victron smart lfp Image

victron smart lfp

This topic has been merged into Lithium Battery . Please use Lithium Battery when editing or creating new content.

Batteries show full chage on Mulimeter, but SOC says less than 30%

[image]

[image]

Hi all, I'm have some issues with the way my setup seems to be reading the SOC for my battery bank. the system seems to be saying that I only have a 30% SOC however when I test the individual batteries with my Multimeter they all have 13.5v which I beleive means they are at 100%? is there something I need to reset within the system?


System set up as follows:

Off-Grid system

Product MultiPlus-II 48/3000/35-32 (ACOut2 switchable)

Firmware version 478

SmartSolar Charger MPPT 150/70 rev2

Firmware version v3.07

battery bank made up of 2 parallel banks of 4 12v 100ah Lithium-ion batteries

using a

Color Control GX

Firmware version v2.73



cameron moodie asked
Alexandra edited ·

2 Answers

Blue Smart IP22 30a charger internal sensor overrides bmv-712a temp for low-temp cutoff

I have 2 Blue Smart IP22 30a chargers in sync with each other and a BMV-712a to receive battery temperature. My LiFePO4 batteries are heated in an external battery box. When on A/C power and the temperature drops below freezing, even though the batteries are at 50 deg. F (10 deg. C) the chargers are remaining shut down due to low temperature where the chargers are located. This appears to be a firmware bug, I cannot find any options to set temperature priority to external via v.e. smart networking or internal.

Is that a known issue? Is there a firmware fix planned for this?

Regards,

jfisher asked

0 Answers

Lynx Smart BMS-500 & CerboGX VRM visibility

Hi all,

I have a new system that includes Victron Lithium batteries, Lynx Smart BMS-500, Lynx distributors and a CerboGX connected to VRM.

How come I cannot see details from the BMS-500, the distributors and/or the lithium BTV's in VRM? Is that due to the recent release of the BMS-500 and it might follow in future releases in VenosOS or should I expect that this will never be visible in VRM?

br,



goldrush asked
Stefanie answered ·

1 Answer

Inrush current Quattro 230V 48/10000VA for BMS dimensioning

Hi!


I am currently looking to build or buy a battery pack for my old Quattro 230V 48/10000VA unit. Talking to some manufacturers they are a bit hesitant to recommend battery packs due to the fact that the Quattro apparently have a quite high inrush current due to the large inductor/capacitor inside the unit. They are a bit vague on it, but are recommending me mush larger battery packs than what i want at this point.

Are there any recommendations regarding what peak inrush currents I can expect with the Quattro 10000 VA unit ? I guess that I will need to find a BMS with sufficient inrush rating based on that.

Or is a precharge recommended/needed when using the Quattro 10000VA together with lithium packs with BMS ?

jontm asked
iand edited ·

2 Answers

Quatro 48/10000/140-100 compatibility with Axitech Li 10s

Datasheet-Quattro-3kVA-15kVA-EN.pdf

I am using Quatro 48/10000/140 inverter and would like to set battery settings for a combined 48V bank of 10s Axitech module (NCA) . I read an old post about such a setup showing battery settings but for the Axitech 7s/9s module. https://www.victronenergy.com/live/battery_compatibility:axistorage

so I want to know that can I use the same Absorption and float charge settings as in that article for the 10s Axitech modules or is it something diff ? In the tech manual for 10kVA Quatro , it has 57.6V Charge voltage 'absorption' (V) and 55.2 as Charge voltage 'float' (V) as per the manual , then setting 60.75V absorption as in the article makes no sense. From what I understand, it cant charge the battery bank above 57.6V for the absorption phase.

So what battery charging and other settings should I set for this Battery type inside VEconfigure? thank you

solartech12 asked
wkirby answered ·

2 Answers

Multiplus Compact 12/1600/70 auf LiFePo umstellen

Hallo,

mein Name ist Frank und ich bin neu hier.

