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doublebubble asked

Mppt's tail current setting for lithium

Recently installed 720ah lithium battery system, 12/3000/120/16 multiplus, 1kw solar, 3 separate mppt's for each solar system and a bmv700, now all the victron units have been set to their lithium profiles, we are in a marina on shore power and all seems well but I'm noticing that every morning the mppt's go into absorption which in turn the battery bank ends up at 14.2v, the multiplus is in float all the time, the mppt lithium profile does not have a tail current just an absorption time of 2hrs, should I be using a tail current setting in the mppt's.

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2 Answers
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Alexandra answered ·

Tail current is usually there to offset the power a battery needs to float.

With lithium the self discharge is usually so low that is is disabled. Lead acid it is a different story usually a percentage based on what type.

So no it is not necessary on lithium in the mppt. On the BMV it is so you trigger 100% correctly.

Are you using the solar wind priority? The mppts you technically want in absorption everyday to charge from renewable sources not shore. (And provide some for loads)

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doublebubble answered ·

Ok thanks for your reply, monitoring yesterday the three mppt's went into absorption first thing in the morning for 2hrs and battery bank voltage went to 14.2v and then settled to float @ 13.5v as with the BMV and the multiplus were all in float mode for the whole day so I guess it's all going ok.

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