Small 12v 100AH LiFePO4 battery system for use in a camper


I do believe that I have already subscribed to 'Dreadlocks outfitting of InTech Discover' thread. will watch for new content.

I also realize I screwed up my last post, will fix that.


Dreadlocks, you have been very tolerant and accommodating. Thank you for your patience & sharing.

At this point I understand these points about your system and the one that I am putting together:

1- Programming, The Battery Protect ACR (BP) Mode has to be set to the 'Li-ion mode'.
"The under voltage thresholds and alarm outputs of the BP are inactive in this mode."
2- Power Wiring, BP IN term point connects to the Li-ion Battery + terminal thru a fuse and battery disconnect switch.
3- Power Wiring, BP OUT terminal point connects to DC Loads and ALL DC POWER SUPPLIES.
My power supplies include a Progressive Dynamics PD9145ALV battery charger and a
RedArc BCDC1240D BC battery to battery charger (output BROWN wire).
4- Control Wiring, The Battery Monitor (BMV712) shunt device term point +B1 needs to be connected to the BP Li-ion Battery + term point (BP IN).
5- Control Wiring, The Battery Monitor (BMV712) shunt device term point +B2 needs to be connected to the BP OUT term point.
6- Control Wiring, The BMV712 COM term point needs to be connected to BP remote term 1.
7- Control Wiring, The BMV 712 NC term point needs to be connected to the BP remote term 2.
(the BMV712 NO term point is not used)
8- Control Wiring, The BP GND term point needs to be connected to the Li-ion Battery SHUNT load/charger power terminal point.
9- Programming, BMV712 relay settings, SOC relay set to 20% .
(opens BP for battery excessive discharge protection)
10- Programming, BMV712 relay settings, Low voltage relay 12.7v .
(opens BP for battery excessive discharge protection)
11- Programming, BMV712 relay settings, High voltage relay set > 13.8-14.2v .
(14.2v is Li-ion batt full charge)
12- Programming, BMV712 relay settings, High Starter voltage relay > 14.2v .
(to allow BP to remain open if power supply to loads can maintain voltage > 14.2v .
13- Programming, BMV712 relay-off delay 1 minute.
(to allow for short load voltage dips for dc equipment start current transients).

If I have this all wrong or partly wrong please let me know.
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I think you are saying that you moved the Li Batt + wire from the BP 'in' terminal to the 'out' terminal and that when the Li Bat + was on the BP 'in' terminal the BP did not isolate the charger when the li batt was fully charged. I would not expect that change in wiring to make the BP fail that function.
The change in BP power wiring must have been concurrent with using the BM712 starter battery voltage input from the shunt B2 point to look at the load/charge voltage on the BP for fully charged voltage state.

Is there any real need to use the BP out term point for the LI batt + power wiring point?
I got it now, you moved the FUSE HOLDER from BP input to output terminal, that's what you were telling me, not the Li-ion + terminal power wire.


Well-known member
#7 is NC not NO, at least on mine.. when the relay triggers you want it to cut off the BP (open circuit).. but you can reverse this in software so I digress it dont matter much since IIRC the relay draws same power regardless of state, which is miniscule.. not even close to a parasitic load, wont practically drain battery further. (I calculated it out, the BMV would take years to drain flat a 100aH lipo)

Also the wire going from the BMV to the BP should be a pair of wires or you pull 12v from somewhere to load the COM port on the relay.. the BP has a 12v output and a 12v input, shorting em connects the BP, floating em disconnects it.

#8 BMV712 dont need ground it gets it from shunt, power/ground are provided through the telephone (RJ11) cable.

#10 might be a little high, I think I have mine set to 12.6v.. I think ideally you want the low SOC to catch first, low voltage second.. with load the voltage would be lower than floating voltage at same SOC.. I put no low voltage, then ran a dummy load til it shut off low SOC, whatever voltage it was under load when low SOC cut it off I set it a little bit below that.. Low voltage is a backup incase the SOC calibration gets outta wack.

Rest of it looks good, remember to test it all out before going into the field.. like a gun, assume its unsafe until you prove to your self its not..

*edits made*
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Thank you for the correction to #7 and #10.
#8- "Control Wiring, BMV712 GND term point needs to be connected to the Li-ion Battery - terminal." this is not right as you have pointed out. The BMV712 does not have a ground term point. #8 should have read "BP GND term point", not "BMV....". The BP does have a GND term point.
I'll make these three corrections to my post #32 in this thread.

