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chrispi avatar image
chrispi asked

DVCC voltage share doesn't work with cerbo Gx, BMV712 and 3xMPPTs

Hi all,

DVCC voltage sense share doesn't work with my 3 MPPT 50/100

I have a system installed in my boat that consists of 1 Multi, 3x 50/100MPPT, BMV712 on the lithium battery, all connected to a cerbo GX and with an electrodacus BMS that's not connected to cerbo. All show up in the device list of cerbo and updated to newest firmware, the BMV712 is correctly configured as battery monitor in system setup of cerbo.

BT link is off, so this doesn't interfere.

DVCC is on and voltage sense share on too. BMS control off or automatic, shows none (tried both)

Due to mvader and manual dvcc with voltage sense share still works but it doesn't.

my system overview shows:

use solar charger current to impove SOC: ON

Shared voltage sense : OFF

Due to manual the voltage sense also works when no BMS is in control.

My issue that the 3x 50/100MPPT only have one VE-direct port and connect that to cerbo to get data for monitoring but I also need to cut all 3 off with a battery protect when lithium is full. This was recommended by mvader to me, you can also find this setup on a victron reference diagramm. The issue with the MPPT (2x are Smart BT but one not)if cut off with BP the MPPT don't see the battery voltage and go haywire and rise voltage till BP220 goes with 16V into overvoltage protection and BMS cannot connect them again. This problem should be solved by using DVCC with shared voltage sense as they get the voltage this way. I did as told but it doesn't work.

What's the issue here?







cerbo gxdvcc control for solar
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8 Answers
snoobler avatar image
snoobler answered ·

Is your BMV setup as a battery monitor or energy meter?


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chrispi avatar image chrispi commented ·
It's configured as battery monitor and also set in system setup as battery monitor for soc.
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Alexandra avatar image
Alexandra answered ·

@ChrisPI

What exactly is happening? Are the batteries being overcharged (amps or voltage) and BMS going into protection?

Are all the mppts configured exactly the same?

With the BMV as the battery monitor, that should be the voltage the system uses for charging. Are you now trying to limit charge amps?


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chrispi avatar image chrispi commented ·

See above.

The Electrodacus BMS is not connected to cerbo and steers all charge and load as spider in the Web. Cerbo is just for monitoring and gets bank data from a BMV712 configured as battery monitor, also in system setup.

As the 3x 50/100 have only a ve-direct port they get switched off on the charge side by a BP220 by the BMS when bank is full. Problem is when switched off by the BP220 the 3 MPPT( 2xsmart,1 non smart) don't see the battery voltage anymore and raise the output voltage till >16V and then battery protect goes into overvoltage mode and charge cannot be switched on by BMS when bank is discharged. To prevent this due to mvader I can use DVCC and switch shared voltage sense and the MPPT get their battery voltage from the BMV712 also when disconnected.

But that's not working.

Followed all steps in the manual...

What's also strange is I have the multi battery monitor off in the settings and a BMv712 but in system status it shows "Use solar charger current to improve VE.Bus SoC" on which means the soc of the multi gets improved when no Managed battery, BMS or BMV is present but I have BMV712 so that should be off but its on.

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Alexandra avatar image Alexandra ♦ chrispi commented ·

[Removed _irrelevant question]

Are the mppts programmed to the correct voltages? This matters. They will stop charging on their own when they reach target voltage set and reported by the BMS.

Is all the firmware up-to-date or was it updated on install.

What is the battery protect for and it's function in the system? [More irrelevant suggestions removed -no remote on the 100\50].

The battery protect under normal condition should not switch off.

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chrispi avatar image chrispi Alexandra ♦ commented ·

The DVCC with voltage sensing but no BMS controlling work independently from the parameters in the mppts, it just shares the bank voltage measured by the BMV712 as reference voltage to all other devices so voltage drop by cables,fuses,connections don't fool them or like in my case when disconnected getting the bank voltage delivered by network as reference.

DVCC is simply not working, i have a simple system BMV712, 3MPPT,1 multi all connected to cerbo, BMV712 set up as battery monitor also in system setting.

