Victron MPPT precise charge current limiting - GX DVCC or VE.Smart Networking?

[sgtcrumb]

If I want to have precise control of the charge current going to the battery, will I need a Cerbo-GX with DVCC enabled or is a VE.Smart Network sufficient? If I have attached varying loads, the MPPT should adjust its current output to match the loads, and charge current. For example, during bulk charging, the MPPT max current output should rise and fall to meet both the max charge current and the load demands at any point in time:

Charge Current	Load Current	Total MPPT Current
30A	4A	34A
30A	2A	32A
30A	3A	33A

In the MPPT manual, I read the following under the VE.Smart Networking heading:

• Current sensing - The measured battery current is used by the charger so it knows the exact tail current at which the absorption stage should end and the float (or equalisation) stage should start. To measure the charge current all charge currents from all chargers are combined, or if a battery monitor is part of the network the actual battery current will be used.

Ref: https://www.victronenergy.com/media...tml#UUID-e9a1c7c7-9717-092c-6645-3689cc42c51d

A comment on the Victron community forums says that a GX device is required with DVCC.

Ref: https://community.victronenergy.com/comments/96556/view.html

Is a GX device with DVCC still required for precise charge current control or is VE.Smart network alone enough?

Thanks!

 

[pollenface]

If I have attached varying loads, the MPPT should adjust its current output to match the loads, and charge current. For example, during bulk charging, the MPPT max current output should rise and fall to meet both the max charge current and the load demands at any point in time

What you are describing is what I have observed with all charge controllers if sufficient PV power is available.

 

[justinm001]

The MPPT over bluetooth will let you set the charge info and when it detects a load (lowered voltage) it increases. If you have a smartshunt or other devices you can use the VE.Smart which will relay the voltage at the shunt to the MPPT instead of at the MPPT output. CerboGX with DVCC lets everything communicate together for the main purpose of limiting charge current and prioritizing solar over grid for charging. If your battery bank can only handle like 10amps charging then you don't want solar pumping 10a and grid pumping 10a, or if you have 10 MPPTs it'll work them together to limit.

All settings are controlled on the MPPT over bluetooth. Cerbo doesn't really even allow you to change settings on many devices.

If you have multiple Victron devices get a CerboGX its amazing.

 

[sgtcrumb]

This system will just have a single MPPT charge controller. From what I've been reading thus far, setting the max charge current in the MPPT alone will only serve as a hard limit of the current coming from the MPPT. That is, if I were to set the MPPT to charge at a max of 32A, varying loads will take away from that.

Charge Current	Load Current	Total MPPT Current
30A	2A	32A
29A	3A	32A
28A	4A	32A

The use of the SmartShunt on the VE.Smart Network will provide the MPPT with an accurate "tail" current reading when switching from absorb to float, and that's all it does. Assuming I understand this correctly, the actual charge current will oscillate unnecessarily. I wouldn't be so picky if I were using lithium, but I will be using FLA in this project due to cold temperatures, and I like the idea of being able to hold a steady charge current if the sun allows it.

This is the issue that user rmorgansd is referring to in this comment. Has anything changed over the past two years? It does seem strange to me that setting a "max charge current" on the MPPT, that is already using the smart shunt current to determine tail current, couldn't also adjust total output to produce both the max charge current AND the load current. The MPPT would simply need to adjust its output so the current going across the shunt into the battery matches the MPPT's charge current setting.

 

[justinm001]

I'd expect this bug would have been fixed after 2 years. The link below has all the firmwares and changelogs, pretty sure anyone can signup, but don't want to post confidential docs. I show for MPPT
v3.04 3/5/21 Fix transition between Absorption and Float states when tail current condition is met.
v3.07 8/3/21 Fix bug for DVCC’s limit charge current when having only one charger connected on the VE.Can bus

They're on V3.13 released 12/21/22

Victron Energy - Victron Professional

professional.victronenergy.com

Could be in other changelogs i didn't see

 

[sgtcrumb]

Thanks for checking Justin. Just to clarify, you mentioned on your previous post, that

All settings are controlled on the MPPT over bluetooth. Cerbo doesn't really even allow you to change settings on many devices.

Edit: So I should plan on getting the SmartSolar variant, and not the BlueSolar? If I do get the Cerbo, I'll connect the MPPT to the Cerbo, so the only VE.Direct port on the MPPT will be used. So I would have no way to change settings on a BlueSolar MPPT when connected to the Cerbo. Do I understand this correctly? I think I'll need to skim through the Cerbo docs again.

 

[justinm001]

Correct. The one weird thing with CerboGX is it pulls all the info but configuration is still stored and maintained at the device. For inverters it has some basic settings i can use from the CerboGX screen (or remote control from app/web) but I don't think there's much you can control for MPPTs. I always use victronconnect to check the mppt settings, it also has better quickview graphs to see max wattage and production.

DVCC part of Cerbo seems to help manage it. I could be wrong though because I haven't dug through every option in the Cerbo and there's a ton plus additional 3rd party apps you can get

 

[sgtcrumb]

Thanks for the heads up. I'll be ordering the SmartSolar variant.

 

[Rocketman]

Yes get the smart solar type- the tracking and info it keeps is great - and can help solve riddles in the system later.