Help me make a portable power source with solar charging? (Mostly explaining the parts list, I can figure out the wiring)

[MysanthropicBuilders]

Bit of backstory... Going to be moving off grid here in 18 months, I've been researching and studying my butt off but I think I've reached the limit of what I can learn through theory alone when it comes to power. I need to get hands on and start building something. One of the things I'm going to need... Is a solar battery source that I can run things like a table saw off while getting everything built. I also want to pick up welding, and if this could be used for that... Then even better, since my home wiring is nowhere near beefy enough to handle plugging in a welder. I want to keep the total budget under $2,000.

So here's what I know so far: I know I probably want to go with LiFePo4 batteries. They're decently priced and last a long time. Since this might be repurposed later as part of my main home energy storage... May as well get the good batteries. Something around 5 kWh should be good. Batteryhookup has some 3.2v 105Ah cells for ~$40 each, if I can do math then 16 should cover me. These batteries have a continuous discharge rating of 105A, so with 16 batteries that "limits" me to around 5,000 watts for the inverter (Will be plenty for a table saw / drill press / whatever... For welding... Idk). I know I'm going to need a bms for the batteries. I've never used a bms before so... No clue what kind I need. I think I'm going to need a charge controller for the solar panel? Idk, half the stuff I read says this is part of the bms, the other half says I need a separate controller. I know I'm going to need an actual solar panel, or panels, since 5kWh would take a few weeks to charge with a dinky 100w panel or something.

And past that... I'm clueless. I know there should be breakers and fuses somewhere. I don't know where or why. I know there should be bus bars. I don't know where or why. I know I should decide on 12v v.s. 24v v.s. 48v. I don't know which would be best for this application. I know there's a way I can monitor the charge on my phone via bluetooth/wifi. I don't know if that's a premium feature only available through certain manufacturer's, or if there's a way I could do that myself.

The biggest problem I'm having is that when I go to watch a youtube video or read an article or forum post about it... Sometimes it goes into what's being used, rarely does it go into why, and almost never does it go into other alternatives or what they would change if they were to make the system bigger/smaller. So I know I'm going to need more than some batteries, an inverter, some wires, and a BMS... But I don't know what exactly.

If anyone wouldn't mind pointing me in the right direction, that would be greatly appreciated!

 

[OffGridForGood]

I can run a full sized cabinet saw(240 3Hp) , and stick (200A) & Mig welders, but not from my portable system, too small, only from my stationary set up, with lots of battery behind those inverters.
Either, you build a portable unit to get some experience, or you build the permanent system to run a table saw and welder. Bit tough for the portable unit to run the big 240v loads.
When you say "Table Saw" do you mean a portable saw on 120 volt AC? - the MPP LVX6048 would run that and could be mounted to a hand cart.
And when you say "Welder" do you mean a 120 volt wire feed? ditto above.
I have a portable Bosch table saw, but I haven't tried this on my portable cart mounted 24v system. (I should try it!) I can run the wire feed on the portable. See my signature for details.
A bit more information, and we can help you out.

 

[Danke]

Where you’re building doesn’t have grid power?

”I want to keep the total budget under $2,000.”

Not much can be accomplished with Solar and that small amount.

 

[MysanthropicBuilders]

I can run a full sized cabinet saw(240 3Hp) , and stick (200A) & Mig welders, but not from my portable system, too small, only from my stationary set up, with lots of battery behind those inverters.
Either, you build a portable unit to get some experience, or you build the permanent system to run a table saw and welder. Bit tough for the portable unit to run the big 240v loads.
When you say "Table Saw" do you mean a portable saw on 120 volt AC? - the MPP LVX6048 would run that and could be mounted to a hand cart.
And when you say "Welder" do you mean a 120 volt wire feed? ditto above.
I have a portable Bosch table saw, but I haven't tried this on my portable cart mounted 24v system. (I should try it!) I can run the wire feed on the portable. See my signature for details.
A bit more information, and we can help you out.

