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Battery Protect

BP65 - use existing relay wiring?

Hi community,

I have a bp65 to use for loads. This is replacing an existing relay which is wired to battery positive (via a fuse) and the negative is wired to the negative contactor enable of my BMS.

Would it do any harm to simply replace the relay with the BP65? As in use the existing relay wiring only running the BP65 with fused battery cable to IN loads to OUT and the existing BMS negative contactor enable to BP65 gnd only?

As far as I could tell it should do the same job, if bms cuts the negative the BP65 would not be powered on and the loads would be isolated? Is it safe to do it that crudely?

Or should I have a negative to the negative busbar and wire a negative from the BMS to the L pin?

Thank you.

Christian Bell asked
Christian Bell edited ·

0 Answers

Battery protect connection to multiplus

I'm having some difficulty understanding how I can connect the BatteryProtect (12v/65a) with the MultiPlus 12/800/35. The MultiPlus when charging should go to the IN but when it's inverting it should use OUT, you obviously can connect both on the BP. It's says clearly in the manual that you shouldn't use chargers on the OUT terminal but how about consumers(aka the inverter mode) on the IN?

The schematic on the Victron site is way too elaborate to translate to my setup. Can I just connect the MultiPlus to the IN of the BP?

e11enn asked
Matthias Lange - DE commented ·

0 Answers

Danger Reverse Current when using Battery Protect for charging

Hi together,

I have a question concerning using a BatteryProtect (BP) to disconnect the charge source in a Lithium Battery System with VE.bus bms.

In the BP manual Figure 5 illustrates how to connect the BP for charging situation and it states that "uncontrolled reverse current will flow through a Battery Protect if Vout > Vin."

Now I wonder what happens, when the Voltage of the charger (Vin) drops, i.e. Solar charger when there is no sun or any other charging source that is swithched of. Wouldn't then the Voltage of the Battery (Vout) be higher and thus reverse current flow causing danger?

THanks a lot for your comments, I am abit affraid of burning down my RV...

cheers, Daniel

DanielK asked
kiko commented ·

6 Answers

Using "battery protect" product to prevent battery bank over discharge by inverter

I have a very modest 480W solar 12V PV system, using MPPT charge controller, AGM batteries and a small (300W ) inverter (no victron products in use, unfortunately).

Like most similar systems, small DC loads can be managed (shut off, timed etc) by using the load output terminals of the solar charge controller.

To further protect the battery bank from over discharge, can the battery protect product be used to prevent the DC inverter draining the battery bank down to the inverter cut off voltage (10.5V)?

Many thanks


artyjones12 asked
Matthias Lange - DE answered ·

1 Answer

Odd battery protect behavior in lithium mode

I have a smart BP-65 connected to a mini-bms and victron lion battery. The BP-65 is configured for LION mode through the app. When I unplug the remote connector, simulating loss of +12v from BMS, nothing happens. My understanding is in LION mode it should immediately disconnect the load? If I unplug the ground, the BP says it's shutting down due to low voltage, which again my understanding is in LION mode the voltage settings are ignored?

Any thoughts? I did a reset to default but no change in behavior.

David_KTN asked
David_KTN answered ·

1 Answer

Protecting DC loads with Victron BP


I have just received my 200 amps isolator and am wiring it in soon, I would also like to wire in the Victron 65 amp BP I purchased, but for the life of me I can't see how these things can work in a solar system if they are not bi-directional (which I am aware they are not). I have attached a rough layout of my system as it stands (dotted lines are proposed connections).

I f the BP can only be connected to the inverter it is pretty much a waste of money, correct or not? Also I can not find a schematic for controlling the BP with the BMV-712 anywhere, although I am assured by several people it is straight forward? Also I cannot find advice on settings in the BMV-712 for same.New LiFePO4 & BMS connections (with BP)..pdf

Tex260Z asked

0 Answers

Victron BMS red led

We have a sailboat with 4 * 200 ah 12v - packs of 2 batteries for 24 V.

Everything is Victron - Quattro 8000 BMS VE and monitor etc.

The batteries made the BMS kick in and the Quattro showed (low battery) - and wound not charge.