Wir haben uns ein gebrauchtes Wohnmobil gekauft, in dem ein Multiplus Compact 12/1600/70 inklusive Digital Multicontrol verbaut ist. Nun möchten wir die AMG Batterien in LiFePo4 Batterien austauschen. Hierzu müssen ja auch die Ladeeinstellungen des Multiplus angepasst werden. Zu den Möglichkeiten, wie ich das durchführen kann, habe ich unterschiedliche (widersprüchliche) Infos gefunden. Es gibt ja zwei Anbindungen: MK-3 USB oder VE.Bus smart Dongle - letzteres wäre mir lieber, da ich damit den aktuellen Status des Multiplus auch über mein Android-Handy anstehen kann. Ich habe aber auch gelesen, dass über Bluetooth nur Werte aus dem Multiplus ausgelesen, aber nicht Einstellungen verändert werden können. Die sei nur über die USB-Anbindung (MK-3) möglich. Stimmt das?

Im DEMO-Modus der Victron Android App sehe ich jedoch unter "Ladegerät" den Umstellschalter für "Lithiumbatterien". Reicht diese Einstellung aus oder müssen noch weitere Parameter umgestellt werden, die nur über den MK-3 Anschluss möglich sind?

Bei den neuen LiFePo4 Batterien handelt es sich um Batterien mit eingebautem BMS und Zellheizung - das heißt es sollte vom Multiplus keine Ladebeschränkung oder gar Abschaltung bei geringen Temperaturen erfolgen, da sonst die Zellheizung nicht funktioniert.

Frage: Reicht es aus, über die Android-App unter "Ladegerät" den Umstellschalter für "Lithiumbatterien" zu aktivieren oder müssen/sollten weitere Parameter umgestellt werden, welche nur über dem MK-3 USB Anschluss zugänglich sind?

Vielen Dank im Voraus!

fraenky68 asked
fraenky68 answered ·

2 Answers

3 x 48V victron battery/multiplus in series for electric vehicle?

After completing a few offgrid installations with victron systems and having converted a vehicle to fully electric in the past, i was thinking through the possibly of building another EV using victron components. 3 x 48v systems in series gives 144v and with a 400a discharge limit (200a cont.) via 6 x series 24v 200ah victron batteries - this corresponds to about 57kw peak and 30kw continuous which is within the acceptable output for a small-medium EV.

since victron equipment only works with up to 48v nominal systems, 2 options could exist to use the multiplus & associated components;

1. parallel the 3 x 48v strings with 350A anderson plugs before charging with a single multiplus

2. or have 3 x 48V multiplus running independently but with the connection to shore power paralleled and 240VAC outputs paralleled?


option 1 requires more steps to charge but only requires 1 large capacity multiplus unit

option 2 however may be subject to ground loops since multiplus 1 would see 0V&48V, multiplus 2 - 48V & 96V, multiplus 3 - 96V & 144v. another post on here suggests the multiplus are infact isolation transformers however i can see a few scenarios where where a ground loop could occur (ie when EN relay reverts to the grid). i also assume multiplus outputs couldnt be paralleled as they are designed to do.


i would be interested to hear from a victron engineer on how this could work ? having a dual-use battery pack could make the investment more justifiable.


look forward to any relevant comments!

brette asked
Matthias Lange - DE answered ·

1 Answer

Combine ARGO FET & Orion TR smart

Our current electrical installation on our sailboat has the following setup: 115Amp Alternator which is feeding the starter battery and the service battery bank through an ARGO FET Diode. The ARGO FET prevents back feeding the starter and service batteries vise versa. Know I plan to upgrade my service batteries with Lithium batteries. This leads to an charging upgrade and I plan to use two Orion TR smart 12/12-30 in parallel. Can I install the two chargers behind the already existing ARGO FET on the used output for the service batteries or should / can I remove the ARGO FET and replace his functionalities with the two Orion TR smart? Below the current installation:

[image]

The question is only focused on the ARGO FET and the Orion TR smart. The Lithium Upgrade will contain several additional changes regarding: BMS, smart Battery Protect and so on.

