Buck Boost low temperature charging

Hello, I am using

Victron Buck-Boost in combination with Victron LifePo4 200Ah battery and VE Mini BMS and I want to ask:

1) Does Buck-Boost cut-off charging when it detects low battery temperature from VE Mini BMS?

2) Or do I need additional Battery Protect between Buck-Boost and Battery?

I am asking, because I'll be using my vehicle frequently in sub-zero temperatures and I want to prevent battery damage that can be caused by charging in sub-zero temperatures.

Thanks for reply,


robertb asked
Southwick answered ·

2 Answers

Does the MPPT have reverse current protection from the battery?

I'm looking at a description of the Cyrix Battery combiner and I would like to confirm if this device can be used for protecting the MPPT from reverse current from the battery.

MPPT data sheet does not explicitly mention reverse current protection from the battery side (but mentioned for the solar side). Does MPPT have its own internal reverse current protection or are diodes necessary to prevent damage from back current?

BTank asked
Matthias Lange commented ·

1 Answer

Switching for a S+/D+ connection to a motorhome Dometic AES fridge

I have successfully installed a Smart Solar MPPT150/35, BP65 and a BMV 912 to my motorhome. My plan was to connect the output from the BP65 (with suitable on/off voltages set) to the S+/D+ input to my Dometic AES fridge so that it would be powered from the battery bank when solar/battery conditions allowed. The fridge works on battery power when the engine is running (with the D+ switching connection from the alternator) but I have had no success so far with switching using the S+ connection. I would be very grateful for any advice/help for this type of connection/configuration.

burnett.simon@gmail.com asked
KevP answered ·

1 Answer

How to properly protect starter batteries

we have an old Mercedes Benz NG 1428 truck with a 16.000ccm engine. I do not exactly know, how much current is drawn at the start fo the engine. The cables are 100mm2. I think it could reach as much as 1000A for a very short period of time.

The vehicle draws some current even having everything turned off. I would like to protect the starter batteries from going low. I woud also like to remotly (Bluetooth) controll the connection of the starter batteries to the system als well as reading the voltage.

What would be the proper devices to do this. I think I understood, that a Battery Protect is not the way to go, as current would flow in both directions while starting the engine and then loading the batteries from the alternator. Right?

Is there an alternative? Cyrix?

Regards, Kilian

kiko asked
Jwfrary answered ·

1 Answer

Using diode in order to NOT backfeed BP-220?

I am trying to find a work-around from pulling a 25' run of cable through a maze. I need to connect my RV engine alternator to my coach batteries. I can make a 2 feet connection from the coach ignition energized relay if I can safely employ a 60 amp diode as shown in drawing. Any reason why this wouldn't work?


Steve asked
Jwfrary answered ·

1 Answer

BatteryProtect and Charger placing issue

Hello All,

I'm a total newbe and I tried to find a solution for my problem.

For my sailboat I've bought a Victron Battery Protect to prevent the battery for draining.

When I am in a harbour I connect my battery to a 10A Charger. When I am sailing the battery is connected to a solar panel.

Because I red a lot about the wrong installation of the battery protect due to positive current from out to in I'm a littlebit confused where to place the batteryProtect into the system.

Can it be installed at the location of the Master Switch? I'm not really interessed in overload the battery. Underload is my main concern.

I hope some of you can help me in the right direction.

Kind Regards,

Koen de Kruijf


koendekruijf asked
koendekruijf answered ·

2 Answers

Battery Protect instead of contactor

Hi all,

We're considering using Victron 48V / 100A Battery Protects instead of coil operated contactors to protect LFP battery banks for under voltage and over charging conditions.

Power consumption of the Battery Protect is significantly less than contactors (0.1W vs 2W). The BMS would drive the Battery Protect via the remote switch inputs, so we'd not need to use the programmed voltages although we could conceivably use those as well.

Silicon often fails short circuited though, hence the norm seems to be to use a device that fails open circuit, such as a contactor.

Any thoughts?


jbakuwel asked
jbakuwel answered ·

6 Answers

Circuit Breaker for Battery Protect BP65

In stead of a fuse in the supplyline I would like to use a 63 Amps Circuit Breaker with Tripping characteristics B like this one...


Is this a good choice or should I better use another Tripping characteristic or even less Amps?

Any advise is welcome...