We called in for help which resulted in loosing the setup and that we had to have the communications card on the Quattro changed and now the blue panel also.. We can no longer access the menus in the panel and we don't have access to the Quattro.

As soon as we use the hydraulics an alarm goes off and we can't see how much power is left on the 2 working batteries ? So we are running the Panda generator all the time.

BUT the Quattro will now only run on 1 pack of 2 batteries. When we connect the other pack the red light comes on on the BMS. With a Victron smart 25 amp 12v charger we measure 14.4 v separately on the 1 pack of batteries that results in a red led and aprox. 13.7 v on the other pair.

What could be wrong? The batteries are from 2016 LiFePO4 . Can a battery be reset so the BMS does not create a red led?

Thank you Tor

Vejle asked
Rob Fijn answered ·

2 Answers

Victron Smart Battery Protect 24v Remote wire to control 12v load?

I am planning to use a 60amp smart battery protect to switch a DCDC Boost converter for charging a 24v house bank from my 12v engine battery when the engine is on.

Is there an issue if the Battery protect is wired to the 12v side of the converter, but switched (remote output) by a 24v signal from my battery BMS?

By wiring it this way, I can set the SBP60 to cut-off at 13v (user defined cut off on the battery protect) to prevent engine battery discharge when the engine is off, and use my BMS to cut off the dcdc boost when it determines the 24v house bank is full.

Much appreciate knowing if this would work.



sharpey asked
sharpey edited ·

0 Answers

Two BP65 - one for DC loads and one for 100/50


I have a 100Ah 24V lithium bank with a housepower bms. There are currently a couple of te connectivity relays as a failsafe, one between the battery and the dc loads, and another between the battery and the mppt 100/50.

I'm looking at replacing the relays (they use 130mA at ~26V each) with a pair of BP65s. This should be a fairly painless swap as my existing relays use M6 bolts also, I'd just need to run the negatives to the bms so it can activate the BP65s


BP65 #1: Lithium battery positive to BP65 IN, then BP65 OUT to DC loads

BP65 #2 MPPT100/50's battery positive terminal to BP65 IN, then BP65 OUT to lithium battery positive

The #1 scenario seems pretty standard, just not sure about the #2 scenario. WIll this work ok?

Christian Bell asked
Christian Bell edited ·

1 Answer

Smart Battery Protect

I am just connecting the system up and on the smart battery protect I am getting on the app Disabled by remote. Any ideas ?Thankyou

Roberthudson859@gmail.con asked

0 Answers

Smart BP220 the 90 seconds load disconnect delay does not seem to be active

I use my BP220 to protect the main battery of a small motor boat. The idea was only to protect the battery if the main switch is left on for a night.

I see the following behaviour:

- If the switch off voltage is on 11V or similar, all works fine but the system cuts immediatly if I crank the engine.

- If I lower the switch off voltage to as low as 8.5V, the engine starts perfectly

So, my only explanation would be that the 90 seconds disconnect delay is not working. If it would work, the engine should start and all would be fine because within 2 seconds we are back to normal voltage.

Any help would be super welcomed!!

Best regards

Christophe Hentsch


0 Answers

Integrating Battery Protect BP-65

Researching the BP-65 to see if I can integrate it into my system.

What I want to do is use it between my MPPT 75/15’s and my 24V LifePo4 to interrupt charging in the event of a cell balancing issue (overcharging).

As I understand it can be used to do this although it is more commonly used to interrupt load output power supply to protect against undercharged state.

My question is, how do the contacts work on the BP-65? I see it has a High, Low and Ground.

I was hoping to be able to use an aftermarket BMS to trigger disconnect. It’s contact outputs are open collector types with High Limit Switch, Low Limit Switch, and Ground terminals. It’s configured to be open at all times and then grounds out when activated to trigger an external device.

Does the BP-65 work the same way? Is it a normally open device?

If so, would it be as simple as connecting the HLS output terminal of the aftermarket BMS to the H input terminal of the BP-65 along with Ground to Ground?

I have a BMV-712 and understand I could connect the BP-65 to it to trigger disconnect, but the aftermarket BMS is able to monitor my battery cells individually versus an overall Over Voltage trigger which is how I understand the BMV-712 and the BP-65 work, with 712 monitoring/measuring if there is an overall Over Voltage condition in which case it triggers the BP-65 to disconnect.

