question

Hi @babeny2001

I'm sorry but there is no workaround for defective batteries.

I wouldn't give up on 2yo batts immediately either, unless you know they've been abused.

But your issues could be coming from several places, and we can't tell from here without much more information. If your VenusOS is linked to VRM, might it be possible for you to post screenshots of the relevant widgets over 24 hours?

(Say) VEBus A/V, Solar A/V, Grid input. Same day, so we can cross-reference to see what's happening..

The multiplus requires battery to start up. You can hook up any size 48 volt battery to get it to turn on to use shore or generator power with the hybrid off. Or you can just bypass the AC through the multiplus all together.

Solar is totally different. An mppt is not an alternator or generator. It does not output regulated power so you need batteries to regulate that dc power.

Hy ,

I also have this kind of batteries , 200AH and exceptionnaly pull more than 250w in one hour . i think those batteries are not adapted for working long period without sun and not being well recharged , but they can help to work has "buffers", meaning unload your electricity bill , particularly in sunny days . For example if you have a venus OS , you could work in ESS mode "optimised with battery life" , with in winter time a minimum SOC=90% and in summer you could go up to SOC=70% . in ESS mode you can also limit the charge and the discharging power , meaning that you work within fixed and reasonnable limits (ruled by the battery constructor , its capacity and age) to load and unload your battery with some experiments , meanwhile the extra power from the sun goes direct to the actual loads , consumption in realtime .

There is some nice victron litterature , easy to find that talk about ESS and its basics (free to download and called "ESS Design & installation manual") , were in FAQ you could find some questions and answers has :

"Is power from MPPT used to power the loads when feedback is disabled?" ,

"Yes. ESS will reduce grid usage to a minimum, preferably to 0W, with or without feed-in enabled...

...In Keep Batteries charged mode...There is a known issue
when using “Keep batteries charged” mode that can result in less production from the MPPT...

This only occurs when DVCC is disabled, and the “Feed-in
excess solar charger power” setting disabled"

I do not know any solution to make work a 48v multiplus in 24 or 12v , without any other expensive materials .

Hope this helps you , at least a little bit , to not feel alone in the so long way to energy independance , in a free world .

Thank-you

Thanks for the screenshots, they do help.

I read at least one very sick batt(s), with a standing V of the string at ~44V and unable to accept much charge. This will mean the good ones will be experiencing overvoltage and will die eventually too. A multimeter across each batt will find the offender(s).

You'll need to replace it, and if you do that with a foreign fill-in, consider reducing the solar target V's to a Storage mode setting of, say, 53V. That way the solar won't push them too hard, and you could reduce or turn off any load completely. Ie. Just use them as a buffer. DVCC could help with doing this too, just in a different way.

The alarms should go away, but you could reset those downwards too if you want.

The solar perhaps a separate issue, maybe you've lost some strings? They're not really set up optimally for poor light anyway, and you could consider setting them up in 3x series strings and orphaning a panel. If you found a dud panel that would be a no-brainer.

But come back..

guys, thanks for feedback

I've spent today with measurements around, today was sunny, but days before not.
Morning
1 - 12.89 V
2 - 12.9 V
3 - 10.4V !
4 - 8.7 V !

noon

1- 14.4
2 - 14.7
3 - 14.5
4 - 13.39

evening
1- 12.79
2 - 12.84
3 - 12.75
4 - 12.40

from this at least last one is bad and maybe the 3rd starts to be.
Also I've measured current with clamp multimeter all 4 wires from the roof (2 strings) (before fuse box) and as others wrote already it seems one string is dead, next step will be to analyze cables on the roof and measure each panel separately, but this will be little bit more difficult due access and set up load for each panel, I have to think about this first.

The goal is now to set up ESS that way it will first take care of loads and then the battery (use them as buffer) , I've turned DVCC on, set SOC little bit higher but all the energy now goes to batteries - problem is SOC indicated 85% but SOC on BMV says 99.6%, I don't have BMV connected to venus, so system works with 85 value, I do not know how to sync these two. I'll try to keep charging batteries for few days until there is 100% and then see if DVCC will serve the loads only.