Have you entered any other relay settings in your BMV712 battery monitor ?

I really had to search and think to find #1, BP mode set to Li-Ion mode and what that does to the BP method of operation. Hope I got that right.

I'm assembling & wiring this project in an enclosure now. Rain is steady outside (a good thing, we need it) and predicted to continue until Friday. Saturday & Sunday I hope to attach the enclosure to the camper/gooseneck trailer, route the wires into the DC load panel & BMV712, install the two solar panels on the roof & route the solar wires down to enclosure, and hookup equipment grounds to Gooseneck trailer & camper. Or at least get the enclosure on the trailer & wires pulled into the camper and Solar Panels on top of the camper & wired thru the camper.


Well-known member
I dont have BP set to Lion mode, it basically disables its internal voltage protection.. I use the difference between the BMV LVD and the BP LVD as my Reserve Capacity, I have the my BMV setup to drop at 20% SOC, and the BP is set to its highest voltage it will take, IIRC like 12.2v.. in my testing the BP LVD disconnected at 5% SOC, this allows my reserve capacity (~15AH) to be totally safe, but it requires manual intervention as regularly draining the battery lower than 20% SOC reduces its cycle capacity.. The Lithium Holds voltage for so long that even at 5% SOC its voltage is still >12v, impressive but why the BP has to be paired with the BMV to disconnect the battery based off SOC and not just voltage.

I plan on pampering this BattleBorn.. the longer it lasts the more cost effective this is.


OK, so you are using redundant under voltage protection for BB battery life longevity , that's a good thing.
Giving you some reserve capacity to use with the reserve switch and reducing the number of entries into the < 20% SOC area.
I should do the same.
Here are the changes I believe this makes in my original post #32 in this thread as I understand it now:
#1 should be changed to read:
-1 Programming, the Battery Protect ACR (BP), with the BP switch OFF (remote contact OPEN) and no wire connection to the BP OUT terminal.
-1A select the desired Under Voltage Shut Down, Under Voltage Reset point.
Using a PROG pin to ground momentary contact switch,
Select display 8, UV Shutdown 12V (highest UV shutdown point offered ) and UV Reset 13V. These settings will be confirmed for the mode 'A' (default mode).
-1B after completing all programming, connect loads/power supplies to the BP OUT term point.

That's it.

What I do not understand is that there is no BP 'Over Voltage' setpoint and the specs do not include a BP over voltage default. But under BP Operation, there is an Error Code E 4 Over Voltage.
The BP Specs DO include Default Thresholds, Disengage: 10.5V, Engauge 12v. I think the programming described above changes those thresholds as noted by selecting display 8 UV parameters.

Do you do anyother programming to the BP relay not described above ?
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Well-known member
I didnt change the letter mode, must put it in #8..

keep in mind as your doing all this, I did it a while ago and somethings may be a bit fuzzy.. right now my rig is burried in snow, so im not going out there.


Buried in snow, I remember that living in Utah years ago. Here in CA mine would be buried in rain, but it all ran off this morning.
I understand a bit fuzzy. But you have the hands on experience and understand the Victron device operation.

Now for the real nitty gritty of my understanding of BMV712 monitor relay programming:

I look at the device, read the manual, and for example contemplate entering a set point, say for the SOC relay (discharge floor). I set it at 20%. Instructions say if the SOC falls below this value, the relay will close. SO I wonder, after the relay closes for a SOC below 20%, if the battery is charged to greater than 20% SOC, will the relay open ? Then I see that there is 'Clear SOC' relay parameter that can be programed into the BMV712. When the SOC has been raised above this value, the relay will open (pending relay min closing time and relay off delay set points).

Then there is the general statement under relay settings paragraph heading- "Remark: thresholds are disabled when set to 0."

SO I guess I do need to specify the clear SOC point or the relay will never clear (open) once closed for a discharge floor event. Or do I need to set it to 0, 'thresholds are disabled when set to 0' if I do not want to specify the clear relay setpoint ?

I see that there are 'clear relay' setpoints for every type of 'relay' set point. So generally if I enter a setpoint for a relay, I need to also enter a clear relay setpoint or set it to 0 to disable the setpoint. Is that true ?

