question

simjoc avatar image
simjoc asked

Multiplus II feeding back into grid

Hello,

I’ve a problem with my multiplus II set up and hopefully anybody can help me, or point me in the right direction.

My System:

Cerbo GX

MultiPlus-II 24/3000/70-32

3x Victron smartsolar

Batrium BMS With Lifepo4 battery’s

Victron ESS


So the Victron devices are communicating with the Batrium BMS over CAN. That is working flawlessly and when the Batrium changes the Charge Current Limit (CCL) the solar chargers are stopping feeding in power. So Victron is listening to the Batrium. Now when changing the setting to grid feed in (DC) there is going something wrong. First it takes way to long when the Multiplus is starting to feed back to the grid. Sometimes the Batrium give the message to stop charging and the solar chargers keep sending power. The Batrium BMS going to bypass mode and that’s not okay. Second eventually the Multiplus is feeding back to the grid, but what than happens is that the Victron is sending about 100watt to the battery’s the whole time. That should not happen because the battery is 100%.

I’m using DVCC @ 28.2 V and getting no errors.


Edit: One possibility for the problem is that @ 100% the victron sees a different percentage, then there is Batrium = 100.5% Victron is 99% (picture nu in the attachments)


Thanks,

Simon

screenshot-20210905-160853.jpg


ESS
screenshot-20210905-160853.jpg (325.8 KiB)
kabels-etc.png (328.1 KiB)
victron2.jpg (18.7 KiB)
nu.png (171.9 KiB)
5 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.

David avatar image David commented ·

I have similar setup and issues with dc feedin, and similar issue to 100% vs 99% display - see my post in the modifications section - it includes two videos.. let me know what you think - I will reply here again when I have some time.

0 Likes 0 ·
simjoc avatar image simjoc David commented ·
Thank you for your reply. Yes we do have the same problem.
0 Likes 0 ·
David avatar image David simjoc commented ·
What country are you in?
0 Likes 0 ·
simjoc avatar image simjoc David commented ·
The Netherlands, EU
0 Likes 0 ·
David avatar image David simjoc commented ·
OK, that rules out the grid setting. Mine is set to Australia.
0 Likes 0 ·
1 Answer
bonie-wanda avatar image
bonie-wanda answered ·

Whilst I’m not sure about the grid feedback issue, you shouldn’t worry about the 100w charging the battery when it’s already full. My old system did that and then my current system does that.

There’s a term for it. I think it’s “Float” charge. The charge state is also indicated in the inverter and/or MPPT. Don’t worry about it.

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.

David avatar image David commented ·

When DC-Feed in enabled, It seems that the CCL value sent by the Batrium BMS is ignored and all the MPPT current goes into the batteries rather than being inverted and fed into the grid.

Lets say the battery is 95% full and the BMS lowers the CCL from say 150a max -> 20a the MPPTS will push as much current into the batteries as they can, rather than only 20 going into the batteries and the rest going to grid via the Multi.

It's like the CCL value is ignored when DCFeedin is enabled. Its very weird - and dangerous as the CCL is IGNORED.

0 Likes 0 ·
Show more comments

Related Resources

Additional resources still need to be added for this topic