Kind regards,

Bronsky asked
Bronsky answered ·

1 Answer

BP 220 remote control using switched battery negative


I have an issue with an RV that I am hoping someone may assist. I want the relay in the BMV712 to isolate the batteries at XX% SOC and have done this for the BP 220 but most of the load in the RV is fed of the same wires as a Victron solar MPPT. I use the BMV networking to supply the MPPT with the battery Voltage and Temperature.

The cut-down circuit below is some of the existing RV electrics and there is an issues I am trying to overcome.

The makers or the RV saved some dollars by only running one pair of cables from the batteries to the cupboard over the sink and there is no way to get more cables inside the walls - well without removing the cladding.

In the cupboard is a Victron MPPT and the battery supply terminals are paralleled across to a Voltech Battery Protector so I cannot use the Victron BP 200 to protect the battery - I would get reverse current through the BP 220 when the MPPT is charging. All of the fuses that supply most of the RV electrics are after the Voltech unit.


My Question is, looking at the picture below, I can get a pair of wires from the batteries, under the floor and over to the door switch that controls the Voltech, Unfortunately the Voltech uses negative wire switching and the BP 220 uses Positive switching.

I use the normally closed contact to open at 25% capacity.

If I connect the BP220 terminals 2.1 and 2.2, BMV and connect the Voltech control wire as shown in the picture below, I believe I could achieve this what I want but it really depends on the manual being right for connection 2.2 as the BMV would connect both terminals to battery negative.

In normal operation the BMV N/C contacts provide a circuit to the Voltech via the RV isolator switch inside the door and the BP 220 is enabled with 12V on terminal 2.1.

When the BMV goes below 25% capacity, the relay changes state and removes the battery negative so the Voltech cannot enable and the BP 220 terminals are now at battery negative so it should disable the BP220.

I would think the BP 220 should be able to operate indefinitely with its terminal 2.2 shorted to battery negative - is this correct.


Paul Skelly asked
Paul Skelly answered ·

4 Answers

BatteryProtect - 220AMP - reset time

The nominal power draw on my 24v bow thruster is 500 A. Generally only used for about 30 seconds at a time, which is within the 600A intermittent range. However, if the BatteryProtect does trip, seems that it takes 90 seconds to reconnect. In a tight mooring situation with side winds, this is obviously completely unacceptable, and thus I should not install this unit.

Is my conclusion correct or have I misunderstood something here?

Meshugga asked
Meshugga commented ·

1 Answer

Battery Protection for Lithium with REVERSE CURRENT for multi Charger/Inverter

I have an older Phoenix Multi 12V2500VA120A Charger + Inverter in a system that I would like to upgrade to LiFePO4.
Trouble is my batteries have an older BMS without over/under voltage protection and the BP series cannot handle bi-directional current from the charger and to the inverter.

Any recommendations for simple and inexpensive voltage protection system that can integrate with the current hybrid inverter/charger setup?

Bonus points if you can suggest integration of low temperature charge protection as well.


Kit asked
nebulight commented ·

1 Answer

Battery Protect 65A - VLRA batteries - Settings selection

I'm currently designing a mobile 24VDC power source for low power applications and I'm interested in decent battery protection to get the most cycles out of the batteries. I like the look of the BP65, but I'm not sure what the settings would be ideal for the batteries.

I'll be running 2x 12V, 120AH VRLA batteries in series (ARMASAFE Plus, 12FV120). But looking at the programming for the BP65, it seems to me like the shut down and restart voltages are a little bit too spread out to effectively save the battery.

Any suggestions on which setting would be ideal for the VRLAs? And will any of the settings operate properly allowing just a 20% discharge before cutoff?

Thanks for the help.


Jade asked

0 Answers

battery protect for wind turbine dump load

I have a small off-grid solar setup and I am looking to add a 600watt wind turbine( 3 phase AC). I had run the included charge controller for about 6 months with solar only , and had a catastrophic failure with it and now have zero confidence in that style.

I am planning on installing a bridge rectifier and running it straight to the batteries, loosing efficiency, but increasing reliability.

I am looking to use the Battery protect for a dump load controller, setting the cut out voltage at around 14.3V . when batteries are fully charged ( 14.4V), battery protect will switch on and divert the excess energy into my dump load. batteries drop to 14.2V, BP turns off and cycle repeats as necessary. I have a big enough Lead Acid battery bank, to where I am not concerned about any lag in time setting that are fixed in programing. Not sure if the BP would be rated for the number of operation cycles , which it wouldn't likely see in its intended use.

