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Duncan Hall avatar image
Duncan Hall asked

Use of Smart BMS 12/200 with Multiplus C12/1600/70

I am considering changing my system with 4801AH of lead accid batteries to lythium.


The system is in a yacht so has an alternator.


The curreent setup has a GX device coupled to the multiplus, a BMV-700 and an MPPT 75/15.


Looking at the options the Smart BMS 12/200 looks like a good way to connect to a pair of Smart LIFEP04 batteries. However I dont believe ther is a way to connect it to that model of multiplus.


Does this matter as the alternative using a VEBUS VMS will require separate methods to protect the alternator.


Regards


Duncan

BMS
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Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

@Duncan Hall

With the MultiPlus Compact 12/1600 (different for other inverters and inverter/chargers) you have two options:

  1. Connect the Multi directly to the System+ port. The BMS interrupts the battery discharge (and charge) through this port if there is a risk of imminent cell undervoltage, high cell voltage or temperature.
  2. If the Multi is not connected directly to the System+ port (but to the battery directly or a bus powered by the battery), it can also be controlled from the Load disconnect and Charge disconnect outputs by using the Smart BMS CL 12-100 to MultiPlus cable (article number ASS070200100). This cable must be wired to the remote on/off connector of the MultiPlus Compact.

Hope that helps.

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Duncan Hall avatar image
Duncan Hall answered ·

Thanks thats helpful.


Its a pitty the unit does not run to 300A as it would be a no brainer. As the 200A fuse limits the multiplus peak output.

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ commented ·

Not sure what you're aiming for with your system. The peak current of the Smart BMS 12/200 system+ port is 400A.

If you want to run larger loads for a longer period of time, then neither the MultiPlus Compact 1600 nor the Smart BMS is the right tool for this type of application. A VE.Bus BMS or a Lynx Smart BMS as well as a larger Multi are more suitable.

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Duncan Hall answered ·

Does that mean that I could put a fuse larger than 200A to cater for the odd ocasion that I draw more. In looking at my systems performance over the last year the max surrent drawn was 298A. I susspect this is when we turned a kettle on on the inverter in error. The inverter manages 3kw peak but not for long!

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ commented ·

No. 200A is max. However, this does not mean that the fuse will blow immediately at 250A. Time is key: https://m.littelfuse.com/media?resourcetype=datasheets&itemid=9fe0cd60-17bf-4fd7-b18d-977d32179af9&filename=littelfuse-mega-datasheet

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Duncan Hall avatar image
Duncan Hall answered ·

Thanks thats all very helpful.

Given the configuration of the system with the MPPT connected via VE direct to the GX device would the multiplus share the charge disconnect signal with the MPPT as I can see two options. One is to remove the MMPT from the GX which I don't want to do and to use an ASS030550320 to stop charging or abandon the idea of the BMS 12/00 to manage the batteries and just use a BMS 12/100 it to limit the alternator using a standard BMs linked via the GX device to manage other charging devices. I cannot understand why there is no VEdirect interface on the Smart BMS 12/200

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ commented ·

Not sure I understand what you're trying to achieve.

Assuming the MultiPlus is connected directly to the battery and is controlled via the Charg and Load disconnect output, why not connect the MPPT to the System+ port?

This allows you to continue to control the MPPT via the System+ port and maintain the VE.Direct connection to your GX device.

A VE.Direct interface is not required on any of Victron's BMSs as there are other ways to control loads and chargers.

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