DVCC on, voltage sense share on and no BT network and its simply not working.

To my system:

Yes they are programmed as per instruction of electrodacus BMS, which is 14,4V absorption and 13,8V float but electrodacus switches off at 3,55V so 14,2V. This is on purpose as electrodacus is in full control as spider in the Web as it is the only source that knows the cell voltages and SOC, different philosophy and many systems run flawlessly incl. Mine before adding cerbo for simple monitoring. Electrodacus has a specific end of charge parameter which triggers the disconnect of the charge sources. The parameters of the MPPT are a 2nd line of defense in case BMS fails which due to design flaw that 50/100 remote output is hot means on when cable gets disconnected is not working. absolute noGO in EE and shame on victron for not fixing this, so I need to fix this. To work around this issue and also to be able to get the data of 3 MPPT into cerbo via VE-direct into cerbo mVader suggested to use a BP220 which switches all 3 MPPT on/off in normal operation and also disaster disconnect by electrodacus BMS. As the 3 MPPT (one not smart) don't see battery voltage they raise voltage output and BP220 goes in overvoltage lock and cannot be switched on unless I interrupt the solar input via breaker. To avoid this due to MVader I can simply use DVCC with voltage sense and the BMV connected as battery monitor, means the MPPTs get the bank voltage from BMV via ve-direct. And that DVCC voltage sense share is not working as BMV has 13,32V bank voltage, the multi shows 13,26V and 3 MPPT show 13,24/13.22/13.21V and if I am disconnecting the BP220 manually it goes right away in overvoltage lock. If I switch DVCC off and create at BT network with BMV712 and the 2 smart MPPT that works flawlessly but as soon as i add a) the 3rd MPPT doesn't work and again the BP220 goes into overvoltage, only if I disconnect if from cerbo and switch it via ve-direct remote adapter cable it works but I don't have the 3rd MPPT in cerbo monitoring. So BT network switched off, DVCC+voltage sense share and all souces show their voltage but not the BMV712 as reference voltage. So it's obvious there is an issue with the DVCC, question is where is the issue?

The issue seems to me that the cerbo doesn't see the BM712 as reference for voltage and therefore has nothing to share.

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snoobler avatar image snoobler chrispi commented ·

Your base configuration is completely wrong. You are literally creating the problem for yourself.

If this configuration is per Electrodacus recommendations, it's a piss poor configuration. It's a BAD idea. Your charge controllers should be set to LESS than the BMS cut-off. Period. No exceptions.

Your MPPT should be set for absorption < Electrodacus cut off and float = 13.5V

The idea of cutting off DC charge on an active charger routinely is a good way do damage chargers.

Until you correct your base configuration from a deeply flawed approach, DVCC functionality is moot.

Fix your configuration.

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snoobler avatar image snoobler chrispi commented ·

Per @Alexandra all of your MPPT should be set for absorption and float voltages suitable for the chemistry and should be set to terminate normally before the Electrodacus triggers disconnect, e.g., charge to 3.55V/cell, but the Electrodacus is set to trigger protection at 3.65V/cell.


BMS should not be relied upon for routine charge/discharge termination. They are safety devices that should only be triggered when things go sideways.


@Alexandra does the 100/50 have remote on/off? I don't think they do.



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Alexandra avatar image Alexandra ♦ snoobler commented ·
Huh, you are correct @snoobler, they do not have a remote on off.


My apologies @ChrisPI for the misdirect. I am used to working with the bigger units, they all have them and that is how we have our safety on.


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chrispi avatar image chrispi Alexandra ♦ commented ·

Yes they only have ve-direct which can be switched with a special ve-direct remote cable but if that cable gets disconnected due to any reason the MPPT stays on...not safe. And to be able to get them into cerbo and also switch them with BMS I was recommended by mvader to use the BP220 in combo with DVCC...

On boats for bifacial panel you want one mppt per panel and the 50/100 fit perfect in 12V (which still majority of boats are) for the new 700W panel class which is the new standard. And that victron is not adding a remote or at least offer an ve-direct adapter cable that can remote steer AND connect to cerbo (I know that's possible) is very poor product management.

