Victron solar controller.

[Admin]

But the smart battery sense linked to by clarkpeacock WOULD enable correct charge voltage yes? Victron blurb says:-
"By measuring voltage at the battery bank terminals, errors arising from voltage-loss due to cable resistance are avoided - guaranteeing the correct charge-voltage."
Just confused about the shunt doing the same job as the smart sense (re charge voltage control) which you seemed to suggest it did. Maybe I got the wrong idea or the smart sense doesn't live up to the blurb??
Confused!!

The Bluetooth Victron shunts can also report the battery voltage to the MPPT. The shunt can also report battery temperature if you use its aux pin for that. There is no point in having a Smart Battery Sense if you have a Victron Bluetooth shunt.

 

[Admin]

My thoughts as well. I have three systems with multiple charge controllers and large lead acid battery banks, each using a smart sense which seem to do just that. ( I live off grid so rely on solar completely for domestic power)

I installed these primarily for the temperature compensation feature on the recommendation of Rolls batteries.

Maybe I misunderstood the Victron description?

Here's one of my systems;
View attachment 122533

Temperature compensation is important with lead-acid batteries. Lithium batteries have their own battery management systems with internal sensors.

In this thread, we are talking about 1 Cup's installation, where he has lithium batteries and a Bluetooth shunt. He can connect them together on a smart network and get better battery voltage data to the MPPT. This will stop the MPPT from going into absorption or float prematurely.

Having a large voltage drop means that his batteries will charge slower and take fewer amps even if the MPPT can provide its full output. The only way that the MPPT could compensate is to increase the output voltage to above the max charge voltage. Imagine that the solar controller is connected to a busbar, and the high resistance is after that busbar. The busbar could have a much higher voltage than the system voltage and could damage accessories connected to it.

The answer is to set up the system correctly to minimise the voltage drop. In this case, it needs the solar controller moved close to the batteries and setup the smart network between his shunt and MPPT.

 

[merl]

Still not sure I follow Phil.
I get that any resistance in the line will affect charge rate and efficiency, I also fully understand the temp comp issue with LA and Lifpo4, those are a given but I'm trying to get my head around why using the shunt to relay back info to the MPPT to increase the battery voltage is potentially harmful when Victron advocate doing exactly this with the battery sense?
You mention the voltage drop AFTER the buss-bar but surely that wont change when he moves the controller anyway so IF voltage drop AFTER the buss-bar is a potential issue then this needs addressing anyway no matter where the MPPT is placed?
Maybe I don't fully understand the intricacies of 1Cups wiring around the batteries/multiplus? Sorry if I'm being a pain in the ass but 'not knowing' is an issue for me, I've had it all my life and seems to run in the family, pretty sure I'm on some spectrum somewhere so only reply if you've got the time and inclination, I'll understand.

 

[1 Cup]

I'm now looking for M10 bus bars 6 holes and covers ? X2 plus 2 M8 plus covers

 

[Admin]

I'm trying to get my head around why using the shunt to relay back info to the MPPT to increase the battery voltage is potentially harmful when Victron advocate doing exactly this with the battery sense?

I said that he should use the shunt to give better voltage data to the MPPT.

You mention the voltage drop AFTER the buss-bar but surely that wont change when he moves the controller anyway so IF voltage drop AFTER the buss-bar is a potential issue then this needs addressing anyway no matter where the MPPT is placed?

I am talking here as a what-if. If there is a system where the voltage drop is after a busbar that feeds accessories, then that busbar could potentially have a voltage that would damage accessories if the MPPT raised its output voltage for a poorly designed system. Victron MPPT controllers do not output more voltage than the absorption voltage, regardless of the data sent to them.

Maybe I don't fully understand the intricacies of 1Cups wiring around the batteries/multiplus? Sorry if I'm being a pain in the ass but 'not knowing' is an issue for me, I've had it all my life and seems to run in the family, pretty sure I'm on some spectrum somewhere so only reply if you've got the time and inclination, I'll understand.

The Smart Battery Monitor or Victron shunt provides data to the MPPT controllers to prevent them from going into absorption or float charging before the battery has reached the fully charged voltage. This is happening on 1 Cups system and would be resolved by linking the shunt to the MPPT. He should do this regardless of moving the solar controller, which he definitely needs to do.

 

[1 Cup]

My old 100ah battery has the smart shunt still connected. The new stand alone battery that runs invertor is connected to mppt. Now moving the b2b charges the 100ah. And I'll swap as and when now both at 80% ish

ish

 

[1 Cup]

Victron Solar controller. for stand alone batteries charging with no smart shunt .

If I put settings on mttp at 14.2 v and charge 100ah fully and then piggy back 280ah times 2 without bms will the solar mttp exta go into China batteries?

Shunt only on relion 100ah still. And i have also lowering battary 5% each time it reach 100% soc as itseems to have come out of sink Volatage is not raching 13.5v on mttp ?

 

[Admin]

Victron Solar controller. for stand alone batteries charging with no smart shunt .

If I put settings on mttp at 14.2 v and charge 100ah fully and then piggy back 280ah times 2 without bms will the solar mttp exta go into China batteries?

Shunt only on relion 100ah still. And i have also lowering battary 5% each time it reach 100% soc as itseems to have come out of sink Volatage is not raching 13.5v on mttp ?View attachment 122994

Your settings are wrong, change them to:
Charged voltage: 14.2v
Tail Current: 1%
Peukert exponent: 1.05
Charge efficiency factor: 99%