Hi
I have two Orion XS units in parallel operating in Power Supply mode so that they provide a constant output voltage to a bank of specialist cameras from a large lithium battery. The settings of both units are:
Function: Power Supply
Input Current: 50A
Output Current: 50A
Output Voltage: 13.6v
Input voltage lockout: 12.0v
VE networking is disabled (having this on made it worse).
Input and output cables are identical to both units.
The problem that I’m seeing is that randomly one unit will work very hard while the other idles, other times the two work perfectly balanced, there doesn’t seem to be a pattern as to why this happens.
This is what I see on VictronConnect when they are unbalanced;
Can anyone suggest why I’m seeing this behaviour and what I can do to mitigate it?
Many thanks.
Hi @Simon_CCES
I assume that you have very short and/or thick cables on the output of the OrionXS’es to the point where both outputs are tied together? This causes both to measure (almost) the same output voltage, independent of the provided current as there is hardly any voltage drop over the output cables. Small differences in temperature or other circumstances might cause the output measurement to differ just a little, causing one of them to work hard and the other to do nothing.
I suspect that using longer (but equal length) cables on the output before they come to a common point might solve this problem as then there is a bigger voltage difference when they have a different output current, causing it to balance out more.
Just for your information (and everybody else), the reason the VE.Smart networking makes it worse is that it adjusts its output based on the reported battery voltage, compared to its own measured output(!!) voltage. So in this case it started to adjust its output voltage based on the voltage reported by the SmartShunt, which is connected to the input(!!) of the OrionXS.
In short, for every VE.Smart network, the battery voltage in the network should always be the voltage of the battery/common point connected to the output of the OrionXS/MPPT/…
With kind regards,
Thiemo van Engelen
Hi Thiemo
Thanks for the information, very useful.
The output cables are 16mm and very short (about 10cm), what sort of lenght do you think would be needed to give the effect that you describe? By my calculation if they were 1 metre long and 30A the voltage drop would only be 0.56% at 13.6v, would that be enough for the Orion units to detect a difference? I’m not sure how sensitive they are.
Hi Simon,
I frankly have no idea what length would be needed. My guess is that 1m would already help as then the voltage drop approaches 0.1V, which is a measurable difference for the OrionXS. Making the cables longer will (most likely) cause the current to be distributed more evenly. The downside is of course that there is a larger voltage drop over the cable and the voltage at the camera end will depend more on the total current drawn.
With kind regards,
Thiemo van Engelen
I have a very similar problem with two Orion Tr 48/48 Dc/DC converter in parallel – one deliver full 6A load, the other idles - and both work if I remove the other, and it seems random which one takes the load. They are both seeing around 52V on the output, and were each adjusted to >53V output voltage (unloaded).
I’m stumped at why they would not just each deliver their full load capacity since they cant “see” each other, and the output rail is 1V less than their setting…
Did you resolve your issue? I’m hoping that could help me as well…
THanks!
on a 24volt system we had similar issues with short (300mm long)16mm cables. Changing to longer 10mm2 cables helped greatly.
When our four units are networked, Two operate as a master and the other two as a slave. The master always operates at max defined output and the slave makes up the rest of the required current. We have dialed the master output down to 40amps to try and make the slave work a bit harder, seems to work in our situation.
As long as our output current targets are met, i don’t worry too much what each unit is doing, we are just trying to even wear and tear out (Heat).
Interesting, so the longer, thinner cables presumably de-coupled the units more from each other? I’m wondering if the switching circuit in the DC DC converters are outputing spikes on the wires that will translate to parallel units, if they are are wired “hard” to each other… In our case there are no networking options (Orion tr). Thanks!
