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How to charge a starter battery from leisure battery?

Goal : I want to use my vehicle's indoor lights and ventilation during the night (3A 12V).

Setup : I currently have an independant solar and battery setup (700W solar 160AH of usable LiFePO4 battery)

Proposed solution : I think I could use an Orion-TR 12/12-9 converter taking power from my leisure battery and use the cigarette lighter circuit to charge the starter battery (15A fuse so everything seem alright). (The vehicule manufacturer said it's ok to let the car at "on" for long periods if I charge the battery.)

- Will it work?

- If I start the engine and the alternator is working at the same time as the converter, will it cause problem? (alternator and converter in parallel, seems ok from the manual from the possibility of paralleling multiple converters)

- Have I other solutions?


mathieu-dubuc asked
mathieu-dubuc edited ·

0 Answers

Orion TR smart 12-12-30 working in parallel ie. twice as productive - Is this actually possible Victron?

I have bought 3 x Orion 12-12-30's but if they are not made to work in parallel, please let me know so I can get a refund before my return receipt expires.

eg. Do the software/hardware allow without conflict? etc

(Mercedes Sprinter 200amp alternator, multiplus 3000W, 300ah Victron battery etc)

(Or is a different alternator required?)

Kind regards


mike-thornton asked
arghhh40k answered ·

1 Answer

Unbalanced load on Parallel 2x Multiplus-II 5000/48 system.

HI All.

I'm hoping to get some assistance. I have been struggling to get my 2x multiplus-ii 5kw units in parallel setup correctly. Sorry. Let me phrase that again. They are set up precisely, in parallel, according to the user manual and is running, but the one always supplies all the load and goes into overload the moment I start pulling more than 5kw, the other unit does nothing the entire time.

When my system goes to pass-through mode, I can see that both AC cable runs thought the individual inverters are carrying the same amount of current. I have Volt and Amp sensors on both input and outputs of my multis to confirm this.

On the DC side, I have double-checked every connection, cable type and cable length, and places DC shunt current sensors inline with both inverters. The resistance through both DC runs should be very close to exactly balanced, but the one inverter will carry 80 to 100A (55V system) and the other inverter is sitting at 0.03A.

To make sure it wasn't anything to do with DC cables/system, I swapped the inverters around on the wall and kept everything else the same. The problem then moved with the inverter.

So my question, can anyone think of something else for me to test/configure/do? Or is it a faulty inverter.

Something I have noticed is that the inverter that never carries any load is disconnected from the shared AC bus, it fails with overload immediately, and then takes down the whole parallel system. It will not start again unless it is corrected to the shared AC bus, it just ends up in a overload loop and resets.

Lastly, I have upgraded my multis to the latest 469 firmware.

PS. Here is my .rvms file to have a look at my configured setup.

Any assistance would be appreciated.



oliverclaude asked
mike90 answered ·

7 Answers

parallel MPPT charger, but not charging simultaneous

Hi all,

I've expanded my system with one additional Charger and new Panels, loading the same batteriebank.(24V, 660Ah OPzS),OffGrid

Old one: BlueSolar MPPT 150/70 ve.can, Firmware 2.05, charging from 6 Panels/260W
Additional, new one. : Smartsolar 150/70 ve.can rev2, Firmware 3.02, charging from 6 Panels/280W

Both chargers are connected with ve.can to a GX control. I can see them also in VRM-Portal. Both chargers with same default settings (no2). They are switching simultaneosly from one mode to another. But the 6 year old bluesolar charger ist only charging as expected, when I deactivate loading of the new one. Why do they not charge together? Maybe the two chargers are not compatible?

I've built up the system in southern Greece by my own in lack of a victron vendor near Kalamata. Now I'm lost.

Thank's for your help


mstoeger asked
Daniël Boekel (Victron Energy Staff) commented ·

4 Answers

Different charging sources - simplest separation way


I have a question about the currently used methods - what is the best and optimal method of separating power sources. I have on yacht following set of charging devices:

1.2x alternator 12V 80A on engine
2. Victron Multiplus 12 | 2000 | 80-50A
3. Wind/solar charger - output max 40A (other manufacturer)

Then I have 3 battery banks:
A. 1x 12V 120Ah standard battery - starting batt.
B. 2x 12V AGM 110Ah (Victron) - bowthruster and winch
C. 3x 12V AGM 110Ah (Victron) - house batt.

