My JK and my meat

[DerpsyDoodler]

And with that said, charging does not require the charger to "see" the battery. If a circuit is complete, then power can flow. Charger pushes at x charge voltage to a max of y current. if it can flow then it can flow. Charger requires no specific knowledge of battery voltage. It just knows what its supplied voltage is being drawn down to and what current it's sending.

Also, I'll qualify my previous post with this addition:

dumb chargers require no specific knowledge. auto sensing (12/24v capable chargers) require knowledge of the battery voltage. Some of those sense the first time, then remember it. Others sense it every time (if set to auto-sense). Regardless, the EPEVERs power themselves from the battery.

Yes exactly. If the SCC is off, and I put a source on it's battery output, it turns on. If there's solar it starts charging and I can remove the source... it stays on and will charge the regular battery no problem. As soon as the panels are disabled though it shuts off again. ie. Once it starts, it can charge no problem as long as charging is enabled on the BMS. If it has no source - like the BMS discharge FETS or the PV - it turns off.

I doubt that functionality is intentional, and I wouldnt rely on it in practice. Its probably just a by-product of good-enough design. That said, and like upnorth said, straying from the topic. recap:

BMS is last line of defense. get the battery protect going to sense bus voltage and trip the inverter's power switch. If you have DC loads other than the inverter and SCC, you'll want those on the protection side of the battery protect (assuming they're small enough to be under the battery protect's amp rating).

 

[BigBrosMo]

Also, I'll qualify my previous post with this addition:

dumb chargers require no specific knowledge. auto sensing (12/24v capable chargers) require knowledge of the battery voltage. Some of those sense the first time, then remember it. Others sense it every time (if set to auto-sense). Regardless, the EPEVERs power themselves from the battery.


I doubt that functionality is intentional, and I wouldnt rely on it in practice. Its probably just a by-product of good-enough design. That said, and like upnorth said, straying from the topic. recap:

BMS is last line of defense. get the battery protect going to sense bus voltage and trip the inverter's power switch. If you have DC loads other than the inverter and SCC, you'll want those on the protection side of the battery protect (assuming they're small enough to be under the battery protect's amp rating).

Totally. And I am down for that... I just can't figure out, even with all the diagrams available, HOW to wire the BP to the Remote jack on my inverter. If someone can explain that to me I am good to go.

1. The remote jack has a Yellow Pos lead and a Red Neg lead. ie. if it put a meter across them I get 26v (the battery)
2. as soon as I bridge them, the inverter turns on. Disconnect them, it shuts off. Perfect.
3. How do I wire this into the BP?? What wires go to what ports/relay terminals etc?

 

[upnorthandpersonal]

If I turn off Discharge there is nothing on the bus. There's no voltage to "detect" at all. I just tested with my meter. I disable Discharge, and everything shuts off. The meter shows 0 volts.

If you disable discharge and keep charge enabled in the app you don't see a voltage with a multi-meter? I don't understand how that's possible with a JK BMS...

 

[BigBrosMo]

If you disable discharge and keep charge enabled in the app you don't see a voltage with a multi-meter? I don't understand how that's possible with a JK BMS...

I 100% do not. My setup:

Batt Neg goes to BMS. Common port (P-) of BMS goes to shunt, then to negative system bus. Batt Pos goes to System Pos bus.

I don't understand why it WOULD show voltage. Wouldn't it have to at least allow a minimal current to do that? And thereby contradicting a disabled Discharge.

 

[DerpsyDoodler]

Totally. And I am down for that... I just can't figure out, even with all the diagrams available, HOW to wire the BP to the Remote jack on my inverter. If someone can explain that to me I am good to go.

1. The remote jack has a Yellow Pos lead and a Red Neg lead. ie. if it put a meter across them I get 26v (the battery)
2. as soon as I bridge them, the inverter turns on. Disconnect them, it shuts off. Perfect.
3. How do I wire this into the BP?? What wires go to what ports/relay terminals etc?

the battery protect is pretty simple and should be clearly labeled. with "out" and "in" studs. The ground wire poking out of the top needs to go to your negative bus, "in" comes from the battery positive being protected, "out" goes to loads positive. In your case, the load should be a NO relay that will close when the BP gives it power. Then wire the relay to bridge the remote pins when closed.

