How to calculate expected tail current when battery internal resistance while fully charged is know?

My lead acid batteries are brand new. The manufacturer supplies a value of 0.33mOhm of internal resistance when a battery is fully charged at 25°C.

We are talking about a 12x2=24v battery bank. So let’s forget about the cables connecting the batteries (2x70mm2 BTW) and assume a total resistance of 12x0.33mOhm = 3,96mOhm

Under an absorption voltage of 28,8v at 25ºC how much tail current should one theoretically expect when SOC=100%?

Does anyone know the proper math?

hvalentim asked

0 Answers

Is their a 3 phase energy meter alternative as there is no em24 availability at the moment
  • I have just installed a 3 phase ESS system with 3 quattro 8000's on a 100 amp supply and found it impossible to get hold of a Em24 or alternative to use with CT clamps.. Carlo Gavazzi UK told me today it would probably be April by time they have the parts and have started shipping them..!(That is a long time to wait!) No one has any thing in stock...Is their an alternative or is it possible to make another meter work for 3 phase victron users?

chris-creative-living-spaces asked
chris-creative-living-spaces commented ·

3 Answers

Orion Tr Smart Non Isolated 12/24 30a Always in Bulk

Hi there,

A quick question regarding the Orion Tr Smart Non Isolated 12/24 30a.

I recently installed it with a Victron Lithium Battery 160ah. The device seems to be working because it is charging the battery. However, it is always in Bulk, even after driving 2 hours while the battery is at about 13.2V (all cells are at about 3.30V).

My installation is:

  • Fiat Ducato 2010 2.3 JTD 130ch
  • Orion Tr Smart Non Isolated 12/24 30a plugged to a Cyrix-Li Charge.
  • The Cyrix-Li Charger is plugged to a VE.BUS.BMS and goes to the battery.

I, so far, never lack battery and the battery is rarely below 12.8V, which is what I want in the end.

The entry V is about 13.5 to 14.0V and the output V is in general at about 13.5V to 14.0V.

The settings are in the below screenshots.




However, I seem to not be capable of getting a full charge.

I sometimes got the absorption and floating mode only once in a few weeks of use.

I am wondering if the fact that the charger is always in Bulk mode is normal or if there is something off?

Thanks in advance for your reply.


remibggx asked
Kevin Windrem answered ·

2 Answers

EV Charger low SOC

Screenshot 2023-01-27 at 8.45.01 am.pngI'm pretty sure they're linked up alright but not sure why the SOC isn't being reported. Just noticed the DNS details don't match up on the EV Charger and the Venus GX. All latest firmware..

Any ideas?

Edit: When trying to charge in Auto or Manual, charging does not start. It says car connected, 'low soc'

Screenshot 2023-01-27 at 8.34.26 am.pngScreenshot 2023-01-27 at 8.33.13 am.pngScreenshot 2023-01-27 at 8.32.03 am.pngScreenshot 2023-01-27 at 8.28.54 am.pngScreenshot 2023-01-27 at 8.28.21 am.png

Isaac Shannos asked
Isaac Shannos edited ·

1 Answer

Are Cerbos with serial starting with HQ224 safe to use with 48V systems?


In the original technote from Victron the faulty Cerbos (i.e. the ones which would fail on 48V systems) were said to be the ones with S/N starting between HQ2201 and HQ2220 included.

Are Cerbos with S/N starting with HQ224 unequivocally safe to use on 48V systems?

I'm asking because there could have been subsequent technotes on the subject, widening the range of "unsafe" S/N.


jterrag asked
Guy Stewart (Victron Community Manager) answered ·

1 Answer

G100 testing UK

We are carrying out commissioning on the following Setup in the UK.

MultiPlus-II 48/5000/70-50 230V (v500 FW)

Cerbo GX

ET112 (grid meter)

SMA 4000 inverter 3.42Kw PV (on AC-Input 1)

ET112 (PV inverter)

BYD battery

The system is setup in ESS mode.

All G98 checks have been carried out and the everything works as expected.

The whole house is on AC-out-1.

The DNO has set a 6KA limit on export. So G100 test is required.

G100 requirement

“The ELS must detect an excursion and reduce the export to the Agreed Export Capacity or less within 5 seconds.”


Settings, ESS, Grid Feed-in

AC-coupled PV Feed in Excess (ON)

DC-coupled PV Feed in Excess (OFF)

Limit System Feed-in (ON)

Maximum feed-in(6000W) Temporarily set to 300W for test.

Feed-limiting active(NO)

In ESS mode the Grid set point was set to -500W. System ramped up to around 500W export and sat there. There was no change to “Feed-limiting active” that stayed at NO. We assumed that “Feed-limiting active” would change to (YES) and export would be restricted to “Maximum feed-in” 300W. This did not happen. Is this because we artificially forced export by setting Grid set point to 500W. Is there another way to Force export?

We tried this with the grid tied SMA inverter charging the battery and with the Grid tied inverter turned off.

We know that in ESS mode there should be very little export. Grid tied inverter can in theory (battery full and no House loads) export max 3.42kw and we have no control over that. There is no DC coupled PV. ENA site lists Multi 5000 as capacity of 4.4kw so DNO totals that as 7.82kw potential export.

