Pop up Camper LiFePO4 system

shade

Well-known member
I am looking for the right way to disconnect my inverter when the battery voltage is too low. The Victron BatteryProtect says you can't connect an inverter to it in the manual so that is a no go. I am thinking about using a Blue Sea disconnect, I would prefer a latching relay to remove the coil load but all of the ones I have found require both an on and an off control signal which I don't have from the BMS control.
As John said, a BatteryProtect can be used to control an inverter's remote on/off switch, which in effect would be similar to what you want to do. See #4.

It may be possible to use a Victron VE.Bus BMS for a control signal for your system design, if you still want to use a latching relay.

Such a thing would be very useful when the alternator would be connected directly to this battery. But it isn't.
So you have the solar power and the DC-DC charger. In both you configure a charging voltage/profile that will not exceed the battery specification.
Voltage cut-offs make sure the battery voltage cannot be drained to low, out of specification.

Next to that, I am expecting that these kind of batteries have integrated BMS that already protects the battery for this.

A small search on the battery confirms this: https://battlebornbatteries.com/wp-content/uploads/2019/09/Battle-Born-Manual.pdf
It already has under and overvoltage protection as well as current.
It also includes temperature protection!

So, to add a battery protect on these things would be redundant, it doesn't make sense.

In fact, you could even remove the low-voltage cut-off as well, because this battery will protect itself from getting to low.
Use of a separate disconnect system makes sense to me, if for no other reason than I'd rather be able to replace a readily available external part than have to crack open a battery and source whatever was needed for repairs. There's also the consideration of using a few hundred dollars in parts to protect a few thousand dollars of batteries.

Either way, I provided the link for consideration; do as you want.
 

Justin Cook

Member
I am looking for the right way to disconnect my inverter when the battery voltage is too low. The Victron BatteryProtect says you can't connect an inverter to it in the manual so that is a no go. I am thinking about using a Blue Sea disconnect, I would prefer a latching relay to remove the coil load but all of the ones I have found require both an on and an off control signal which I don't have from the BMS control.
Although I'm (for obvious reasons) overly-biased toward recommending Victron products, the particular application that you're referencing would be a perfect place for a Sterling ProLatch-R, which is a programmable, waterproof, bistable, magnetically latching relay that does not require any external signals from anything. It has 4 modes, one of which is a "battery protect" mode which has fully programmable low voltage on/off thresholds... it costs a little more than a Victron BatteryProtect and it's far more difficult to program (I actually had to write a readable manual for the things so our customers could manage it) but once it's programmed it's bulletproof, and is designed to handle the high inrush currents of inverters that the Victron BP cannot, and being bistable, can also handle the reverse current that the Victron BP cannot. Just a thought; here's a link to the 240A model in our store, but shop around if you decide you want one; we definitely don't always have the lowest price around.
 

shade

Well-known member
Although I'm (for obvious reasons) overly-biased toward recommending Victron products, the particular application that you're referencing would be a perfect place for a Sterling ProLatch-R, which is a programmable, waterproof, bistable, magnetically latching relay that does not require any external signals from anything. It has 4 modes, one of which is a "battery protect" mode which has fully programmable low voltage on/off thresholds... it costs a little more than a Victron BatteryProtect and it's far more difficult to program (I actually had to write a readable manual for the things so our customers could manage it) but once it's programmed it's bulletproof, and is designed to handle the high inrush currents of inverters that the Victron BP cannot, and being bistable, can also handle the reverse current that the Victron BP cannot. Just a thought; here's a link to the 240A model in our store, but shop around if you decide you want one; we definitely don't always have the lowest price around.
Interesting product. Do you have a link for your manual?
 

Justin Cook

Member
Interesting product. Do you have a link for your manual?
We do send one out with every unit we sell, but let me see if this will let me attach a PDF here. To be clear, you need Sterling's manual too (downloadable version hotlinked there), as there are charts that you need to cross-reference, not to mention wiring and such... but if you read through Sterling's manual you'll see (as with so many Sterling products, unfortunately) why I had to write my own :rolleyes:
 

Attachments

shade

Well-known member
We do send one out with every unit we sell, but let me see if this will let me attach a PDF here. To be clear, you need Sterling's manual too (downloadable version hotlinked there), as there are charts that you need to cross-reference, not to mention wiring and such... but if you read through Sterling's manual you'll see (as with so many Sterling products, unfortunately) why I had to write my own :rolleyes:
I've read some of their documentation. :)

Thanks for the pdf. I can see why you wrote it! Fortunately, my configuration shouldn't be changed after the first successful round of programming.

I like the idea of having a single, automated, everything-completely-disconnected device, so I may add one of these to my plans.
 

Justin Cook

Member
I've read some of their documentation. :)

Thanks for the pdf. I can see why you wrote it! Fortunately, my configuration shouldn't be changed after the first successful round of programming.