 

[DerpsyDoodler]

Note, if the battery protect has already been used, you'll need to reset it. they auto sense voltage the first time and remember it. Go to victron's site and grab the manual. Get familiar with the details.

 

[DerpsyDoodler]

Victron has a ton of different rated versions of their battery protects, so you'll need to know your model, as well. Mine is a 12/24 100A smart battery protect (dont recall the specific model). I have no idea which yours is.

 

[upnorthandpersonal]

I don't understand why it WOULD show voltage. Wouldn't it have to at least allow a minimal current to do that? And thereby contradicting a disabled Discharge.

BMS MOSFETs Explained

I'm writing this post since it seems there is a lot of confusion (especially in the comment section of a certain youtuber in Australia) on why both MOSFETs in a typical single port BMS are controlled individually and why/how this works when they're in the same series circuit. It will hopefully...

diysolarforum.com

 

[BigBrosMo]

Note, if the battery protect has already been used, you'll need to reset it. they auto sense voltage the first time and remember it. Go to victron's site and grab the manual. Get familiar with the details.

I appreciate your help. I have the manual. Have read it back and forth. It (and many sites) say you don't need a seperate relay if you have a remote port on your inverter. You only need a seperate relay if you are trying to hardwire it into the actual on/off switch of the inverter. But there is no diagram or instruction anywhere showing that remote port wiring! Mine is the "dumb" 65amp.

I have a CS degree. I manage cell tower construction. I have spent much of my career as a telecom CO technician splicing fiber and wirewrapping terminals. And yet here embarassingly am!

 

[DerpsyDoodler]

I appreciate your help. I have the manual. Have read it back and forth. It (and many sites) say you don't need a seperate relay if you have a remote port on your inverter. You only need a seperate relay if you are trying to hardwire it into the actual on/off switch of the inverter. But there is no diagram or instruction anywhere showing that remote port wiring! Mine is the "dumb" 65amp.

I have a CS degree. I manage cell tower construction. I have spent much of my career as a telecom CO technician splicing fiber and wirewrapping terminals. And yet here embarassingly am!

"remote port" sounds vaguely and maybe ambiguously defined. I would NOT, for instance, connect a positive line to one side and negative to the other, especially based on you saying you just bridged them and it worked. Sounds like you just need to close the circuit (with a switch or relay). Refer to your inverter manual if you're not sure.

 

[upnorthandpersonal]

I messed up - mixed charge and discharge... ignore what I wrote. Some charge controllers don't need to sense the battery, like Victron for example and the one I have.

 

[upnorthandpersonal]

@upnorthandpersonal, are you tired?

You have no idea...

 

[John Frum]

Arg. Can someone explain to me HOW to connect the Battery Protect to the remote port on the Inverter? I don't understand how to wire it....

1. Pos+ comes from positive system bus to BP + IN.
2. BP + OUT goes to where?

https://www.victronenergy.com/upload/documents/Manual-Smart-Battery-Protect-12V-24V-65-A-100-A--220-A-EN-NL-FR-SV-DE-PT-ES-IT-TR.pdf

The way you want to use it is different then I suggest so I will show you how to get it to functional baseline

Battery_protect goes in the current path between the positive busbar and the load.

busbar.positive->fuse->bp.in
bp.out->(not connected for first iteration)
bp.gnd->busbar.negative

That will get it running and you can develop incrementally from there.

3. Remote switch on inverter has a + and - lead. Where do they go on the BP? ie. if I put my meter across the yellow + wire and the red - wire of the remote cable, I see the battery's voltage. What ports on the BP do they connect to?

What is the voltage between inverter_switch.pos and inverter_switch.neg?
I suggest you need to know this before you integrate the battery protect.

If you have pure dc loads you can connect dc distribution positive feed to bp.out to give them low voltage disconnect.

 

[BigBrosMo]

https://www.victronenergy.com/upload/documents/Manual-Smart-Battery-Protect-12V-24V-65-A-100-A--220-A-EN-NL-FR-SV-DE-PT-ES-IT-TR.pdf

The way you want to use it is different then I suggest so I will show you how to get it to functional baseline

Battery_protect goes in the current path between the positive busbar and the load.

busbar.positive->fuse->bp.in
bp.out->(not connected for first iteration)
bp.gnd->busbar.negative

That will get it running and you can develop incrementally from there.



