question

ldevos avatar image
ldevos asked

Caravan Solar Install Issue with 2 Mppt Ve.Can 150/85

Hi all,

I am finding an issue that my installer and I do not understand.

We have installed 2-phase system on a caravan.

Phase A is 4 x 180 watts Enerdrive Totaling to 720W which is connected to a Victron MPPT 150|85-Tr VE.can which produces about 55Amp when this phase is the only one running. img-6467.jpg

Phase B is also running the same 4 x 180 watts Enerdrive Totaling to 720W which is connected to a second Victron MPPT 150|85-Tr VE.can which produces about 55Amp when this phase is the only one running.

view-recent-photos.jpeg

They are both connected to 3 x 300 AMPs Enerdrive Battery to charge them.


My Issue is then we have them both running they only produce 30 amps each!

img-6469.jpg

But when running them individually they are running close to 55 amp each.

Why can't I get both Phases running at the same time and get the 55 each?


I have documented some more details on this setup on the following links.

https://workdrive.zohoexternal.com/external/writer/8d1899419560c1dd8beec8d59a2984974d8239a96455269a739385ed291837db

I have also attached some screenshots from the App.

Thank you so much for your help.

MPPT ControllersMPPT SmartSolarmppt calculator
img-6467.jpg (231.5 KiB)
view-recent-photos.jpeg (743.0 KiB)
img-6469.jpg (234.5 KiB)
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
bathnm avatar image
bathnm answered ·

I would guess that DVCC has been configured with a charge limit of 55A. The system is therefore splitting that request 55A of charge between the two systems. I do not have access at the moment to the manual to pull the relevant sections, but search the manual or internet for DVCC

1 comment
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.

semlohnhoj avatar image semlohnhoj commented ·

Sorry, posted this in the wrong comment :)


Ah, I see now, I think your issue is the voltage drop on the cable between the MPPT and the battery. Even though the MPPT is sending out 14.2V, only around 13.74V is reaching the battery. You can see that when you have only one MPPT enabled. When you enable both you still have the same issue with voltage drop I suspect so you are probably only charging the batteries at around 13.74V which is the float voltage and not the absorbtion voltage.

What size cable are you using and how long are the cables? I'm not used to 12V system, mine is 48V but I'm guessing you'd want 35mm at least at that current even under 2 meters but maybe someone else can advise on that.

Another thing is the absorbtion voltage for those batteries can be up to 14.6V so you could happily up the settings on the MPPTs a bit though I wouldn't go all the way, maybe 14.4V, that would at least help with the voltage drop on your cables.

Are the cables getting warm?

0 Likes 0 ·
semlohnhoj avatar image
semlohnhoj answered ·

My initial comment would be about the shunt only being rated at 50A but that aside, the battery voltage the MPPTs are measuring should both be almost identical. How come they are so different if they are connected to the same battery?

It's there a wiring diagram?

As @bathnm mentioned the DVCC setting would apply a limit but this is only if you have a Cerbo GX managing the MPPTs.

The batteries also quote charging between 20A to 50A assuming towards the lowers amperage range. If you take that on face value then 3 of them would total 60A minimum, 150A Maximum. So if you do get this working properly then you'll need to decide if you are happy charging at 110A.

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.

semlohnhoj avatar image semlohnhoj commented ·
Could you post screenshots of the battery settings pages on the MPPTs?
0 Likes 0 ·
ldevos avatar image ldevos commented ·
Thank you for your response.


Both phase are going though it own shunt.

I don’t have an electrical diagram but will ask the installer to supply.

We don’t have a verbose GX installed.

As for the battery. They are the 300 amp Enerdrive and I think if I read the correctly the minimum is 60amp to 120amp max. Do I them multiple by 3?

0 Likes 0 ·
semlohnhoj avatar image semlohnhoj ldevos commented ·

Ah, I see now, I think your issue is the voltage drop on the cable between the MPPT and the battery. Even though the MPPT is sending out 14.2V, only around 13.74V is reaching the battery. You can see that when you have only one MPPT enabled. When you enable both you still have the same issue with voltage drop I suspect so you are probably only charging the batteries at around 13.74V which is the float voltage and not the absorbtion voltage.

What size cable are you using and how long are the cables? I'm not used to 12V system, mine is 48V but I'm guessing you'd want 35mm at least at that current even under 2 meters but maybe someone else can advise on that.

Another thing is the absorbtion voltage for those batteries can be up to 14.6V so you could happily up the settings on the MPPTs a bit though I wouldn't go all the way, maybe 14.4V, that would at least help with the voltage drop on your cables.

Are the cables getting warm?

0 Likes 0 ·
semlohnhoj avatar image semlohnhoj ldevos commented ·
Also, regarding the 60A to 120A charging limit per battery, you are correct. I was reading the spec for a smaller battery sorry. So yes, multiply by three would be 180A to 360A which is fine.
0 Likes 0 ·
semlohnhoj avatar image semlohnhoj ldevos commented ·
And another also :), how charged are the batteries? A good test would be too discharge the batteries down to 30-50% to make sure that when you are charging with solar they will draw maximum current available.


0 Likes 0 ·
delf67 avatar image
delf67 answered ·

It looks to me like the MPPTs (either individually or both together) are limiting the charge current to maintain absorption voltage. If they were to put the full 110A in, the battery voltage would be way higher.

What is your absorption voltage set at?

1 comment
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.

ldevos avatar image ldevos commented ·

Thank you for helping out. Here is the details of the setting of the battery in the app.

0 Likes 0 ·
img-6475.png (251.5 KiB)