Victron 100/20 Under Performing in a 6S Battery (24V)

[Sundog33]

He keeps talking about 3.4v is just the nominal voltage.
The nominal voltage means fully charged and at rest. You only get higher voltage out of it when it’s charging
A fully charged 6 cell pack is only 20.4v
It’s not a 24v system
This is his confusion

 

[Sundog33]

In summary, stop with buying testers, worrying about panels etc.

You have two cc's limiting input WATTAGE to the 12V output setting.

The cc's are working as designed.

It's your oddball low voltage battery that is throwing the cc off. End of story. Why are you running that weird battery?

Finally someone with a brain on here!

 

[BuffaloTrace]

I cannot change the maximum battery voltage. It is fixed to 24 - 25V. It would be pushing to go above 24 as sense voltage can be off and thus a higher battery voltage can actually sense lower. The 24 gives me head room. Also, we are using less to give longer life out of the battery.

You are right about the MPPT thinks it is doing best because it believes it is connected to 12V and not 24V. And your idea to see if the gauge is showing full at 290W is an excellent thought.

Sir, a 6S LTO battery is actually considered a 12v with respect to charging.
6s x 2.5v per cell max charge voltage is only 15v.

 

[Sundog33]

Sir, a 6S LTO battery is actually considered a 12v with respect to charging.
6s x 2.5v per cell max charge voltage is only 15v.

 

[richard cabesa]

That is no different then any other charge controller. Charge controllers are all listed as 12V/24V/48V nominal. The battery configuration of the OP is 18V nominal which is being interpreted by controller as a 12V nominal since it is still less then 24V nominal.

Sir, a 6S LTO battery is actually considered a 12v with respect to charging.
6s x 2.5v per cell max charge voltage is only 15v.

But because of the OP's lack of understanding as to what he has, It MUST be due to the shitty Victron equipment

 

[Crowz]

To find out if its the battery simple get two old 12v car batteries and see what happens with those in place of the frankenbattery.

If it charges as expected with the car batteries there's nothing wrong with the victron

 

[Sundog33]

Wow. millennials I suppose…

lifepo4 Cells are not 2.5v. They are. 3.4v. 3.4v x 6 = 20.4v

the Victron knows exactly what he has and its Not a 24v system
even tho he’s trying to force it to be.

 

[BuffaloTrace]

Wow. millennials I suppose…

lifepo4 Cells are not 2.5v. They are. 3.4v. 3.4v x 6 = 20.4v

the Victron knows exactly what he has and its Not a 24v system
even tho he’s trying to force it to be.

Correct! And NMC are 4.2v max charge. 4.2v x 6 = 25.2v.

I did see that the system is supposed 24-25v max which OP has indicated.

I'm not making any assumptions, I just brought up LTO because I did not see OP make any indication as to what chemistry is being used. Sorry if I'm mistaken.

 

[richard cabesa]

And I did not see OP make any indication as to what chemistry is being used. Sorry if I'm mistaken.

He does not seem to want to tell us

 

[JazzRVwSolar]

Wrong comparison.
The open circuit voltage is used to determine the layout of the panels with a given SCC.
So, 40+ volts(can we please get a precise number) x2 panels = less than 100 volt rating of your charge

Finally someone with a brain on here!

Odd ball battery has nothing to do with it. The SCC manual says it works at any voltage from 12V to 48V. I am well above 12V, even if the battery is dead at 18V, by 6V. The SCC is suppose to work!

If such a limitation exists then point to Victron specifc document that says your claim.

 

[JazzRVwSolar]

But there is nothing in the SCC that says it's 6S. And in all purpose, the only thing that should matter is volts and amps. The voltage of operation is well above 12V and the amps it can accept is well above 20A. Even at 20V (which is the lowest the battery has been, and 20A that's 400W. The MPPT is never going above 290W).

What if I'm not using Lithium? What should the SCC care about chemistry type? It's 100% programmable. That's why you spend so much extra over other SCC that are not. You folks are too hung up on 6S or 4S or 8S. Volts are volts. Amps are amps.

What if I want to dead short the output and see how hot it gets a water heating element? Should the SCC care what voltage? No! It should track the solar panel to optimum voltage and current and deliver max wattage.

And if there is something specific to the 6S, 8S, etc than point to it in Victron manual.

 

[richard cabesa]

Odd ball battery has nothing to do with it. The SCC manual says it works at any voltage from 12V to 48V. I am well above 12V, even if the battery is dead at 18V, by 6V. The SCC is suppose to work!

If such a limitation exists then point to Victron specifc document that says your claim.

