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Fuses and Earth of the DC side of 3-phase system

Hello, how to understand the "It is essential the negative battery terminal between the units is always connected. A fuse or circuit breaker is not allowed" in the Multi II Manual? The interconnection between the units is meant? The BMS in error case disconnects the minus pole of the battery by N-MOSFETs, there is no way to do it in other way. And the DC terminals of the Multis see no difference (except of the stray capacitance) which pole is disconnected. Is it correct to earth the plus pole of the battery and insert the fuse and the DC switch into the minus line which can be interrupted by the BMS anyway? Thanks.

Anton asked
Anton commented ·

2 Answers

2 x Multiplus II 5000 auf L1+L2, low battery nur bei Multiplus auf L1

Ich habe eine Problemstellung, welche ich nicht selber lösen kann. Meine Konfiguration sie aus wie folgt: 2 x Multiplus II 48/5000, zwei SmartSolar MPPT RS 450/100. Als Batterie verwende ich zwei DLG Pytes per CAN-BUS angebunden mit jeweils 5.12 kWh.

Morgens früh, bei einem SOC von ca. 40 % zeigt der Multiplus auf L1 "low battery" an. Es ist immer nur der Multiplus auf L1. Die Batteriekabel sind alle gleich lang, die Anschlüsse fest verschraubt. Alle Einstellungen wurden per VEConfig auf beide Multiplus übertragen. Hat jemand eine Idee was es sein könnte?

getacca asked
maha commented ·

5 Answers

Solar Invertor AC coupling of Mulitplus on AC input?

Hi all,

The context of my question is for a grid coupled solar system with local battery.

I've been reading documentation on the Victron (MultiplusIIGX) and some posts here on AC Coupling (

What I've understood so far (
- AC Coupling is done on the output of the MP/MP2
- Rule: MP2 Power rating >= Solar invertor power rating
- Battery capacity (Lithium): 1,5 kWp installed AC PV power requires 4.8 kWh of battery storage

The questions I have:
a) Is there a hard requirement to couple the solar invertor on AC Output of the MP2?
b) Can some of these rules not be avoided by coupling on AC Input (see reasoning below)?
c) How to control the MP2 to only charge the battery when there is solar power available?

I found this post ( but very little other info.

The reasoning for this question:

Suppose the MP2 is coupled to the grid/solar invertor on input: i.e. the Solar invertor generates power if there is sun, and injects into the grid when there is not enough demand. The MP2 takes care of the loads coupled on the AC output, i.e. when there is demand and Solar power available in the AC input the loads can be fed from the AC input, when there is no solar the loads can be fed from the the battery and if the battery is depleted the loads are finally fed from the AC input (i.e. grid).

In this way the power rating of the MP2 can be selected in line with the power required by the load behind the MP2 and the battery can be sized accordingly.

For a household, a big part of an electricity bill is caused by low power devices that are powered for a large period of time, i.e. (led) lights, routers, clocks, computers, ... -> i.e. a large part of the bill could be avoided by a relatively small MP2/battery system.

The only thing I've not found is to control the MP2 when to charge the battery, thus only charge the battery when there is solar power or when the grid is cheap.

What am I missing?

Thanks for helping out.

Best regards,


rubens asked
rubens commented ·

1 Answer

MultiPlus Settings for LiFePO4 2x 200ah Ampere Time Battery Bank


I have just purchased all the parts for a Victron branded solar setup on my motorhome.

Im using two Ampere Time 200ah LiFePO4 batteries in paralell for my bank. What should I set the absorption, float and bulk to when I set up my MultiPlus 3000VA 12v inverter?

I've read a few similar posts and they all sound very forign to me. This is my first solar setup.

If you dont mind... please explain to me like im 5.

outerspacemannn asked
earthadam commented ·

2 Answers

Pylontech battery balancing

Just added to US3000C batteries to an existing pair of US3000C batteries. Started balancing operation all commss cables removed as well as lines to inverter. balancing started as expected but after a few hours the 2 existing batteries continue to show discharging but the new batteries are in standby. Restarting the balancing procedure shows that the new batteries are still on 3 LEDs whereas the old batteries are on 5 LEDS. Balancing continues for a few minutes and then they go into standby again. Is this normal and do I just have to wait overnight for balancing to complete. Or is there something I’ve missed.

Roberto Znconato asked
Alexandra answered ·

1 Answer

Multiplus II 5kVA 48V random output voltage dips

I fairly recently installed a Multiplus II 5kVa 48 system (including Venus GX), connected to 2 x Hubble AM-2 5.5kHw lithium batteries. System runs as purely backup system for load shedding purposes.

This issue that has arisen is that the inverter randomly cuts the output voltage to the loads for a couple of second.

The latest instance happened after a blackout (load shedding). The system took

over and returned seamlessly, and roughly a hour after, the output voltage dipped for a couple of seconds.

-Inverter and GX has latest firmware installed

-System is not overloaded

-AES is not enabled

-Battery bank is CAN bus connected to the GX, via its own logging device (Cloudlink\Riot)

I have checked settings multiple times, and compared to other installations.

