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Quattro 48/8000 maintain maximum charge output voltage

I have a REC BMS connected to my quattros. My batteries are 16S li-ion. I was aware that the quattros had a maximum voltage of 66V - which is close enough to my battery 90% charge of 66.9V (my set limit).

However, the voltage only sits around 64V - less than 65% capacity.

The BMS is reporting a Charge Current Limit of 92.9A and max charge voltage of 66.9V to the Venus when the charge current drops to 0A at 64V.

How do I get that extra 2V of charge?

ceriw asked
davidrenaud answered ·

2 Answers

PASSIVE ERROR - Problem to get communication started between Multiplus 2 GX and BYD B-Box BMS

Dear Forum,

hope you can get me some hints regarding the setup between BYD B-BOX (L3.5) BMS and Victron Multiplus II GX (3000er), which I bought new.

I recently bought the BYD B-BOX battery used from another user who had it running with a Victron Multiplus but now switched to PylonTech.

My setup is as following: MPPT SmartSolar DC connected to battery (short test: charging works, as indicated by the BYD battery (low rate white LED flash and battery voltages are in a reasonable range) and Multiplus GX connected to the battery.


Actually, I not have AC-IN connected to the grid nor the EM24 (my electrician will do that next week). Connection with SmartSolar via the VE.Bus worked very nicely. Also I follwoed the video instruction of Guy to setup the Victron for first Multiplus setup (setting to 500kBaud, DVCC, etc). I used a Typ A cable for the CAN between BMS and VE.CAN. I have an end plug / resistor on the VE.CAN as well.

Status message after reboot the Multiplus is: Not connected. In the BMS-CAN port i found following error message: Error-passive TEC:0 REC:128. Some Multiplus continues pushing packets. See the screen shot below:


Do you have any hints which root cause the error message may have?

Thanks for your support!

uksubs asked
Alexandra commented ·

3 Answers

BMS-CAN zeigt keine Fehler aber es wird kein BMS Device angezeigt


ich habe eine Pylon kompatible Batterie am BMS-CAN angeschlossen.

Der BMS-CAN Netzwerksatus zeigt keine Fehler auf TX und RX und zählt stetig hoch.

Es wird aber weder bei "Device List" noch bei "Batterie Monitor" die Batterie angezeigt.

Was kann ich tun damit das BMS angezeigt wird?

reflexc1 asked
reflexc1 commented ·

3 Answers

Pylontech 3000C ohne Kommunikation betreiben

Hallo zusammen,

Ich habe 3 Pylontech 3000c mit Multiplus2/3000 und Cerbo GX in Betrieb.

Soweit als i. O.

Eine vierte 3000c ist defekt! Anscheinend ist das BMS defekt. Die Batterie habe ich im März über EBay gekauft. Trotz vorhandener Rechnung und Garantie bekomme ich weder von Bosswek noch von Pylontech eine Reaktion auf meine Mängelanzeige.

Meine Fragen ins Forum

1. Hat jemand ein Idee wie man da weiterkommen könnte.

2. Wenn eine Reparatur nicht möglich werden sollte, möchte ich die Batterie einfach mit im Verbund betreiben aber ohne Komunikation. Ist das möglich?

Danke voraus

winsun1626 asked
holger Bleckwehl answered ·

3 Answers

Smart BMS 12/100 low charge rate

I have a victron lifepo4 90ah battery connected to my smart bms 12/100 and a smart victron shunt. I am using the bms to charge the house battery from the vehicle alternator. The vehicle has a temperature controlled alternator (new hilux) I have fitted 2 x 30amp fuses and set the bms to charge 40amps. This is a new set up and the most charge I can see from the shunt is 12amps when the engine is cold, and drops down to 5amps when hot. The house battery is at 40%. Why can I not get any more charge ? My friend has same car and enerdrive dcdc and he can get 40amps. I have triple checked wiring and all is good.

thanks Luke

luke4140 asked
ell249 published ·

0 Answers

Cerbo GX BMS CAN Protocol

Ist es möglich das CAN BMS Protokoll vom Cerbo GX zu erhalten? Da ich eine Batterie habe welche ein CAN Protokoll spricht welches der Cerbo GX nicht versteht und ich gerne einen "Übersetzer" bauen würde.

solar-53-6f-6c-61-72 asked

0 Answers

Smart BMS 12/200 voltage difference

I'm scratching my head with the Smart BMS 12/200, and hoping someone can shed some light for me.