Please advise how is the optimal solution for connecting this different charging sources. I think to use three AgroFET 100-3 or 200-3 separators for each charging source. But maybe experienced users can advice more optimal method which control the charging current from different sources?

Do you think it is advisable to also separate the alternators and treat them as two separate power sources.


elektrotechco asked

0 Answers

How to balance 2 MP-IIs in parallel

For last 3 months I trying to set-up 3 phase/parallel system out of one EasySolar-II and 5 MultiPlus-IIs.

First, in June 2020 I purchased ES-II and 2 MP-IIs and set-up my 3 phase system.

After couple months I realized that 2.4kW per phase is not enough for my house.

Decided to add 3 MP-IIs in parallel.

Asked my Victron supplier if there is a MP-II still compatible with my MP-II for parallel operation.

In turn he asked Victron the same question and got the positive answer.

"There is no problem to connect the actual produced unit in parallel to existing. The only thing is - firmware must be identic (which means that the units are identic also)."

At the beginning of 2021 I received 3 new MP-IIs.

To make this story short, after setting all up I have a problem with load balancing in all 3 parallel channels.

All wires on the DC and AC are equal lengths from the point they split to master and to slave.

On DC side wires are 35mm2 (around 50cm long from the split point) and on the AC side 6mm2 (around 60 cm long from the split point).

FWs are identical.

I am getting the following results when each phase is, one by one, loaded with 2.4 kW resistive load.

L1 Total 66A, Master 38A, Slave 28A

L2 Total 54A Master 32A, Slave 22A

L3 Total 55A, Master 32A, Slave 23A

Any suggestions how to make the currents equal?

The stickers on the boxes show the model numbers and part numbers of the first and the second batch.



marekp asked
Guy Stewart (Victron Community Manager) commented ·

3 Answers

Einfache Installation im VW Bus

Guten Tag zusammen

Ich würde gerne eine sehr einfach Installation für meinen VW Bus vornehmen und bin mir nicht sicher ob das was ich mir vorstelle reicht.

Ich dachte an eine Lithium Batterie 12,8V/100Ah - Smart. Laden würde ich diese gerne ganz einfach über ein Orion-TR Smart 12|12 - 30 und parallel einen bestehenden MPPT 100 | 20.

Für den Entladeschutz sollte der LOAD des MPPT Laders reichen.

Kann mir jemand sagen, ob das Funktioniert oder ob ich da noch ein Batterie Managment System benötige?

Besten Dank und liebe Grüsse


schurmak asked
schurmak commented ·

1 Answer

Multiplus 2 as second storage system with zero control possible?

Hello all,

I have a technical question for you.

I already have a PV system with SolarEdge SE8K (the new one without display) inverter and a Senec V2.1 storage with 7.5kw battery.

Please do not tell me if this makes financial sense or not, I know it does not make sense :-)

But you can suggest me a cheaper / better solution.

Current state

The Senec storage has already a zero control at my house power connection (ergo I have a consumption and too little PV pushes the Senec battery power after / If I have PV surplus and the battery is not yet full the Senec is charged / etc.)

- I would like to install an additional independent second battery in my house.

- Planned here would be a Victron Multiplus II 48V 3000 watts

- The Multiplus together with a new to be purchased EM24 should also create a zero power regulation

- If that runs cleanly, cancel the parallel operation in 6-12 month and sell the Senec storage

The goal is

- when my Senec battery is full and the zero regulation from the Multiplus / EM24 detects a feed that my MultiPlus charges the battery pack on the Multiplus

- if my Senec delivers power to the house grid (e.g. at night or at noon while cooking) and it does not manage to cover the power demand or is empty, that my MultiPlus II / EM24 detects a grid draw, the Multiplus also delivers power to the house.


- Would this be possible with a MultiPlus 2 and EM24?

- Can I set the MultiPlus 2 so that it does not start at 20 watts at the house connection and regulates to zero but at a higher threshold value, say only from 100 watts reference / feed? The background is that the two zero controls of the Senec and MultiPlus should not work against each other.

Why the whole thing?

I am extremely dissatisfied with my Senec and want to build a parallel battery, observe this over max. 1 year and then throw out the Senec. And because I have maximum flexibility with a MultiPlus (expand battery / etc.).