Has anybody had similar problem, or have advice as to remedy?



botessj asked
nickdb commented ·

4 Answers

Victron Quattro coupled to NiFe battery bank


I am examining the systems architecture of a quattro 48/15000/200-100/100 VE.Bus 48V 15000W VA 200A Inverter Charger, Coupled to a NiFe (nickel iron) battery bank, comprising of 1.2v x 40 cells. Fundamentally, they are a relatively safe, extremely robust solution, that can stand up to DOD's that would finish Li banks, that leaves other battery technologies in their wake, as long as, you are prepared for the top up requirements.

I am looking for someone that has attempted this solution. generally, the 4 brands of NiFe cells, have a specification as follows, with small variation;

Chemical System - Nickel Iron (NiFe)

Battery Type - Rechargable Deep Cycle, Flooded with Alkaline Electrolyte Electrolyte Chemistry Potassium Hydroxide (KOH) And Lithium Hydroxide (LiOH)

Electrolyte Refresh Rate Suggested every 7-10 years to sustain maximum performance Terminal Poles, Cell-To-Cell Busbars Nickel-Plated Steel, Tinned Copper Cell Container Translucent, Corrosion-Free Polypropylene or ABS Engineering Plastic Vents Flame-Arresting Flip-Top Vents

Nominal Voltage -1.2 Volts (per cell)

Charging Voltage - 1.65 Volts (per cell)

Efficiency - 80% Cycle Life 11,000 Cycles At 80% Depth Of Discharge

Float Life / Shelf Life - 30 Years / 85 Years

Optimum Charge & Discharge Current C/4

Minimum Charging Current -C/20

Maximum Continuous Charging Current C/2

Maximum Pulsed Charging Current 1C

Maximum Discharge Current C/2

Self-Discharge Rate 1% per day

Operating Temperature -30⁰ C To +60⁰ C (-22⁰ F To +140⁰ F)

I would like to hear from people that have done a implementation, of a quattro and NiFe cells, to understand where the stumbling block might be.

owenski asked
kami answered ·

2 Answers

What size battery storage is recommended for a 3kwp pv system?

Hi, I'm currently in the process of building a 3kwp pv system. Im not sure how many batteries I will need. The batteries need to be either 12v or 24v if possible. Thankyou.

ggi2020 asked
southsideph edited ·

2 Answers

Solar Edge Se5K 3 phase + victron ?


I'm looking for a good solution to add battery to my installation. But right now , only one way ... Change my Se5K for an hybrid ( bit expensive ...)

So, a friend tell me Victron should be available with my Se5K .

My installation : Se5K solard edge 3 phase

20 panel 395 hyundai + optimiser

I'm looking for a battery 5-10kw ( I have VE ) .

Someone have an idea ?

Thks you

loic-dhooghe asked
lalluyn answered ·

6 Answers

2 x 100ah batteries. Charge Controller / Inverter considerations?


I am a new to Solar power and have purchased some equipment and I'm trying to figure out the correct battery. I have brought 3 x 175W Victron panels, a phoenix 500/12 inverter and charge controller 150/35. I have also brought a 100ah Lithium Iron battery.

I want to know if I can buy a 2nd battery and connect them in parallel to get 200ah at 12v.

Is there anything I need to consider? Will the charge controller and inverter support this?

Many Thanks,


thomas-whittle asked
Sarah answered ·

1 Answer

Lynx Dist with 2 strings of batteries

I currently have a single string of AGM batteries wired for 48 V. 4x12 200ah. Runs to the Lynx dist in the usual fashion with a Smart Shunt at the batteries before the Lynx. I want to add a second string of identical bats for 400ah. I have an extra connection in the Lynx. Should I run the second string to the Lynx and make my parallel connection for the two strings there? Also, would I need a second Smart Shunt for the second string since its an ESS system? What is best way to do this?


duswami asked
Jeff Jensen answered ·

4 Answers

Discharging instead of charging on dash: is my setup actually working? Or are these issues serious?


I'm a newbie with a new installation in East Africa (Victron Multiplus 5KVa, Smart Solar 250/100, Venus Cerbo GX, 10 solar panels of 345W and one Weco 4k4 battery). It's fully off-grid.

There seems to be a few issues with the setup and I was hoping some here would know how to fix it, or let me know if there's nothing wrong. Any help would be really welcome, thanks!!

I had a professional install this but there seems to be mistakes in their setup (e.g. initially there was no power usage showing on the dashboard) and so I want to check that everything is in order.

1 - The charging lights on the 4k4 Weco battery always indicate that it's discharged, even fully charged:


2 - The Cerbo dashboard is showing the battery discharging when it's actually charging and vice-versa, like here:


3 - At night, the system (fridge mostly) takes 0.05KWh of power on average for around 11-12h. It starts discharging from 6pm (until then it's 99% full) and charging from 6am. But it looses 1kWh during the night and the battery is at 70% charge in then morning (6am) when the sun comes back. I'm guessing my math is wrong but can't make sense of this.


4 - Should the DVCC be activated (it is now)? I couldn't find out which settings should be used.