[image]

mzurkirchen asked
Sarah answered ·

1 Answer

Victron ip65 12v 10A charging lithium on 0 current

Sorry if this is dumb. I have very little idea what I'm doing.

I have a very new ATLAS 120AH Lithium battery which I assumed was charged when I hooked it up to my existing AGM set up in my van. It worked for 4 days of camping with a combination of the alternator and solar which I was impressed with.

I have since bought the ip65 12v 10a charger and it has brought it back to life, but I assumed it would automatically recognise it as a lithium ion battery. It was in normal mode for hours and successfully charged the battery through bulk and into absorption charge until I realised I should probably change it to li-ion mode. As soon as I did that, it registered 0 current.

The current has been sitting on 0 for a few hours and the voltage is 14.21. Is it doing anything? Will it eventually graduate into float mode? Have I damaged the battery?

Thanks for any help.

jamiefellover asked
jamiefellover commented ·

1 Answer

Lynx Power In vs Distributor Fusing Requirements for Lithium Batteries

Many Victron diagrams show Lithium batteries connected to a Lynx distributor using a MEGA fuse. A number of online resources seem to indicate that MEGA fuses are not safe for Lithium batteries. And that a class T fuse is the best option. Victron smart lithium battery manuals do not specify. Is there any kind of Victron guidance here. For example, should I use the Lynx Power In and Class T fuses on the battery cables, or am I safe using the appropriately sized MEGA fuses for my Victron Lithium batteries? My system has 4x 330ah 12v batteries.

brucevanderbilt asked
brucevanderbilt commented ·

2 Answers

Pylontech UP2500 100% charged but staying in absorbtion

Hey guys,

I have recently installed 2x Pylontech UP2500 batteries, Multi-Plus-II, Smart Solar MPPT 150/100 & Cerbo GX.

I am currently in the process of cell balancing the batteries. I am charging them through the Multi at the moment due to PV array not installed yet. I am balancing them individually.

I have set the current to 1A and have slowly been increasing the voltage up from 27.5v which has worked to get the battery to 100% charged. I should note that I have been changing the charge settings using Victron Connect with DVCC turned off on my Cerbo GX. The reason I am doing it like this is because that is the only way I can control the voltage due to my DVCC settings not having the "Maximum charge voltage" control option (Firmware is up to date). And to my understanding, If I turn DVCC on, the voltage adjustments I make in Victron Connect will have no effect and be overridden by the Pylontech BMS.

Anyway, once the battery had hit 100% charged, it stayed in absorption for another 20 minutes or so before giving me the high voltage alarm. Shouldn't the Multi have gone into float mode well before this?


Sorry for the ramble on but I have 3 main questions:

1. Shouldn't the Multi-Plus go into Float mode before the SoC reaches 100%? Or at least once it hits 100%?

2. It's my understanding that the best way to balance LiFePo4 batteries is to get them fully charged and them keep them fully charged for a little while to help balance them, then the high voltage alarms should go away in future charges. Is this right? If so how long are you supposed to leave them fully charged?

3. My first battery is 100% SoC. Can I call this battery charged for the sake of this exercise or should I be leaving it hooked up to the Multi and lowering that voltage again until it goes into float mode?


Thank you in advance for your help!

Brandon asked
Brandon commented ·

3 Answers

Charging LiFePO4 with Alternator and Diode

Hello,
I have an existing system with a starter battery (12V AGM 100Ah), a bow thuster battery (12V AGM 280Ah) and a new service battery bank (12V LiFePO4 560Ah with REC Smart BMS). Additionally this will be charged via Victron Multiplus using shore power or a VICTRON MPPT solar charge controller (only for the service battery bank) or it all can be charged by an alternator, which is connected via a diode (VICTRON ARGOFET 200-3) to all three batteries.

