question

Lionel SEYDOUX avatar image
Lionel SEYDOUX asked

SOC vs Voltage

High in the southern french Alps, my house is powered by 2kWp on the roof, 30kWh OPZS lead batts and a 3kVA generator all manages by a full Victron system. The last 3 months the sun has been scarce and erratic but I kept my Multiplus 24/5000/230 running to keep a fridge and a congelator running as it is good to have something under your teeth after a 2 hours climbing in the snow. Max watts 150 when both run, but as the room temperature is about -4°C it should be for very short periods with a daily load under 1 kWh/day .

Q1: But on VRM, the voltage stays very low: Yesterday afternoon 24.77 for a 100% SOC and this morning 24.41V for SOC=99.3. These values are not consistent and I fear my settings are wrong though set as required (Ah at C20 for BMV). Or my bats are completely out of order.

When I manage to get there, probably April, I shall test my settings and SOC with electrolite density, but I may have to switch to LiFePo bats a little later.

Q2: Another idea: I tried to have some information about REDOX batteries which could store enough to regulate my power the whole year round (100kWh should do). No answer yet.

Q3: A third idea: I may have to change my panels so I look for wood looking things which could easily cover the whole roof, all spare place being filled with somme look alike materiel or wood. Any idea?

The last two questions are a bit far away from sea-faring devices, But our community is universal isn'tit?

More info as needed

Lionel

SOC
1 comment
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Jesse avatar image Jesse commented ·

Lithium batteries will be unchargeable at -4 degrees and will require heating to survive, perhaps not the best option given your limited needs.

I've no experience with OPSZ batteries, let alone at -4. Getting 2V per cell at this temperature doesn't sound too bad though?

0 Likes 0 ·
2 Answers
Lionel SEYDOUX avatar image
Lionel SEYDOUX answered ·

Thanks Jesse, will go on searching the proper info.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Lionel SEYDOUX avatar image
Lionel SEYDOUX answered ·

Hi Jesse,

This forum does not always accept long answers, so here is another piece...

I understand that with the batteries going down to -4 in winter, I should better stay with lead ones. Thanks for the tip.

As for SOC, Volts and Temperature. No clear answer yet. I shall go on searching. 2 volts at -4°C look like 50% soc, unlike what is shown on VRM .

Will report

Lionel

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Related Resources

Additional resources still need to be added for this topic