfig. Checking... Nope, it does not. It only accepts 1-hour increments too. Bummer.