In my setup I have a Batrium connected to the Venus GX via CAN-bus to control the charging of the battery pack.

The battery pack is made up of 14s60p to have a 51.8V system (@ 3.7V nominal/cell)

The Batrium is setup for Lithium-ion long life, so it should only charge up to 57.4V (4.1V/cell).

The remote voltage (screenshot) defaults to 58.1V (4.15V/cell)

I did follow the guide from the Batrium site to get the Venus GX setup working, but it is not clear to what the Absorbtion and Float voltage parameters should be set at.

To my understanding, their is no float charging required with Li-ion?, but this cannot be disabled on the charger.

Anyone here with a similar setup who can advice?

If you research, you will find the most suitable voltage for Li-Ion is 3.90 V per cell. So, I would set to 14x3.9 V = 54.6 V. (FLOAT & ABS)

That is the best, because it avoids SEI and SEO effects in LI-Ion.

I agree with @Javi Martínez.

Yes but bear in mind these are not new cells ,  so to get the most out of them alot of folks use 4.1v

16 hours ago, seant said:

Yes but bear in mind these are not new cells ,  so to get the most out of them alot of folks use 4.1v

Sean, yes this is what the Batrium wizzard defaults to. and yes older cells

20 hours ago, Javi Martínez said:

If you research, you will find the most suitable voltage for Li-Ion is 3.90 V per cell. So, I would set to 14x3.9 V = 54.6 V. (FLOAT & ABS)

That is the best, because it avoids SEI and SEO effects in LI-Ion.

one cannot set the FLOAT & ABS to the same voltages on the Multiplus it only accepts a higher ABS value than the FLOAT (I don't understand why not the otherway around) 

My question is, should I set the ABS to a value that will never be reached (ie 60V) and the FLOAT to 57.4V.

with the current setting the charger stays in BULK mode all the time (Batrium just limits the current) 

Can you set the abs time? On the flexmax 80 I use I've set the abs time to 5hrs so it doesn't go into float. Then set your abs voltage  to slightly higher than you want for the full pack and the longmons should bleed off the extra power .

2 hours ago, vandyh said:

one cannot set the FLOAT & ABS to the same voltages on the Multiplus it only accepts a higher ABS value than the FLOAT (I don't understand why not the otherway around) 

You can if you enable DVCC on the color control. Then whatever charge voltage is sent by the BMS is used by the Multi and it ignores the veconfigure settings. In fact, then the whole notion of absorb and float goes away, the only voltage it cares about is the "MaxChargeVoltage" sent by the battery.

In veconfigure you are right though: float has to be lower. So just set absorb 0.1V higher :-)

On 2019/01/12 at 8:24 AM, seant said:

Can you set the abs time? On the flexmax 80 I use I've set the abs time to 5hrs so it doesn't go into float. Then set your abs voltage  to slightly higher than you want for the full pack and the longmons should bleed off the extra power .

Yes I can increase the ABS time, this can work

Edited January 14, 20197 yr by vandyh

On 2019/01/12 at 9:34 AM, plonkster said:

You can if you enable DVCC on the color control. Then whatever charge voltage is sent by the BMS is used by the Multi and it ignores the veconfigure settings. In fact, then the whole notion of absorb and float goes away, the only voltage it cares about is the "MaxChargeVoltage" sent by the battery.

In veconfigure you are right though: float has to be lower. So just set absorb 0.1V higher 🙂

Does the DVCC option have any other effect on the system other than the battery voltages?

So I can then set the ABS and float voltages on the veconfigure to 60 & 60.75V receptively as per the Batrium and Victron connection guide as it will be referenced by the Batrium with DVCC enabled?

Edited January 14, 20197 yr by vandyh

14 minutes ago, vandyh said:

Does the DVCC option have any other effect on the system other than the battery voltages?

DVCC is an acronym for Distributed Voltage and Current Control. It has effects beyond just battery voltages.

First and foremost, when you turn this on the BMS (if you have one) is in charge. If the BMS requests a particular charge voltage, then the entire system follows suit (including solar chargers). The voltages configured using veconfigure is ignored. If there is no BMS, then the veconfigure settings is used.

Second, for this to work the Multi must have a firmware version above 418 and the solar chargers must be above 1.29. So it is adviseable to update all to the latest.