I like the idea of having a single, automated, everything-completely-disconnected device, so I may add one of these to my plans.
They're a fantastic product, for sure. I'm super fond of them once they're programmed, I just hate being on a tech support call helping someone program one... inCREDible PITA. But once it's programmed, it's freakin' bulletproof.
 

Mlachica

TheRAMadaINN on Instagram
question....

with the REDARC dc-dc charger and Victron 100/50mppt, will they charge simultaneously? Or will one charging source fool the other charger that the battery bank is full?
 

Justin Cook

Member
question....

with the REDARC dc-dc charger and Victron 100/50mppt, will they charge simultaneously? Or will one charging source fool the other charger that the battery bank is full?
Multiple charge sources can be attached to a single battery bank in parallel with no ill effects so long as 1- they are all connected properly, 2- they are all fused appropriately, and 3- at no time do you exceed the maximum charge current recommendation for your particular batteries.
Both (all) sources will charge concurrently; that being said, however, if you're already charging your bank with the DC-DC charger when the MPPT "wakes" up, it will see a higher voltage at the battery than it would have if you hadn't been charging from another source, and the MPPT will adjust its absorption timer accordingly. So, I mean, if your DC-DC already has your bank pretty much full, of course the MPPT isn't going to charge the bank very much, because it won't need to... the same (presumably, though I don't know Redarc products) goes for the DC-DC charger if the MPPT has already charged your battery by the time you start driving.

Bottom line: They won't interfere with each other, but how much current each one puts into the battery bank will be affected by whether or not the other one has already charged the bank up. As long as you end up with a full bank at the end of the day, however, it's all good.
 

Rando

Explorer
many inverters have a remote switch included

otherwise just get a good contactor to cut off inverter input

contact current handling well above your max - DC spec!

signal matching whatever the BMS uses

Or get an independent all in one LVC, adjustable sensor and relay included together, no need to use the BMS for this.

Your fridge should be set lower than the screens / entertainment, and Essentials circuit lower still

Just to be clear the Victron inverters and inverter/chargers already have a low voltage shutdown - to there is not need to use another (third) low voltage disconnect to shut off the inverter.
 

john61ct

Adventurer
Those LVC included with load devices are usually not adjustable and spec'd to prevent damage to that device.

Again, not what I am talking about above varying cutoffs per circuit by how "essential" those loads are.

Obviously your rig, do what you like. . .
 

Rando

Explorer
With the Victron charger/inverters the low voltage shutdown is adjustable, so you can set the inverter to 'load shed' itself at what ever voltage you would like.
 

Rando

Explorer
I’m building a truck camper with the following. See any compatibility issues? I know the redarc handles solar and alternator but i didn’t want all my eggs in one basket. Also, now i should be able to charge 50a from the truck in addition to the solar while driving.

2020 ram 3500 diesel, dual 220a alternators

2x 100ah battleborn batteries
Redarc 50a DC to DC
400w solar to victron 100/50 MPPT
Victron bmv 712
Victron color control GX
Victron 2000w inverter charger

Lmk whatcha think!

This sounds like a great system. The only advice I would have (and others have also suggested) is to use the Victron Orion Tr DC-DC charger so that everything will speak VE. If you can't wait that long, put a cheapo renogy in for now and switch to the Victron when it comes out.
 

Justin Cook

Member
This sounds like a great system. The only advice I would have (and others have also suggested) is to use the Victron Orion Tr DC-DC charger so that everything will speak VE. If you can't wait that long, put a cheapo renogy in for now and switch to the Victron when it comes out.
It's worth noting that the Orion-Tr Smart DC-DC chargers aren't VE.Direct; they have bluetooth built in for monitoring and setup purposes, but (currently) no VE.Smart networking capabilities (may change with later FW updates) and no VE.Direct port, so no communication to a CCGX/Venus/etc. I still concur, though... the ease of their setup alone (compared to Sterling or other DC-DC manufacturers) is worth the wait, if you can.
 

Mlachica

TheRAMadaINN on Instagram
This sounds like a great system. The only advice I would have (and others have also suggested) is to use the Victron Orion Tr DC-DC charger so that everything will speak VE. If you can't wait that long, put a cheapo renogy in for now and switch to the Victron when it comes out.
Thanks for the suggestions.

For now, I will run the system as I described. I'll see how it all works together, if I feel like I'm lacking I'll sell the redarc and replace with a victron. Initially, the 50a output of the redarc is appealing, plus battleborn approves of it. I will work with battleborn to program all the victron equipment, or my camper manufacturer will order from them preprogrammed... Any AC loads in our case will be non critical so I will use the internal setting on the victron inverter/charger to load shed.

I am considering the sterling latch r that justin recommended. I really don't see myself over consuming the batteries, I'm usually overly aware of it's status, but accidents happen. If I do use this relay, I'd probably use it to isolate ALL load from the battery as a last resort of preventing deep discharge.

I looked but couldn't find a voltage chart for this style battery. Voltage vs Percent charged. I saw the logic behind current draw and the bms shutting off, but do we know at what voltage the bms would disconnect? At what voltage would you guys disconnect all load?
 
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