Any thoughts or recommendations?

Bret_G asked

0 Answers

control Cyrix or BP with BMV instead of BMS

Is it possible to control the disconnect function in Cyrix Li-ct (or Battery Protect) with the relay function in BMV712 (instead of the BMS)?

I would like to use the BMV alarm functionality to disconnect the alternator from the house battery when SOC gets close to 100%.

trostek asked
astor commented ·

1 Answer

Battery protect 100amp

To connect my battery protect I am using 35mm2 cable and 120amp fuse. Run ..25 m is this suitable

Roberthudson859@gmail.con asked
MichaelVausR commented ·

0 Answers

Charging 2 Lithium banks with MPPT


I'm looking for a way to charge my 2 lithium banks with MPPT and keep them isolated a the same time.

Here is a picture of what I have so far.

The starter has a switchable circuit to keep the Argos energise circuit live and prevent the MPPT shutting down each evening and messing with the history metrics and also give the MPPT a voltage reference when charging as I don't believe it will get one from the Argos input terminal (please confirm if I'm wrong on that). I understand that this will draw around 0.05A to have the Argo and MPPT active, which will be easily replaced by the solar charge going to the starter battery.

The 2 65A BPs are configured to lithium settings and will disconnect using the BMS charge disconnect going via the BMV relay.

This will not be an approved setup, but will it work as I've gone through serveral designs and this is the only one I haven't spotted any problems with - yet.... :)

If you have a better and supported setup for doing this I would be very interested in the details :)



stocksy asked
stocksy edited ·

0 Answers

Is BP-200 bi-directional

I'm having some issues with the system I install last summer. My converter is tripping my shore line GFI. I'm not sure yet as to the cause, but I'm hunting it down. My question; is the BP-220 bidirectional? The dealer I worked with okay'ed my drawing, but I'm thinking now there was an oversight somewhere? Due to wiring pull restrictions my converter (battery charger) output is connected to the load of the BP-200. The orange arrow is the output of my converter. I'm thinking now this isn't going to work. If the BP-200 is bidirectional it should work.


Steve asked
Steve commented ·

1 Answer

MBV 700 relay on/off/on

I installed BMW 700 customers and set it to signal me 95% charge and 95% battery discharge. Everything is set up correctly according to the operating instructions. It just doesn't work. , I set up my BMW via Victron dontge. Interestingly, according to the voltage on the battery works well according to SOC 95% does not work.
my requirements
When the battery is over 95% charged, it turns on the internal relay. If it drops below 95%, the relay switches off. this doesn't work for me on the bmv 700. please help


Miroslav Katrencik asked
WKirby answered ·

1 Answer

Battery Protect settings What is the difference between Li-ion mode and Normal? Is it simply different voltage parameters or is there more to it? In Li-ion mode, it says Shut down at 10v and Restart at 13v. I feel that might be a little low for comfort and quite a wide range, can I put it on Normal mode and set my own limits e.g. 11v shutdown and 12v restart? Or is it best set to Li-ion mode? I am using LiFePO4 batteries.

brassmonkey001 asked
nebulight edited ·

2 Answers

Positive grounding with Battery Protect

I am wondering if there are any problems when using a battery connect device (BP48/100) with a positive ground system.

I have a communications system where the battery is charged from a fully isolated and floating charger and at the DC Distribution to the comms equipment the positive feed is grounded (after the battery Protect.

example schematic below


Gadget007 asked

0 Answers

How do I use battery protect to make my 24v system work??

Hello I have a Tesla battery and have 2 battery system. I would like to be able to charge the battery and discharge it safely.

Here is my system layout I plan on building, how do I make it safe??


Chinaka asked
Mike Deau answered ·

2 Answers

Fusing Smart Battery Protect

Hi all,

another novice question.

just a quick question, I’m planning to use a 100a smart battery protect (SBP-100) to cut dc loads against under-voltage to prevent damage to the lithium batteries...

Do I need to in-line fuse directly before the SBP-100? With let’s say 100a fuse or less?...

It’s a 12v motorhome system, it’s fused (200amp) immediately after the batteries- goes up to the Victron lynx distributor And then the DC loads will be fused accordingly- but do I need to fuse from the +ive busbar to sbp with a 100a fuse. The 4 lynx connections will be used to connect and fuse the charging sources, dc/solar/ac-dc etc so my intentions was to use the un-fused m8 connections on the right hand side of the unit that would ordinarily be used to connect further lynx distributors.

so earlier on the system is protected by a 200amp fuse and the dc loads will be protected after the BP but does the SBP require fusing. I understand that fusing generally protects the wire/cables and not the device, I’ve oversized cables so that’s not an issue.