What is the voltage between inverter_switch.pos and inverter_switch.neg?
I suggest you need to know this before you integrate the battery protect.

If you have pure dc loads you can connect dc distribution positive feed to bp.out to give them low voltage disconnect.

Awesome thank you. Voltage between inv switch + and - is the battery voltage, ie 26v

 

[John Frum]

Awesome thank you. Voltage between inv switch + and - is the battery voltage, ie 26v

The problem with using the relay port on the bp is that it only closes for ~30 seconds.
This is from memory so please confirm.

 

[John Frum]

I've not had enough coffee yet to explore the ramifications of connecting....
inverter.switch.line->bp.out and inverter.switch.load->busbar.negative.

 

[John Frum]

This is how I would do it with an SSR.
WARNING: diagram my cause helmet fire.

legend {
    {} { functional block }
    nnn|NNN| { fused busbar position where nnn is wire size in awg and NNN is fuse size in amps }
    nnn|UUU| { un-fused busbar position where nnn is wire size in awg }
    <-> { bi-directional current flow }
    -> { uni-directional current flow }
    <- { uni-directional current flow }
    @ { back reference }
}
dc_domain {
    busbar.positive {
        006|100|->bp.positive.in
        nnn|NNN|->inverter.current.positive
    }
    busbar.negative {
        016|UUU|<-bp.gnd
        nnn|UUU|<-inverter.current.negative
    }
}
inverter {
    current {
        positive@
        negative@
    }
    switching {
        line<-ssr.1
        load->ssr.2
    }
}
bp {
    positive {
        in@
        out->1A_fuse->ssr.3
}
ssr {
    1@
    2@
    3@
    4->busbar.negative
}

 

[BigBrosMo]

This is how I would do it with an SSR.
WARNING: diagram my cause helmet fire.

legend {
    {} { functional block }
    nnn|NNN| { fused busbar position where nnn is wire size in awg and NNN is fuse size in amps }
    nnn|UUU| { un-fused busbar position where nnn is wire size in awg }
    <-> { bi-directional current flow }
    -> { uni-directional current flow }
    <- { uni-directional current flow }
    @ { back reference }
}
dc_domain {
    busbar.positive {
        006|100|->bp.positive.in
        nnn|NNN|->inverter.current.positive
    }
    busbar.negative {
        016|UUU|<-bp.gnd
        nnn|UUU|<-inverter.current.negative
    }
}
inverter {
    current {
        positive@
        negative@
    }
    switching {
        line<-ssr.1
        load->ssr.2
    }
}
bp {
    positive {
        in@
        out->1A_fuse->ssr.3
}
ssr {
    1@
    2@
    3@
    4->busbar.negative
}

I am so exasperated with this setup. FFS Victron. The stupid Battery Protect doesn't actually go to 0v/disconnect when it's undervoltage. There is still a 2.5v potential on the BP output during undervoltage. So my relay, which operates at a 3v minimum, flickers on and off and causes the inverter to go on and off. Why does the BP do that? Like why the hell not actually TURN OFF? Do I need a different SSR with higher turn-on set point voltage? SO frustrating.

 

[DerpsyDoodler]

I am so exasperated with this setup. FFS Victron. The stupid Battery Protect doesn't actually go to 0v/disconnect when it's undervoltage. There is still a 2.5v potential on the BP output during undervoltage. So my relay, which operates at a 3v minimum, flickers on and off and causes the inverter to go on and off. Why does the BP do that? Like why the hell not actually TURN OFF? Do I need a different SSR with higher turn-on set point voltage? SO frustrating.

Have you reached out to victron tech support? sounds faulty to me.

 

[John Frum]

I am so exasperated with this setup. FFS Victron. The stupid Battery Protect doesn't actually go to 0v/disconnect when it's undervoltage. There is still a 2.5v potential on the BP output during undervoltage. So my relay, which operates at a 3v minimum, flickers on and off and causes the inverter to go on and off. Why does the BP do that? Like why the hell not actually TURN OFF? Do I need a different SSR with higher turn-on set point voltage? SO frustrating.

Which SSR are you using?
You had mentioned controlling the inverter directly from the battery protect, did that not work out?