Many greetings,


PS: hope you understand my terrible englisch, normaly i speak germany

willi9974 asked
willi9974 answered ·

3 Answers

Using LiFePO4 Battery 12,8V/300Ah for a large battery bank


I understand for a 48V system the max number of LiFePO4 Battery 12,8V/300Ah is 20 units (4 series by 5 parallel). For a PV system that requires 220kWh in battery bank can can I use multiple sub battery banks of 20 units?

dgmar-ni asked
iand answered ·

2 Answers

Multiplus or Quattro in parallel cascade - How do they operate to cover increasing loads?

Just for the sake of clarity... ( i thought i understood this - but as ever the info is grey or not specific)

Multis or Quattros working in parallel for a larger output capacity. (single phase)

Do the paralleled units mirror each other and operate in the same fashion


Is it a cascaded arrangement, where the master is loaded up first, then the second unit starts to come in to cover the load... and so on....?

And then so.....

Shore / generator AC input

Can this be connected to the Master alone , or does it have to connect to each paralleled unit ? (there are schematic examples for both arrangements - ie. two AC sources, but then other information "infers" symetrical connections required.) There is the note about the shore power setting needs dividing by the number of conencted units.



Chris asked
Alexandra commented ·

8 Answers

Mehrere Landeregler 75/15 parallelschalten?

Aber kann ich ohne einen Master oder Slave zu bestimmen und ohne Anbindung der zwei Laderegler Victron 75/15 die beiden Laderegler an eine Lithiumbatterie anschließen?

Anders ausgedrückt: Brauche ich dazu irgendeine intelligente weitere Verdrahtung der Laderegler mit einer Logikschaltung wie CAN-Bus, oder reicht es aus, wenn man die Ladeausgange des Ladereglers jeweils mit den Polen des Liontroakkus verbindet?

photov21 asked
richi1230 answered ·

1 Answer

Search Mode for four Multiplus II in parallel + split phase (2+2 configuration)


I am looking at purchasing four multiplus II 48/3000/35-50 120v to put in a 2+2 configuration -- 2 parallel unites on each phase of a 240v split phase. I'm primarily going this route over a larger 230v Quattro + autotransformer due to the significantly lower zero load draw (52w for 4x mutiplus II vs 110w for a 15kva Quattro).

With low power consumption in mind, I can't find a clear answer to whether or not parallel / split phase muliplus II units can be configured to go into search mode under zero load conditions. This would bring my standby power draw down to 12w which would be excellent.

I know the manuals state AES mode does not work in a non-standalone configuration, but what about Search mode?

yld asked
yld edited ·

2 Answers

Running 2 x Multiplus 2 48/3000 in a single phase setup with ESS

Hi, I am having toughts of running 2 x Multiplus in paralell with a single phase system, and maybe expanding up to a total of 4 later on. Using 1 source of single phase AC (230V) from grid.

I have a couple of questions:

  1. When running ESS, can both Multipluses feed back into the grid (doubling the normal feedback contra using only 1)?
  2. The transfer switch when grid is on, will that be "duplicated"? When I use 1 multiplus, the transfer switch is 32A when grid is connected. When I use 2 in paralell, will I get the same as 2 x 32A transfer switches? Or is there something im missing?
  3. My phase coming into my house is fused with 63A, therefore I would like to use as much as possible from that before supplying from battery (powerassist). So using 2 x 32A fuses (1 for each multiplus) should in theory give me 7360W pr multiplus of grid use, and 2400W of non-grid use? Or did I misunderstand the concept of transfer switch?

    Thanks in advance :)

lassestu asked
basil katakuzinos commented ·

1 Answer

SmartShunt in Parallelschaltung - Wohnmobil

Guten Tag,

ich habe mir den Victron 500A/50mV - SmartShunt gekauft und möchte diesen in meinem Wohnmobil einsetzen.
Aktuell habe ich zwei Batterien parallel geschaltet, an denen der Verbraucher am negativen Pol einer Batterie und am positiven Pol der anderen Batterie angeschlossen ist.
Den Verbraucher habe ich einfach als BlackBox dargestellt.
Nun habe ich aus der beiliegenden Anleitung versucht den SmartShunt-Aufbau auf meine Gegebenheiten abzuleiten. So möchte ich die negative Leitung meines Verbrauchers an "Load Minus" anschließen und "Battery Minus" am Minuspol der Batterie. Da in diesem Fall wohl Bilder mehr als Worte sagen habe ich versucht das zu visualisieren:


Wäre mein Aufbau soweit richtig?
Gehe ich richtig mit der Annahme, dass dieser Aufbau beide Batterien misst, ich durch den parallelen Aufbau also quasi beide Batterien als eine Batterie interpretieren kann?
Beide Batterien sind auf 12v ausgelegt, sodass die Parallelschaltung diese 12v beibehält.

