LiFePO4 w/ Redarc 1225D & Victron BMV712 & Vic IP65

[MsTaboo]

Hello smart battery people, could someone please look over my setup and let me know if I'm missing something obvious?

As I understand the manuals and other reading I've done, all the negative circuits need to pass through the Victron 712 shunt from the load side to the battery side in order to see the battery activity.
I've included a three way manual switch to change the charging source from the Victron AC charger to the Redarc DC/DC charger. And added a redundant Redarc low voltage disconnect to protect the battery from total discharge from the Victron BMV712.
Battery is a 100ah self heating LiFePo4 from Renogy.
Hope the drawing is clear enough.

_________________
Currently:
'90 Syncro Westy 3 knob w/Zetec

The information age has morphed into the age of disinformation and willful ignorance. Agnotology!
Help the fight against Truth Decay.
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[Howesight]

I see nothing wrong in your circuitry (nice drawing, BTW), but I think it would be good to have CrazyVanMan Mark chime in. I just read the directions for each component in my system and muddled through in that way.

I drove the Syncro to work today (gotta run it from time to time) and noticed, for the first time, that the Redarc BCDC 1240 has a low-temperature cutoff. Nice.

Our Vancouver temps have not been that cold, but the van was parked outside for a week, and the Redarc would not charge this morning at first. The LED's blinked out the "low unit temp" signal, so I ran the CDH (blowing warm air towards the Redarc) for a few minutes while running an errand. That was enough to get the Redarc to start charging. This was not a feature that I was aware of, as far as I recall from reading the Redarc manual months ago. I suspect that this feature is engaged when you choose the LiFePo4 setting on the Redarc. In your neck of the woods, you will likely see this in operation more than I will here.
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'86 Syncro Westy SVX

[jimf909]

That's exactly how I wired a BMV712 in a house system and how I plan to wire it in my van later this week: first thing after the negative battery post. I've found I use the Victron Connect app on my phone 97% of the time because it's easier to use and provides more info in a single screen.

Do you have a plan for wire gauges? I mostly used 6awg with smaller wires on the solar side.

One last point: you can pick up the starter battery positive from the battery, the starter, the alternator or the junction box in the engine bay (assuming wire gauge is adequate which I assume it would be), no need to run a separate wire.

(I'm not claiming to being a battery smart person. )
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- Jim

[MarkWard]

I’m the furthest thing from an expert when it comes to these things. I’ve posted this in other threads. After I installed my DC to DC charger, I realized I did not want the auto charging feature. There are times, when I don’t need it on. Actually most of the time. My 20 amp charger will recover the battery from overnight in less than an hour. I have also read in multiple places Lithium batteries would rather not be charged at 100% SOC when stored. Our van sits a lot. It’s really up to the individual. I added a small toggle and LED on a small bracket using a steering column bolt. Don’t like drilling holes. To ensure I don’t have the dc to dc charger powered up during starting, my toggle gets power from the X or defogger circuit. Similar to using the alternator D+ circuit in your drawing.

My Lithium battery BMS has Bluetooth and I use my phone app to monitor the SOC, loads, and charging. No solar.
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☮️

[Pchill2]

The low voltage disconnect is essentially redundant and not necessary. Wont hurt though but you could exclude it from your system to save a few bucks. The Renogy battery has it's own low voltage disconnect in the internal BMS.

The BMV 712 is nice but the bluetooth smart shunt will keep you from needing to mount an additional monitor somewhere in your van. The Victron bluetooth connection is very reliable in my experience.
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87 Syncro Westy
Honda K24 swap

[DuncanS]

[MsTaboo]

Hey everyone, thanks for taking the time to look over my drawing!

[jimf909]

[MsTaboo]

[crazyvwvanman]

I think the BMV712 power is over the same small cable labeled "battery temp".
If so it is on the battery side of the low voltage protection device.

Mark

[MsTaboo]

[MsTaboo]

Any feedback about the T-Tocas 50amp circuit breaker on the starter/alt line?
I've read some negative opinions about using these thermal breakers vs a magnetic breaker but that T-Tocas (and others like it) seem to get good reviews.
Is there a compelling reason to use one over the other?

My setup is pretty low power. 100ah battery powering my Edgestar fridge, Propex, and a couple LED lights. I might add a small power amp to the stereo in the future.
_________________
Currently:
'90 Syncro Westy 3 knob w/Zetec

The information age has morphed into the age of disinformation and willful ignorance. Agnotology!
Help the fight against Truth Decay.
Defend democracy, support Ukraine.

[jimf909]

[1988M5]

Seriously folks, take a night class at your local community college, ELEC101.

BK
_________________
1991 tin top GL
2002 Winnebago Vista. VW VR6 24V Eurovan front clip powered class C 21' RV.
Some BMWs.

[MsTaboo]

[fxr]

[MsTaboo]

I guess what I'm having trouble wrapping my head around is this; even if the start battery is drawing off voltage to recharge it's low state, wouldn't the voltage drop still be noticeable from a wire attached directly to the alternator?

e.g. the alternator is putting out 14.7 but drops to 13.5 because of a low start battery, wouldn't a wire connected directly to the alternator see 13.5?
So, the Redarc would know there's a load and adjust it's output to the aux?

I understand that the condition of the wiring to the start battery could have an effect on voltage drop compared to a reading directly at the alternator. But if the wiring is good doesn't the above apply?

I will go ahead with plans to connect to the start battery to play safe, but it's fun to noddle out the differences.
_________________
Currently:
'90 Syncro Westy 3 knob w/Zetec

The information age has morphed into the age of disinformation and willful ignorance. Agnotology!
Help the fight against Truth Decay.
Defend democracy, support Ukraine.

[fxr]

Redarc don't know what sort of alternator you have, and whether it's capable of supplying both a full charge to the starter battery (can be 20A or more for a few minutes) as well as a full charge to the LFP (again, 20A or whatever your device charges at). So they play safe.

*IF* you have an upgraded alternator from the original, then *perhaps* it's OK to connect to the alternator. As I wrote above, this is what I've done. But if your alternator is original, it's pretty much essential to connect to the starter battery, as that is the most important one to get a proper charge, and ASAP after starting.
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Jim Crowther
1984 1.9l EJ22 Westy Wolfsburg Edition
Vespa GTS 300

[1988M5]

I apologize for my suggestion of formally/truly learning how and why electrical circuits work the way they do and don’t. If you had more mastery of the topic, none of your original questions would have been asked nor the problems with your diagram been considered in the first place. Years of service working are cars is no qualification to this matter. Trust me when I say that once you solidly get your head around the basics, the rest is easy.

Cheers,

BK
_________________
1991 tin top GL
2002 Winnebago Vista. VW VR6 24V Eurovan front clip powered class C 21' RV.
Some BMWs.

[MsTaboo]