Float voltage settings

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piet-hein-van-asselen asked Mar 13, '21

Float voltage settings

Hello

I am wondering:

I have a victron super cycle 230 ah battery. It is connected to a multiplus. The standard float voltage setting is 13,8 volts.

According the datasheet this battery's float voltage setting should be in between 13,2-13,5 volts.

From my understanding and what i have been told it is better to keep the float voltage a bit lower: Otherwise the battery get lazy and sulfatising might occur.

The idea is the battery voltage will drop a bit more and will start charging later as i understand. So the battery is charging less time.

Am i correct and what is the best setting?

battery system voltage

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Answer 1 · 2021-03-14T18:27:59Z

Warwick Bruce Chapman answered · Mar 14, 2021 at 06:27 PM

The short answer is, "It depends who you ask."

Lead batteries are analog. They perform differently in differently climactic and different use conditions. Many swear that you should charge at a lower voltage, others not.

Victron has concluded that lower is better for longevity, hence "storage" mode being a default from Victron which is a lower voltage state of float:

"The Storage mode kicks in whenever the battery has not been subjected to discharge during 24 hours. In the Storage mode float voltage is reduced to 2,2 V/cell (13,2 V for a 12 V battery), which is close to the open circuit voltage of a fully charged battery.

Corrosion and gassing are reduced to absolute minimum, but self-discharge is not compensated. To compensate for self discharge, and to stir up the electrolyte, the voltage is raised back to absorption level once every week.

Note: although sealed (VLRA AGM or gel) batteries can be float charged at 13,5 V to 13,8 V during long periods of time (no topping up needed!), some studies have shown that the Storage mode will increase service life of sealed batteries (see for ex. ‘Batterie Technik’ by Heinz Wenzl, Expert Verlag, 1999)."

From: https://www.victronenergy.com/upload/documents/Adaptive_charging_how_it_works.pdf

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piet-hein-van-asselen commented · Mar 14, 2021 at 06:52 PM

Thank you for your time and explanation.

So if i understand correctly:

For ibnstallations whwn you dont have a storage mode maybe it is better to keep float voltage a bit lower and when you have storage mode you can keep normal setting?

Thanks for the link. I will invest some time in this.

Best regards, Piet

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Warwick Bruce Chapman piet-hein-van-asselen commented · Mar 14, 2021 at 08:49 PM

No.

I wouldn't change the manufacturer recommended float voltage.

"To compensate for self discharge, and to stir up the electrolyte, the voltage is raised back to absorption level once every week."

You can rely on the Victron 4-stage algorithm to manage this for you.

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piet-hein-van-asselen Warwick Bruce Chapman commented · Mar 15, 2021 at 09:47 PM

Thabk you foe your reply.

I understand. Thats why i mentioned "for installations when you dont have storage modes" e.g. solar systems with mppt (without storage mode) maybe keep the float voltage a bit lower?

Best regards

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