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chrispi avatar image
chrispi answered ·

The issue with DVCC here I assume is that the cerbo doesn't see the BMV as reference voltage/best voltage in system and has nothing to share.

That DVCC is working in background i can see when I can add one mppt to ve.smart BT connection and as soon as I want to add 2nd that's not possible. Only when I switch DVCC off and switch off the multi via hardware switch to reset VE-Direct (which again stands nowhere in the manual and I by accident found when I done research what could be the issue) I can add the 2nd mppt and the BMV712 to the BT network. If enable then DVCC I cannot delete the BT network, only when I delete the DVCC and then switch off the multi with hardware switch to reset VE-direct only then I can delete the BT network.

Again these procedures stands nowhere. And that BT VE.smart and DVCC interferes and shouldn't be used together also not.

So I completely deleted all BT networks (was already the case but for test above i made one with BMV712 and 2 smart MPPT) and reset again the ve-direct network and then switched on DVCC but no change....

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chrispi avatar image
chrispi answered ·

Could you please help with the DVCC not working.

As described System is all Victron (besides BMS) and fairly simple:

BMV 712, 3x50/100 MPPT, multi 12/3000 connected via ve-direct and ve bus to cerbo GX running newest release. The cerbo does only monitoring, battery data via BMV712. The LFP bank has an Electrodacus BMS which steers the load and charge like Victron smart BMS via Victron remotes and is not connected to cerbo.

DVCC is not working, neither voltage share or current limiting.

No VE smart networking, ve bus was reset by switching on/off multi via hardware switch, cerbo rebooted. BMV712 set as battery monitor in settings of cerbo and no bms in control.

The multi has the BT dongle, I tried with and without dongle connected. Can keep it connected for DVCC or not, stands nowhere and till now no info from anyone on that.

I simply need DVCC so it’s sharing the bank voltage from BMV with all the other devices, especially the MPPTs.. As I need the ve-port of the 50/100 MPPT for monitoring I used a BP220 smart to switch on/off the 3 MPPTs as it was suggest by mvader and can also be found on the reference install diagram for the Victron smart BMS. Problem is without DVCC the MPPTs don#t see battery voltage when BP220 disconnects them and go haywire=raise voltage and BP220 goes in overvoltage mode.

So I need DVCC to work. But what’s the issue here?


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snoobler avatar image snoobler commented ·

Again, fix the electrodacus configuration. You've created this situation yourself.


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Justin Cook avatar image
Justin Cook answered ·

You list 4 VE.Direct devices; the Cerbo has 3 VE.Direct ports. Please post photos of your connections at the Cerbo so we can examine the connections that have been made. I'll agree with @snoobler that the system clearly isn't configured correctly in any case, though since it's an unsupported system that's up to you to work out, but the connections at the Cerbo will of course directly affect its operation in being able to perform its DVCC operations.

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chrispi avatar image chrispi commented ·

wrong its a fully supported victron standard:

victron BMV712 as bat monitor, 3xMPPT 50/100 cut off via BP220 instead ve-direct remote adapter cable, 1 Multi 12/3000/50 and cerbo. the cerbo should just monitor all that and via DVCC share bank voltage meassured by BMV712, actually a very basic and simple standard victron system.

the electrodacus BMS with the bank is fully independent from that (and i exactly done it on purpose like that, if cerbo is dead system still works) and interferes in no way. i could also just connect the BMV712 to negative on my lead starter and the output of the BP220 to the positive terminal and let the BMV 712 switch off the charge with the BP220 if above 15.6V...the issue would be the same DVCC not working.

And that's also how victron wires it here in the reference diagram for the smart VE Bus BMS (electrodacus works identical to VE BUs BMS, steering via remote ports).

SBP as Mppt charge disconnect. exactly how i have it wired.

i have all VE-direct device connected via https://www.duppa.net/shop/isolated-4-port-usb-to-ttl-uart-ftdi/?v=04c19fa1e772 . like this i have to route only 1 USB C cable to cerbo which is much safer (the heavy duty USB C cable is much more sturdy then these flimsy ve-direct cables) , easier and cheaper as Cerbo is 2,5m (cablerun is 4m) away. but tried it with 3 Ve-Direct cables i borrowed directly to cerbo, no change...also thats excluded as error source.