Also dc loads will be no where near 100a but it was just as cheap to buy a 100a over a 60a so I went for the 100.

Thanks for any advice

Harrison asked
Harrison commented ·

0 Answers

About my victron system using battery protect


Hello I have updated my electrical design for my wiring, I made sure that the current would flow into the BP in and leave from the out. Can you please let me know if this is safe thanks

Chinaka asked
Chinaka commented ·

1 Answer

Battery Discharge Protection - Inverter

I have a mobile (Caravan) system that is Lithium based but I DO NOT have Victron Lithium batteries. My batteries also do not have an accessible BMS. They are a Renogy 170 AH lithium batteries.

My system is charged via a Victron 100/50 Smart Solar MPPT and a Victron 30 amp AC charger. I also have fitted a BMV712, smart battery sense and a 65 amp Smart Battery Protect.

I am about to install a NON Victron Inverter 2800/5600 watts to see how much I can do via 240v instead of gas. Induction cooking etc.

my question is about how I best protect my batteries from over discharge whilst using the inverter.

I have read that you should not use a Smart Battery Protect on an inverter. Is this correct?

if you can then the 220 amp model it may be a bit small (2640 watts).

Can I use the BMV712 to activate a relay to disconnect the inverter?

Are there any other alternatives?


Strop asked
Matthias Lange commented ·

3 Answers

Protecting LiFePO4 batteries from all sorts of things If I connect my MPPT, DC2DC charger and a EHU charger to one side of a Battery Protect and the other side to the battery, and connect my BMV712 relay output to the Battery Protect, would that then disconnect my battery bank to prevent being charged when the temperature drops cold (as well as if it gets too hot) and disconnect in the event of low (or high) voltage events? Or is it not so simple as that?

brassmonkey001 asked
brassmonkey001 edited ·

2 Answers

SBP100 (not product failure)

This is a relatively new and small system that has previously worked as expected. Has been disconnected past two months. Was reconnected yesterday. The two SBP's were updated. One SBP is 'charge' and other is 'load'. The VE Li-ion battery was charged to full via solar and orion Tr smart as of today. There was no DC load output from the 'load' SBP. On the smartphone I could not toggle this SBP to "active", it did display consistent battery volts. Voltage checked with 13.35 on the 'IN' and 2.64 on the 'OUT'. I could not reboot unit from default/power off. The 7 digit display does go thru a flashing mode with 'zero' above and below, (not a full digit or letter) briefly, then no further blue indicators.

I'm curious what I did to toast it. I feel confident that directional wiring is correct. Have ordered a replacement.

rodney abbott-buchanan asked
rodney abbott-buchanan answered ·

1 Answer

smart battery protect 12/24 won't connect to victron connect app

My smart battery protect 12/24 shows up as a device on my victron connect app dashboard, but when I click on it to connect, it gets stuck at 20% and wont fully connect. it says "connecting" and progress bar is stays at 20%. I have 2 smart battery protects and the other one connects just fine. Is there some sort of factory reset? Any thoughts?

mikeras asked

0 Answers

Connecting Battery Monitor BMV-712 with Battery Protect BP-100

How can I connect the relay terminal of the BMV-712 battery monitor with a BP-100 battery protect? I want to disconnect the battery in case the capacity of the battery has reach a defined percentage. I only can programm the cut off voltage off the BP-100, but I want to use the capacity information from the BMV-712.

Adversor asked
Reklusiv commented ·

1 Answer

Will a GX device turn off MPPT chargers in response to a VE Bus over-charge event?

Currently I have all my LFP charge sources connected to the charge bus via a Battery Protect 220. I have become aware that this is no longer recommended due to reverse current flow in the BP, I have an anchor light connected to the MPTT load port drawing a few milliamps using the Streetlight function, this small current is passing through the BP the wrong way.

My question is this. If I connect my MPPT controllers directly to the charge bus, (bypassing the BP), will my VE Bus BMS shut down the MPPT charge controllers in response to an over charge event or do I need to interuppt the MPPT charge current some other way?

Tim Chapman asked
Tim Chapman edited ·

0 Answers