My home is running with an off grid system for almost a year, and I’ve had this trouble for the last two days: I realised that more ore less 2 hours after swtching on my electrical water heater, the power goes off and the system registers this error: High DC Ripple: Alarm. What could be wrong? How could I solve it? I describe my installation as follows:
High ripple current is the DC voltage at the input to the multiplus varying with the ac current. It normally occurs due to too high resistance in the DC cables. Likely causes are you have poor DC cabling and you have started drawing a higher load recently or something has come loose and developed a high resistance such as a failing isolation switch, crimp, terminal bolt, fuse block etc.
Assuming my DC cables are OK (you can see the photo I posted a few minutes ago), could the problem be the heater? Could something be wrong in it? The problem only occurs when it’s fully charged.
The 48/3000 doesn’t need huge cable.
The battery is unhappy (so is protection is being activated) and rapidly disconnecting and connecting which is creating the ripple.
You will need to lower your charge voltage.
Also separate your cables from all the other cables.
Especially move the comms cable from the bunch.
DC and AC should also be separate.
You need to get the installer back and check the dc wiring particularly the crimping and torquing of the crimps, as mentioned above this is the most likely cause of your problems.
And ask the installer to provide you with the exact dc wire specification.
Seen your installation wiring from the inverter to/from the battery, mmm, very thin, and as mentioned above these are best with a multi-core cable.
Can you activate in VRM a graph where you can see this ripple, since that tells you basically directly that your cables and/or fuses make too much resistance.
See also this topic, VDC ripple, there you see also some of these graphs and a similar issue.
Hi a couple of things you need to look at. in the first picture your installer has run the AC & DC wiring together, this is not good practice and should be avoided.
In the second picture, where the DC wiring goes to the batteries it looks like a metal box? if so the wires could (by rubbing on the edge) short out, something i would sort out ASAP.
Hi Dave, thanks. The installation is quite new and very static, so I doubt that the cables’ protection have been damaged by rubbing. This problem hadn’t happened until two weeks ago. So I have a question: could this problem have something to do with humidity? I live in Valencia and last two weeks it has been raining dogs and cats. The room where the installation is located has humidity. So the problem started from these days. Maybe it’s independent but only asking.
It’s unlikely that humidity alone could cause your problems (how humid is it exactly) but what can happen is water vapour can get in-between connecting (poor or loose connection) causing a number of problems, typically affecting analogue circuitry on a pcb if not protected with a coating.
All products will have a maximum humidity rating and that must not be exceeded, can you measure the humidity?
Have you or your installer checked all the dc connections because they will loosen off in time and must be checked at regular intervals.
Just back onshore from sea trials with only 24000bhp.
Sorry to say, seen the above, and photos, your cabling is jointed together, never a good idea as said above, then the cable trays (as is the professional term) are made of plastic, very good, but in the corner of the wall it passes a steel L-strip.
In the trays you should keep the + and - very well seperate, not together as I presume…can’t see.
Well, on high currents, with this very very thin isolation of your cables it might create “induction”.
Please activate your ripple graphics and show us, as that makes everything very clear even better.