Also tested my duppa board on another install with cerbo where DVCC was working flawlessly. same Andy from Offgrid garage who is using them too for his 3 smart shunts and 3 MPPTs connected to cerbo with DVCC running.

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delf67 avatar image
delf67 answered ·

It sounds like you are using the BP220 to open-circuit the MPPTs (on the battery side). If the MPPTs have 20V+ from the panels and you disconnect the battery of course you will get over 16V at their battery terminals. This is not what the battery protect is designed for. You should be using the MPPTs to limit the charge voltage to your battery, not using the BP220 to just disconnect the MPPTs.

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klim8skeptic avatar image klim8skeptic ♦ commented ·

@delf67 SBP manual. It also provides an alternative to disable chargers without a remote on/off port to protect from over-voltage.

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delf67 avatar image delf67 klim8skeptic ♦ commented ·

I meant not designed specifically for MPPTs. I'd say switching off a "charger" as the manual says, is meaning an ORION DC-DC type charger which wouldn't cause such a big spike in voltage.

He's getting the problem when his BP220 disconnects the battery from the MPPT (with a panel feeding it, during the day),and the voltage spikes to more than 16V, so the BP220 shuts down.

Surely the Voltage set in the MPPTs should be stop the solar charging BEFORE the BP220 cuts them off? And the BP is really only there for serious under or over voltages due to faults etc?

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klim8skeptic avatar image klim8skeptic ♦ delf67 commented ·

@delf67 SBP as Mppt charge disconnect.

@ChrisPI What mode have you programmed the SBP? Li-ion mode behavior looks promising.

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delf67 avatar image delf67 klim8skeptic ♦ commented ·
I stand corrected.
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chrispi avatar image chrispi klim8skeptic ♦ commented ·

Can we please come back to why the f... DVCC is not working

@def67: not discussing if thats the right way to connect...

1) as there is no other way to get the 15/100 or 30/100 or 50/100 (which all just have one ve-direct port ) to work with a LFP BMS and report to victron cerbo at the same time. i could get a normal relay instead BP220 and let the MPPT raise the voltage, wouldn't harm anything...but BP220 offers additional security (see below). Not the first time i connect them like this in installations but before always with BT connect charge sync as there was no cerbo in the system, cheaper with one BP220 then get 6 ve-direct adapter remote cables if you wanna shut 4x 30/100MPPT and 2x 15/100MPPT off (on a sailing boat each panel its own MPPT due to shading issues).

2) exactly to do it like this was recommended by mvader to do so. What he forgot to tell me (and in diagram below its also nowhere mentioned) that all MPPT must be smart so they then can sync charge voltage via BT connect OR/Better use DVCC (if they are not smart). exactly that the diagram SBP as Mppt charge disconnect.

3) yes that diagram shows exactly how i have it connected /wired (instead one MPPT i have 3) and how mvader told me to do the wiring. this one off 2 reference diagram from Victrom, here for the VE-Bus to disconnect the whole charge bus (MPPT/DC2DC). there is a 2nd for victron Smart BMS which has an identical wiring setup with BP220 and 3xMPPT 50/100. Both show identical wiring switching of the BP 220 and 50 /100 MPPT.

@klim8skeptic : yes BP220 is on Li-setting, works like intended and is by the way a 2nd last resort because when the MPPT output or DC2DC goes above this 16V it would switch the chargebus off too. operational level charge cut off by Electrodacus, 1st line of defense parameter in MPPT/DC2DC, 2nd line desaster or overvoltage cut off by Electrodacus, if electrodacus fails 3rd line or last resort the BMV712 disconnects at 14,6V or 200mV deviation everything from the bank and if that all would fail the BP220 (and the other 2 BP220 in load too) disconnects at 16V (not adjustable but better then nothing). most system have one level of security, i have 4 and all stress tested to work under full 220A load on the BP220 to work.