The Relay mode apparently can be set to 'DFLT' or 'CHRG'. I think 'DFLT' allows the use of all the relay set points to control the relay, and that 'CHRG' only allows the use of two relay control functions, SOC and LOW VOLTAGE to control the relay. I'll be using DFLT.

I think that the relay control settings (SOC, LOW VOLTAGE, HIGH VOLTAGE, LOW START VOLTAGE, HIGH START VOLTAGE) are all OR statements for relay control. Like parrallel circuits energizing a relay coil, any one of the parallell circuits can energize the relay. Is that about right ?


Well-known member
Install the victron app on your phone, even if you dont have your BMV setup yet you can load up a demo unit and play w/config.. here's a screencap:


I only see a threshold for SOC, I think the voltage relays reset once the voltage goes back over/under and the delay has expired.. all of these are definitely OR and not AND's

I can probably get close enough to camper from my bedroom to connect the BMV tonight and take screenshots of my actual settings.. I'm pretty sure my mode is default


OK, I'll download the BMV712 app and install it on the iPhone or iPad. Good Idea to play with the demo product.

Do you keep your trailer above freezing inside all winter ?
DO you turn OFF the Li-Ion Batt disconnect switch and leave the PD power supply feeding the DC load distribution Panel ?
I know, too many questions. Just wondering what you do in the frozen season to the trailer to keep it alive.
If you can connect to the BMV withour freezing your tail OFF, I'd appreciate the screen shots of your setup.

Talking about 'Freeze Your Tail OFF' , are you familiar with Utah Expedition Forum 'Freeze Your Tail Off' yearly winter equinox event ? I have always wanted to do that event.


Well-known member
for storage I discharge the battery to ~50% SOC, then pull my disconnect key out and then hookup shore power.. its just sitting idle outside in all temps.. the PD is providing DC power still so the lights and fridge still work.. Lipo's are fine to discharge below freezing, but not charge.. so it should be fine idle, and unlike lead they prefer to idle long times at partial charge.. I plan on getting a furnace installed right near the battery, it will intake air from that compartment and have a vent so it should end up being the same temp as the rest of the trailer.. if its below freezing I'll likely keep charge sources disabled until the heater has warmed it up for a while.. right now I just have a wave heater and thats not enough for winter camping.

I dont really do events anymore, I like to get away from people.. if I join any group it'll be ARES/S&R but I need a job that would still pay me if I'm off on a extended mission first.. I'm contract right now so every time I take off work it hurts financially.

I am planning on winter expeditions in the future, I'm adverse to extreme heat so there's alot of the world that I'd like to see in the winter time cuz I sure in hell aint going to Death Valley in the summer.. hence grand canyon in March, I've been putting it off for far too long.. right now I think I can handle April-Nov in the Rockies, which is substantially longer of a season than I ever got out of a tent, also It'd save alot of money on a snowboarding weekends if we can stay in my trailer comfortably so I'm shooting for 4 season high altitude capabilities.. even if I have to retract the canvas popouts and pack everyone into hammocks and cots.. was just shopping for a set of snow chains for trailer, Ive needed em and not had em before towing in mountains and it was the worst driving I've had to deal with.
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Thanks for the cold storage Li-Ion battery info. The Freeze your tail off event is planned thru Expedition Utah. As I remember its usually a small group of vehicles, usually less than 10 vehicles and most know of each other. Death Valley, the East Mojave, Canyonlands (fall & spring, snow in the winter) and Anza Borrego in the fall, winter and spring are delightful, Summers too hot. Winter expeditions requiring chains on the trailer might be a it much for me. Do canyon Lands, the Maze and Pinnacles district in the spring. Make sure to see the Doll House, walk the Joint trail into Chesler Park, camp at devils Kitchen, Doll House, Peek-a-boo. Lots of good times there for 2-3 vehicle groups. Too Remote to go alone. Also checkout the Arizona Strip North of the Grand Canyon, Parashant. Very remote, Late Spring trips after snow and mud are gone from the dirt roads..

Well if you ever get some screen prints of your BMV712 control programming settings, please send them my way.


All wired up including external to box input/outputs. This did not work as I had expected it to. The Solar input and dc-dc battery charger input thru the redarc bcdc complicated control of the battery protection switch.