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bathnm avatar image
bathnm asked

New to Lithium and Cycling to 28.4 every day

Hi All,

I am new to Lithium and the Smart Lithium 12,8 batteries vponfigurtbed 2S2P. My boat is not accessible at the moment due to lock down and I have CANBus connected Smart Solar MPPTs.

When I left the boat, I forgot to adjust the MPPT controllers to charge to 27v, therefore maintaining the batteries at float. As there is very little load it means that my Solar charge controllers are cycling the batteries through absorption, and the Victron set 2hr's each day.

Is there anyway to reconfigure the CANBus MPPTs remotely? Will doing this for what is likely a month going to damage the cells.

Many Thanks

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MPPT SmartSolarLithium BatteryVenus OS
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bathnm avatar image bathnm commented ·

@Guy Stewart (Victron Community Manager), Sorry to tag you directly. Was hopping to get some guidance from Victron. This is continuing. Latest graph...

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I can't get to the boat till likely end of March due to lock downs. This means that for the next 3 months my Lithium bank will go through a charge cycle every day. Will this be a problem?

Everything I have read is that Lithium batteries should not be left in a fully charged state for prolonged periods of time.

Unfortunately I have VE.Can MPPT controllers (SmartSolar MPPT VE.Can 150/70 rev2), connected via VE.Can and not VE.Direct so I can not remotely reconfigure these to a lower charge voltage via VictronConnect.

So the question is am I going to damage the batteries, and if so is there any way I can reconfigure the Solar controllers remotely.

Many Thanks

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Alexandra avatar image
Alexandra answered ·

@Bathnm

Not to my knowledge. It's the ve direct ones you can do over victron connect app if they are up to date enough.

https://www.victronenergy.com/media/pg/8778-VictronConnect_manual-html5/en/victonconnect-remote--vc-r----configuration-and-monitoring-via-vrm.html#UUID-65239e95-58a8-c9a3-ba27-0875083ba016

On the bright side the cells in your battery packs should be well balanced since that is what is happening during the absorption phase.

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bathnm avatar image bathnm commented ·

Yes fully aware. of this capability. Shame you need VE.Direct to make it work.

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ bathnm commented ·

Maybe not ideal, but I don't see this could become a problem for the batteries.

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bathnm avatar image bathnm Stefanie (Victron Energy Staff) ♦♦ commented ·

So why do all the articles I read talk about nots trying batteries full for long periods of time. What is the Victron Smart Lithium battery any different?

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ bathnm commented ·

It's most probably not any different to other lithiums. But there is a lot of talk going on and most of it then taken out of context.

What do you call a long period of time?
What do you call full? 100%?

Charging Victron SmartLithium to 14.2V (3.55V per cell - speaking of 12.8V batteries now, but similar with 24V systems) is pretty much on the safe side, while other brands ask the customers to go as high as 14.8V or even call max allowed charged voltage 15.2V (as can be seen in another thread from today).
Furthermore absorption time is limited to 2 hours. Right after that voltage drops down to 13.5V (means cell voltage of 3.375V). Far from the maximum allowed cell voltage of like 3.65V or even 3.8V for some other brands (which more or less use the same chemistry).

You say there is very little load. But still there is a load and discharging as can be seen in your diagram. Some amps still going in hence your batteries did not sit at "full" for the entire day.

I think Victron selected 14.2V resp. 28.4V for a specific reason.

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Alexandra avatar image Alexandra ♦ Stefanie (Victron Energy Staff) ♦♦ commented ·

I agree with Stefanie on this one. While the bms reports 100% really the cells are not charged to their full capacity. Any good bms never lets the cells deplete too much or charge up to full as it is bad for the cells.

So really it's a myth that the end user (that is you and I) needs to worry about that. It is only the designer and manufacturer of the bms and battery that is concerned about that.

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bathnm avatar image bathnm Alexandra ♦ commented ·

Understood. Hence why it would be good for the manufacturer (Victron) to actually provide some guidance. Last think I want after investing a significant amount in Victron equipment is to have problems 2-3 years down the line.

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bathnm avatar image bathnm Stefanie (Victron Energy Staff) ♦♦ commented ·

Thank you foe your insights. It does put my mind a little more at ease. It would however be good for Victron to actually provide some guidance.

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ bathnm commented ·

Welcome!

Not sure but I think you hardly won't get this kind of guidance from a supplier, regardless of the brand. Maybe marketing is playing also a big role here. Don't misunderstand me, I'm with you and wish I had way more information public available than I actually know.
Maybe not reassuring but batteries have a 3-years warranty.

When still in doubt, you always can tag one of the Victron staff here and see if you can get more information.

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bathnm avatar image bathnm Stefanie (Victron Energy Staff) ♦♦ commented ·

I have tagged @Guy Stewart (Victron Community Manager) above, but no response as yet. After all the investment it would be good to know if I am likely to cause myself issues further down the track. I guess if I want complete peace of mind I need to make the trip to the yacht and set the solar charge values a lot lower! It's also a shame that there is no ability to remotely configure the controller when CANBus connected. Connecting via both CANbus to get synchronisation and via VE.Direct for remote configuration I suspect will just confuse the system, by thinking it has 4 MPPTs!

Oh well.

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Related Resources

Additional resources still need to be added for this topic

MPPT product page

VictronConnect manual

PWM or MPPT

MPPT calculator

MPPT codes

Victron Venus OS Open Source intro page

Venus OS GitHub (please do not post to this)