And still, no battery specs

 

[JazzRVwSolar]

And still, no battery specs

Sir, a 6S LTO battery is actually considered a 12v with respect to charging.
6s x 2.5v per cell max charge voltage is only 15v.

By that kind of reasoning a 12V lithium battery is 4S which is only 10V. And so people who use 10V batteries should not expect 290W. All this is moot. The SCC has been told the voltage to charge at, which is 24V.

 

[Crowz]

Were still waiting on battery info to try to come up with suggestions.

 

[sunshine_eggo]

@JazzRVwSolar

I'd really like to help, but I don't have time to read all 6 pages...

1. How are these panels mounted, tilt and orientation?
2. Have you conducted manual Voc and Isc measurements of your panels.
3. At high noon, have you applied a > 700W load to check PV output?
4. Are your batteries made from 3.7V nominal cells in 6S, and you're charging to 24V absorption with float right below it?

Your 20A controller should put out up to 480W at 24V (20A * 24V) IF the attached PV can provide that power.

 

[sunshine_eggo]

Wow. millennials I suppose…

lifepo4 Cells are not 2.5v. They are. 3.4v. 3.4v x 6 = 20.4v

the Victron knows exactly what he has and its Not a 24v system
even tho he’s trying to force it to be.

LFP cells are 3.2V nominal.

I'm sure you've seen 12V, 24V and 48V LFP batteries with the listed nominals.

4 * 3.2V = 12.8V (not 13.6V)
8 * 3.2V = 25.6V (not 27.2V)
16 * 3.2V = 51.2V (not 54.4V)

 

[JazzRVwSolar]

By that kind of reasoning a 12V lithium battery is 4S which is only 10V. And so people who use 10V batteries should not expect 290W.

@JazzRVwSolar

I'd really like to help, but I don't have time to read all 6 pages...

1. How are these panels mounted, tilt and orientation?
2. Have you conducted manual Voc and Isc measurements of your panels.
3. At high noon, have you applied a > 700W load to check PV output?
4. Are your batteries made from 3.7V nominal cells in 6S, and you're charging to 24V absorption with float right below it?

Panel mount etc makes no difference. We tested the optimum tracking point with a test tool and it showed the panel to produce 330 - 350W. The SCC was only delivering 270 - 290W while in bulk. The charge voltage was set to 24V there was no restriction put on charge current.

All this talk of series panels and cell count are non-issues -- at least they are suppose to be in a fully programmable SCC.

 

[sunshine_eggo]

Panel mount etc makes no difference.

How does this not make a difference?

We tested the optimum tracking point with a test tool and it showed the panel to produce 330 - 350W.

So, you did this manually, with the panel perfectly perpendicular to the sun at high noon?

Is this tool reliable? Have you correlated it to other systems? Have you confirmed panel performance with manual measurements?

To get 330-350W out of a 375W panel this time of year in the northern hemisphere is a tall tale. I have 330W panels tilted at 29° in a cold climate. They only produce about 278W this time of year.

The SCC was only delivering 270 - 290W while in bulk. The charge voltage was set to 24V there was no restriction put on charge current.

And this was at high noon with the panels perfectly perpendicular to the sun, no shading and clear skies?

All this talk of series panels and cell count are non-issues --

Perhaps from your perspective, but many of us on here trying to give advice want to ensure we have a working knowledge of the system.

at least they are suppose to be in a fully programmable SCC.

"Fully programmable" means different things to different people, but in this context, as I indicated, the MPPT is capable of outputting 480W @ 24V.

If your panels are flat on your roof, and you're getting 270-290W out of them, that's fantastic for this time of year assuming you're in the Northern hemisphere.

 

[BuffaloTrace]

By that kind of reasoning a 12V lithium battery is 4S which is only 10V. And so people who use 10V batteries should not expect 290W. All this is moot. The SCC has been told the voltage to charge at, which is 24V.

There are a few varieties of "Lithium" batteries.
Lithium Iron Phosphate (Lifepo4/LFP), at 3.2v Nominal may be used in a 4s configuration in a 12v system.

Some other Lithium chemistries, because of their differing in nominal voltage may be used in different series configurations.

So which chemistry Lithium battery do you have? Are you trying to get help with a problem and figure it out? Any and all possible technical information and data no matter how small or insignificant you may think it is, will help someone more knowledgeable than you figure out whatever you don't understand.

 

[richard cabesa]

Panel mount etc makes no difference. We tested the optimum tracking point with a test tool and it showed the panel to produce 330 - 350W. The SCC was only delivering 270 - 290W while in bulk. The charge voltage was set to 24V there was no restriction put on charge current.

All this talk of series panels and cell count are non-issues -- at least they are suppose to be in a fully programmable SCC.

And still, no battery specs