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Discussion Starter #1 (Edited)
Hey all,

I tried to do as much research as possible before posting here. I've been chipping away at building out my van since I got it in July. I've also been planning the electrical system during that time as well as picking up things that I knew I'd need.

I am not an electrical expert so tried to research as much as I could when putting the plan together. My goal is to have a decent DC system for extended weekend trips. My biggest loads will be the fan and the fridge (maybe eventually a propane heater fan). I already have the Renogy 200W solar kit (as well as the battery).

The only thing that I knowing have omitted so far is a battery monitor / shunt so please feel free to provide any critiques! Thanks for all the help and info on this forum that have enabled me to get as far as I have.


[Image removed in favor of updated plan below]
 

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It looks pretty good for a first draft! Good and simple, too. A few initial comments to get things rolling:

You have 50A breakers on the Battery Doctor. You should probably up those to 80A, which is the max output (brief spikes) most folks see from the van to the house batteries.

Your solar panels are in series, so I assume your controller handles 24+ volts? Series vs. parallel is a personal decision. But a lot of folks (most?) go parallel to minimize shading losses. In series, if one panel gets partially shaded, it affects output from both panels.

A battery monitor is essential in my opinion. It helps you notice problems early and also manage charging from your two sources. A multi-stage solar controller does a better job of finishing off a charge, while the van's alternator (via Battery Doctor) provides more amps for initial bulk charging.
 

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Nice simple system. Shows how simple and useful a system can be without bothering with shore power or 120VAC stuff.

Agree with Steve on the 50 amp vs 80 amp fuses on the alternator charging line. Be sure to put each fuse as close to its respective battery as possible.

I have a Victron battery monitor and it works fine, but if I were to do it again, I'd go for one of the cheap ones on Amazon or AliExpress -- at $50ish, its nice to have. But, we did survive through 3 previous RVs that did not have one :)

The Battery Doctor does work and lots of people here like them, but for me a simple isolator also works fine for less money.

For this pretty simple system with few connections, you could do without the busbars at the house battery terminals and just connect the wires directlt to the battery terminals. Kind of a personal choice thing -- the busbars do allow some future flexibility if you add more stuff later.

Gary
 

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Discussion Starter #4
Thanks for the feedback @SteveSS and @GaryBIS!

I'll bump the breaker fuses around the Battery Doctor to 80A close to the battery.

Re: the solar panels in series -- that is straight from the wiring diagram provided by Renogy to their Rover 20A MPPT Charge Controller. I did not look into series vs parallel yet but after reading this I'm thinking parallel may be better for me.

I'll do some research on the battery monitor's next. I've seen the Victron monitors talked about quite a bit, but it seemed pricey for something that I wasn't sure was 100% needed. If I can find a cheaper alternative maybe I'll pull the trigger for the peace of mind of monitoring my battery

Thanks again!
 

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Discussion Starter #5 (Edited)
So here are some slight changes
  • Battery Doctor fuses bumped to 80A
  • Solar panels in parallel
  • In-line fuse bumped from 10A to 15A -- I already have a 10A in-line fuse but reading specifications makes me think the in parallel config will require >11.44A fuse. Is that correct?
[Image removed in favor of updated plan below]
 

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Hi Whitney,

4 USB receptacle: the picture is for one for home use i.e. power supply 120V AC. Are you sure it will work at 12V DC system?
 

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Hi @Whitneyj

Looks like you have an MPPT solar controller, so if you have 2 panels if you size the wire for both series & parallel then you can change the configuration easy & use whatever works best in your situation. I am still in the process of experimenting with parallel & series & am not convinced one is always better than another configuration. I believe it depends upon the conditions & equipment. MPPT controllers need more voltage typically (kinda like inertia) @HarryN can explain it in depth.

I can not say enough good about the Victron BM712 Smart. It is pretty much a battery sensor/computer that can broadcast Bluetooth onto my smart phone or tablet. When I consider Im into my Van for somewhere between $50k to $55k Canadian $250 is not a huge expense for what I consider a very valuable piece of monitoring equipment. My AGM battery bank was around $1,000.

Maybe a disconnect switch between the solar panels & controller? Others might have opinions on this, but it looks like you can disconnect the battery bank from the solar controller? My understanding is some solar controllers want a battery connected whenever the solar panels are connected to the controller.
 

