New Victron MPPT Firmware

[noelex 77]

Victron have released new firmware for their solar controllers (1.42). It includes an “expert” mode that allows the adjustment of settings that were previously fixed.

Importantly, it allows for tail current to be adjusted or even disabled. Yeah! This should remove the serious and annoying conflict that I have been complaining about for a long time. It occurred when multiple solar controllers (or other charge sources) were used.

Thank you Victron . This removes a major problem with these controllers.

Caution:
I have only just loaded this software. It appears very stable and adds a great deal of functionality, but I have not had a chance to fully evaluate how it works.

[conachair]

Sounds great, especially adjustable tail current. thanks for the heads up

[noelex 77]

The other advantage of the tail current adjustability is that you can now force the controller to drop down to float. It is a slightly messy work around, but it is better than altering the absorption voltage to the float voltage setting, which was the only solution before the tail current adjustability was added.

[Mike OReilly]

Cool. I just did the update, but didn’t really know what it was updating. Probably wouldn’t even have noticed the change since I just use the defaults. But maybe I should start to play.

You know what they say about a little knowledge .

[john61ct]

Does this change allow all the SCs to drop to Float based not off their individual tail current readings, but the centralized one reading **bank acceptance** off the BMV shunt?

[noelex 77]

Originally Posted by john61ct

Does this change allow all the SCs to drop to Float based not off their individual tail current readings, but the centralized one reading **bank acceptance** off the BMV shunt?

I don’t have a BMV shunt (I am using a Pico system) so I am not sure what happens when this is added. I would hope it allows the shunt to control the tail current presumably with the solar controllers tail current disabled, but this is just speculation. Someone with the shunt will need to try and see.

I have been playing around with settings today and so far it is working just as I hoped it would. One of the solar controllers no longer drops into float prematurely and incorrectly, which previously was a nuisance.

[Davidhoy]

Originally Posted by noelex 77

Victron have released new firmware for their solar controllers (1.42). It includes an “expert” mode that allows the adjustment of settings that were previously fixed.

Importantly, it allows for tail current to be adjusted or even disabled. Yeah! This should remove the serious and annoying conflict that I have been complaining about for a long time. It occurred when multiple solar controllers (or other charge sources) were used.

Thank you Victron . This removes a major problem with these controllers.

Caution:
I have only just loaded this software. It appears very stable and adds a great deal of functionality, but I have not had a chance to fully evaluate how it works.

For those of us unfamiliar with "tail current", would you mind explaining? Very interested as I'm in the midst of a solar upgrade on my boat, and have two LG NeON 350 watt panel (already installed) about to be connected to independent Victron SmartSolar 100/30 MPPT controller....

-David

[RickG]

So very happy to hear. With Fireflys the tail current setting is key. We splash the boat in October and this software update will be a priority. I am going to read the release notes and the Victron Q&A forum is active on the subject.

https://community.victronenergy.com/...arging-ti.html

Cheers, RickG

[RickG]

Originally Posted by Davidhoy

For those of us unfamiliar with "tail current", would you mind explaining? Very interested as I'm in the midst of a solar upgrade on my boat, and have two LG NeON 350 watt panel (already installed) about to be connected to independent Victron SmartSolar 100/30 MPPT controller....

-David

As the battery completes charging internal resistance slows the current that the battery can accept. Battery manufactures define what that tail current for the transition from absorption to float. On my Firefly batteries the tail current is 1.5amps. Without the ability to set tail current my Fireflies have been flipping to float early. There is more to it. You can read the posts in the Victron Q&A link above.

Cheers, RickG

[sailcrazy]

following. We have a Victron solar controller, and this is the first we've heard about this upgrade.

[Mark Thurlow]

One thing I learnt today- Victron firmware is automatically notified when available but not if connecting by an (iPhone) phone. I connected with a tablet and it all clicked through!

Mark

[noelex 77]

Originally Posted by Davidhoy

For those of us unfamiliar with "tail current", would you mind explaining?

A major part of charging lead acid batteries correctly is the transition from the absorption voltage (typically around 14.7v) to the float voltage (typically around 13.8v). Leave the batteries at the absorption voltage for too long and the batteries will be “overcharged”, shortening their life. On the other hand, changing to float voltage too early will undercharge the batteries, once again shortening their life. It is important to realise that slight overcharging is much better than slight uncharging, but the ideal is for the solar controller to pick the correct transition point.

The ideal way is to measure the voltage and current entering the battery. At absorption voltage the current entering the battery will gradually reduce and when this reaches around 1% of battery capacity (so 4A for a 400 AHr battery) this is an appropriate point to drop down to float. The 1% number is debatable and depends on the battery type, but the ideal range is narrow (0.5% to 2%) as the current drops off rapidly as the battery becomes charged. This 4A number is the tail current.