The old system was quite simple as usual in yachts, as the alternator just charges as the service battery tells him, how much more can be charged.

Now with LiFePO4 I read this should be charged via DC-DC charger from the starter battery.

Is this really necessary or cannot the ARGOFET still make sure the LiFePO4 batteries are charged by the alternator, especially since the SmartBMS will shut down the loading process, as soon as there is bad voltage/current coming to the system?

DC-DC chargers only deliver up to 30A and charging a 560Ah battery bank from a 100Ah starter battery seems unlogical, especially using a 130Ah alternator.

Is there something to make sure, if I want to charge the LiFePO4 directly from the ARGOFET?


Thanks for the feedback...

-Marcus

Marcus asked
bathnm commented ·

5 Answers

Lifepo4 smart temperature issues.

Anybody else experienced the following.

Victron Lifpo4 200Ah purchased April this year.

When my battery is about 6 or 7 °C it won't allow my to Orion's to charge in bulk, they will go straight in to absorbtion wathever the SOC is. Once temperature of the battery above 13°C there is no problem, the Orion's work fine together.

Same happens with a 'high' load.

When 6°C or something about that and I use my coffee maker asking around 120A out from the battery the voltage drop more then 1V. (Depends what SOC, with 55% I have seen it drop 1,2V)

Once the temperature inside the battery is higher the voltage drop with the same load is a acceptable 0,5V.

Together with the low inside temperature voltage is much lower then normal compared to SOC and LFP chemistry.

Heating up the battery with a heat gun (from a distance) results in much higher voltage without charging. (Easily from 13,10V to 13,25V with the same SOC)

Friend off mine with a 160Ah has the same issue.

My supplier will perform a test with other battery's, he never heard of it.


All wiring and connections are ok, checked and checked again. (50mm2 70cm long for the mulitplus, 16mm2 80cm for each Orion.)


Thanks for your advice

tom-dv asked
wkirby answered ·

1 Answer

Orion-Tr Smart, VE.Direct and integration with GX devices?

Hey there, as I commented on the blog post,

"I'm curious if future versions will have VE.Direct or some sort of integration like that with GX devices? Currently, it seems that the MPPT and MultiPlus are able to coordinate their total charge rate with external BMS via the GX devices. But it seems that the Orion-Tr does not participate in this?"

I'm wondering if there's a way to integrate the Orion-Tr Smart chargers with the CCGX. In particular, as far as I understand, GX devices can coordinate with external BMS via CANBus to determine the charging parameters of a battery. It seems that the Victron MPPT and Victron MultiPlus can respect these limits via VE.Direct and VE.Bus respectively, which is great and a big reason why I bought this BMS and the suite of Victron product.

Now I'm considering purchasing Orion-Tr Smart chargers, however I noticed that they don't have any VE.Direct connectivity, or any other VE connectivity aside from the Bluetooth one. Is something like VE.Direct, VE.Bus or VE.Can planned? Will Orion-Tr Smart chargers integrate with GX devices?

aybabtme asked
bathnm commented ·

15 Answers

Hovercraft - Victron Lithium Battery?

Hi to all the LFP lovers in here!

So I have been looking into this, but would like to get opinions and gain further knowledge about what may be viable for my application.

I would like to install a LFP battery into my hovercraft, if possible. Currently the craft has a single 65Ah FLA. The weight saving of LFP would be an obvious, and welcome benefit. Of advantage too, would be the ability to take the battery to a lower DoD compared to the FLA, for when the engine is not running but power is being consumed for accessories (VHF / music!) etc. I would like to avoid the extra weight / complexity of an additional starter battery.