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Discussion Starter #8 (Edited)
4 USB receptacle: the picture is for one for home use i.e. power supply 120V AC. Are you sure it will work at 12V DC system?
Good eye, exactly why I wanted to post my plan here. I think Amazon suggested a 120V AC outlet after I followed a link to a 12V DC and I didn't notice the different. I updated the plan now


Hi @Whitneyj

Looks like you have an MPPT solar controller, so if you have 2 panels if you size the wire for both series & parallel then you can change the configuration easy & use whatever works best in your situation. I am still in the process of experimenting with parallel & series & am not convinced one is always better than another configuration. I believe it depends upon the conditions & equipment. MPPT controllers need more voltage typically (kinda like inertia) @HarryN can explain it in depth.

I can not say enough good about the Victron BM712 Smart. It is pretty much a battery sensor/computer that can broadcast Bluetooth onto my smart phone or tablet. When I consider Im into my Van for somewhere between $50k to $55k Canadian $250 is not a huge expense for what I consider a very valuable piece of monitoring equipment. My AGM battery bank was around $1,000.

Maybe a disconnect switch between the solar panels & controller? Others might have opinions on this, but it looks like you can disconnect the battery bank from the solar controller? My understanding is some solar controllers want a battery connected whenever the solar panels are connected to the controller.
Reading more on MPPT and panel configuration I think I'll keep it in series for now. I already have the connections / fuse I need for that so unless I feel like I'm not getting the performance I'd expect I'll keep it like this for now. Seems easy enough to modify down the road if need be.

I'll look more into the Victron monitors. There is this one on Amazon for $45 (including shunt), obviously not as good as the smart monitor though ($210 + shunt)

I think you're right on the disconnect between panel and controller. I originally had one planned there but took it out per a recommendation. Re-reading the controller manual I see they say "do not connect to controller without battery connected". I've added one back in so I can shut the power to the controller (y)


[Image removed in favor of updated plan below]
 

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My BM712 smart included the shunt;

I’m not against the cheaper units, just have no experience with them, thus I try to recommend stuff I have experience with & love.

Here is a link to a recent of parasitic draw another member asked, which I was able to (coffee in hand) go into my van & obtain my systems information within minutes.




@MsNomer is replacing her batteries after 5 years. If I understand correctly what happened it was around a solar charger setting & disregarding an over voltage anomaly. Having monitoring equipment & paying attention to it is key in my mind (caveat; I am a gadget guy & an experienced private pilot so I am very use to & trained in monitoring equipment & engines for abnormalities).



Then there is Julie’s issue. Not sure if they monitor their electrical system or not. Not sure if they have the training to look at a BM & see whats what; FWIW here is their link




One Good Thing about proper DIY if designed & built properly, you end up knowing your system & thus should be able to diagnose, maintain, & repair it.



I have enjoyed friendly teasing by some forum members for my love of the Victron BM712 Smart; & I get it not everyone has the budget for a $250 BM. For me it is invaluable.

Ok, I stepped down from my soapbox. 😁

Good Luck with your electrical.
 

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I agree with Gary on connecting straight to the batteries and eliminating two bus bars, the 250 switch and large cables. I did that and just had to buy longer bolts for the battery terminals (I also have an inverter in my system).
 

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I would add or substitute one of the USB outlets to a 12V cigarette lighter type outlet for non-USB 12V devices, such as a electric blanket for example. You can still use it for a USB device by simply plugging in a car charger, perhaps one with a USB-C port for fast phone charging or for a laptop. Gives you more flexibilities.
 

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Discussion Starter #12
@RV8R alright alright, consider me convinced :) -- I pulled the trigger on the BMV-702. I did not get a chance to look closely at the wiring diagram so I need to check back if I added that into my plan correctly.

I think I'll keep the busbars as I already have them and I added in a socket receptacle + some switches

Thank you everyone for all the feedback

66853
 

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On my setup;

I used the Victron shunt as my negative bus bar (I really do not have many negative connections - Ground to Chassis / 12V fuse panel / Battery negative)

It is not good practice to have too many connections on one lug, but I think I’m ok if I do not add to much more.
 
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