Vielen Dank im Voraus
Mit freundlichen Grüßen

pdr123 asked
netrange answered ·

1 Answer

Any known issues with firmware 430 on a Multiplus 5kW ?

Two 5kw Multis operating in parrallel - single phase system.

Bench configured and all was well. However, while loading the system up in anger on site, some strange things happen. Master goes into overload and the slave bugs out.

It was looking like they were working together as you woudl expect - i.e. mirroring each other.


When generator is operating - the Multis seem to load it up to around 300w then they trip again on overload.

Cabling is as near as damnit same lengths.

Chris asked
wkirby commented ·

2 Answers

Paralleled Battery Wiring Order for Lynx Power In/Distributor


Does it matter how I wire my 3 LifePO4 batteries to a Lynx Power In/Distributor as far as the order of positive/negative connections of each battery from left to right on the Lynx?

In other words, should the positive connections be connected to the busbars in reverse order of the negative connections to reduce imbalanced current draw of the paralleled batteries?

Examples that have caused my confusion:

From 'Wiring Unlimited'



From Lynx Power In Manual - Design


If I wire like the 2nd reference picture (from the Lynx In Manual: system design) than the current flow would go through the furthest right battery more than the furthest left battery, hence why 'Wiring Unlimited' (first picture) recommends having the flow go diagonally through the battery bank. So shouldn't the second picture show negative/positive cables connected in reverse order of each other? So confused.....

Max amps through my entire system will be 300amps

Thank you in advance!

randy-reyes asked
randy-reyes answered ·

1 Answer

Do I need a fuse here?


I have my 12v side already setup in a van conversion and I'm about to add the MultiPlus 3kw.

I have 3x 200ah batteries with 300amp MRBF fuses at their terminals, in parallel brought together with 120mm2 cable to battery posts.

From the posts, 120mm2 cable connects the bus bars.

The MultiPlus will connect to the busbars via a 400amp T Fuse and 120mm2 cable again.

Should I also have a 400A T Fuse between the battery posts and busbar?

My original wiring diagram had this, but I then opted for the terminal fuses, and an electrician said the extra 400a in the single cable from the post therefore wasn't necessary. I'm now thinking that single cable is not fused correctly (as the 3x 300A MRBF fuses combined are too high) to the bus bar, except for the fuse between busbar and MultiPlus which is (I believe) the only route for that amount of current to run without blowing another much smaller fuse.

Thanks in advance!

And thank you all for your contributions across this whole community, it has been very useful in my learning.

centaur16 asked
centaur16 commented ·

2 Answers

How to connect Orion-Tr Smart 12/12 30a in parallel

Hi. I have one victron orion-tr 12/12 30a in my van and I'd like to install another to give me 60amps,total charging. Can anyone advice my how I'd need to wire the 2 units many thanks

moonhead911 asked
mateoing commented ·

3 Answers

monitor dual boat cranking batteries

Two cranking batteries wired thru 3 way switch: Bat 1, Bat 2, both. Negative leads parallel to negative bus. I understand the shunt goes in the negative lead. The shunt power wires to Bat 1; 2nd 702 input wires to Bat 2. 702 set to monitor voltage on 2nd battery. Question: Should total AH entered be sum of both batteries? When engine runs switch is set to "Both" so both batteries charge. When engine is off switch is moved to either Bat 1 or Bat 2. Will this set up work to give me some idea of status of both batteries? Or does someone have a better setup method?

hartrh asked
Kevin Windrem answered ·

1 Answer

Adding second battery to MPPT 75/15 disables load output

I'm using 2x100W panels with a MPPT 75/15 controller to feed a 105Ah lead acid deep cycle battery and a fridge.