Some considerations:

1) Cranking current
The overall power drawn to start the engine I have consistently measured at no more than 202 amps. I understand it is inadvisable to regularly draw very large currents from lfp cells, which can degrade them over time, also assuming the BMS will allow it. However I see batteries of say 100Ah available now which are specified and able to supply a continuous discharge of 200 amps, with much higher discharge currents for a limited time. I see for example, the Victron LFP- Smart 12,8/100 has a maximum continuous discharge current of 200 amps. In my application, 202 amps would mostly (hopefully) be a matter of a couple of seconds. I would likely carry a lithium jump starter for backup.

2) Alternator suitability
The current alternator is a Bosch 85A unit with internal regulator. I am happy to replace this with a more suitable alternative + associated regulator / controller.

3) Voltage spike / load dump
I’ve read much about this, and the varying solutions (Sterling APD / TVS diodes). Main concerns appear to be from sailboat owners, where ancillary current draw is low? In my application, with the engine running, the absolute minimum current draw is 12 amps (fuel pump, ignition, ECM, instruments). So if the BMS decides enough is enough, would the resulting jump from whatever the battery was consuming down to 12A still cause an associated spike of concern?

4) Location
The battery in my application would be mounted inside the cabin, negating excessive heat issues associated with an engine compartment installation. I also have no plans (or desire) to run the craft in sub-zero temperatures! ❄️

Any thoughts and other considerations most welcome!

[image]


machineage asked
snoobler commented ·

2 Answers

How does Cyrix-Li-Charge work with Smart BMS?

Connecting Victron 200AH Lithium battery with Smart BMS 12/200 to existing Magnum charger/inverter & Magnum ARC50 Remote Control in marine system with alternator and starter battery. According to the smart BMS literature, I need the Cyrix-Li-Charge to protect from overcharging the battery.

My question is, doesn't the BMS disconnect the battery from being overcharged? Also, doesn't the Magnum charger controller stop the charger from overcharging the battery? Just confused how the Li-Charge fits within the BMS and the Charger controller.

Thanks!

aleainc asked

0 Answers

Victron BAT5214130410 circa 2018 self-discharging from factory for 3 years: any suggestions?

Hi! I just uncrated a new-from-factory, but (ouch) misplaced and warehoused for 3 years Victron 200Ah Lihtium (BAT5214120410). It was manufactured mid-2018 and self-discharging since then.

Directly from uncrating, I’m reading 0.5V across the terminals, and it doesn’t show up on bluetooth. Of course, I know its quite possible the cells have succumbed to self-discharge damage, but I’d like to make sure I haven’t missed something obvious (“you need to turn it on”, “it needs to be plugged into a victron bms to open an internal circuit on first uncrating”) and/or I’m hoping to get advice on seeing if there’s a chance it can be brought back.

Is there any circuitry inside the battery that may have triggered to self-protect from cell undervoltage? I haven’t tried charging it yet, or plugging it into a victron bms.

If this is self-discharge damage, can anyone suggest if attempting to charge it with, e.g. one of the Victron IP65 chargers @ 5A, or another suggested procedure, has a snowballs chance of working?

Any other advice or procedures appreciated.

thanks!

-Seth

seth-nickell asked
Matthias Lange - DE answered ·

3 Answers

Lithium battery bank reliability

I am looking to replace 16x 240ah AGM batteries with a lithium battery bank. This is configured as a 48v bank, with 3x Victron battery balancers across each series string of batteries (a total of 4x series strings connected in parallel).

Does anyone have thoughts on reliability issues between replacing these AGMs with 12v lithium batteries using the same battery balancers and connection as the current setup, versus using multiple 48v lithium batteries in parallel? Would the 48v batteries do a better job at cell balancing compared to 4x series connected 12v lithiums with external battery balancers?

wally01 asked
kevgermany commented ·

3 Answers

Absorption to Float triggered at 40% or 60% of SoC (Multi + BMS + VE Smart Lithium LiFePo4 300ah Battery)

Multiplus is going from ABSORPTION to FLOAT charging state when the SoC is at 40% o 60%, which should actually been triggered when the battery is fully charge, if I'm not wrong.

