In this post in the Van Life Q&A, a user asks:
Schematic Rev 1 Review Please!
Much better, you may want to repost the whole thing so it’s a new post and maybe gets more attention.
I am no pro at this, so take this with a grain of salt. Here’s a couple things I see:
* No cutoff switch for the PV before MPPT. You want one, it makes it much easier to disconnect it when you need to.
* No fuses on PV. I would.
* How long is your PV to MPPT run? 8ga seems heavy to me. You say X4 in parallel but it looks like you 1parallel of 2 in series? That is how I have it set up and used 10ga. It’s only pushing like 12a max at 24v.
* Commercial batteries should have their own BMS under the case.
* I don’t see why you’d *need* any management screen for the DC2DC, especially if you use the BMV I link below with a shunt, it should give you a reading of the total charge amps coming in from any/all sources.
* You should’t go up a wire gauge just because. It’s wasteful and more costly and there’s no reason to. I do, however, recommend getting high temp wire and using fine stranded wherever feasible.
* You need a cutoff switch for the batteries
* Don’t user circuit breakers for cutoff switches. They’re not meant for that, get a real cutoff switch.
* Personally, I’d get a monitor with a shunt. I really like [this victron one with bluetooth](https://amzn.to/2kylW9W).
* Speaking of, I also really like the [victron charge controller with bluetooth](https://amzn.to/2kwqD40).
* You will probably need more than 8ga for the batterie wiring, especially if you’re fusing it at 200A. Fusing should be sized to the lesser of the wire or battery’s max output capacity.
* I don’t know what the amperage of the MPPT is so I can’t comment on that 50A breaker specifically. I see some of these recommendations to have them the next size up and that doesn’t really make sense to me if you don’t have the amps to meet that. Size it to the wire and the output of your PV when converted to from 24v to 12v. Your 400W panels aren’t going to produce 50A so that breaker won’t trip unless there’s some serious issue. Your panels are only going to produce 23A at open (at maybe around 18v) so you’re not going to be anywhere near 50A at 12v.
I like the bluetooth ones because they are easy to program and monitor from your phone from wherever as long as you’re in range – so outside, driver or passenger seat, bed, etc plus it’s one less thing (screens) to have to mount somewhere and wire up. The victron CC is much smaller than the one you have shown. But yes, they are more expensive.
Also, make sure you have a multimeter! So many people do this without one. They’re $5-15 and well worth it. Don’t buy the crap one from harbor freight.
If anyone would like to correct any of my mistakes/misinformation, please do!