Everything works just fine, but as the fridge tends to consume more energy than a battery can store, on cloudy days it gets empty.

Then I had a thought to connect the starter battery (100Ah lead acid) also to the setup in order to switch it to the circuit on cloudy days when having longer distances to cover. Wiring the batteries in parallel went just fine and charging the secondary battery (that is mainly charged on solar) seems to work, but, unfortunately, right after I connect the two batteries, VictronConnect app shows that load output state is set to OFF and there's no possibility to switch it on.

I understand it's some kind of safety measure in order to avoid short circuits orsth, but what could be possibly wrong here? Having two ~100Ah lead acid batteries behind such controller in parallel shouldn't be such rare case, or what I'm missing here?

raid23 asked

0 Answers

Cerbo GX connection to multiple MPPT not parallel

Hello everyone, I am almost confuse about to monitoring 3 MPPT Smartolar charge controllers that we are going to connect to the Cerbo GX. Because the solar installation is more than 20 years old, "unfortunately" we have 3 string of solar panels connected with 3 battery banks and after by schottky diodes to the load (MM.WW. system), but we can´t optimize the banks because the space of each one is limited to joint them on one battery bank. for that reason we should monitor each MPPT Charge controller separately. Is it possible to monitor each MPPT (PV power, BAT power and load consume) or each MPPT should be connected to a GX device?.

Thanks for your support.

Jonathan Carrasco from Chile

Jonathan Carrasco asked

0 Answers

Existing Phoenix inverter, wish to purchase and add a MultiPlus in parallel.

I have an entirely off-grid installation with an existing Phoenix (48V/5000VA) 230V inverter and wish to purchase a MultiPlus (48V/5000VA) 230V inverter/charger to be installed in parallel configuration. The primary goal is redundancy (in case one inverter fails) and to enable charging of the batteries (if needed) from a 3kW generator (continuous 2.5kW capability). A secondary purpose would be to increase the power output capability.

I know there can be compatibility issues that have to be taken into consideration with paralleling.

The original firmware that the Phoenix inverter came with was 2624413. I have updated the Phoenix inverter from v413 to the latest v482 firmware version today, so if the MultiPlus doesn't come with the latest firmware I am more than capable of updating that to the same version.

I would be seriously concerned if a new MultiPlus didn't come with firmware starting with 26 (VE.Bus - new microprocessor, 230VAC) now, but I've cross checked the list of models document and 2624 is listed as "MultiPlus 48/5000/70-100 (+EasySolar)". It is literally the only model on that list that is 70-100 (70-amp battery charging and 100-amp AC transfer capability).

Am I correct in concluding that if I purchase a 2624 (i.e. a MultiPlus 48/5000/70-100) and update the firmware to v482, if needed, then it should be capable of being paralleled with the existing Phoenix inverter?

Second question is, if I was to purchase the MultiPlus and it failed to parallel could I instead fall back on a configuration to feed the AC output from the Phoenix into the AC input of the MultiPlus to increase the output capability?

I already have a changeover switch in the configuration to change the house AC supply from the Phoenix to the generator and could easily reconfigure that output to feed into the AC input of the MultiPlus instead. I'm not sure how the MultiPlus would handle that changeover from the Phoenix to the generator, I suspect it wouldn't too well, and it might get more complicated if the "Dynamic current limiter" setting needed to be enabled for the sake of the generator.

In the worst case scenario, I would feed the Phoenix output into the MultiPlus input and keep the inverters and generator separated by the changeover switch. This would provide the redundancy and increase in power capability. In this case, if I wanted to meet the goal of charging the batteries I would need to purchase a Skylla 48/50 TG Charger, which is practically doubling the cost as it's price isn't much different from the MultiPlus and it'd probably more beneficial to just buy another MultiPlus and just use that purely as a charger (if it can be configured that way). Really don't think I could stretch the budget to handle this.

My preference would be to parallel the Phoenix and feed the generator into the MultiPlus charger, this would eliminate the need for the changeover switch entirely and I think more likely to meet all the goals, but it would also be nice to know that even if I do everything right, there was a fallback position if the paralleling did not go as planned.

Happy to take advice if anyone has a better option to achieve the goals.

william-croft asked
offroadflow answered ·

5 Answers

Inversores en paralelo .