[image]

Multiplus settings are the recommended ones for Lithium batteries. So floating is at 13.5v and absorption is at 14.2v.

[image]

[image]

- Could it be the Absorption time?


Any help would be really appreciate!!! thanks in advance to this great community.

esteban-moreno asked
klim8skeptic edited ·

1 Answer

Protocol for charging/equalizing parallel battery bank with Multiplus II

Hello everyone. We have a MultiPlus II with a bank of 4x48V Lithium Iron batteries in parallel (with internal BMS and no communication with the batteries). The batteries are currently at different voltages and we need to get them all up to the same voltage (say, 52.5V) so we can use them. The multiplus has been configured with the correct charge parameters for the batteries. Each battery has its own breaker.

What is the best way to get them charged up using the multiplus?

I was thinking we would switch on just battery #1 (with the breakers off for the other three batteries), let the MultiPlus charge it up, then simply turn OFF battery #1 and switch ON battery #2, let battery #2 charge up, etc and keep doing this for all 4 batteries.

Are there any problems with this? What would you do?

ev-gavia asked
snoobler edited ·

1 Answer

Addding Victron LifePO4 battery & Smart BMS 12/200 to existing charger/inverter system?

Hello! Looking for some help iwth a marine setup. I am swapping out my old AGM house batteries for a new Victron lithium battery with a Smart BMS 12/200 (since I have a starter battery and alternator). I want to keep my Magnasine Inverter/Charger and have upgraded to the new ME-ARC remote which has a lithium option.

Questions:

  1. I was told I need a Cyrix Li-Charge to tell the BMS when to stop charging? Is that the case?
  2. Will the ME-ARC be able to tell the charger when to shut off appropriately?
  3. Am I missing anything?

Thank you for any help you can provide!

aleainc asked
aleainc answered ·

1 Answer

Pb batterie 100 HA lithium Super Pack : variations de la tension

Bonjour,

Je viens de changer ma batterie GEL pour une batterie Victron Energy 100 ah lithium superpack

La batterie tient assez longtemps sur 13,0V puis dès qu'elle passe sous la barre des 12 V, la tension fait n'importe quoi : au lieu de descendre progressivement (admettons jusqu'à 10,5 V), elle se met à descendre à 9 puis 4 V, ce qui me coupe tous mes équipements : chauffage gazole, convertisseur ....

Sur ma batterie GEL, même si ça l'abimait, je pouvais descendre jusqu'à 11 V sans conséquences pour mon équipement (qui se mettait en sécu à 10,5 V), ici avec la lithium je ne peux même pas bénéficier de cette descente jusqu'à 11 V et taper dans la batterie lithium.


Très décevant, merci pour vos remarques, suggestions ou retours d'expériences.


florent-p asked
Thierry Cortassa (Victron Energy Staff) answered ·

3 Answers

Which charge controller to buy for 11.1V Li-Ion 3S2P battery packs?

Which charge controller to buy for 11.1V (nominal) Li-Ion 3S2P battery packs? Background is I want to hand out LED lights to food truck festival guests, and have a well working battery pack/LED set-up working. I would like to go completely off-grid during the summer months and no longer charge from the mains during the day, but use PV modules for the task instead.

Which victron solar charge controller would be best suited for this type of battery cell chemistry and pack configuration?

Thanks in advance for some advice!

lagom asked
kevgermany answered ·

4 Answers

Quattro with no battery and no solar

Sorry to ask yet another no-battery question, but I believe my situation is a bit different from the sources I've been able to find so far.


I currently have a lithium (LiFeP04) battery bank, that is below freezing (10F/-12C) so I can't charge it in a camper van. I'd like to connect the shore power, which goes via a breaker to the Quattro. I'd like to keep the batteries disconnected (via BlueSea switch that usually is used to cut power to the Quattro, not the other way around) while I run an electric heater from the grid power while it is hooked via the external port (i.e. not leave a door to the van open while heating). My solar will also be disabled until the batteries are up to temp.