@snoobler : the issue has nothing to do with the electrodacus which is working absolutly flawlessly, better then victron stuff...the installation is heavly stress tested and works absolutely fine as is with BP220 disconnecting them IF the smart 50/100 sync the charge voltage via BT connect (and 3rd MPPT not smart is disconnected). Problem is the 3rd 50/100 which is not smart and i got told to disable BT connect completly (which i did incl. reset VE Bus and rebooted cerbo) anyway and use DVCC with voltage share (even if 3rd MPPT was smart) as DVCC can do much more then BT connect charge sync. But that DVCC is not working. as soon as that f... DVCC works all is working as intended.


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chrispi avatar image chrispi commented ·
and you can avoid to open curcuit the MPPT on battery side by syncing the battery bank voltage from the BMV712 via BT connect or even better by DVCC. which means the MPPT is not measuring the battery side voltage anymore but getting it via BT or via DVCC to optimise charge from the BMV712. it works flawlessly with the BT connect but DVCC is not working..why..nobody can tell till now.
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snoobler avatar image
snoobler answered ·

There are high tech and low tech solutions. There is a third category..."no tech" - where technology is used to provide a problem rather than a solution - THAT is the Electrodacus.


It is a primitive solution. It has its place, but in all cases, equipment should operate INSIDE the limits of the BMS - not be configured so as to force the BMS to terminate routine operations. That's just a garbage design.


I don't have the expertise to know for certain, but I suspect that if you disconnect the MPPT from the battery, you break DVCC, OR DVCC may not work if the measured voltage and the SVS voltage differ by too much.


You're looking for DVCC to fix a problem introduced by Electrodacus limitations and/or bad design choices. It's like you've put Shinko tires (cheap chinese tire brand) on a Ferrari, but you still demand the Ferrari perform like it's on Pirellis.


Fix your design.

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klim8skeptic avatar image klim8skeptic ♦ commented ·

@ChrisPI I don't have the expertise to know for certain, but I suspect that if you disconnect the MPPT from the battery, you break DVCC, OR DVCC may not work if the measured voltage and the SVS voltage differ by too much.

I think there is something to this. If the DVCC voltage grossly differs from the devices battery terminals voltage, the device will revert to stand alone operation and ignore DVCC. That is my best uninformed guess.

Choosing the right Mppt to operate with Electrodacus is important, it must have a remote port to disable the mppt charging. That is a Electrodacus recommendation?? There is a workaround more complexity!!

1) is the BMS switching the SBP (and mppt) off as a battery protection measure. Or as a means to control charging.?

2) what is the voltage at the mppt's batt terminals? (that is causing the SBP to not reconnect)

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chrispi avatar image chrispi klim8skeptic ♦ commented ·

@klim8skeptic: i have 700W bificial panels and the 50/100 is perfect size for one MPPT per one panel, on a catamaran so due to shading i need it that way.

why is everyone look still that i make things complex or wrong?

its victron who is delivering MPPTs with a major design flaw since years and don't care to fix it (even they got a lot feedback also from proffesional on that) and the DVCC doesn't work as victrons says it works on a very simple basic standard system.

the DVCC doesn't care about deltas as it simply take the voltage a BMV712, smartshunt or compatible BMS measures at the battery and delivers that to all charge sources as reference value instead its own fooled voltage measure and adjusts the charge voltage according to that reference value.

DVCC is also not working with mine if I simply take BMV712, 1 MPPT and 1 multi plus cerbo...it still doesn't share the voltage. no BMS involved, no BP220...due to victron simple enable it and it works...well no.

and well a cerbo you cannot even wipe system completly, a reset is not full reset as i figured with another issue i solved...with raspi and venus OS you simply wipe the SD card and start fresh (would have done that long ago)...would never get a cerbo again but raspi+Venus OS.


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chrispi avatar image chrispi commented ·

@snoobler No DVCC works or not: due to victron no BT connect (as it interferes) and all devices must be on some minimum system version...all checked and all on newest DVCC compatible version.