Third, the Multi adds an offset to the voltage you specify depending on various circumstances. When DVCC is not used (ie the old way of doing things), it adds a bulk offset, which on a 48V system is a whole 4V. During bulk charge it uses this higher voltage. This is to ensure that any voltage drops on cabling is overcome and that the absorption voltage can be reached. Once it reaches absorption voltage, it removes the bulk offset. This voltage is known as the charge voltage, and consists of the voltage the BMS specified plus any added offset. When DVCC is ON however (and your firmware is 430 or newer), then the bulk offset is removed. This is important for LFP and other Lithium chemistries. In other words I am saying DVCC is kinda mandatory when messing with Lithium. I will explain that next.

Fourth, the charge voltage (including the offsets) are copied to all the solar chargers every 3 seconds. That means that the solar chargers potentially charge at a voltage higher than the Multi (to prioritise solar among others). This is why it is important to use the latest firmware and DVCC, because Lithium chemistries can spike to the higher voltage in less than 3 seconds, so it is better to have no offset at all. It avoids overvoltage events.

Fifth, when you use ESS with the feature "Keep Batteries Charged" or you enable "Feed-in excess solarcharger power", a 0.4V offset is added to the charge voltage, and the Multi and the Solar Charger gets into a tug-of-war (or Touwtrekkerij in the Dutch) where the Solar charger attempts to push the voltage up by 0.4V and the Multi attempts to drag it down, in other words it synchronises on the voltage. Powering the loads while keeping the batteries charged and without feeding into the grid is ONLY available if you enable DVCC. Additionally there is no fancy regulation here, if there is more power than loads, then the voltage rises by 0.4V. This is normally not a problem, but might be something to keep in mind.

Sixth, the Maximum Charge Current parameter sent by the BMS only works when DVCC is on.

So basically... you always want to use DVCC. It is the new way of doing things :-)

Where do you get to know all these things? 🤔 Many thanks!

let me explain my system.

AC-coupled system with Multiplus, Fronius PV inverter connected on AC-2 and Batrium BMS connected to Venus GX via CAN-bus. Simple

So, I've managed to set both ABS & FLT voltages the same to 58.1V (just in case the BMS looses connection)

With the DVCC enabled (with SVS & STS disabled) the BMS control shows ON.

I assume that only the BULK charge LED on the inverter will light up with these settings.

I'll run it for a while and see what it does.

 

   

6 hours ago, plonkster said:

DVCC is an acronym for Distributed Voltage and Current Control. It has effects beyond just battery voltages.

First and foremost, when you turn this on the BMS (if you have one) is in charge. If the BMS requests a particular charge voltage, then the entire system follows suit (including solar chargers). The voltages configured using veconfigure is ignored. If there is no BMS, then the veconfigure settings is used.

Second, for this to work the Multi must have a firmware version above 418 and the solar chargers must be above 1.29. So it is adviseable to update all to the latest.

Third, the Multi adds an offset to the voltage you specify depending on various circumstances. When DVCC is not used (ie the old way of doing things), it adds a bulk offset, which on a 48V system is a whole 4V. During bulk charge it uses this higher voltage. This is to ensure that any voltage drops on cabling is overcome and that the absorption voltage can be reached. Once it reaches absorption voltage, it removes the bulk offset. This voltage is known as the charge voltage, and consists of the voltage the BMS specified plus any added offset. When DVCC is ON however (and your firmware is 430 or newer), then the bulk offset is removed. This is important for LFP and other Lithium chemistries. In other words I am saying DVCC is kinda mandatory when messing with Lithium. I will explain that next.

Fourth, the charge voltage (including the offsets) are copied to all the solar chargers every 3 seconds. That means that the solar chargers potentially charge at a voltage higher than the Multi (to prioritise solar among others). This is why it is important to use the latest firmware and DVCC, because Lithium chemistries can spike to the higher voltage in less than 3 seconds, so it is better to have no offset at all. It avoids overvoltage events.