Unfortunately, this requires communication with a shunt close to the battery, which is not available in many systems. In the absence of this, ideal system controllers try to pick the point of transition without knowing how much current is entering the battery. This is normally done by holding the absorption voltage for a set (but adjustable) time, usually around two hours. This sounds hit and miss and in many ways it is, but with some care selecting the absorption time it can still work well.

The Victron controllers have incorporated a second method by using a tail current setting into the algorithm, but the solar controller on its own cannot measure the current entering the battery, only the current leaving the solar controller.

The Victron controllers were previously fixed with a tail current value of around 1A (this depended on the size of the controller). So if the solar controller was putting out 1A or less and the battery voltage was at the absorption value, the solar controller would assume the battery was charged and drop down to float. The problem with this system is that it does not work with multiple charge sources and most boats have multiple charge sources. Particularly in the case of multiple solar controllers, the tail current caused problems with one or more of the solar controllers dropping to float too early because the controllers tail current criterion had been met.

For example, with two solar controllers set for the same absorption voltage, when the battery needs say 5A to maintain absorption voltage, ideally each controller would supply 2.5A, but this never happens. In practice one controller might supply 4A and one supplies 1A. This is due to slight manufacturing and wiring differences. It is of no consequence to the battery, as it receiving the correct voltage and current, but the solar controller supplying only 1A concludes the battery must be charged, because the voltage is high and the current is low. The but solar controller does not realise the voltage is high because another charge source (the other solar controller) is supplying 4A of current. Thus the change to float is incorrect.

Very few solar controllers incorporate a tail current criteria into their algorithm unless they can communicate with a battery shunt for this reason, but it was until recently a fixed and unchangeable part of the Victron controllers.

Without a battery shunt communicating with the controller the “tail amp” setting is not the real tail amp setting so unfortunately you cannot set the value to the number quoted by the battery manufacturer.

If you have a boat with multiple solar controllers this is very likely to be causing one solar controller to drop to float incorrectly. Even with one controller and a smart alternator controller, there is a reasonable chance this setting was causing problems. If you leave the boat for long periods with no loads, or have a motor home or home solar system, the tail current setting is likely to be helpful, but for most boats that meet the above criteria it is much better turned off. Now you can.

[noelex 77]

Absorption time:

The Victron controllers have always used a strange absorption time that counts down even when the absorption voltage is not met.

It seems this has all changed with the 1.42 firmware. The absorption time now takes voltage into account, as it should do. Confusingly it does not indicate a return to bulk mode when the absorption voltage is not being met, but this is effectively what is happening.

The net effect is absorption timing will be very different to the previous firmware version. The default absorption time does not seem to have been changed to compensate for this, but I think this will need to be done.

The bottom line is that with this software update there appears to be a major change in the algorithm even if you stay with the default settings. It is a change for the better. I have been grumbling about these quirks of the Victron controllers for some time, but it like getting a new controller. It works nothing like the old model. It will take some time to evaluate these changes, but I expect the controller to perform very differently following the firmware upgrade.

[john61ct]

Originally Posted by Davidhoy

For those of us unfamiliar with "tail current", would you mind explaining?

A battery is full, only when the Absorb Voltage is held long enough for the current accepted by the bank to fall to a certain C-rate, aka endAmps, spec'd by the manufacturer.

A charge source should be adjusted so it does not drop voltage to Float, until after that has occurred, ideally most cycles. But not too long after, for chemistries sensitive to overcharging.

Most charge sources only know their output current, so if loads are running no way of knowing amps accepted by the bank.

Hence coordination with a central BM is the ideal.

Edit: see #12, likely goes into greater depth

[BigAl.NZ]

Originally Posted by noelex 77

Without a battery shunt communicating with the controller the “tail amp” setting is not the real tail amp setting so unfortunately you cannot set the value to the number quoted by the battery manufacturer.

If you have a boat with multiple solar controllers this is very likely to be causing one solar controller to drop to float incorrectly. Even with one controller and a smart alternator controller, there is a reasonable chance this setting was causing problems. If you leave the boat for long periods with no loads, or have a motor home or home solar system, the tail current setting is likely to be helpful, but for most boats that meet the above criteria it is much better turned off. Now you can.

Thanks for the detailed explanation.

Are you suggesting for boats with multiple charge sources the tail current is best switched off? (We have Alternator+Solar)

Does the new FW allow the SC to communicate with a BMV712 on the same network?