[Feedback Please] RV Plans: LiFePO4+Growatt+Electrodacus SBMS0

[Whinny]

So now you got me stuck on LittleFuse stuff! I'm supposed to be watching hockey....
Mega fuseholders and fuses look nice as well might be worth looking at for after the class T

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[andrewl04]

Updated the diagram again (PDF attached and embedded as JPG) to incorporate feedback to date. I still have ANL fuses off my positive bus bar for now; still working out if I will switch those to a MRBF setup like the Blue Sea 5196. Although I doubt I wll ever need it the 5196 is limited to 240a per circuit and my inverter can burst to 6000w (250a+). ANL and bus bar is cheaper too. Will decide soon on which approach to take.

If anyone has Electrodacus experience I am still unsure about if the SSR to isolate the PV inputs is required ([d] on my diagram).



Thanks to all for your feedback. Getting ready to start ordering soon but further feedback is appreciated.

ETA: No sure why the jpg is so blurry above. PDF attached if you have trouble with the diagram.

 

[HRTKD]

Most likely, the forum decreases the resolution of inline images. PDF documents don't get the same treatment.

 

[andrewl04]

One more Electrodacus question:
How do I take care of low voltage protection? It seems something like a Victron BatteryProtect is needed since the SBMS0 can’t physically disconnect loads from the battery itself. Is a SSR better or even an option?

ETA: I’m actually realizing this might be a deal breaker (due to cost and complexity) for the Electrodacus since I’ll need to spend about $100 on the 220a Victron BatteryProtect BP-220 if I want to fully disconnect all battery loads. In theory I could use the 65a ($40) version to isolate only my 24v-12v converter and associated loads as the only 24v load is the inverter itself that the SBMS0 will be able to physically switch off.
I’m trying to rationalize the added functionality of the SBMS0 against a traditional BMS with built-in low voltage disconnect (leaning towards ANT) plus a Victron BMV-712 Smart Battery Monitor. Total costs are similar but complexity is a bit of a concern. Any thoughts?

 

[andrewl04]

In case anyone is interested I emailed Dacian about my plans. My questions and his answers are below. He also made two other observations based on reviewing my diagram regarding v and c from v4 of my plans above.

d. Do I need a SSR to allow the Electrodacus SBMS0 to isolate the PV input from the Growatt 24v SPF 3000TL LVM? If needed, 1 or 2 poles? Normally open or NC?
d. yes that is needed and should be normally open circuit.
e. Confirming SBMS0 to control the Growatt inverter by wiring into the Growatt's switch?
e. Yes the inverter will be turned off that way if any of the cells drops below 2.8V
f. Confirming the need for a SSR to allow the SBMS0 to control shore power isolation by only isolating the line (not neutral) of the AC circuit? What type of SSR, NO or NC?
f. Yes, that is also needed to protect the battery from overcharge as Growatt has no remote ON/OFF for the charger. Again normal open SSR is needed.
s. If I understand correctly the SBMS0 will be able to control all battery discharge by switching off the inverter except for the 24v to 12v converter. Correct? How would you recommend I handle low voltage disconnect? Victron Smart Battery Protect? Another SSR controlled by the SBMS0? Something else?
s. Victron battery protect should be a good option for disconnecting the DC loads.

v. you need to move that fuse after the shunt
c. unfortunately you can not use the PV shunt as you can not have that connected there. You will need to only use the battery shunt j and no PV shunt in your setup. The shunts need to always be at battery positive potential or below (but not below zero). That shunt as installed there will be at huge potential even over 100V in some conditions that will damage the current shunt amplifier and possibly more than that.

 

[reflxshn]

Good to hear about the DIN breakers. I haven’t seen a lot of them around here so good to confirm they are a good option. Thanks
Is a dual pole necessary for the solar inputs vs. just the positive? Dual needed for safety/maintenance isolation?

Correct, not a fifth wheel. It’s a 32’ Keystone Passport (bumper pull). Curious why you were asking?

I was reading on Keystone's site that some trailers come prewired for solar standard. Are you using any of this? Just curious. It would be great to see more RV/Trailers prewire for DIY (assuming it was well done of course).

 

[andrewl04]

I was reading on Keystone's site that some trailers come prewired for solar standard. Are you using any of this? Just curious. It would be great to see more RV/Trailers prewire for DIY (assuming it was well done of course).

Unfortunately my Keystone’s prewired consists of a Zamp plug near the tongue only. No wiring going to the roof. I agree it would be good for more RVs to have it done; even as a paid option.

 

[fsch97]

andrewl04, thank you for sharing your setup! I really like it and I consider a very similar solution for my camping trailer.

However, I am a bit hesitant for a couple of reasons:

- The Growatt seems to be a unit that is rather used in houses than in RVs or trailers. For instance, it does not come with a remote and I am also not sure, if a small trailer compartment gives enough room to operate it safely .

- As Dacian pointed out, the electrodacus does not allow you to monitor the incoming PV power, which is a piece of information that I would like to have (without looking at the Growatt display)

Did you build it already and, if yes, are you happy with it? Any issues (like the ones I mentioned)?

 

[fsch97]

Thinking about it a little bit more, I noticed something else: In case your battery is fully charged and you are hooked up to the grid, the electrodacus will open the relay (f) and there will be no diversion for the shore power. So the transfer switch will randomly toggle between shore and battery. I don't know if this will be a problem, in practice, but it seems just not optimal.