question

adelante avatar image
adelante asked

limiting battery charge when on grid

Hello, my system is with two lithium batteries 330Ah each - Multiplus 12/3000/120-50 - Smart BMS CL 12-100 - Certo GX - Smart Battery Shunt and a battery protect.

I have been told, living most of the time onboard, that I shouldn't have the battery all the time at 100% of the charge. Because on board I use the coffe machine, the hairdryer, an electric heating, the vacuum cleaner and other 220V appliance I need to have the 220v from the grid on board without damaging the batteries. Any solutions that could allow me to have 220V onboard without damaging the batteries ?

Sorry for the language.

Best regards.

Roberto
SOC
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2 Answers
Alexandra avatar image
Alexandra answered ·
@Adelante

The BMS does exactly that... Manages the battery.

The battery usually charges up to a higher voltage then drops to a slightly lower one on float. So while 100% is displayed it does move up and down a bit.

So don't stress about it. If it was a real issue the manufacturer would have made a different way to manage them.

Of course this is a topic that has many people throw their opinion in on. But at the end if the day do what the manufacturer recommends. If you have done that, then Warranty is secure.

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adelante avatar image
adelante answered ·

Thanks for the answer Alexandra. I am a newbie in this area and I am trying to better understand how the system work and specifically how it work better. I have been told that the life of my batteries could considerably drop if I keep them charged as explained before. I have been then suggested to insert, I have no idea where and to connect to what, a relay and a switch that should allow to limit the charge to 80%. The switch will allow to select the condition grid or no grid. Any thought on that ?

Best regards,

Roberto

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nickdb avatar image nickdb ♦♦ commented ·

Ignore what people say, most don't understand the topic or where it applies.

Like Alexandra has said, in commercial batteries, this has been designed in already, you don't need to worry about it.

You can do more harm to your batteries by leaving them undercharged than what you are trying to save. Follow the recommendations of the manufacturer.


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adelante avatar image adelante nickdb ♦♦ commented ·
Thanks nickdb, could you link me to the recommendations related to this specific issue ? Thank you.

Roberto

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nickdb avatar image nickdb ♦♦ adelante commented ·

https://www.victronenergy.com/media/pg/Lithium_Battery_Smart/en/operation.html

Section 5.1 Battery Care.

And 5.3 charging/discharging/balancing.

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adelante avatar image adelante nickdb ♦♦ commented ·
Thank you very much.

Roberto

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