The voltage on the alternator terminal appears to be 0.2V higher than the voltage on the System+ terminal when the absorption voltage of the charging is reached. Eg, when absorbtion voltage of 14.2V is reached on the alternator terminal, the System+ terminal reads 14.0V. I have resorted to installing a DC-DC charger to the alternator terminal and set the absorption voltage to 14.4V, this brings the System+ (battery) voltage to around 14.2V. In the BMS I've set the battery charge limit voltage to 14.5V to keep the DC-DC charger alive in order to provide power to loads like a 12V fridge - otherwise the BMS cuts the alternator charging and the fridge draws down the batteries until the alternator charging kicks back in (lots of micro cycles)

Does anyone have any idea why this is?

I have the "dumb" older version of the BMS 12/200 and the voltage readings on the AB and LB terminals are the same...

cuanb asked
cuanb commented ·

1 Answer

Smart BMS 12/200 and Xantrex 3000 XC Pro?


I have a small RV so very limited space. I have a Xantrex 3000 XC Pro Inverter/Charger because I don't have enough space for a Victron Inverter. I also have solar and a Victron 50 amp MPPT controller (also Victron Venus and BMV).

I am considering 2-3 Victron 200 ah batteries because they are also quite small. And a Smart BMS 12/200.

I would be connecting the alternator to the alternator terminal (I can get rid of my DC-DC charger). The solar and load I can connect to the System managed bolt.

That leaves the Xantrex. Inrush current on startup is MUCH less than Victron Inverter but still way more than the BMS 12/200 will handle, so I am proposing to wire the Xantrex directly to the batteries and then use the BMS charge/load disable terminals so it can signal the Xantrex when to disconnect loads or charger if needed,

Is that a viable solution? Has anyone done this? It bothers me a little because if the Xantrex and Victron miss-communicate a cutoff situation I could fry $6,000 of batteries.

But it should work fine I believe.

tampsteve asked
chrisdeveyrac answered ·

1 Answer

REC BMS / Cerbo GX / Multiplus II absorption and bulk charging method?

My question is: when does the charger change from absorption to bulk charging and how domI ensure that the battery is not trickle charged to death. I have contacted REC BMS and had quick replies, but I am not able to resolve my issue.

l run a REC BMS, Cerbo GX and Multiplus II 48/3000/35 on a 16S 300Ah LiFePO4 battery pack on my electric boat with all the components connected via CAN. The BMS controls the charger/inverter via DVCC and I share the current and temperature sense from the REC BMS.

I started using the default settings from the BMS and I adjusted some paramters afterward, like capacity, max charge and discharge current.

The parameter: cell end of charge voltage is set to 3.58V which is good

The parameter: end of charge hysteresis per cell is 0.25V which would be good (3.58-0.25=3.33V) BUT somehow REC BMS factors this 0.25V with 0.2 ( see latest REC Q BMS manual, which means that the battery floats at 3.58-(0.25*0.2)=3.53V per cell … which is in my opinion REALLY BAD?! for LiFePO4 cells…

The reaction from REC BMS:

I checked again and you are right, the factor 0.2 is used. It is because better MPPT efficiency when the battery is charged, more energy from the sun is used. This was developed together with Victron recently.
SOC hysteresis cannot completely switch off the charger, it only limits charging current for chargers.

So why does Victron wants these cells to be trickle charged to such a high voltage…

To resolve the high trickle charge voltage I changed the parameter: end of charge hysteresis per cell to 0.9V instead of 0.25V. Because 3.58-0.9*0.2=3.4V which I would think is a better float voltage (should even use a lower voltage). I have done this in concert with REC BMS support.

