Initial check on first system charge settings please

[gcap]

I have just installed the first components to my home backup system charging from the grid, solar will follow in the spring.

Multiplus II 48/3K - Smartshunt - CerboGX - 2x 48v100ah batts.

I’ve read ( haven’t stopped ) way too many posts and second-guessing myself, so wish your input to either tell me I’m ok, sit back and relax or what tweaks to perform to optimize what I have.

My main issue really is to know if I’m over or undercharging my batteries, should I push a bit more or pull back? I synchronized the shunt around the time the multiplus went to float.
On the initial charge the VRM showed 100% / 56.73V while the bms was 100%-54.6v. It then dropped to 100%-53.9v. I get that the cells settle down after the charge but are these numbers OK? My gut thinks they should be a bit higher given the bms is nowhere near its charge cut-off ( I hesitate because the charger voltage does approach it though)

The MP soon after, went into Storage state, passing AC from the grid to the loads and batteries slowly drain from the shunt and the Cerbo draw. It has not come out of storage since then

A bit over 24hrs. from commissioning, the shunt and batts are expressing the same following readings respectively (98.7%-53.21v) & (99% and 53.2v) individual cells are 3328-3330mv


Battery bms charge cutoff is 57.6v and discharge cut-off is 43.2v
Shunt Charged Voltage is 56v, 2.0%, 3mins
MP default LFP Fixed, charge 56.8v, float 54v

As stated, I think I should charge a bit higher yet during the initial charge, my nerves made me think I should not.

Help, and peace of mind requested.

Thanks,

Gino

 

[sunshine_eggo]

My main issue really is to know if I’m over or undercharging my batteries, should I push a bit more or pull back? I synchronized the shunt around the time the multiplus went to float.

If you had to manually sync the shunt, it's configured incorrectly.

On the initial charge the VRM showed 100% / 56.73V while the bms was 100%-54.6v.

Battery comms with cerbo?
DVCC enabled?

How do values compare to voltmeter directly on battery terminals?

It then dropped to 100%-53.9v. I get that the cells settle down after the charge but are these numbers OK? My gut thinks they should be a bit higher given the bms is nowhere near its charge cut-off ( I hesitate because the charger voltage does approach it though)

53.9V is probably the 54V float. Victron tends to undershoot slightly. Should stay at or near 100% @ 54V.

The MP soon after, went into Storage state, passing AC from the grid to the loads and batteries slowly drain from the shunt and the Cerbo draw. It has not come out of storage since then

I would disable storage mode, but that may be the display value if float mode is not yet energized.

Disregard charge current. I would set it up as follows:

A bit over 24hrs. from commissioning, the shunt and batts are expressing the same following readings respectively (98.7%-53.21v) & (99% and 53.2v) individual cells are 3328-3330mv

If you observe all cells at 3.45V with near 0A going in, then you are close enough to 100% to not matter.

Battery bms charge cutoff is 57.6v and discharge cut-off is 43.2v

Recommend you change discharge cut-off to 48V. You definitely want the inverter to stop using the batteries before the BMS cuts it off.

Shunt Charged Voltage is 56v, 2.0%, 3mins

Change shunt charged voltage to 53.8V (0.2V below float)

 

[gcap]

Thanks for your info, I'll answer what I can and will try to find the answers to the rest in another post if necessary.

If you had to manually sync the shunt, it's configured incorrectly.

While the batts were charging the shunt was constantly displaying 100%, I read in multiple places as well as video tutorials that I had to sync when they were fully charged. Can I redo this initial setup?

Battery comms with cerbo?
DVCC enabled?

Unfortunately I don't know how to set this up yet

How do values compare to voltmeter directly on battery terminals?

Within .1 as best I can measure

would disable storage mode, but that may be the display value if float mode is not yet energized.

The VRM states Storage but the front panel Float light is on, storage is not selected in the settings

Also , I'm not sure yet how to get the multiplus to appear in Victronconnect, working on it

If you observe all cells at 3.45V with near 0A going in, then you are close enough to 100% to not matter.

3.39 is about the max I've reached, could this be because of my premature shunt synchronizing? If not, how to get to 3.45v?

Recommend you change discharge cut-off to 48V. You definitely want the inverter to stop using the batteries before the BMS cuts it off.

I agree 100% just not sure where to set it... yet

Change shunt charged voltage to 53.8V (0.2V below float)

Done!

Thanks for your help.

 

[gcap]

HI sunshine_eggo , In your screenshot above your battery is at 57.76v, at what voltage does your bms charge cut-off engage?

Also, I set the discharge cutoff to 48, just tired so I didn't remember where it was configured.

 

[sunshine_eggo]

While the batts were charging the shunt was constantly displaying 100%, I read in multiple places as well as video tutorials that I had to sync when they were fully charged. Can I redo this initial setup?

Not necessary.

Unfortunately I don't know how to set this up yet

DVCC is under settings on the Cerbo. You want to turn it on. Turn on SVS and SCS. This will propagate your shunt voltage and current to all devices.

Within .1 as best I can measure

Decent.

The VRM states Storage but the front panel Float light is on, storage is not selected in the settings

That may be the default if it hasn't dropped to float voltage yet.

Also , I'm not sure yet how to get the multiplus to appear in Victronconnect, working on it

If you are using VEConfigure3 via VRM download, that's fine. That's my preferred way.

You either need a MK3-USB adapter + VictronConnect for monitoring/programming OR The VE.Bus smart dongle for monitoring only.

Most don't use VEConfigure3, so I assumed you were. I would stick with VEConfigure3.

3.39 is about the max I've reached, could this be because of my premature shunt synchronizing? If not, how to get to 3.45v?

No. The shunt is a measuring device. It exerts no direct control/influence on anything unless specifically programmed to do so.

I agree 100% just not sure where to set it... yet

Veconfigure3 Inverter tab.

Install Veconfigure3 (PC only)





Double click the downloaded file.

Inverter page:



Charger page (52A charge is limit of this demo setup, so use your own unit's current):




Save the file and then upload it at the same screen from which you downloaded it.

HI sunshine_eggo , In your screenshot above your battery is at 57.76v, at what voltage does your bms charge cut-off engage?

Also, I set the discharge cutoff to 48, just tired so I didn't remember where it was configured.

Most LFP batteries protect at 3.65V/cell or 58.4V. You want to avoid triggering the BMS unless something goes wrong - configure the system to work inside BMS limits.

 

[gcap]

Hi
After updating settings MP went immediately to Bulk, Absorption and finally Float

With your setting suggestions ( copied from your screenshots also) the batteries entered float and have been in float for much longer than with my previous settings, Storage has not appeared in the arm this time, batteries still show 99% - 53.9v constantly for the past 12hrs. the shunt displays the same at 100%- 53.94

Do I want my batteries to reach 100% as previously or are theses settings a "happy place " for them and not causing possible damage?

Current Settings recap:

 

[sunshine_eggo]

100% isn't significant as a quantity. If the cells attain > 3.40V for a couple hours every couple weeks, they should be very very close to 100% and remain balanced if they are well matched.

The primary issue with imbalance is reduced capacity. Capacity is limited by the cell with the least amount of charge, so you might lose as much as 1-2% if the cells get a little imbalanced. Hopefully, 1-2% doesn't matter much. If it does, the design should be revisited.

 

[gcap]

Much Appreciated,

The settings will remain.