Buenas noches , dispongo de un Múltiplus 24/3000/70 que se me queda corto cuando hay algún consumo puntual alto , cambiándome como es lógico a consumir de la red aún teniendo suficiente potencia solar para soportarlo .Quisiera poner un inversor de apoyo en pararelo y necesitaría saber si son compatibles o como saberlo . Me han ofrecido (retirado de otra instalación por ampliación) un Phoenix 24/3000 que me bastaría aunque no lleve cargador ya que el mío lo tiene . No quiero adquirirlo sin saber si son compatibles . Les agradecería me dijeran como saberlo o que referencia haría falta de las que disponen los aparatos para saberlo .
Gracias de antemano.

aurelio-nieves asked
Mike Dorsett answered ·

1 Answer

Quid sur batteries 12V

Chers tous,

Je viens vers vous car je n'arrive pas à trouver réponses sur le branchement optimal de batteries.

Matériel : 2 batteries 200Ah avec 1 BMS sur chaque batterie, 1 Lynx Power In

Besoin : Rester en 12V, donc pas de branchement en série. Ça, c'est fait.

Par conséquent, il ne reste que deux possibilités : en parallèle ou en indépendant ( chaque batterie est connectée au Lynx ).

Mes questions :

Mieux vaut-il connecter en parallèle pour obtenir les 400Ah, ou, et c'est ici que ça se corse : connecter chaque batterie en indépendant + et - sur le Lynx ( 2 câbles pour chaque batterie ) ?

Si l'on fait de cette manière ( 2 batteries indépendantes sur le Lynx ), quelle est la valeur des Ah, 200Ah ou quand même 400Ah ?

Si l'on connecte 2 batteries de différents Ah en indépendant sur le Lynx, exemple avec 1 batterie 200Ah et 1 batterie 100Ah, les ampères s'additionnent pour obtenir au total 300Ah ?

Est-ce réalisable ?

Si l'on connecte en parallèle 2 batteries, que les batteries sont de même Ah, mais ne sont pas du même fabriquant ou du même lot, j'ai lu que ceci engendrera des risques d'usure prématurée, est-ce correct ?

Je vous remercie de m'avoir lu déjà et je me réjouis de vos réponses écarlates.

myhomebuzz asked
myhomebuzz commented ·

1 Answer

Smartshunt - positive wires for two batteries


I have two lifepo4 batteries with take offs drom both terminals of each batteries as recommending for ‘parallel’ wiring by the manufacturer of the batteries I have.

Just wiring in my smart shunt - looking at the diagram in the leaflet with the shunt it shows both positive in the vbatt and aux connections for what looks to be a series wired battery setup.

Do I need to connect both my batteries positive wise to the shunt?

Chris Marks asked
wkirby answered ·

1 Answer

EasySolar-II GX and MultiPlus-II in parallel. Lights are not synchronised, Is it correct?

I have paralleled a Multiplus-II to my EasySolar-II GX.

I have it working but I’m not sure if it’s 100% correct as I couldn’t get the assistants to work.

It’s an off-grid setup with battery charging done by solar and if I need a boost charge I temporarily connect a portable generator. I followed the paralleling tutorial and combined the 2 units via the system configuration tool and all went well.

Then it came to the configuration of the 2 units, it all started going wrong when I selected ESS assistant as I have grid code “none”. Then I changed grid code to one of the Australian codes and next I had bus errors, low voltage alarm etc.

Pushed ahead and loaded the file into the Multi as well. Couldn’t get the units to output power and bulk/float lights flashing on Multi. Went back in and put grid code back to none and deleted assistant, uploaded both units with this file.

EasySolar fired back up but Multi still had mains and inverting lights alternating. Started to pack away so I could work on it again tomorrow and when I got close I could hear the Multi humming. Turns out the system is up and running even though the mains and inverting green lights are alternating on the Multi. I test ran my lathe and it started no problem multiple times. Before the paralleling I couldn’t get the lathe to start at all.