However, now my charger stays in float and chargers the battery to 54.4V (3.4v/cell) even when the battery voltage is lower then 54.4V when the charger is switched of.

I wonder when does the BMS decide to charge the battery to 57.3V (3.58V/cell) again? Is that the case when the battery voltage drops below the end of charge voltage-hysteresis which is in my case 3.58V-0.9V= 2.68V?

The parameter: end of charge SOC hysteresis (default 5%) does not appear in the settings tab when using the REC BMS WIFI module. Not sure what this does.

What i have seen is that my battery was at 53V (below the float voltage) with the charger off and at 83%. The DVCC CVT voltage (charge voltage) is still 54.4V (3.4v) and not 57.3 (3.58v)

So how do I charge my battery to 100% full when I want that before going on a boat trip, how do I ensure that the battery is not trickle charged to death?

I could reset the hysteresis to 0.25V again and this will probably recharge to 3.58V when the battery voltage is below the 3.58v-0.25V, and switch of the charger after charging is finished, but this will not work when I connect the solar array in the near future. So I assume in this case that the bms commands to bulk charge the battery voltage is below the hysteresis voltage, but i am unsure if this is how it works.

Why the 0.2 factor on the hysteresis? The BMS charge method would be OK if the factor was not used. The battery would then float at 3.33V instead of 3.58V and the bulk charge would start again when the battery drops below 53.3V (3.33V/cell). The SOC end of charge hysteresis of 5% would ensure that the battery only recharges when the SOC is below 95%!

THIS WOULD BE PERFECT I THINK, but the 0.2x factor ruins the whole charge algorithm and the 5% SOC hysteresis can not be set anymore, and perhaps also not used in the algorithm anymore.

I am the edge case as some people in this forum would call it, but I think the BMS is totally useless to me for charging the battery when the BMS will destroy the expensive battery by trickle charging it to death.

I wonder what
- other users experience is,
- whether some of my findings and ideas are actually correct.
- hot to get a working system, ideally as described above

taede asked
basm answered ·

7 Answers

Best 48v BMS

Hi everyone,

I am expecting a shipment of 16x280Ah prismatic LiFePO4 cells. It is my first experience with non-lead acid batteries. I understand that I need a BMS, but there is incredible selection and profound difference in cost between models. I currently have a Cerbo GX which I understand has two data busses, a CAN bus and a proprietary VE.bus. This paragraph is the entire sum of my BMS knowledge, +/-.

I want to find a BMS that integrates maximally with the Cerbo. I'm happy to pay for quality. I don't necessarily need it to be a "supported" solution by Victron, as long as it integrates well. In another group on DIY Powerwalls, Batrium seems to be the most popular name in BMS. Is anyone running a similar system to what I've described, with a Batrium BMS?

What other options do I have? I'm also impressed with REC-BMS, but it's very pricey. A couple other ones I've glanced at are 123Smart BMS, Tiny BMS, Chargery BMS and DIY BMS. Also Daly?

The two most important things to me are 1) safety and 2) integration with my Victron products. This will be a 16s, 48v (although it's not a strict design requirement) LiFePO4 battery with low-moderate current requirements (probably something like a 3000 watt inverter). Thanks for any input!

whafa asked
autox commented ·

7 Answers

Disconnecting Large DC Loads

Hi! I've been searching here, but haven't found any discussion around this question.

I'm looking at setting up a large lithium house bank on a boat (800Ah) to drive both DC loads and a multiplus inverter and a VE.Bus BMS. I understand that the BMS should be able to switch the load off under certain conditions. The suggested route is to use a BatteryProtect, and the remote option on the Multiplus.

Switching the Multiplus seems straightforward, but switching the large DC load less so. Max DC ampacity for the load is roughly 600A, although the highest current draws are very intermittent — windlass (100A), electric winches (200A x 2). Even so, my understanding is that I need to switch everything off when indicated by the BMS.

The largest constant current ampacity I see for the BatteryProtect is 220A. While some loads are intermittent, when in use, they may be used for minutes at a time, so I think I must remain within the continuous current rating for the Battery Protect.

