question

bones83 avatar image
bones83 asked

victron lifepo4, color control, mppt and multiplus, bms charge disconnect necessary?

Hi,

I am designing my system and I'm unsure if i need to connect the charge disconnect from the BMS to the mppt (and multiplus?), in order to stop charging in the event of cell over voltage. The BMS is connected to the multiplus via AC detector with VeBus, the color control is connected to the multiplus via VeBus, and the mppt is connected to the color control via VeDirect.


My system will be;

4 x victron 90Ah lifePo4 (2 series, 2 parallel for 24v)

Victron Mppt Solar Charge controller with vedirect port (model not certain yet)

Victron Multiplus 24/3000/70

Victon color control GX

Victron VeBus BMS

Having done some research i have reached a point where I have the following questions, but cant find a definitive answer;

1. Will the color control recieve a signal from the BMS via VeBus to halt charging from the mppt (or multiplus if ac in active) in the event of imminent cell overtemperature or overvoltage?

Or

Is it neccesary to use a Battery Protect or Cyrix li-Charge between the mppt and the battery positive busbar to monitor the bms signal and disconnect the Charge supply from mppt (and or multiplus)?

2. If the BMS cannot communicate to cut the charging source through VeBus, considering the MPPT VeDirect port is already in use to the color control, which is the correct solution?

Should I;

Use a battery protect in "reverse", or a Cyrix Li-Charge?

Thanks

MPPT SmartSolarBMSCCGX Color Control
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3 Answers
Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

Hi @bones83,

the BMS will control both your MultiPlus and MPPT in case of high voltage, low voltage and temperature. No need for a battery protect or a Cyrix-Li, unless you really need one. But it might be a good idea to add at least a Smart Battery Protect on the load side of your batteries to protect them in case of low battery voltage. If your going this route, then you need to wire the SBP from the Load Disconnect of the VE.Bus BMS.

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bones83 avatar image
bones83 answered ·

Hi stefanie,

Thanks for the response.

Just to clarify, the BMS will communicate via VeBus with the mppt and inverter in the case of individual cell overvoltage?

Also in response to your advice on the load side, my only load will be the multiplus. Is there still any reason to use the Battery protect to control LVD, or can I rely on the mulitplus LVD value i set within veconfig?

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

Yes, the VE.Bus BMS communicate via VE.Bus to the MultiPlus and the CCGX. The CCGX will control the MPPT via VE.Direct.

No need for a SBP then in case the MultiPlus is your only load. Just make sure not other load is connected to the battery.

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bones83 avatar image bones83 commented ·

Thanks so much =)

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ bones83 commented ·

You're welcome :-)

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bones83 avatar image
bones83 answered ·

Thanks for your help,


I have been assuming that the soc measurement from the multiplus will be quite accurate as I have no other loads. In your opinion is this a fair assumption? Or should I include a shunt and BMV in the design?

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seb71 avatar image seb71 commented ·

Include a SmartShunt.

Replace Color Control GX with Cerbo GX.

Switch to a 48V system (assuming you did not bought anything yet).

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bones83 avatar image bones83 seb71 commented ·

Hi Seb.

I already have the batteries, multiplus and color control from a previous installation we were lucky enough to inherit!

The batteries are not new (6 years old), so i am hoping to make the most out of what i have, as i expect the batteries might only last a few years more. At that point i will think about upgrading parts depending on prices for the chemistries available.

What would be the reason for switching to 48v? To avoid parallel battery connections, or based on the system size? Or something else?

As im keeping the color control should I still include a Shunt?


Thanks for the help!


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seb71 avatar image seb71 bones83 commented ·

In short, it is more efficient to use higher voltage.

But if you already have the equipment, use it.

-------

Yes, get a SmartShunt.

Color Control GX is the "brain" of the system.

A shunt (SmartShunt or the shunt from a BMV) is a device which will better (more accurately) track the state of charge of your battery.

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bones83 avatar image bones83 seb71 commented ·

But if you already have the equipment, use it. - That's definitely what i thought too =)

I think I was very lucky to have any batteries at all, i received them at varied voltages between 9v and 11v!!

I was quite amazed to see them accept a charge, from a small 3,5A max car charger set to its lowest motorbike battery preset. Then i balanced them each at 14.2V down to ~150mA, and discharged each battery to 12.0V with a 4.5A load and it looks like they have varying between 75 and 82 of their original 90Ah.

Now fully charged and balanced again Im keen to build the system to see how they go, without buying anything unnecessary.

Obviously want to give them an easy time so i'll include the shunt if the state of charge will be more accurate =)

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