question

h-copter avatar image
h-copter asked

BSLBATT voltage too low

Hi, I have a newly installed MP-II 48/5000 with 3 x BSLBATT B-LFP48-100-RM in ESS configuation. The system is working, but isn't performing well as it goes into Sustain mode when at around 50% SoC with only a modest discharge current due to voltage dropping below 48V.

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When freshley charged, the battery is only just hitting 51V, and quicjly drops down. I am not convicned my Charger settings are correct, they are:

1674854685823.png

and accoring to the Victron manual they should be

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Should I change the charger settings to match Victron's manual?

Many thanks

Multiplus-IIbslbatt
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5 Answers
JohnC avatar image
JohnC answered ·

Hi @h_copter

Why would you hesitate? The BSL manual (linked by Victron) says the same.

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Alexandra avatar image
Alexandra answered ·

@h_copter

If it is going into sustain mode, then you also need to adjust the ESS assistant values. Your poor batteries are being chronically undercharged.

Just follow the manual. It literally spells out what to do. Dont forget the mppts as well.

I have several systems with BSLBATT 7.0s working well using the recommended settings. And the systen work mostly offgrid these days with the blackouts.

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h-copter avatar image
h-copter answered ·

@Alexandra @JohnC Thanks - will apply the recommended settings with confidence now! One other question, how should I get the batteries back to full strenght? Should I switch the MP to 'charge only' mode for a while to ensure they get a full 100% charge? Thanks

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Alexandra avatar image Alexandra ♦ commented ·
@h_copter

In the ESS menu, set the system to keep batteries charged.

In the VRM have the widget for the battery bms cell voltages. You may see one or two high voltage warnings for a bit.

As long as they are not alarms don't stress about them. Let the battery sort itself out for a few days. Then start cycling them again.

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h-copter answered ·

@Alexandra Monitoring cell voltages would be great, but currenlty I can only see the min/max through the Cerbo. What is the BMS cell voltage widget you refer to, and how do I install it?

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Alexandra avatar image Alexandra ♦ commented ·

@h_copter

That is perfect for local monitoring and for what you need to check.

But you can on the VRM in advanced you can add a widget there, if you have it set up there.

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stroller avatar image
stroller answered ·

@h_copter I to have these same batteries and have had same sort of issues as you with them...

Mine have mostly gone now but not completely. I have also struggled to find any definitive charging, absorb and float values for these batteries. BSLBATT's two websites are woefully lacking with any detailed and specific data for these values and what there is appears to change from one document to another.

Happy to chat on here or offline somehow to work together to gain the definative data needed.

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h-copter avatar image h-copter commented ·

@Stroller If we can work together to get to the definative answer that would be good. Can we chat? Call me on +447980 800615

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