5 - Bonus question: how bad is it to discharge the battery to 30-40% on some nights? Should I get a second one? What happens if it goes to 0%?

Thanks a lot!!


solarmanu asked
weco-uae commented ·

11 Answers

Batteries et rechargement par groupe


Mon questionnement est certainement basique mais je rame encore un peu sur le fonctionnement de mon installation. Ma maison n'est pas reliée au réseau électrique, elle est complètement autonome. Les anciens propriétaires ont fait l'installation photovoltaïque (en 2015/2016?). 2 PV 250w, 2 régulateurs MPPT 100/15, 4 batteries AGM BTL12/200 (qui ont déjà 5 ou 6 ans mais très bien entretenues), un onduleur Multiplus Compact 24v/1200va/25a, et un contrôleur de charge. Au départ, chaque PV était branché sur un régulateur. J'ai rajouté deux PV 280w car la production était trop insuffisante pour les longues périodes nuageuses. Et j'ai aussi un petit groupe électrogène de 2kw. J'ai mis les PV en série branchés par deux à un régulateur par série (les deux anciens sur un régulateur et les deux nouveaux sur l'autre, soit 2×250w et 2×280w). Alors oui, les régulateurs sont sous-dimensionnés pour absorber toute l'énergie produite par les panneaux mais le vendeur des derniers PV m'a dit que ça ne gênait pas le fonctionnement, l'installation n'était simplement pas optimisée. Il me faut redimensionner tout ça mais je n'en suis pas encore là (d'ailleurs tous vos conseils pour dimensionner une installation sont les bienvenus). Et jusqu'ici tout fonctionne. Mais ce weekend, les fusibles des régulateurs m'ont fait faux-bon. L'un a grillé, et l'autre était en partie mal connecté. Je n'ai pas établi la cause, je n'étais pas là ce weekend mais une erreur de manipulation de la part des personnes présentes pourraient bien être l'origine. Toujours est-il que personne ne s'est rendu compte que les fusibles étaient grillés. Les régulateurs n'ont pas rechargés les batteries qui se sont déchargées progressivement (le frigo est branché en permanence) jusqu'à ce que l'onduleur se mette en sécurité pour éviter une décharge profonde. En rentrant dimanche soir, je réalise qu'il n'y a plus de courant, les batteries sont à 10v, je trouve la panne, je règle le problème, je fais tourner le groupe 2h pour recharger un minimum vu qu'il fait nuit et que le frigo va redémarrer. Lundi, pas de soleil, les PV rechargent très peu, le frigo consomme toujours, hier, pas de soleil, les batteries rechargent très peu, le frigo consomme toujours, en rentrant hier soir : pas de courant, onduleur en sécu, les batteries sont aux alentours de 7,5v! Il est trop tard pour démarrer le groupe (j'ai des voisins). Ce matin, nuageux, les PV produisent peu, je démarre le groupe. Maintenant j'essaye de comprendre.

1) Est-ce que lorsque le groupe recharge, les panneaux produisent toujours ? Les deux modes de productions sont-ils en simultanés ou est-ce que le groupe prend le relais et les panneaux "tournent dans le vide"?

2) À partir de tous les éléments de puissance décrits plus hauts, combien de temps dois-je faire tourner le groupe pour recharger les batteries ? Quelqu'un peut-il m'expliquer quel est le calcul ?

3) Les batteries sont descendus à 7,5v, elles ont passé la nuit comme ça (environ 8h). C'est des batteries AGM. Quel impact sur leur durée de vie ? Dois-je envisager de les changer rapidement ? À quel point peuvent-elles supporter ce genre de décharge profonde (sachant que c'est la première fois) ?

Merci pour vos réponses. Je ne suis pas hyper au point sur toute cette technologie mais j'essaie de comprendre et je progresse doucement.

erika-grenouille asked

0 Answers

ESS large battery draw on Scheduled Charge

System details :

  • MultiPlus-II 48/3000
  • Pylontech US2000B Plus 4.8kWh Li-Ion Battery
  • Venus GX
  • ESS

I'm running an ESS system and noticed that the startup of large AC loads are being powered from the battery / inverter when on scheduled charge. The scenario is as follows:

  • Scheduled charge period
  • Target charge has been reached
  • Grid is available
  • Zero PV

Under these conditions, my understanding is that the system should be relying on the grid to power the loads (with minor background losses). What I'm seeing is that the batteries are used to support the startup of large loads while the grid contribution is slowly ramped up over a few seconds. In the screenshot below, we were using a clothes iron that switched on and off frequently. This resulted in large loads being pulled from the battery each time the element switched on and corresponding charges pushed to the battery when the load switched off. Any way to change the behaviour and get the system to rely on the grid in this scenrio?




Here is less extreme example where a kettle is switched on and pulls 14A from the battery during a scheduled charge period:


kempza asked
ianjoyner answered ·

2 Answers

Is it possible to mix Pylontech US2000 and US3000?

Hi, does it work if i start with an US3000, that i later add an US2000 to the system....or an US2000 requires an US2000 and they cannot be mixed up?

Kind Regards


njordan asked
woldog commented ·

4 Answers

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