Fifth, when you use ESS with the feature "Keep Batteries Charged" or you enable "Feed-in excess solarcharger power", a 0.4V offset is added to the charge voltage, and the Multi and the Solar Charger gets into a tug-of-war (or Touwtrekkerij in the Dutch) where the Solar charger attempts to push the voltage up by 0.4V and the Multi attempts to drag it down, in other words it synchronises on the voltage. Powering the loads while keeping the batteries charged and without feeding into the grid is ONLY available if you enable DVCC. Additionally there is no fancy regulation here, if there is more power than loads, then the voltage rises by 0.4V. This is normally not a problem, but might be something to keep in mind.

Sixth, the Maximum Charge Current parameter sent by the BMS only works when DVCC is on.

So basically... you always want to use DVCC. It is the new way of doing things :-)

Where do you get to know all these things? 🤔 Many thanks!

let me explain my system.

AC-coupled system with Multiplus, Fronius PV inverter connected on AC-2 and Batrium BMS connected to Venus GX via CAN-bus. Simple

So, I've managed to set both ABS & FLT voltages the same to 58.1V (just in case the BMS looses connection)

With the DVCC enabled (with SVS & STS disabled) the BMS control shows ON.

I assume that only the BULK charge LED on the inverter will light up with these settings.

I'll run it for a while and see what it does.

On 2019/01/11 at 8:12 AM, vandyh said:

The battery pack is made up of 14s60p ......

I assume you mean 6p ?

I've got a similar setup - WM4 + Expansion + Leaf cells.

The advice given above, saying the BMS is in control, is spot on, it's very well integrated. I use shunt LVD, or any low cell critical logic to load shift AC, with inverter off slightly below. I've also got motorised DC breakers to disconnect the DC feed, just in case. I'm still tweaking the charge cease settings, setting limited charge while in bypass while not actively cooling is my aim - given the dissipation of the bypass components this will likely be less than a few amps.

I've somewhat changed my views on this BMS since connecting it to a MultiPlus. I've previously rejected this BMS for a commercial project (far to many bugs) - I'm now using the rejected components to build an ESS for home, and so far its impressed me in this home setup (but still has a shunt lockup when in/out of bypass to be address by the folks)

Currently have a 24kWh pack in service - with 3x 30kWh packs and another 24kWh pack to be reassembled.

Existing system is 2kW DC MPPT, 8kW 2 aspect AC into a Fronius Primo 8, an OhmPilot, a homemade surplus cascade switch - 6kW of wind.

New member from Orkney.

Hello.

5 hours ago, Sean said:

I assume you mean 6p ?

I've got a similar setup - WM4 + Expansion + Leaf cells.

The advice given above, saying the BMS is in control, is spot on, it's very well integrated. I use shunt LVD, or any low cell critical logic to load shift AC, with inverter off slightly below. I've also got motorised DC breakers to disconnect the DC feed, just in case. I'm still tweaking the charge cease settings, setting limited charge while in bypass while not actively cooling is my aim - given the dissipation of the bypass components this will likely be less than a few amps.

I've somewhat changed my views on this BMS since connecting it to a MultiPlus. I've previously rejected this BMS for a commercial project (far to many bugs) - I'm now using the rejected components to build an ESS for home, and so far its impressed me in this home setup (but still has a shunt lockup when in/out of bypass to be address by the folks)

Currently have a 24kWh pack in service - with 3x 30kWh packs and another 24kWh pack to be reassembled.

Existing system is 2kW DC MPPT, 8kW 2 aspect AC into a Fronius Primo 8, an OhmPilot, a homemade surplus cascade switch - 6kW of wind.

New member from Orkney.

Hello.

Hi,

I've made my own battery pack of 18650 cells (60P x 14S) around ~5.2kWh

Batrium WM4 + 14 cellmons + shuntmon2

ESS system with Multiplus with Fronius Primo on AC_out

My limited charge power set to 1.2A and seems to work fine and allow sufficient cooling to the longmons.

What shunt lockup are you referring to?

My system works good with the DVCC setting switched on, but now the inverter on LED keeps on flashing while supplied by mains.

I see that this happens when the shunt reads negative (when it consumes power), but I will always draw a few Watts as I have a DC bus to power the watchmon and Venus GX  

34 minutes ago, vandyh said:

My system works good with the DVCC setting switched on, but now the inverter on LED keeps on flashing while supplied by mains.

That is perfectly normal. It does that when it runs parallel with the grid.