Does Grid Feed-in work for anyone. What are we doing wrong. Any advise would be greatly appreciated.

In the document G100 Declaration Victron Energy ESS

Test 1

Removed wire from ET112 (grid meter) Multi Continues exporting. But shuts down inverter and goes into pass through at 60seconds. Not 3.6 seconds as in document as above.

Unplugging rs485 USB adapter has the same result.

Test 2

Disconnected VE.Bus cable (simulates power loss on Cerbo) Multi Continues exporting. But shuts down inverter and goes into pass through at 60seconds. Not 2.1 seconds as in document as above.

“The response time under loss of communications, or loss of power, response time is less than 3s”

So we are well outside the 3 seconds. Is this again because we are forcing the export by Setting Grid set point?

Have we missed as setting or a box is not ticked somewhere?

Any help would be very much appreciated.

fellside asked
wkirby commented ·

2 Answers

Is cerbo's power connector standard?


Has anyone figured out if the little plastic connector at one end of the cerbo's power cable is something standard that can be found on, say, digikey?

(and, yes, I've searched the forum and I've seen the posts with the standard "just ask your local dealer". They don't have the little connector or even the whole cable as spare parts)


jterrag asked
jterrag answered ·

1 Answer

Which Power Rail for 6 or 9 Quatro 48/15000?

I have a customer which want to install first three Quattro 48/15000.

The Batteries are 4 sets of SOPzS Cells with 4350Ah hence 17400Ah @48V in total.

Each Battery Set should get its own BMV 702, appropriated Shunt and 3 Balancers.

Also there will be a 20kW (400V 3P) Windmill on ACout and

DC Coupled at least 6 SmartSolar MPPT 250/100 VE.Can hence 32kWp.

According to "Wiring Unlimited" the Quattos should be connected between the Batteries to equaize the load on the Batteries.

The question is:

Which Power Rail should I use, IF the customer has the intention to add in the comming 2 years 3 or 6 additiional Quattros?

With 3 Quattros under full load I have already 900A, hence I can get with 9 Quattros just 2700A. I have nothing found of this dimension, hence I assume, hat I have to make such PowerRail myself?

My own Batteries are connected to an Aluminium Power Rail of 60x10mm, hence 600sqmm and support without any problems 1000A but 2700A would mean an Aluminium Power Rail of at least 120x20mm because I have from EACH battery set not 1 cable but 4! Hence I need space on the Power Rails for 12 Battery cables (H01N2-E 70sqmm) and for each Inverter 2 Cables of also 70sqmm hence 18 cables. If I use Bolts M10, then I would need a spacing of 30mm and the Power Rail would be around 1m long.

Any suggestions?

Michelle Konzack asked
Michelle Konzack commented ·

1 Answer

Relying on earth rod in off grid?


Some thoughts about building a three phase system with multiplus 2 with off grid capability. Is there some way of confirming the connection to earth when in off grid (the multi disconnects L and N on AC in, correct?)

Seeing as I don’t want to risk sending a current back to the grid from the multi when using battery power, I cannot connect the AC out to the grids neutral or PEN. When in off grid mode the idea is to use a grounding rod as the neutral point and earth (effectively creating a TN-C from the multis when in off grid)?

How do I eliminate the risk of losing my neutral point (connection to earthrod is lost somehow, or the resistance to earth is to high) and thereby risking damaging electronics connected if the loads are uneven over the three phases (0-400V on regular outlets)?

Has anyone experienced problems with this? Is there some kind of module that could be installed that measures the ground resistance continuously and breaks the AC out if ground is lost?

calle asked
delf67 commented ·

3 Answers

Explain the rule of max 3-4 batteries in parallel

In another thread there was someone who pointed at a statement in the Wiring Unlimited document saying there should be a maximum of 3 or maybe 4 lead acid batteries connected in parallel. Reason, as stated in the document, is that large battery banks become tricky to balance and that imbalance is created because of wiring and due to slight differences in the internal resistance of the batteries.

My experience, but also the result of some tests that I have seen reported, is that imbalance is created in bigger banks but when the batteries are on float charging quite soon these imbalances are reduced into a level which is similar to as if the bank was only fewer (3?) batteries.

So, as you understand I only partly agree with this statement in the WU-document and have seen several installations with many batteries working just fine.

Could someone explain, in other words than the WU-document, how this imbalance would be of such importance that it would make installations with a higher number of batteries bad/useless/non-recommendable?

christern asked
christern commented ·

2 Answers

MultiPlus-II connection with Daly BMS / Daly Interface Board (WNT) via CAN?

Hello Together,

I'm trying since a week or so to connect my MultiPlus-II GX wthy my BMS, which is an Daly 16s 48V 250A BMS. It has communication interface (RS485/CAN) and I set it with the PC-Monitor Software to VICTRONENERGY/CAN. I have also the Daly Interface Board (WNT) that they set to Victron Protocol, as they said, before they send it to me.