DVCC was actually created for exactly that case that devices cannot read properly the battery voltage due to multiple reasons starting with all losses in cables, fuses, contacts...and to optimse charge with multiple different charge sources which all get one unique voltage from BMV 712, smartshunt or a Venus OS compatible BMS, so they don't need to measure battery voltage (so if its there, correct, wrong doesn't matter anymore).


your bashing of electrodacus is completely wrong, electrodacus has simply a different design philosophie (and by the way Victron VE Bus and Victron Smart BMS work exactly like this, developed with the support of the creator of electrodacus...) that it controls on cell level everything. nearly all commercial BMS work the same way, as spider in the web that controls all, they do it more complex with bus systems.

the MPPT with systems you describes just know total bank voltage fooled by losses of fuses, cables, contactors etc. ... and has no glue about cell voltages...take a 8s battery and you easily overcharge a cell by absorbtion where its totally fine from total voltage for MPPT and BMS.

Electrodacus does that based on cell level and simply tells the MPPT or any other charge source when to stop charging with an end of charge parameter but till shut off the charge source is responsible to do it best way.

Electrodacus does it very simple by switching with remote, a hardware function that is tested on every victron device by Q&A to last over 10years with 7/24/365 switching...also very effectiv on the low current side, not the hot side. its a very simple, extremly reliable and robust way of steering and being a battery optimising and battery protection(=the BMS side) device. also very easy to trouble shoot. thats why i wanna have it like that and completly seperated...

imagine that full blown cerbo with bus systems and every device does on its own what it wants...have fun troubleshooting that in the middle of the ocean when it goes dark and you need your bank to supply power to autopilot, radar and navigation equipement....actually done that on a buddy boat in feb last year and after that desaster owner wanted me to install what i have, electrodacus...one does all, i see on the optocoppler with one view without any tools if charge and or load is enabled, if any of them is not on...another view on the victron devices on the on/off led and i see exactly where the issue is. everything wired with a cat 5 cables/3 twisted wire pairs as reserve per device, so if a connection issue with the remote cable I can quickly switch to another twisted pair of cables.

have fun figuring out a defective bus cat5 cable or corroded rj45 connection ...done that...prefer electrodacus.


.


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klim8skeptic avatar image klim8skeptic ♦ chrispi commented ·

@ChrisPI dont forget to @ so ppl know who you are replying to.

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chrispi avatar image chrispi commented ·

i actually work around a major design flaw of victron MPPTs. 15/100or 20/100 or 30/100 or 50/100...the remote on/off via ve-direct remote cable is on and HOT when cable is disconnected due to any reason (on purpose when I or BMS switches it off or due to an event the remote cable gets cut) the MPPT stays ON and NO shut off via remote possible!!!


so to actually shut these MPPT off you need to supply a voltage to high contact...absolute eletrical engeneering BIG NO GO. Means if the BMS needs to do a desaster shut off of MPPT and the remote cable gets disconnected thats not possible anymore and the MPPT continous to deliver power and i have to rip out the hot power cables to stop it...



to avoid this I use the BP220 where the remote cable is low, means an interrupt of the remote keeps the chargebus disconnected. if i need it on in emergency, just short the remote terminal...quick fix

and the possibility then to have the data into cerbo because the VE-direct port is free now. the actual issue is victron did a very very poor job on these MPPTs when used with lithium batteries and nothing to do with electrodacus.


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chrispi avatar image
chrispi answered ·

So after updating to V3.30 DVCC started magically to work, but only partly without changing anything. Partly because the MPPT show now the reference DVCC voltage of the BMV712.

But When the BP220 disconnects because battery is full then it starts with battery voltage delivered by DVCC but then rises and still goes in overvoltage at 16V but not into overvoltage lock anymore means BMS can switch it on when battery drained. As it’s rated for 24V I am not worried about BP220 but that means still DVCC does‘t work correctly.

But the DVCC voltage is not a managed voltage by the MPPT as the DVCC manual states it would be and work. If I set managed limited battery voltage to 14,6V that has no effect.

Using BT connect the 2 smart MPPT use the BMV 712 reference voltage and manage charge based on that, means when BP220 disconnects they stay on battery voltage delivered by BT connect like if they where connected. But I have one non-smart.

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