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ako avatar image
ako asked

Lithium Presets

I am completely new to Lithium batteries and about to add one as a backup now and intend to replace my AGMs with them when the time is right however i noticed that the MPPT and DC to DC charger preset for Lithium includes a Float stage , the battery manifacturer and everything i have read say NOT to have a Float stage as it can cause overcharging ,. They say that al that is required is a Bulk and Absorption charge and give the Charging Voltage where there is not a Preset Option .

Could someone please explaine why the presets contridict manifactures recomendations .

Lithium Battery
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3 Answers
seb71 avatar image
seb71 answered ·

If it is LiFePO4, set the float voltage to 3.35V (cell voltage; multiply with the number of LiFePO4 cells in series in your battery; so for instance in case of a 16-cell battery, set Float to 53.6V).

A charged battery will not charge further at that voltage.

Keeping the DC battery bus at that voltage will power the loads (inverter for instance)., without discharging the battery, if the MPPTs can provide enough power for those loads.


I answered a similar question here in more detail:
https://community.victronenergy.com/questions/228156/712-bmv-settings-with-renogy-inverter-charger-not.html

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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

The preset is Victrons recommendation for the Victron lithium batteries.
If you think that doesn't fit your batteries you can freely change the settings as you want.

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ako avatar image
ako answered ·

Thanks Seb , The Charger and the Lithium battery are both new and i was in the process of setting them up , the battery came 40% charged and i read that they had to be charged to 100% before use and thats what i was in the process of doing .The charger when i tried the other day was runing at 57c degrees and the charge after the battery had stood stil for an hour was 26.62 , today even after one and a half hours it was not giving off any heat , not even warm and voltage reached 29 then it went into float at 27 volts ( The chargers preset for Lithium ) so i disconected it , the voltage dropped quickly to 27.3 then over about 3 hours slowly down to 27 so im sure now that they are full .

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seb71 avatar image seb71 commented ·

Charger is disconnected because engine shutdown is selected " strange as i didnt touch anything or even have the App open and have no idea what the engine its refering to is .

It's time to read its manual, I suppose.

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