question

loadinglevelone avatar image
loadinglevelone asked

(Yet another) LiFePo4 charging charging Question

So I have a Blue Smart IP22 Charger with a LiFePO4 battery. The charger charges the battery up to 14.2V then after some absorption time goes into float at 13.5V. Fine - except that every where I look says to NOT use float with lithium. So, with that in mind:


  1. Do I leave float enabled or not?
    Answered. Leave float ON for Lifepo4 Batteries. Reason - @Justin Cook "The old "never float" argument tends to be a regurgitation of arguments from 15-20 years ago before anyone really understood how the chemistry works, and is usually no longer relevant."

    1a. What float voltage should I set the charger at? (The battery spec says 14.6V charge and 13.8V storage)
    Unanswered.

  2. When float is done (or if I disable float) it goes straight into storage voltage mode.
    2a. Should I turn this off?
    Unanswered.
    2b. Is there a way to turn it off?
    Unanswered.
    2c. What voltage should storage voltage be set at?
    Unanswered.

  3. BatterySafe - Keep on or off?
    Unanswered.

  4. What absorption time do I use?
    Unanswered.


Yes, yes - I know this has been asked a million times before - but the more I look on this forum and elsewhere on the web the more answers I find and the more confuse I get. It seems no-one has a straight answer.

Lithium Batterychargerbluesmart ip22float
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

3 Answers
Justin Cook avatar image
Justin Cook answered ·

Every reputable brand of LFP battery I'm aware of lists a float voltage and will also tend to list absorption time if needed; Battle Born for instance, is bulk 14.4v, absorb minimum of 30 minutes per 100Ah, float at 13.6.

Check with your battery manufacturer/user manual for the appropriate settings for your particular battery.

The old "never float" argument tends to be a regurgitation of arguments from 15-20 years ago before anyone really understood how the chemistry works, and is usually no longer relevant.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

loadinglevelone avatar image
loadinglevelone answered ·

The datasheet only states "Storage charge voltage (for Standby use) - 13.8V". So I'm assuming this is the float voltage?

But if the storage voltage is the float voltage, then what is the storage voltage in the victron? Should I set these at the same voltage? (There's no option to disable it).

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Sten avatar image
Sten answered ·

The float voltage for lifepo4 batterys are best set to 13,5V. With this voltage you have a fully charged battery and the charger at the same time support your load. If you are not using your battery for a longer time it is best to disconnect the battery so there is no load and charge on it. If you need to have the charger connected for a longer time, you can use the storage mode set to a voltage somwhere betwen 13.3V and 13.4V.

the absorption voltage and time you should use are the voltage recomended by the manufacturer.

If you use a lower absorption voltage and/or shorter time, you risk that your cells in the battery will get out off balance.

If you don't have specs for absorption voltage and time, then use the standard profile for lifepo4 in the charger. If you experience issues you can set a longer absorption time. Normaly the charge voltage should not be higher than 14.4v. Lifepo4 cells normaly have a max voltage of 3,65V witch in a 12V battery is 14,6V

Battery safe should be off. It is for lead batterys.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.