question

Gregory Cavanagh avatar image

Why is the default Lithium absorption time set to 2h?

Hello all,

Just wondering why the new firmware sets the lithium preset to 2 hours fixed absorption time with no tail current cutout?

My understanding after a lot of reading was holding these batteries at these higher voltages causes them to wear alot faster and its recommended that once they finish bulking it goes straight to float

Thanks,

battery
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1 Answer
Guy Stewart (Victron Community Manager) avatar image

Hi @Gregory Cavanagh,

I am not sure which product you are talking about, and this topic applies to MPPT's solar chargers, inverter/chargers, and battery chargers.

There is no default that will be perfect for all circumstances and all products, though it it should at least be safe for all, and acceptable performance for the majority of cases.

One reason to have a longer than 0 absorption time can be for passively balancing BMS's that require time at the top end of the voltage to equalise all the cells internally.

It can also be useful for the recalibration of 100% SOC.

Some BMS's will actively manage the time the batteries are held at target voltages, at various charge states.

The default setting should get the system safely online at least. The best thing to do is use a battery that has been tested to perform by Victron and the battery supplier, those are available from this Victron Battery Compatibility list - https://www.victronenergy.com/live/battery_compatibility:start

The second best is to get a specific recommendation from your battery manufacturer, and adapt those to the Victron parameters. For some products, additional settings have now been made available to further tailor to requirements, and are available under the Expert Mode.

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Thanks for that,

This was in regards to the MPPT charger which is installed in my small camper,

I am looking at purchasing drop in lithium batteries that a local australian reseller sells and notice on their recommendation to use a 2 stage charge profile, which im guessing setting the absorb time to 0 will achieve, I was just curious why in the updated build it now uses a flat 2 hour absorb timer instead of the variable one for lithiums now, and with no tail current,

Im guessing that is for passive balance for victron batteries?

You can set the "fixed" absorption time to whatever period you would like.

Thanks, i understand that, i was just curious why the preset lithium profile was changed to 2 hour fixed