Simplest possible solar battery for minivan?

[RudyGreene]

Hi folks! I'm new here and found this forum after watching some of Will's recent videos. It's a fantastic resource and I think I've learned enough to describe what I currently have and what I want to achieve with a new system. I live in a minivan and I want to upgrade my solar/battery setup to power a diesel heater.

My current setup is a Goal Zero Yeti 400 inside an approximately 14"x14"x10"H vented space under the floor. It's fed by a 220W portable/flexible solar panel that I manually place over the windshield on sunny days. This setup was purchased secondhand about seven years ago so it's usable Ah capacity is probably in the single digit range by now. I use the Yeti to charge my phone/laptop and it usually retains enough energy to run the lights/fan overnight. I've determined it's not worth spending $99 replacing the 33Ah AGM battery in my GZ; plus I want extra capacity.

Given my space constraints, I'm tempted to buy another integrated power station such as a refurbished Delta Mini ($549). But I can't be sure it's DC outputs will handle the draw needed to warm up a glow plug (up to 10-12A from what I've read online). The current objective is to build the simplest possible solar->battery system. I value safety, reliability and low maintenance over having lots of features.

The solar upgrade path seems pretty straightforward: Ditch my 220W fabric/folding panel and roof-mount 2x 100W glass panels. Easy. I rarely see more than 60W from my cheap "220W" panel so going rigid should be a significant performance improvement.

The battery upgrade path is trickier because everything needs to fit in the same spot as the Yeti and still have room for air circulation. My plan is to attach a small SCC and a small fuse block directly to the exterior of a SOK 100Ah battery using heavy-duty 3M dual-lock tape.

My wiring diagram (attached) takes inspiration from Will's "Minimalist Solar Package" and the "Milk Crate Solar Power System" which both exclude bus bars in favor of wiring the SCC directly through the fuse block. Once installed in the van, my battery system is not easily accessible so I would only be disconnecting the panels and battery when servicing it. I'm just not yet confident about what can safely be eliminated for an absolute minimal battery system. Here are my newbie questions:

• Will it be safe to use a 60A fuse and 6 AWG wiring instead of the large 250A "catastrophic" fuse I see in other van designs? I don't use an inverter and there is no scenario where I would be drawing more than 30A continuously from the house battery.
• Do I need that main disconnect switch? I assume I could just hand disconnect the positive cable directly from the battery, but I'm still unsure about what are the best practices (or if some of these choices are mostly for convenience versus safety).
• Do I need a breaker on the PV input? There's one in my design because lots of van builders include them, but Will's design doesn't show one and the Victron manual only mentions fusing the battery and SCC.
• How do I properly ground a mobile solar configuration? And would that grounding method change if I add a DC-DC charger later?
• Is there anything else non-essential I can remove?
• Is there anything essential that I'm missing?

EDIT: Instead of the SmartSolar 75/15 proposed in my diagram, I'm thinking the SmartSolar 100/20 would be a better choice because it includes a heatsink for improved cooling. The 100/20 model also includes an extra grounding point so I'll have to research it's purpose.

My proposed parts list totals $855 (excluding the solar panels): https://www.currentconnected.com/share-cart/QKF1F3

 

[RudyGreene]

It seems that solar charge controllers put out a lot of heat so I'm rethinking my idea to attach the SCC directly to the battery case. What the closest these items can be put together in the same space? Is there a danger of spark or gassing having the SCC and Lithium battery right next to each other? It also doesn't appear that the SOK battery has a low-voltage disconnect. Do I need a separate device to prevent draining the battery to 0%?

I'm starting to think I just need to buy another integrated power station such as the EcoFlow. Are there any basic power stations that just have a Lithium battery and solar input? That's all I need and I don't want to end up dead trying to hook the SCC and battery together. Even my simple design seems monumentally dangerous because I don't know what I'm doing.

 

[12VoltInstalls]

I'm starting to think I just need to buy another integrated power station such as the EcoFlow

That isn’t the best bang for the buck. An independent battery, SCC, and inverter is fine. You can just buy a battery with low temp cutoff or buy a cheap battery and replace the bms

 

[RudyGreene]

That isn’t the best bang for the buck. An independent battery, SCC, and inverter is fine. You can just buy a battery with low temp cutoff or buy a cheap battery and replace the bms

It sounds like you don't understand what I'm trying to do. I don't use or want an inverter.

While it's an imperfect solution, the EcoFlow is much cheaper than my simple battery build. And I'm not an electrician so I'm still uncertain if the plan I detailed above will work or if it will electrocute me. There doesn't seem to be any custom builds to draw on that are just a battery and SCC.

I'm thinking the original EcoFlow Delta would be best since it has about the same Ah as a SOK battery and is inexpensive.