This is how my Setup looks like:


I also created an customized RJ45 Cable for VE.CAN so they communicate together correctly:
Green/white GND 3 - 3 GND green/white
Brown CAN-L 8 - 4 CAN-L blue
Brown/white CAN-H 7 - 5 CAN-H blue/white

Then I set in the Remote Console the VE.CAN to Other BMS and 500 kbit/s, in the Network status the packets are counting up correctly:



But there is no BMS in the device list or the battery monitor list:


This is how I set up the BMS:


There is an video on youtube where they demonstrate that it is possible:

Has anyone managed to connect an Daly BMS to Victron via CAN? What do I need to do to get it work?

Here is the Datasheet of the Daly Interface Board (WNT):
DL-WNT-V1.0 datasheet of collection board.docx.pdf

Greetings Jack

panicman asked
xf2334 commented ·

3 Answers

Parallel Multiplus configuration oddities

I have encountered a couple of odd unexpected issues during configuration of my two Multiplus' in parallel. System as described in earlier post.

I started by running VictronConnect and used that to update both inverters firmware to 5.01.

I then used VE.BUS System Configurator as per the Victron professional video to configure the inverters as a parallel pair, then used it to launch VEConfigure for each inverter. Two issues were encountered:

1) As per the Victron video I configured the first inverter and saved the configuration. I then tried to load this configuration and use it to setup the second inverter. This failed due to an issue setting the grid-id and it asked me for a grid password to continue. I guess this is either a bug or at least a special case if the grid code has never been set? I therefore backed out and manually duplicated the configuration on the second inverter.

2) During ESS wizard setup on the second, it failed to ask me to set the aspects such as restart offset or dynamic cut off values. I have run through duplicating the configuration for both inverters a couple of times now and both times it failed to ask me for these values on the second inverter. This seems odd - did I miss a step or setting or something, or is this normal for a parallel system?

ESS summaries for each inverter are posted below - odd large difference in the "size" of assistants too?:

Appreciate if someone can shed some light on the second issue in particular.

Thanks, Paul.



Paul Beskeen asked
Paul Beskeen commented ·

1 Answer

Mounting Non isolated Orion-Tr Smart 12|12 - 30

I'd be very grateful for guidance on best position to mount the above unit. I have a Citroen Relay (6m wheelbase) and will also be using a Lynx, a Multi Plus and an MPPT Smart Solar. The installation will be at the rear of the vehicle mounted on the wall above the rear wheel arch.

The manual states to mount it close to the battery but is not clear which one ! Is it the starter battery or the leisure/house battery? Does it make any difference?

If at the rear near to the leisure battery, is it ok to use the common earth on the Lynx bus bar and run the positive feed, via appropriate fusing, from the starter battery the length of the vehicle?

martinp asked
seb71 commented ·

1 Answer

Is it possible to use Smart BMS CL 12V 100A just for alternator current limiting?

what i understood is this Smart BMS CL 12V 100A BMS has some kind of built in current limiting functionality based on the installed fuse.

so the question is can i use just this functionality of the device without using other bms features ?

or if i ask in another way, if i connect alternator input to an alternator and output to a battery or load, without bms bus related cables connected will it work and be able to limit the current at the output ?

if the answer is no to above question, is there a way to dummy the bms bus or a setting to turn of bms bus checking and work it without these features ?

ers asked
ers edited ·

2 Answers

Quattro II - Wrong advertising promise or misunderstood ESS with generator?

Hello friends of the blue devices,

is there a false advertising promise from Victron?.

I bought 3 Quattro II, a Cerbo GX and 6x MPPT 150/70 VE.Can. Then I installed 14kWp PV and a 11kWh battery with diyBMS. Everything has been going great for about 2 months - except for the advertising promise with the generator.

Of course I installed the ESS Assistant in all 3 Quattros - there's no other way if you want to use the PV power yourself and want to store excess power in the battery. My 8kVa generator with Honda motor and AVR on each phase is connected to AC In1 as the owner's manual recommends.

Germany with internal NS protection is set as the grid code. LOM activated at AC IN 1+2. The generator is not recognized. LOM disabled at AC IN1 - nothing! Then I found that the generator is set to 52Hz, so I set it to around 50Hz - the generator is recognized after a very long time and serves phase 1+2+3. But no charging of the battery - which is the most important thing for me. After this connection was not stable either, I switched to EXTERNAL NA protection. This keeps the generator stable in the system. However, there is no PowerAssist and no support from the Quattro II inverter.

IF I suddenly switched on 4000W the Quattro II throw the generator out of the system again. I only want to charge the battery with the generator and the other consumers as before with an inverter using MPPT and battery power. So as if the grid is available on AC IN2 and no generator is connected. It works there too. I've tried everything with the generator - minimum SOC set to 100% or always keep the battery charged - all the setting options...nothing. You can only use the generator to operate connected consumers in the house without any support from the QUATTRO II. That sounds somehow different in the advertising. It doesn't say "all this will only work with your generator if you don't install an ESS". Then I should have saved a lot of money and would have bought 3 Multiplus II and 3 additional power supplies with a total of 7kW to charge the battery with the 3-phase generator.

Is there someone among you who knows more about this and can help me?


mrfrodo asked
baronner commented ·

12 Answers

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