Multi RS 48/6000/100 - BMS Questions

DIY
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Hi All,
Not new to the forums, my account randomly went missing?? Anyway.

I’m new to the LifePo4 market. I recently purchased 16kWh of raw cell batteries from Alibaba. Those batteries look beautiful, smooth, very flat, and oddly very heavy for such a tiny battery; they are 3.2V, 314Ah each.

I made sure that the BMS that came with the device was Victron compatible, which they replied with yes, if you have the cerbo it will connect to the CAN port.

When connected I made up my own CAN RJ45 cable using fresh CAT6, I had to do the pins in that 123 654 configuration it was like 123 one end and 654 the other end.

Anyway, the cerbo detects it and tells me what BMS it is, but the charge state only says “EXTERNAL CONTROL” Do you know if that’s an issue with the BMS or the BMS isn’t compatible? I would love to know if it’s possible to get the 3 / 4 states back BULK | ABSORPTION | FLOAT

Thanks
Daniel

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The cerbo side uses pins 3, 7 and 8

[See here] (VE.Can to CAN-bus BMS cables manual [Victron Energy]).

for the gnd h and l. You can skip the ground.

Can’t help you with the battery side.

Yes. Remove external control from the battery. It can be done in DVCC (on the cerbo). Just be aware that on the multi rs you will have to reset bms control with victron connect.

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Sorry it would of been that configuration on the RJ45 I forgot

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Remove external control? As in remove the BMS from the batteries box?

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Oh heck no.
Remove bms control in the cerbo under dvcc

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“External control” effectively means the Victron gear is using BMS supplied values for charge voltage and charge current to the BMS.

If your BMS is a good one and is set up correctly, it should mean finer control, reduced charge current with low cell temperatures, better balancing etc.

If you’re not sure of that then as @lxonline says, stop using the BMS for that - but you might have to, for example, reset any MPPT in the system (…)

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Makes sense, I don’t think it’s a really good BMS it was $120 US ($240 Australian dollars)

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So there should be no option if you are on newer firmware to remove it there or set it there if you want to monitor the battery but not let it control the system.

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Ok so I selected the No Control BMS and it stopped charging the batteries - Better check for firmware updates

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Yes because the inverter had a signal and now doesn’t. So as a precaution it would have stopped.
You have to reset the inverter to no bms control using bluetooth and Victron connect. And program it accordingly with the voltages etc.

Your bms appears on the list there though. So you should be ok if it is compatible.

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Thanks all for your help. I will check directly when I get home tonight.

I will need to open another topic up about the best way to manage AC Grid and Battery charging
It happened when I had the the AGM batteries as well, when they went flat / 50% I had the ESS set to 50% Minimum and the AC input Control “Connect When SOC Drops Below 54%”

What used to happen it would drop to 50% and start charging from the grid to 54% disconnect repeat 40 times per night. What is the best practice