question

mfred68 avatar image
mfred68 asked

Batteries discharging after hitting 100%

For the first time my batteries have hit 100% (I recently installed more panels)

I have 12kw of solar on the roof, 42kwh battery storage,

10kva multiplus ii

Mppt 450/100 and mppt

And a pv inverter 3kw

The system is configured as ESS and to only feed pv inverter into the grid, no victron power is fed into the grid.

The batteries finally reached 100% soc and both mpps turned off into absorption mode, and now my loads are all being powered by my batteries, and they are discharging even though the sun is shining and I have plenty of potential kw's on my roof. I thought the mpps would feed into the inverter and power the loads, like my pv inverter does. So what's going on here?

How much do the batteries have to discharge before the mppt's start to top them back up to 100%?

Is my configuration possibly set wrongly, or is it normal to use battery power once its100% soc

battery charging
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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

3 Answers
bulraydin avatar image
bulraydin answered ·

This happens to our systems as well, however for a short time, I think this has to do with the communication to the batteries, probably the system doesn't want to risk to overcharge. Therefore usually after a couple of minutes of discharge of batteries, the mppt's should ramp up again. At least this is what we observe in our systems.

6 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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

mfred68 avatar image mfred68 commented ·
How long is a short time as mine is down to 98% and over an hour, and the mppts are still sleeping though the sun is shining.
0 Likes 0 ·
bulraydin avatar image bulraydin mfred68 commented ·
to understand better , we need to know the whole setup. What batteries are you using ? have you enabled DVCC , or are the chargers acting on their own ?
0 Likes 0 ·
mfred68 avatar image mfred68 bulraydin commented ·
I use Rahvolt 7kwh batteries 6 wired in parallel, they are compatible and show up as Pylontech in the vrm. Not sure where to look to see is DVCC is enabled or not can you please guide me? Should it be enabled or disabled?
0 Likes 0 ·
bulraydin avatar image bulraydin mfred68 commented ·

if it shows as pylontech, then it should force to have the DVCC enabled, just check it. by enabling the dvcc , you give the command to charge or discharge to the batteries. and this is really essential to use lifepo batteries safely. DVCC is a section right under settings. if you share your site, I can check it if you like

0 Likes 0 ·
mfred68 avatar image mfred68 bulraydin commented ·

The DVCC shows as being "forced" on so I think it's working OK

Not sure how to share my site with you though, and is it safe to share my site? Someone could tamper with it.

0 Likes 0 ·
bulraydin avatar image bulraydin mfred68 commented ·
if it sais forced , then it should be fine. probably the battery was not allowing the mpps to charge.
0 Likes 0 ·
Dieter Buchholz avatar image
Dieter Buchholz answered ·

You wrote "no victron power is fed into the grid"

I think, thats the solution, you have to allow DC to feed in.


Dieter

4 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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

mfred68 avatar image mfred68 commented ·
I've purposely set it to only feel pv power into the grid as I have a feed in tarrif which only allows me to feed in from the pv inverter. Although I am allowed to feed in 4kw, my pv inverter only produces 3kw maximum, so would it make sense to feed 1kw from the Victron system into the grid? And how would this affect battery charging, would I lose potential battery power into the grid?
0 Likes 0 ·
Dieter Buchholz avatar image Dieter Buchholz mfred68 commented ·

But the electricity from the DC system (MPPT) is only fed into the grid when the batteries are full, that's what you want!?

0 Likes 0 ·
mfred68 avatar image mfred68 Dieter Buchholz commented ·
I've noticed that it starts to recharge via solar once that batteries drop to 96% so I'm happy with that. However I don't mind feeding in 1kw to the grid when the batteries are 100% because it would divert to my hot water, but I tried setting feeding to 1000w and it was using my battery power not the mppt power, is that normal?
0 Likes 0 ·
mfred68 avatar image mfred68 commented ·
I just tried feeding 1000w into the grid, but it appears to be taking that power from my batteries, the mpps are still sleeping.

I would upload a screen shot but I keep getting an error message saying "parsing failed" what's that mean?

0 Likes 0 ·
Dieter Buchholz avatar image
Dieter Buchholz answered ·

You have to go through the settings again, for me it works perfectly in normal ESS mode, when the batteries are full the surplus is fed into the grid.


Dieter

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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