Solgato asked
Solgato commented ·

1 Answer

Lithium Starter Battery


I've received some equipment to upgrade my boats electrical system. However the company have sent me the wrong battery (100ah drop-in lithium) - should be 100ah Victron smart.

Anyway, they are going to do a swap out, but I was thinking if it would be possible to use it as my starter battery and maybe run a few other things from it - deck wash, nav lights...

My system will have 4x 100ah Victron Lithium batteries for the house bank. This is connected to a 12/3000/120 multiplus.

The solar MPPT and Alternator are connected to a 85ah agm battery and that connects to a cyrix li-ct in order to charge the house bank when charge is available.

What I'm thinking is to do the same with the MPPT, but run it through a Battery protect and have the ignition wire for the balmar external regulator also go through a small battery protect - both will be connected to the BMS charge disconnect that I have routed through my BMV 712 relay and set to disconnect at 14.2v.

Main concern is that currently when the Cyrix disconnects when solar charge is occurring the starter gets a quick dose of around 15volts before the MPPT reduces current.

Will the BP catch this quick enough in order to stop it getting to a lithium starter battery?

I don't think the same will occur with the alternator as once the regulator ignition wire goes out the stop off current should be instant, but say if you think I'm wrong.

Hope you can clear this up and maybe give alternatives I haven't thought of.



stocksy asked
dazey77 edited ·

2 Answers

Smart BatteryProtect BP-100 Remote doesn't work

I recently installed my new Smart BatteryProtect BP-100 for a pure resistive load (Orion-Tr 24/12-20 and a bunch of 12V lamps and a small fan for a toilet, max load about 6A).

I have a ElectroDacus SBMS0 BatteryManager that controls the Remote input via an optocoupler.
When testing the system in a testbench at home everything worked as planned, BP-100 switched off at 2.9V at one of the LiFePo4 cells

Now the BP-100 is installed with a Ground wire to the negative Busbar, The IN to the positive Busbar, via a 100A fuse. The Remote contacts are connected to the SBMS0 optocoupler output.

Testing the function by disconnecting the Remote plug reveals that the load is still On (batteries are fully charged so the output from the SBMS0 is not a viable way of testing).
Testing via the VictronConnect App by deactivating the Load Output yields the correct result, i.e. Load is turned Off, activating Load turns the Load On.

But the removing/replacing the Remote plug doesn't do anything.

Tested the various settings A, B and C in the App, no change whatsoever.

The BP-100 is NOT used to control my Victron 24C1600 Inverter.

When removing the power to the SBMS0 (BMS) the inverter is disconnected (separate optocoupler that opens) but the BP-100 is still on.

// Patrik

Patrik Kall asked
Patrik Kall commented ·

2 Answers

BatteryProtect BP220 OverVoltage activating at 14v instead of 16v

I'm having an issue with multiple BP220s where they disconnect power for just 1-2 seconds and then reconnect.

I have a 12vdc saw, hydraulic pump, and air compressor connected to the output of the BP220. There are 2x 12vdc batteries in parallel on the input side. If the battery voltage is at 13.9vdc or higher and the hydraulic pump is run, the BP220 immediately disconnects the power and then comes back on in a few seconds. There is no error code displayed.

I have tested 3 different BP220s and all have behaved the same way.

If the battery voltage is lower than 13.9vdc, the BP220 does not disconnect power when the hydraulic pump is used.

I've connected a multimeter to the input and output of the BP220 and the voltage does not go above 14vdc or below 12vdc (multimeter set to capture min/max voltage spikes as short as 250us).

I've also changed out the hydraulic pump with the same result.

This is installed in a 2019 Dodge Ram Promaster 3500.

I have an additional 8+ vehicles with this configuration that are not experiencing this problem.

I have re-detected the battery voltage by going to mode d on the BP220, same result.

I'm wondering if the BP220 is detecting a very short spike in voltage above 16vdc (faster than my Fluke multimeter can detect). Or if the BP220 has a bug which causes it to shut off on overvoltage at 14vdc instead of 16vdc. Or is there some other problem I'm missing?

kurt asked
kurt edited ·

0 Answers

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 - DE 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. 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

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