What's the best way to switch this DC load?

I've considered paralleling several BatteryProtects, both on the load and on the signaling circuits, but I'm currently leaning towards a 600A contactor with 4000A surge rating, despite the appearance that the signal from the BMS will likely need to drive a relay to provide the necessary current to the contactor.

Please advise.



pmolettiere asked
pmolettiere commented ·

7 Answers

24/3000 shuts off BMS when battery connected

Just finished wiring my system in an RV. I have the Multiplus 24/3000 and a Bestgo 24 V 200ah battery. I’m using a 200 amp breaker/disconnect. If I’m not plugged into shore power or the solar panels, when I turn on the battery breaker the voltage drops to 2 volts across the battery terminals. Yet the Bestgo battery readout stays at the 26 volt range. In another forum they suggested the inverter/charger capacitors are likely tripping the BMS cutout.

I bought a resister and if I jump it across the breaker terminals for a few seconds, then turn on the breaker and everything fires up fine. My question is if this is a common problem and if so, why doesn’t Victron address it?

Just trying to learn.

gregwcil asked
gregwcil answered ·

2 Answers

Charge pylontech us3000c from smart solar mppt without bms communication

Hi All,

I'm upgrading my smaller 12v solar setup that I had for few years to 48v system

I changed the battery voltage of my scc100/20-48 from 12 to 48 v and bulk 52v and float 51v. Then I change my JA 460w solar panels to series. After that I connect the pylontec battery to scc100/20-48

For few hours all went good without any issue. I was able to see the scc charging the pylontech with 850+ watts. and pylontech charged to 4 bars(leds). but today when I was checking the scc, it was charging only 15w of power even with full sunlight. Inverter connected to pylontech is turned ON always and running without any issues (meanwell ts-3000) but the battery is not charging.

Then after some time it again start charging with full 850w power. but this idle stage went like 10-15 mins and I'm loosing the solar energy from this period.

My setup not configured with any communication between pylontech and scc 100/20-48. I'm waiting for my cerbo-gx to do this part. Also my inverter not support any communication with battery or scc

What is the reason for this ? is pylontech BMS doing this ? if yes why and how to fix it. And is there any way I can keep using this setup for few weeks without damaging pylontech ? what are the risks ?


semiraue asked
semiraue commented ·

3 Answers

BYD Overvoltage MPPT shutdown

Hi all

Strange occurrence, GX alarm battery Overvoltage at 55.1V with BYD batteries.


RS 450/100 MPPT, tracker 1: 5 x Longi 450Watt (231V) tracker 2: 8 x Longi 450Watt (381V) It's within minimum spec for Float V of 52.5V

BYD comms working on GX (BYD shutsdown if comms aren't working)

BYD is supposed to control both MPPT and inverter for charging, but I set up charge tab to 54bulk and 52.5 float in any case. Battery monitor is on, at 400Ah, 98% and 0.99 efficiency.

What seems to be happening is that when generator is on, AC2 input, and the battery reaches 100%, the voltage climbs beyond 54V over to 55.2 is highest I saw with incessant alarms.

Switching off gen input seems to stop the problem, but no AC mains was available to test during this phenomenon, and solar yield had dropped too low to test with it.

MPPT shutdown on overvoltage, error #29.

What I don't understand is why BYD didn't control the situation as it is supposed to......

Talfan Stamps asked
Talfan Stamps commented ·

3 Answers

Lynx Smart BMS 500 peak current rating with 2x MultiPlus 3000W@24V

So I have 2x 24v 3000watt multis.

Just specing up a lithium upgrade, and I'm on the edge I think when it comes to a the lynx BMS which is 600 amp max for 5 mins, in theory the inverters could get there, they are actually fused at 300 amp anyway. But 3000 watt is only 125 amps so 250 for the pair.... Maybe I'm over doing it?

Other dc loads are very minimal.

What's the consensus, I would just fit a 1000 amp version if there was one as I usually over spec but in this case the shunts just neat and tidy!

jwfrary asked
Stefanie answered ·

1 Answer

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