60P with 18650s makes sense, for some reason I thought you'd used rather a lot of leaf cells.

The shunt lock up, was a known issue, that 2.07 was supposed to resolve (previously attributed to weak wifi) - mine still does it, Jaron is aware, I'm yet to let him remote in - I expect it will be resolved.

I'm using the LeafMons, they do get rather to warm rather quickly when in bypass.

Our grid is very stable, so my AC PV is on mains in, system is grid parallel - wind is split between 3kW AC, the remainder into a DC charge controller (Outback) - the wind input here is significant.

Mr Plonkster, could I say a public thank you for you having taken the time on this forum, to share your in depth knowledge of the Victron range. This knowledge, of how systems actually work, does make configuration far less suck it and see. While the Victron documentation is good, it lacks any detail as to the inner logic and operation.

 

 

 

Edited January 22, 20197 yr by Sean

12 hours ago, plonkster said:

That is perfectly normal. It does that when it runs parallel with the grid.

Ok great.

Can you please clarify the following settings: "has DC system" (I see no change when enabling this) and SVS & STS 

9 hours ago, Sean said:

The shunt lock up, was a known issue, that 2.07 was supposed to resolve (previously attributed to weak wifi) - mine still does it, Jaron is aware, I'm yet to let him remote in - I expect it will be resolved.

Have you tried installing the Alpha release v2.09rc?. (Maxine recommended it for known CAN-issues)

12 minutes ago, vandyh said:

Can you please clarify the following settings: "has DC system" (I see no change when enabling this) and SVS & STS 

In some installs some loads run directly from the battery. Venus can calculate this, because it will see them via the battery monitor (the BMS or the BMV), but it won't be accounted for in the vebus current (power drawn by the inverter). It can then show this difference power in a little box on the screen. But it doesn't make sense to show this box unless the user wants it, and because there is always a slight discrepancy between what the battery and the Multi reports, it is not sufficient to merely check if this "ghost current" is zero. The box only show up on the Overview screen (the balls screen as we sometimes call it), in the bottom middle of the screen between the battery and the solar charger.

So the idea is that you turn this feature on if you actually have DC loads.

STS is shared temperature sense. If the battery publishes its temperature, then this is copied across to the Multi and the Multi can compensate for temperature. There is really just one useful configuration for this: A BMV 702 with a temperature sensor attached to a lead acid bank. If the battery does not publish temperature values, then STS does nothing.

SVS is shared voltage sense. The system automatically selects a suitable device that serves as the master voltage reference. Usually it will pick the battery (the BMS or a BMV), but if it has neither of those, it uses the Multi. It will then periodically communicate the voltage of the selected reference to the other devices, and those other devices can then calculate a delta. The delta corresponds to any calibration differences and losses on the cable. It essentially causes the different devices to agree more closely on voltage, which is required for smooth operation of things like Feeding in excess solar power, which relies on an overvoltage of a mere 0.4V (and can therefore be rendered useless if you have that much in calibration or losses).

Both SVS and STS only syncs every few seconds. STS is fine, but in rare cases SVS can cause strangeness. To give one example, let me use a Pylontech battery that has requested for a charge voltage of 53.2V. We're attempting to feed in the excess PV power as well, so we've told the solar chargers to charge to 53.6V, and we have an 0.1V calibration issue and an 0.3V drop on the cable as well, which is compensated for, so our solar chargers are really aiming for 54V. Then a sudden change in load causes the 0.3V drop on the cable to lower to 0.1V, but because SVS only syncs every few seconds there now exists a window in which the solar chargers are aiming for 54.2V. The BMS however disconnects at 54V.... and *click*... it is dark.

So when using SVS, it is adviseable to stay well clear of cut-off voltages. Which is already done: Pylontechs are charged only to 52V.

1 hour ago, vandyh said:

Have you tried installing the Alpha release v2.09rc?. (Maxine recommended it for known CAN-issues)

I wasnt aware of that release, I dont see any mention of it on their site yet, I'm in no rush just now so I'll likely wait untill it's a full release.

What issues is it intended to resolve .

Is yours fully working ?

