Victron SmartSolar MPPT 75/15 Load Switching Issue

Q&A and troubleshooting
, ,
1

Hi,

First time user of Victron, configured many EPEVER Charge Controllers. The application is to provide (solar) power to a remote PTZ camera and it currently works fine using an EPEVER Charge Controller. I elected to clone another but this time using Victron, since it was cheaper and smaller. I was very impressed with the build quality of the Victron charge controller.

My application uses NMC leaf cells (4s) for the BATTERY and setting absorption (16.80V) and float (16.40V) on the Victron was very straightforward and works fine.
Then I came to set the LVD, low voltage dropout. I went to ‘Load Output’ menu in settings and selected ‘User Def Algorithm 1’ and set ‘Load Switch High Voltage Level’ to 14.20V and ‘Load Switch Low Voltage Level’ to 14.00V. So it disconnects when the BATTERY drops to 14.00V and reconnects when the BATTERY reaches 14.20V. That works fine.

I was testing my setup on the bench and found that with no load on the ‘Load’ connector, it all worked great. I measured the voltage at the ‘Load’ connector using a DMM. The problems started when I connected the real application to the “Load’ connector. Nothing worked, not even ‘Always On’, the Load output remained off, which was also reported in the APP.

Digging into the problem showed that connecting an LED load worked fine. I tried two light strips, 700mA and 2.0A and both behaved flawlessly. I broke out the scope to see what was happening, screenshots included. We get good switching with the light strips connected. With the application, which takes about 300-400mA, it tries to bring up the load, but then gives up. The load for the application is a PTZ camera (Hikvision) with POE injector and a CPE210 (TP Link) wireless client driven by another POE injector. The 24V and 48V required by the CPE210 and CAMERA are generated using DC-DC converters powered from the LEAF (NMC) cells. The DC-DC converters appear to be the cause of the ‘Load’ failing to switch. I can provide a schematic and a BOM if required.

Any ideas why this is happening.

Regards,

BRIAN

Screenshots:

#1 PTZ application connected

DS1Z_QuickPrint10
DS1Z_QuickPrint10800×480 11.2 KB

#2: With the 700mA lightbar connected

DS1Z_QuickPrint8
DS1Z_QuickPrint8800×480 11 KB

#3: With 2.0A Lightbar connected.

DS1Z_QuickPrint9
DS1Z_QuickPrint9800×480 11.3 KB

2

Update:

OK, so I read the other posts relating to this issue. It’s pretty clear the cause are my DC-DC converters connected to the ‘Load’. The current monitor on the ‘Load’ seems to be very fast and the in-rush current of the DC-DC converters exceeds the spec of 15A and causes the charge controller to turn off the ‘Load’.

The remedy is to use an external slave device, relay or transistor, to switch the load. I used an ‘N’ channel MOSFET, P30N06LE, in a very simple circuit to take over the switching chores. Of course the downside is that you lose monitoring the Load current and any protection that it provided. It’s not clear if this issue is limited to just the in-rush current, when the DC-DC converters start up, or it’s more general. If it’s limited to the transient in-rush current then slowing down the response time of the current monitor would help, but that’s something Victron would have to implement.

IMHO path of least resistance, excuse the pun, is to use an external transistor since it provides the user with almost unlimited solutions for their application.

Thanks to Mr AI for providing the other posts. There seems to be no end to AI’s usefulness.
Regards, BRIAN

3

You could also try using NTCs on the inputs of your DC/DC converters. When switching on they will provide a series resistance and thus limit the inrush current.

4

Thanks for the suggestion. I’ll take a look at them and see if they will work.