I see the manual has recommended battery sizes, but has anyone tried this passthrough mode approach? Many answers linked above talk about low voltage alarms/ripple warnings, some say it'll work, some recommend against.


I would be doing this for hopefully < 5 hours (but perhaps from time to time if the weather is cold and the van is unused), and simply to avoid adding a dedicated outlet powered by the the shore power circuit.

owenfi asked
owenfi edited ·

3 Answers

Cable length between two lithium battery banks

My 46" Sail Boat has 2 battery compartments due to space limitations. 3 batteries on the starboard side, 2 batteries on the port side where the main DC power grid is based. 4 feet between banks. Batteries are wired in parallel. I understand that Lithium batteries should have equal cable length. Is there a workaround to cable this scenario or is it ok/not ok to wire them this way?

kenamorosano asked
seb71 answered ·

5 Answers

Redirect solar DC energy to heater when temperature is too low to charge lithium batteries?

I have a remote cabin with 5 kW solar, a 150V/100 Victron MPPT and Victron Lithium batteries with a 5 degree C charging cut off. When the temperature drops it's often sunny out, but the batteries won't charge due to the low temperature. Is it possible to redirect the MPPT power to some form of DC heater? Does the MPPT output turn off at 5C or is it the battery BMS that tells it to shut down? I'd like to redirect the DC power to warm up the cabin and ideally get it over the 5C cutoff to start recharging the batteries.

Thanks!

craigh-1 asked
craigh-1 edited ·

4 Answers

Lithium Smart Battery Config with Lynx BMS 500

In a 24v configuration, I understand that the Lynx BMS 500 is spec'd for a maximum of 5x of the 24/200 Lithium Smart Batteries. My Question is; could I have 8x of these batteries in the battery bank, but have 3 of them switched off (at any given time) through manual switches? Also, could those 8 batteries still be daisy chained together with the BTV cabling even though 3 of them would be offline? This setup would give me the ability to cycle through batteries and have additional backup.

Thanks in advance for any help,

Brian New

brian-new asked

0 Answers

Lithium Battery Smart - Charging Has Been Disabled

Wondering if charging is physically disabled by the battery or if simply a signal is sent to the BMS when the Bluetooth connection for a Victron lithium battery displays the alert "Charging has been disabled due to low temperature".

bsqr asked
bsqr answered ·

3 Answers

Solar -> LiFePo4 -> DC-DC Charger -> Lead Acid

Hello,

I have 450AH of AGM lead acid on my boat. I am looking to add a 310AH LiFePo4 battery to the house bank. I am mounting 450w of solar.

From my understanding, LiFePo4 will take a complete charge much faster than the AGM. To me it makes the most sense to connect the solar to the LiFePo4 using my Smart 100/50 solar charge controller; and then to put a a 12/12 30A DC-DC charger from the LiFePo4 to charge the AGM. This would keep the AGM at float charge most of the time and I can keep the LiFePo4 between 20-80% SoC. In this situation the AGM would still service the house loads. From my understanding the AGM can deal with heavier loads than my LiFePo4.

My question is: Is there a reason more people don't do this? Is this a bad idea?

Most info that I can find online has an alternator charging a lead acid bank and a DC-DC charger topping up a LiFePo4 bank which is used as the house battery.


Thanks

gardner asked
jimj answered ·

4 Answers

MultiPlus II shuts down when grid fails

Note: please see my latest update for additional information and findings.

---

Hi all,

I've been having issues with my MP2 since installation. Every so often when the grid fails ("load shedding", substation trips, etc.) the MP2 shuts off for about a minute before starting up again).