 

 

14 hours ago, plonkster said:

In some installs some loads run directly from the battery. Venus can calculate this, because it will see them via the battery monitor (the BMS or the BMV), but it won't be accounted for in the vebus current (power drawn by the inverter). It can then show this difference power in a little box on the screen. But it doesn't make sense to show this box unless the user wants it, and because there is always a slight discrepancy between what the battery and the Multi reports, it is not sufficient to merely check if this "ghost current" is zero. The box only show up on the Overview screen (the balls screen as we sometimes call it), in the bottom middle of the screen between the battery and the solar charger.

So the idea is that you turn this feature on if you actually have DC loads.

SVS is shared voltage sense. The system automatically selects a suitable device that serves as the master voltage reference. Usually it will pick the battery (the BMS or a BMV) .......

I've been pondering trying to separately meter DC charge input from a non Ve device (wind, on an Outback CC) but through a BMV and shunt.

The main system shunt is the BMSs, which appears to be reporting correctly - if a second shunt (connected on DC wind CC output) was introduced (connected directly to battery, thus bypassing the BMS shunt) would Venus still correctly give the BMS shunt top priority as the voltage source reference, and would the DC charge be depicted separately (attached to the DC load) within the overview screen.

Perhaps not bypassing the BMS shunt would be a better option as the SoC reporting wont be correct unless the BMS shunt sees the throughput.

37 minutes ago, Sean said:

would the DC charge be depicted separately (attached to the DC load) within the overview screen

You can select the main battery service on the System Setup page in the GUI, and you can set that to the BMS. Your other shunt will however show up as a battery (which is incorrect, it is a wind charger), but you can still do it if you really want. It is not going to show up on the overview. It will however be logged to VRM.

38 minutes ago, Sean said:

Perhaps not bypassing the BMS shunt would be a better option as the SoC reporting wont be correct unless the BMS shunt sees the throughput.

Yup, don't do that 🙂

Thanks Mr Plonkster.

The problem with data, is that once you start getting some, you just keep wanting more.

I used to be happy with a 30 - 0 - 30 centre zero ammeter and a voltmeter (checked once a day).

22 hours ago, plonkster said:

In some installs some loads run directly from the battery. Venus can calculate this, because it will see them via the battery monitor (the BMS or the BMV), but it won't be accounted for in the vebus current (power drawn by the inverter). It can then show this difference power in a little box on the screen. But it doesn't make sense to show this box unless the user wants it, and because there is always a slight discrepancy between what the battery and the Multi reports, it is not sufficient to merely check if this "ghost current" is zero. The box only show up on the Overview screen (the balls screen as we sometimes call it), in the bottom middle of the screen between the battery and the solar charger.

So the idea is that you turn this feature on if you actually have DC loads.

STS is shared temperature sense. If the battery publishes its temperature, then this is copied across to the Multi and the Multi can compensate for temperature. There is really just one useful configuration for this: A BMV 702 with a temperature sensor attached to a lead acid bank. If the battery does not publish temperature values, then STS does nothing.

SVS is shared voltage sense. The system automatically selects a suitable device that serves as the master voltage reference. Usually it will pick the battery (the BMS or a BMV), but if it has neither of those, it uses the Multi. It will then periodically communicate the voltage of the selected reference to the other devices, and those other devices can then calculate a delta. The delta corresponds to any calibration differences and losses on the cable. It essentially causes the different devices to agree more closely on voltage, which is required for smooth operation of things like Feeding in excess solar power, which relies on an overvoltage of a mere 0.4V (and can therefore be rendered useless if you have that much in calibration or losses).

Both SVS and STS only syncs every few seconds. STS is fine, but in rare cases SVS can cause strangeness. To give one example, let me use a Pylontech battery that has requested for a charge voltage of 53.2V. We're attempting to feed in the excess PV power as well, so we've told the solar chargers to charge to 53.6V, and we have an 0.1V calibration issue and an 0.3V drop on the cable as well, which is compensated for, so our solar chargers are really aiming for 54V. Then a sudden change in load causes the 0.3V drop on the cable to lower to 0.1V, but because SVS only syncs every few seconds there now exists a window in which the solar chargers are aiming for 54.2V. The BMS however disconnects at 54V.... and *click*... it is dark.

So when using SVS, it is adviseable to stay well clear of cut-off voltages. Which is already done: Pylontechs are charged only to 52V.

Thanks, I understand the workings