 

[12VoltInstalls]

The EcoFlow is much cheaper than a simple battery build

$1100-3500?

There doesn't seem to be any custom builds to draw on that are just a battery and SCC.

not unusual and not uncommon

same Ah as a SOK battery and is inexpensive

you can get the help you need here to get a normal system up and running. It’s not too complicated really.

 

[RudyGreene]

$1100-3500?

not unusual and not uncommon

you can get the help you need here to get a normal system up and running. It’s not too complicated really.

The EcoFlow is $799 (refurbished). My custom build plan shown above totals $855 and doesn't include any monitoring or wiring.

I tried to detail what I want to achieve for this thread, but there hasn't been any response. I don't mind getting my hands dirty, but I'm not an electrician so I'm not going to start a project that could kill me without someone else looking over the plan. Maybe there's a better forum for newbies.

 

[rodrick]

Are you using any 120 volt ac

 

[MisterSandals]

I'm not going to start a project that could kill me without someone else looking over the plan.

Your design looks simple, safe and easy.
Why are you choosing 2 small panels instead of a single big one? Roof tetris?
If you can run panels in series without shading, it is usually better and does not involve Y connectors or MC4 fuses.
You did a good job choosing the most important piece (SCC... you will love the bluetooth).
Battery looks like a very good choice.

What are your largest loads? Simultaneous loads? This will determine your battery and fusing requirements.

Looks well thought out. A couple tweaks (biggest panel(s) you can fit) will help.

 

[12VoltInstalls]

sounds like you don't understand what I'm trying to do

I completely understand

I'm not an electrician so I'm not going to start a project that could kill me without someone else looking over the plan.

There are electricians and even EEs that hang out here to guide you along

Maybe there's a better forum for newbies

Probably not.

But the opening was more than two paragraphs and very broad with a lot of sidetracks imho. Few people read deeper than a couple paragraphs on a new post because it’s a lot to digest in busy lives.

sounds like you don't understand what I'm trying to do

I read what you are trying to do and shared my opinion.

I could give you what to order right now but…

EcoFlow is $799 (refurbished). My custom build plan shown above totals $855 and doesn't include any monitoring or cabling.

…that probably will not be enough power for your needs

There doesn't seem to be any custom builds to draw on that are just a battery and SCC

Will has multiple build instructions in his book and youtubes doing smaller systems.
All custom builds.

live in a minivan and I want to upgrade my solar/battery setup to power a diesel heater.

don't use or want an inverter.

The echoflow is mostly an inverter… with a small battery.

EcoFlow is $799 (refurbished).

So it appears that the price point is very important to you. I get that - except if you spend and get only 66% of what you need it ain’t worth it, is it?

Maybe there's a better forum for newbies.

I am not being critical or trying to put you in your place or anything like that. But in text this might sound a little coarse and I’m sorry that’s not the intention. But a lot of the details there if you go to the resources section you’ll find multiple educational articles and papers that will help you learn those basic information so you can consolidate and make your questions more pointed and succinct. That usually gathers more responses especially as you develop some learning – as we all do – we start asking questions that have “mistakes“ in them and people will correct you and you learn the more advanced specifics once you’re able to converse with what’s necessary to begin. And all those basic vernacular and ideas are located in the resources section of the beginner sub forum. So again I’m not trying to sound harsh but your long post covered multiple questions that are easily answered in that resources section which is essentially an FAQ .

I just want you to have 100% success- it’s no skin on my part either way, but at least for myself your goals are easily accomplished with no electrocution involved.
The primary reason I see to skip the $800 price point suitcase is you will have insufficient Solar charging to accomplish your goals from my wildhat guess. So it’s out.

 

[12VoltInstalls]

Are you using any 120 volt ac

I don't use or want an inverter

He doesn’t want an inverter I guess.
Which is fine.

Small 120V fridges are inexpensive and so is an appropriate small inverter to run one if you wanted. I’d just have it and only turn on when needed.
I started out with solar on a 200 W panel, 1200 W inverter, and a couple of cheap lead acid batteries. In summer with good sun that would run a mini fridge all day and overnight. Just barely and in good sun- but that’s not recommended; I can’t say that worked well. I can just say it worked for a three week experiment.

 

[RudyGreene]

Your design looks simple, safe and easy.
Why are you choosing 2 small panels instead of a single big one? Roof tetris?
If you can run panels in series without shading, it is usually better and does not involve Y connectors or MC4 fuses.
You did a good job choosing the most important piece (SCC... you will love the bluetooth).
Battery looks like a very good choice.

What are your largest loads? Simultaneous loads? This will determine your battery and fusing requirements.

Looks well thought out. A couple tweaks (biggest panel(s) you can fit) will help.

