I see that the Smart Shunt can send voltage and temperature information to the MPPT 100/20 charge controller, but can it send battery charge current that I can then use to set the "taper" setting on the charge controller? I have parasitic loads, so the charge controller would receive invalid charge current information using only its current output without using data from a shunt instead.
Hey @Cpt Pat ,
Absolutely it does that. See this text from the manual, link below:
Current sensing - The measured battery current is used by the charger so it knows the exact tail current at which the absorption stage should end and the float (or equalisation) stage should start. To measure the charge current all charge currents from all chargers are combined, or if a battery monitor is part of the network the actual battery current will be used.
Ps. I moved your question to the general Q&A. As this is standard functionality, no need to put it in Modifications.
Thanks for your answer. Do I understand correctly that the SmartSolar solar chargers will substitute the current data from a Smart Shunt in a VE network in place of the current output from the SmartSolar solar charger itself? I can't find any documentation that indicates that is the behavior.
A solar charger uses current only for one thing: to determine when to switch from the absorption stage (~14.4V) to the float stage (~13.5V).
and in VE.Smart it uses the current as measured by the shunt for that. Which makes it much better: it will switch from absorption to float when the battery no longer accepts a significant current, ie when its fully charged.
Instead of switching from abs. to float when the charger *thinks* the battery is fully charged.
All the best, Matthijs
Ps. I see the fonts issue in the new editor is affecting you too; lets hope its solved soon.
I have an issue that may be related to this. It seems the Smart Shunt current data is not being properly utilized by the MPPT controller. I have a smart solar 100/50 MPPT, a smart shunt connected to the negative post of an 80AH battery, and the output of the battery connected to a Phoenix inverter running a simple 100 W load. For background, I am an electronics engineer and I understand completely how these things work.
At one point the inverter demand was 10A and my battery was charging at 10A. Total output of the MPPT was 20A.
Under the VE Networking menu the MPPT said it was “using external battery current sense from smart shunt”
I thought ‘great, let’s test that’. So I set the MPPT’s battery max charge current to 7 A
What SHOULD have happened is the MPPT output should have decreased from 20 A down to 17 A. Leaving 10 for the load and now 7 going into the battery.
What DID happen is the MPPT output went down to 7A causing the battery to DISCHARGE at 3A to make up for the 10A the inverter required. Battery voltage was now decreasing.
That’s tells me the MPPT blindly set its output to the MPPT’s [battery max charge current] instead of looking at the shunt to see how much current is actually going into the battery.
If the MPPT controller does not use the Smart Shunt’s measured battery charge current to determine the value for its [battery max charge current] setting, this is either the world’s greatest missed opportunity for a feature or it’s a bug. It seems so obvious this is what should be occurring that I vote bug.
I have yet to determine if this happens at different current levels but it definitely happened as above. Still trying to characterize this.
As of July 27, 2021 I have all the latest firmware.
Hi @rmorgansd
It's not a bug. What you seek is nothing to do with the 'Tail' functionality of the mppt.
If you want current limiting, then you'll need to look further to DVCC. This requires a GX device, as there are complexities that arise with a mixture of kit. And even then there are limitations to what it can do. It will always honour the current limit set in the mppt anyway as first priority, so the mppt will never output more than it's own setting.
Thank you for the info. This is a real shame, and a missed opportunity for the MPPT to precisely control the battery charge current. Because with the smart shunt it has all the info it needs to do exactly what the name of the setting implies it will do ….set the Maximum Battery Charge Current. Any remaining current would be taken by the load, typically an inverter input
The MPPT already has the ability to throttle its output, it would be simple programming to allow the shunt reading to control the output the same as the user setting does.
I’ve designed industrial battery chargers and I’m frankly astonished it doesn’t give you this control since all the necessary ingredients are present, and it’s an expensive setup. In smaller battery systems it becomes necessary to pay attention to battery charge current. If you just leave it to the battery’s internal impedance to limit the charge it may be too high and damage the battery.
I suppose they have reasons for not making this work, but if that’s the case they should change the name of the setting from ”battery maximum charge current“ to something like “Maximum Output Current”, because it’s misleading.
Again, I appreciate your input.
‘Robert
I am in the same boat as you, I was about to pull the trigger and purchase the MPPT 150/100, the smartshunt, temp sensor, and the display but I just wanted to confirm that it would actually regulate the charge current before buying.
Its a shame that this cant be programmed as an option, its a simple verify the difference between the output SCC current with the shunt current, from this the SCC should be able to adjust to the configured current selected in the settings.
Thanks for your input on this @mvader (Victron Energy) , however, our testing has shown this is not working.
We logged an issue with this back in Nov 2020 with a response from @mkuiken that it is indeed an issue and it would be resolved soon.
https://community.victronenergy.com/questions/68013/mppt-10050-not-using-ve-smart-networking-voltage.html
We scan the releases thoroughly and have had no responses to indicate this has been fixed.
Do you have any verification this has been resolved and what version, please?
Thanks
David
But, not getting an answer on your issue in that other thread isn’t good; I’ll look into it and get back to you.
have a good weekend, Matthijs