System:

  • 1 x MultiPlus-II48/5000/70-50 230V
    • Firmware: v490
  • 1x BSL Battery LiFePO48 Battery 8.2kWh (160Ah)
  • 1 x SmartSolar MPPT 250/100-Tr VE.Can
  • 12 x LONGi 450W mono panels
  • Cerbo GX
  • ET112 Energy Meter

At first I suspected a battery (BMS or otherwise) issue, due to the fact that the shut off coincides with "Low battery voltage" warnings and alarms, as well as "High DC ripple" warnings. There's a whole thread about this. I however do not believe this is actually the issue, but rather just a symptom.

A battery supplier technician was on site a few weeks ago to inspect the battery, and reported that everything seems fine (checked battery params via RS-485). He said:

There's a known issue with the MP2 and BSL and FreedomWon batteries. The MP2 has some low voltage offset bug where it would shut down on a battery voltage that isn't actually too low. The issue has been reported to Victron.

He suggested the installer set the "DC input low shut-down" lower as a workaround for now, until Victron fixes the bug. They set it to 46.80V (at this point the BMS should shut down the battery in any case). They also checked all wiring and replaced all fuses as a precaution.

After this, the issue seemed to go away. There was a "Low battery voltage" warning at one point, but no alarm and the system didn't shut down. However, last night when the grid failed (minisub explosion led to panel trip at substation, i.e. probably brownout) the MP2 shut down again for a minute. What is very strange is that there was only a "Low battery voltage" warning - no alarm. I don't understand why it shut down on a warning.

I am skeptical that the cause of the issue is actually a MP2 bug, since this happened on v481 and v490 firmware. Does anyone know about this bug?

EDIT: I just realized that the MPPT reported a large drop in battery voltage - see the VRM screenshots I replied with. It shows a voltage drop to 46.58V, which is well below the 46.80V DC input low shut-down. I measured the voltage on the battery terminals and at the MPPT with a multimeter. The battery terminals currently measures 53.7V, while the MPPT battery terminals measure 53.9V. Does this seem okay?

My theory of the actual root cause:

- I've seen threads about similar issues, such as this one: MultiPlus II overload on grid failure. One comment that stood out:

Hi. Solved a similar problem. If you have No grid code set please set you Ac low disconnect to 195vac of even 200ac....low reconnect from 202ac and above. Where i am in Zimbabwe my grid is above 240ac sometimes on failure it browns out as low as 170ac! Unless you install some external capacitors the Mp2 struggles to get into inverter mode from such a low voltage to raise it to 230! HENCE DC RIPPLE SHUTDOWNS..LOW BATTERY LIGHTS.and BMS SAFETY SWITCH OFF..etc.

- I have a feeling that when the grid fails (often due to equipment failure) the grid actually experiences a brownout. Then the MP2 tries to follow the voltage down, and finally attempts to switch over to inverter mode, but now the voltage is low enough that it struggles to reach 230V, draws a large current on the battery (thus causing a voltage drop), and shuts off.

- The "AC low disconnect" is currently set at 200V, but maybe this is still too low. The grid runs at anything from 235V - 251V. Should I maybe set the low disconnect to 210V or even higher?

- An external energy meter is beings used via USB (ET112) on the Cerbo. Could it be that it is too slow, and when the grid browns out the MP2 actually follows the grid below the "AC low disconnect"?

- I checked the BMS warning & alarm history via RS232 and PBMS Tools. There is only one alarm in the log since I purchased the battery, and that's when the "Low battery voltage" warning occurred without the system shutting down. The BMS reported a "SCP" protection (which I assume is Short Circuit Protection). Is this maybe due to a large current being drawn? There was about 4500W that was being drawn at that point, but the battery is 160AH @ 1C, so it should easily be able to handle that.

[image]


Does anyone have any ideas or suggestions? The installer has been on site multiple times and they can't figure it out, so I don't know. Should I maybe just insist that they replace the MP2 and battery?

P.S. screenshots of system configuration to follow.

anrich asked
anrich edited ·

6 Answers

904 Posts
9 Users
0 Followers

Topic Experts

Stefanie
0 Points