If my battery is not large enough to provide all the amps that the inverter needs what occurs.
Does the inverter simply take all that is available and simply is not be able to provide all the watts it could do.
Or does something else occur?
Thanks
asked
What happens when a Victron Multiplus wants more power than the battery can provide
Or does something else occur?
If your battery can not sustain the current draw, its voltage will continue to drop, until the inverter will shut down due to low battery voltage.
Plus you will eventually damage your battery...
Or if it has a BMS, it could go into a protection mode.
If you are under-sized, rather just limit the inverter output. It will be cheaper in the long run.
Limiting the output power only works in ESS with grid connected.
Without grid the inverter will always pull from the battery what is needed to supply the loads.
So I have presently got a 12v 110ah battery and a multiplus 1200. The battery obviously cannot provide the peak watts the inverter might want 2000wats (~166A).
Short of getting more batteries/me just not using the inverter for items needing more than say 800watts (~66A) is there anything else I can do, and will me simply not using it beyond what the battery can handle a solution until I look into larger battery bank?
110Ah battery not able to handle 120A? That doesn't sound right. Not good for it, but periodic bursts for something like a small microwave (700W output, 1100W input) shouldn't be an issue.
What gauge and length of wire connecting your batteries to the MP?
Are all connections properly torqued?
For standard operation, I would expect no less than 2awg/34mm^2. If you're using thinner wires, that's the problem. If you have a long-ish wire run, you need thicker cables.
2awg, 5' run and a healthy lead-acid battery with 5mΩ resistance should only see about 0.7V voltage drop.
If you really expect to get into the surge, it's going to be closer to 200A, and you'd need 2/0 or 67mm^2 wire.
If this is a Lithium battery, you're BMS limited, so you're just going to have to manage your loads.
The best solution is to size your battery bank and cables for the application.
@snoobler 110Ah battery not able to handle 120A? That doesn't sound right. Not good for it, but periodic bursts for something like a small microwave (700W output, 1100W input) shouldn't be an issue.
I would be more comfortable knowing what battery the OP has before recommending they run a microwave from their setup.
The OP says "I have presently got a 12v 110ah battery".
Also it is not clear where the figure of 120A comes from.
Maybe the confusion is between the capacity of the battery (110Ah) and its maximum current rating. Depending on the exact battery type I would be very surprised if it cannot supply a Multiplus 1200 at its short term peak power rating (5-10 seconds).
If it is a leisure type battery it may shorten its life a bit. If it is a car battery then this is probably less than starting the engine in cold weather, typical figures for Cold Cranking Amps are around 400A. As the OP says it is "until I look into larger battery bank" anyway.
Thank you for your responses. I am quite new to wiring and 12v systems so yes I think I have a number of gaps in my understanding. Apologies for the original lack of information.
I have a 12v 110Ah lead acid car battery at present.
It is connected to the inverter with 35mm^2 wire with a ~4m roundtrip distance. The manual for the inverter says this is acceptable.
I think your comment about my confusion between battery capacity and maximum current rating is correct as that is exactly what I don't get. So can you please help me understand what I am missing.
My questions then is as follows:
1. With a 12v 110Ah lead acid car battery what roughly would be the maximum current rating it could provide for a short burst (5-10 seconds)?
2. If the inverter can at peak power rating provide 2000w of power, then it would ask for 166A from the battery. If the above battery cannot provide that, what happens. Does the inverter simply draw what it can and the device requesting the power (say a blender for the sake of conversation) would simply not run at its maximum power or would something else happen?
Note: I realise that putting such a strain on a battery which is not big enough is not wise and so I plan not to, I just really want to understand the implications of doing so were it to happen.
Thanks again.
A healthy (continuous) discharge rate for such a battery would be around 15A(+/- 5A).
166A would cause a high voltage drop and maybe the inverter will shut down due to low voltage.
As I wrote above, the inverter will pull all the current from the battery that is needed to power the loads.If that causes a voltage drop below the low voltage cut-off it will shut down.
ok, so are you saying that in the scenario where too much is asked of the battery the inverter would shut down due to a low voltage and no damage will be done to the system?
It will depend on the battery how much voltage drop and when it cuts out. The cut out voltage can be set in the multiplus. But requires extra things to do it. But only the battery will be damaged.
Nb. Car batteries are designed for short bursts of high current and generally small discharge. Followed by immediate charging.
It will be OK for testing/setup. But using it where you're going to discharge by 50% regularly will kill the battery very quickly.
The inverter will just shut down at some point without damage but it is not good for the battery though.
