Hello everybody,
I have a continous problem with my system generating low battery warnings all the time, especially by night. The battery SOC and the voltages are OK:
I really do not know where this comes from. Any advices?
Thank you.
Steffen
asked
low battery warning althoug SOC and Voltage is OK
please can you supply more details like schematic? component details?
@SteffenBrand2607 I suspect that the battery voltage has actually dipped below what the recordings have shown.
Not sure what happened to your system details post, as I got them in an email, but they don't appear here.
What looks like is happening, is that you are getting a big voltage dip every time your fridge starts. Starting load will be many times higher than the running load. This dip is too short for the remote monitoring to pick up explicitly, though the alarm does. This can be caused either by the warning voltage setting, or by high resistance on the battery dc circuit, or just old batteries. Best to inspect the dc connections and the alarm setting. If all good, check with voltmeter on the battery to see what the actual voltage is - though you might need something faster than a standard voltmeter to see the real volt dip.
Hi @Mike Dorsett ,
thank you for your quick reply. Of course I can, our components are:
- 2 x PV modules with each 405 Wp, in series
- 1 x MPPT 100|50
- 1 x MultiPlus Compact 1600
- 2 x AGM batteries abs-line 150 Ah, in series
- 1 x Orion-Tr 24|12 - 9
- 1 x battery balancer (missing on the attached photo, was installed afterwards)
- 1 x BMV-700
- 1 x Color Control GX (cannot be seen on the attached photo)
We have a continuous power demand of around 18-20 W (Internet router, light, further small electrical components) and one small fridge which starts around each hour for around 2-3 minutes. If it is running, the power demand is around 130 W for these 2-3 minutes.
The voltage drops you can see in the picture occur when the fridge starts. However, SOC and voltage even then is OK:
A current picture (screenshot made at 07:16 am) of the system you can see here, no fridge:
... and with fridge (7:21 am):
Thank you for your help.
You may have to adjust low voltage alarm - motors and compressors etc are demanding on start up and the sudden draw can trigger alarms.
https://www.victronenergy.com/media/pg/SmartShunt_IP65/en/all-features-and-settings.html
A mini refrigerator uses between 70-90 watts and 280-360 starting watts and more.
Double check the bat connections. No experience for voltage drop @ AGM but check the Ve config setting (example is for a 12V set up)
There's a low voltage alarm setting in the Multiplus. You need a mk3 to usb adapter, VE configure software to set it. Software is a free download. I found it easiest to pull the RJ45 cable out of the CCGX and use that for the connection. You must disconnect that anyway.
Thank you very much for your answers @kevgermany and @Lifeingalicia. I know the settings for the multiplus and have such an adapter. I did also configure it that way. Which setting do you recommend for a 24 V system? Thanks!
Posts above suggest you check your wiring. One way to check this is to add a large load to the system such as a 1000 W fan heater and then measure both the voltage at the battery and the voltage at the Inverter and see if you have excessive voltage drop and then try and find where this is. For interest, my 50W fridge often records 900W at start up if I happen to catch the Cerbo display when it comes on.
Wiring might be a problem due to long cable? Or what might be the problem exactly with the wiring @pwfarnell?
I sometimes see also Overload warning. Sometimes during the same time like the low battery warning
Long cable, cable diameter/ cross sectional area too small, poor crimps, bolts not tight enough, low quality isolation switches or fuse holders. Put a large continuous load on the inverter then use a digital multimeter to see what voltage drops you have between the battery and inverter to see if there is a problem. The instantaneous overload is probably not an issue but does indicate fridge starting currents are very high compared to normal running. I would set a low voltage alarm around 21.8 to 22.0V on a 24V system.
