Building a small Victron system, have some questions before I order everything

[ADDvanced]

Thanks guys

 

[ADDvanced]

Update: Have Smart Solar 150/45 installed, and it's saying the batteries are at 100%. I have the settings set to 12v, and preset to Smart LiPo4, but when I am watching the status, the voltage is jumping from 12-13v up to 17v, then back down to 12-13. I don't understand why it's showing 17v, as in the preset it says 14.2v max, not 17. Ideas? Still need to wire in the smart shunt and the rest of the 12v system, kind of pissed that absolutely none of this stuff came with teh VE Direct cables. WTF. How does the cerbo GX not come with VE cables?! So dumb.

 

[sunshine_eggo]

LFP battery entering over-voltage protection, cutting charge off and causing MPPT to spike as a result of the charge "load" being removed?

Set MPPT absorption to 13.8V and float to 13.5V and see if it stops jumping to 17V.

EDIT... where does a MPPT show 100% charge? Mine doesn't.

EDIT2: Sorry... didn't think to warn you about the lack of VE.Direct cables. Fortunately, my seller knew to charge me for them when I ordered everything.

 

[ADDvanced]

Sorry, the renogy controller I had installed yesterday said the batteries were at 100%, but it was guessing. That said it'd been running for a few days with no load.

 

[cs1234]

Still need to wire in the smart shunt and the rest of the 12v system, kind of pissed that absolutely none of this stuff came with teh VE Direct cables. WTF. How does the cerbo GX not come with VE cables?! So dumb.

Victron stuff is nice, but like much of the rest of the solar industry, they nickle and dime you to death.

 

[ADDvanced]

Just spent $45 on about 50 cents worth of cables. So stupid.
Anyway, I disconnected the panels until I get this figured out. Here's my settings, and here is what I am seeing for voltage. Why is it spiking and going up and down like this???

 

[cs1234]

Have you tried it with just one battery connected? Even in parallel, they might not be balanced very well and one might be engaging it's charging protection, causing it to spike.

 

[sunshine_eggo]

It's very common for LFP batteries to arrive imbalanced right out of the box. I can't remember if we recommended you fully charge the individual 12V to full before deployment.

On the VC trends, enable battery current as well.

 

[ADDvanced]

I mean, how else would I fully charge these. A traditional charger? I don't have AC. I mean I guess I could run a generator for a few hours but they both read 12.8V or so when disconnected.

Is the voltage spike the output of the MPPT? How would a battery BMS cause a voltage spike?

 

[740GLE]

So no smart shunt installed?

Can you measure the impedance of the battery + terminal to the MPPT battery + terminal?

Another option is measuring the battery terminals to verify if they are seeing the voltage spike.

The controller may think the battery terminal is climbing, but if there is a bad connection the actual battery terminals may not be climbing as high.

If the terminal voltages are seeing the spike in voltage which is most likely, you’ll have to lower the voltage settings, the SCC should throttle back current so the BMS high voltage disconnect never operates.

Just an idea.

Also mad props for spending what $1000-$1500 in Victron gear for a <700w PV system. When are you ordering a 3k Multiplus?

 

[740GLE]

I mean, how else would I fully charge these. A traditional charger? I don't have AC. I mean I guess I could run a generator for a few hours but they both read 12.8V or so when disconnected.

Is the voltage spike the output of the MPPT? How would a battery BMS cause a voltage spike?

The BMS shuts off charging, the SCC still thinks it needs to shove max current and keeps rising the voltage in an attempt.

Check your inter cell connections, you have a picture of the setup and wiring? Any cheap circuit breakers?

 

[cs1234]

I mean, how else would I fully charge these. A traditional charger? I don't have AC. I mean I guess I could run a generator for a few hours but they both read 12.8V or so when disconnected.

Is the voltage spike the output of the MPPT? How would a battery BMS cause a voltage spike?

You can charge them one by one with the MPPT. Disconnect one once fully charged, charge the next one. Even if it takes days, it would still be fully charged when you hook it back up.

@740GLE just answered the question about possible reasons for spike from MPPT while I was typing this.

12.8v if measured immediately on disconnecting is not charged up.

 

[740GLE]

Have you tried to draw any load on the batteries to bring their state of charge down?

What does the SCC show for voltage if you shut off charging on the main screen?

 

[cs1234]

Man, all lifepo4 batteries should be required to have bluetooth or an individual cell voltage readout on the case.

 

[ADDvanced]

The BMS shuts off charging, the SCC still thinks it needs to shove max current and keeps rising the voltage in an attempt.

Check your inter cell connections, you have a picture of the setup and wiring? Any cheap circuit breakers?

Literally as basic as you can get. 2 batteries in parallel, charger, breaker, panels. Only breaker is before the charger.

 

[740GLE]

So cross the negative from the SCC to the bottom battery.

Also can you verify battery terminal voltage are hitting +15v?

What AWG is that going to the SCC? Did you use furerls (sp?) for the SCC connection? One of the bad things about Victron SCC is thier terminals and large gauge wire.

 

[ADDvanced]

So no smart shunt installed?

Can you measure the impedance of the battery + terminal to the MPPT battery + terminal?

Another option is measuring the battery terminals to verify if they are seeing the voltage spike.

The controller may think the battery terminal is climbing, but if there is a bad connection the actual battery terminals may not be climbing as high.

If the terminal voltages are seeing the spike in voltage which is most likely, you’ll have to lower the voltage settings, the SCC should throttle back current so the BMS high voltage disconnect never operates.

Just an idea.

Also mad props for spending what $1000-$1500 in Victron gear for a <700w PV system. When are you ordering a 3k Multiplus?

Measured impedance and its .1ohm.

This is just the start. Plan to have an off grid garage/apartment eventually. Really needed remote management and renogy is garbage.

 

[ADDvanced]

My apologies. Both batteries read 13.13v after being disconnected a while.

 

[ADDvanced]

Have you tried to draw any load on the batteries to bring their state of charge down?

What does the SCC show for voltage if you shut off charging on the main screen?

That’s odd. Both batteries read 13.13v when disconnected but when I hooked them up individually to the SCC it’s saying it’s 12.8V which I verified on the terminals.

 

[740GLE]

Terminals of the SCC or the batteries?

First connection to the battery should be the SCC, then you could double stack the inter battery connections.

Again cross up that negative SCC lead to the bottom battery negative terminal.

 

[ADDvanced]

Terminals of the SCC or the batteries?

First connection to the battery should be the SCC, then you could double stack the inter battery connections.

Again cross up that negative SCC lead to the bottom battery negative terminal.

Batteries. Put the leads right on them with the SCC connected, one at a time. Didn't even have them hooked up in parallel for this test.

 

[740GLE]

hmm the battery terminal voltage drop ~.3v when making the connection to the SCC?

Odd

 

[sunshine_eggo]

deleted.... replied before I saw subsequent messages.