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David avatar image
David asked

BYD, Multiplus, SMA - System shuts down at 100% SoC

Hi Victron Team. DPA has sold a 3kVA Multi, 2 x BYD batteries, CCGX to an installer for an off grid site and the installer supplied a new SMA inverter for AC coupling. The installer spoke with SMA rep to determine the ramping frequencies to input into the PV support assistant. Ramping starts at 51 ends at 52hz. The SMA ramps down nicely and Soc shows 98%, 99% but the system shuts down when SoC gets to 100%. The installer has gone back and updated CCGX firmware, selected DVCC, checked all settings but problem persists. No errors or notifications on the Multi but potentially the Alarm (ARM) led on the batteries are flashing once per second when interrogated indicating low batt voltage.

Any suggestions

David

BYD
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3 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi Ross,

With this new information, perhaps it would be better to adjust the PV inverter assistant settings instead of the BYD charger voltage settings. Try increasing the frequency so that the SMA will cut out sooner.

There is a bit more discussion and information in these links. Please report back with your findings and results:


https://www.victronenergy.com/live/ac_coupling:start

https://www.victronenergy.com/live/assistants:pv-inverter-support

https://www.victronenergy.com/live/vrm_portal:remote-veconfigure

https://community.victronenergy.com/questions/6649/multiplus-shifting-to-52hz-before-charging-complet.html

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ross-skyenergy avatar image ross-skyenergy commented ·

Hey Guy

So I took your advice above and changed the target voltage to 54v, I also changed the PV Inverter settings to 51/51.9/52.


Been running flawlessly for the last 7 days.



Thanks for the help on that one, this config seems to work great.

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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ ross-skyenergy commented ·

Great to hear Ross,

If it causes anymore issues, please come back again. Till then this will be the accepted answer.

Please be aware that a BYD battery voltage of 54V is too low for long term re-calibration of the BYD State Of Charge meter.

There will be a setting that allows for the battery to be fully charged, and the PV to behave itself, but you may have to fiddle to find it (and report back!)

Thankfully this can all be done remotely now (though the customer may get unhappy).

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·
If the battery is dropping out at 100%, almost certainly there is an issue with overcurrent leading to over voltage. If the spike is very high, then it may not even get recorded before the battery cuts and signal is sent to the CANbus.


My first suggestion would be to decrease the target charge Absorption and float voltages in the Multiplus to give additional headroom for large PV charge spikes.

The default target voltage is ~55V. I would suggest reducing it to 54V with the remote VEConfigure tool and seeing if that stops the issue. You may notice a reduction in the usable SOC range. And this might require some ongoing tweaks to find the optimal reliability vs performance.

In my experience when charging batteries there is always compromise in AC bus solar, and DC bus MPPTs are much more reliable, and smoother in their current and voltage control.

The exact cause WOULD be recorded on the battery BMS, and you can access that with the Victron RS485 to USB converter and the BYD technician diagnostic tool.

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byd-service avatar image byd-service commented ·

Following up on this. Did reducing the voltage to 54v work? If that´s the case as Guy says it was probably an overvoltage alarm. However, please note that the voltage of 55.2 set in the manual is to make sure the battery SOC is calibrated correctly so work trying to adjust parameters until you can come back to the 55.2 as recommended.


Other things to check:

-Is the voltage when it shuts down exceeding 57v?

-Are you using the ´allow to charge´ relays (if so please update the CCGX software and remove them)

-At what current are you charging when you reach almost 100% (It should be slowing down the charge).


If that didn´t work as Guy recommends get in touch with our friends of Alps power in Australia to get you the ´query and read history´ software.

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David avatar image David byd-service commented ·

Hi BYD Service - really appreciate your input. Ross from Sky Energy is the installer and he is heading back to site (Vic Australia) and will try some of the suggestions and may post further questions in this chain.

Much appreciated

David

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David avatar image David commented ·

Hi Guy - really appreciate your input. Ross from Sky Energy is the installer and he is heading back to site (Vic Australia) and will try some of the suggestions and may post further questions in this chain.

Much appreciated

David

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ross-skyenergy avatar image
ross-skyenergy answered ·

Thanks for the response guys. I will be on site today.


SMA has told me the SB is 51hz and under is full power and 52 is 0 power with a linear gradient in between


So I set the frequency shift settings in the multi to 51/51.5/52


It seems though the multi is not shifting the SB fast enough and it's going into overvoltage as mentioned above. See below, SOC at 100 but frequency still at 50hz..


I will try the above suggestions and update you.



20190130-183159.jpg (3.5 MiB)
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boekel avatar image boekel ♦ commented ·

how big is your battery? is the battery BMS set as Battery monitor?

and can you post graphs of battery voltage / current and SOC when this happens?

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