I haven't purchased anything yet so I could switch to a single large panel. 200W is about the max roof-space available and the SCC controller can handle either wiring configuration. I like the idea of 2 smaller panels for redundancy, but that's probably not necessary. It might come down to whatever is on sale when I'm ready to purchase.

The largest DC load would be the diesel heater (not yet installed, but could draw up to 12A for several minutes at a time). The rest of my electrical needs are minimal. There is no appliances or inverter use. I currently consume less than 10Ah/day so this would be a massive energy storage upgrade from the old GZ.

 

[rodrick]

what threw me was the inverter/battery units you kept referencing

 

[RudyGreene]

I just want you to have 100% success- it’s no skin on my part either way, but at least for myself your goals are easily accomplished with no electrocution involved.

Thank you for communicating how my presentation comes across. My frustration is not with you and I'm sorry that it was directed poorly in my writing. I mostly feel stuck because I have a researched plan outlined, but no way to know if it's safe to move forward.

My preference would be to hire an electrician that can help with specific questions about wiring everything together. I know these questions may seem very basic, but it's important to me to have those double-checks on something I'm doing for the first time. I tried calling some electricians local to me, but they had no clue about small DC projects. It sounds like my overall diagram is safe so I guess I'll order it and see what happens.

 

[rodrick]

Size wire properly and fuse you will be ok, hardest part will be setting up scc most likely
make sure you have good connections/crimps tight lugs ect and ask questions if not sure there is a lot of knowledge on this site someone will help you

 

[RudyGreene]

Size wire properly and fuse you will be ok, hardest part will be setting up scc most likely
make sure you have good connections/crimps tight lugs ect and ask questions if not sure there is a lot of knowledge on this site someone will help you

I tried to detail out everything I was planning and the associated newbie questions, but that was probably too much information for a first post.

My questions could be summarized as "What can safety be cut out when there is no inverter desired?" This seems to be an uncommon van wiring configuration hence my confusion.

 

[rodrick]

Battery, scc, solar panels, fuse block/panel and correct wire size, pv disconnect, battery disconnect will give you a solid 12volt system remember to hook up battery first scc don’t like pv with no battery that’s why a pv disconnect is important in case you want to work on the battery side or wiring you can shutdown pv easily

 

[MisterSandals]

hook up battery first scc

This is good advice. BEFORE you install any of this, get it going in you garage or driveway first. Slowly add one piece at a time.
You will probably learn a few things that help you install it right, the first time.

Keep us posted! Send pics of anything you have questions about BEFORE powering them. Someone will help you!

 

[Doggydogworld]

The EcoFlow is $799 (refurbished). My custom build plan shown above totals $855 and doesn't include any monitoring or wiring.

EcoFlow Delta 1300? Specs show the max 12V DC output is 8A vs. the 12A your diesel heater needs. The AC outlets have ample power if you instead buy a diesel heather with a 120V plug. The EcoFlow's built-in inverter lets you power a bunch of other devices in the future, too, even if you don't use it now.

EcoFlow is lithium-ion, rated at ~800 cycles, vs. 3000-5000 cycles for LiFePO4. If you fully cycle the battery each day then 800 cycles is only 2+ years. If you continue to use only 10 Ah/day you'll be fine. Then again, if you continue to use only 10 Ah you could save $400 with a 50 Ah LiFePO4 from EcoWorthy, Ampere Time or one of the other semi-generic brands.

The Victron 75-10 in your price list will only send ~120W from your panels to the battery (I know you also mentioned other SCCs, just noting this).

 

[RudyGreene]

if you continue to use only 10 Ah you could save $400 with a 50 Ah LiFePO4 from EcoWorthy, Ampere Time or one of the other semi-generic brands.

The Victron 75-10 in your price list will only send ~120W from your panels to the battery (I know you also mentioned other SCCs, just noting this).

The battery Ah choice will come down to what will fit in my tiny space. My battery compartment is similarly-sized to a milk crate build so I know a 50Ah will fit, but the 100Ah is a tight squeeze and it's still unclear if it's safe to have these all these items right next to each other. I'd like as much capacity as possible because I rarely make upgrades so it needs to last awhile (I've been using the Yeti 400 since 2016).

My choice for the SCC is either the 75/15 or 100/20. The Currency Connected website shows the smallest model in their photo, but the correct one is selected in the fine print of their shopping cart. As you noticed, it will need to support 200W of solar input. I appreciate the double-check.

 

[JBennettBus]

I tried to detail out everything I was planning and the associated newbie questions, but that was probably too much information for a first post.

I've got 20 years of experience as a technical writer, and I still have problems being clear and concise. It's not always easy. I just have two comments.

1. Bulleting your questions is a nice touch.
2. Yes, it's a great forum. It's certainly helped me a lot.