Can anyone confirm if this sounds to be correct or should the lights not be alternating on the Multi?

the-doon asked
the-doon commented ·

1 Answer

2x Multi II 48-5000 in Parallel Very Low Charging

Hi to all

Trying to troubleshoot a charging problem with 2x Multi II 48-5000-70 in parallel Master & Slave. I also have Venus GX connected. The two units have been inverting great for couple months now but I had not used any grid charging my solar takes care of that. I normally switch the multis over to grid at 00.00 - 06.00 to take advantage of cheap rate and save my 1000 Ah FLA battery from cycling too low. Today, I decided to switch on the charger on the Master Multi to test charging and at 00.00 when the grid kicked in I see the Master go in to Bulk phase but... only 7-10A of charging ?? I realise by default the Multis only charge at 75% as when I only had one unit I never seen more than 53A charging (and I never figured out how to get the full 70A). I was expecting to see about 100A charging with two units in parallel?? The Input AC current Limit is set to 30A (15A on each unit) as my grid supply is 32A. All cables are uniform acoss the two units.

I don't understand why the charging is so low any help to figure out what is limiting the charging current much appreciated as I will need to charge overnight sometimes when the Winter arrives


PS I also put a DC clamp meter on each units DC cable and they are sharing the charge output, about 4-5A each.



rithym1964 asked
rithym1964 commented ·

2 Answers

Smart shunt wiring (LiFePO4) in non-typical parallel wiring..


I've searched and cannot find an answer to the question I have. I have 2 x 100Ah poweroad infinity LiFePO4 batteries - and after noticing that they were discharging/charging with different loads via the inbuilt BMS I contacted the vendor who put me in touch with the manufacturer. The manufacturer has suggested rather than a typical parallel wiring configuration (+ve terminals connected, -ve terminals connected, then a take off from 1 battery's +ve terminal to the load, and from the other battery, the negative feed), they've suggested that I have take offs from BOTH battery +ve and -ve terminals into the respective +ve and -ve busbars I have on my system. Whilst I'm not that familiar with it batteries I was a bit surprised at this suggestion - but I'm about to do it as currently I have this abnormal load + cell balancing going on (I'm sure its the BMS personally...)

Here's the wiring diagram that they've supplied me with.


For completeness, their reply to my question was as follows:

Thank you for getting in touch
Your method or wiring is absolutely fine for a Lead acid Battery fit out, but not the ideal recommended way for lithium
This is because the current flow (red cable) goes to the battery on the left ….  And then has to decide how much current goes through the left battery and then how much goes through the right hand battery …….  There’s no guarantee that the current  will split equally 
(same on the negative side)
So the cable 1 (charger) should go to the busbar – and a cable OF EQUAL LENGTH – from each battery to the busbar
Same for the negative - - cables of the same length form each battery to the busbar
Fundamentally there’s nothing really wrong in what your have done (don’t get concerned) , but getting the exact cell balancing won’t occur automatically
If you use the app you might find there are different Voltage rating on the cells ……. However the batteries will readjust in time
Its just your app will show a variation
Therefore to get over this and do it correctly, which is better longer term, if you can change to what I am suggesting would be better

Anyway, in the meantime I bought a smart shunt. With the docs saying that this should be the only thing on the negative battery pack terminal to measure the current correctly how should I wire this up?

There's two possible options that I'm thinking of:

1) BOTH -ve batteries connecting to the shunt, then the shunt to my -ve busbar if I can get the terminals on there.

2) An intermediary -ve busbar, where the two batteries connect to this new bus, along with the shunt, which then feeds my system -ve busbar?

Any help would be greatly appreciated.

Thank you.

Chris Marks asked
Chris Marks commented ·

1 Answer

Parallel/Serial - Excel V4.0 spreadsheet (Beginner question)

Good morning all,

I'm just starting out on my foray into solar and playing around with the v4 and looking at small systems. I think I'm being daft, but I don't understand the spreadsheet when it comes to parallel and serial strings, I'm only looking at a two panel system to start with but:

Going from one panel to two in parallel doubles the current as expected

Going from one panel to two in serial doubles the voltage and the current (?) Is this unexpected current increase because of how MPPT works as I'd expected voltage only to increase?

I hope I'm not missing something obvious

keiron asked
Vance Mitchell commented ·

0 Answers

Paralleled strings of same panels on different orientations

Hi there,

Is it acceptable with Victron MPPTs to install parallel strings of the same module type on different orientations? EG, 3 modules facing west, paralleled with 3 modules facing east, into the same input on the MPPT?

Cheers, Anne

anne-wilson asked
Phil Gavin answered ·

3 Answers


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