For the welding... I've literally never welded before and want something to learn haha. I want to do my own ground mounting for the solar panels with not wood (some sort of steel but... Again... I'm pretty ignorant in this area) eventually, so if you could point me in the right direction that way since it sounds like you have experience that would save me a good few hours of researching mig v.s. tig v.s. arc and figuring out which one would work best for a novice trying to make a ground mount for solar panels, which would be a godsend haha. But if utilizing this power bank for welding is out of the question completely then... It is what it is, I'll have to get something else figured out.

By table saw I mean something like this: https://www.homedepot.com/p/VEVOR-T...pacity-Woodwork-ZLXMGTJWZJMC19JOUV1/325580653 (Not this one specifically, I just googled table saw and picked something that looked like what I was talking about). According to the specs it's 1800W/15A AC. But just a lot of things like that in the 500-1000w+ range. The types of things I would need to run when constructing a house.

Where your building doesn’t have grid power?

”I want to keep the total budget under $2,000.”

Not much can be accomplished with Solar and that small amount.

I want to keep my budget for this project under $2,000, not the budget to get electric for off-grid living My budget for that is closer to $25,000, but I still have a lot to learn before I can design that system. It's fine if I have to run a single 400W panel or something and let this thing charge over multiple days, it's mostly for the learning experience and to have something to use when I do make that move

 

[OffGridForGood]

”I want to keep the total budget under $2,000.”

Not much can be accomplished with Solar and that small amount.

MPP LVX 6048 =899 on Watts247 (refurbused unit) {$809 for new on Maximum solar + shipping}
48V DIY from cells 100Ah = (about) $1,000 in a plywood case.
Solar panels extra/optional
With tax and shipping it will be over the 2k budget but not by much.
down side - high idle

Smaller system, and more portable:
MPP 2724 $285 plus shipping (Maximum solar online)
DIY 280Ah 8s pack in a box (about 1100 in a plywood case)
Cart to attach it too ($75 bucks)
Comes in under the budget, pretty capable system - I built one.
Down sides: can not be paralleled to expand, only 800W PV limit (or add a SCC)

EDIT: I have the 2724 running on a 311Ah DIY pack, but never tried to start a small portable TS with it. Can't say for sure.

 

[HighDesertOffgrid]

my portable cart mounted 24v system

Sounds like that would be ideal for OPS first project. Individual cells don't seem terribly portable. What does yours consist of?
Cross post lol

 

[OffGridForGood]

For the welding... I've literally never welded before and want something to learn haha. I want to do my own ground mounting for the solar panels with not wood (some sort of steel but...

There are ready made ground mounts that are pretty cost effective. Learning to weld from scratch is a process. Best not to set the bar too high for first projects while you learn.
Perhaps one project and learning topic at a time. Review some of the solar generators on the forum and on YT, pick one that suits you and build it. Go from there.

 

[OffGridForGood]

Sounds like that would be ideal for OPS first project. Individual cells don't seem terribly portable. What does yours consist of?
Cross post lol

Search on the forum - "Building a mobile 8s Cart based Solar Generator - sort of..."

I have done a wide range of tests with an In-Rush meter, to see what the 2724 can start and run.
The list included successful start-up run of chop saws (wood and metal type) skill saws, ginders, shop vac etc.
I found the key to starting bid loads is having enough battery capacity behind the inverter.
The 2724 calls for 123A 24vDC as a minimum, with the 311Ah pack behind the inverter, it can run things that will trip with a single 100Ah pack.

 

[Danke]

MPP LVX 6048 =899 on Watts247 (refurbused unit) {$809 for new on Maximum solar + shipping}
48V DIY from cells 100Ah = (about) $1,000 in a plywood case.
Solar panels extra/optional
With tax and shipping it will be over the 2k budget but not by much.
down side - high idle

Smaller system, and more portable:
MPP 2724 $285 plus shipping (Maximum solar online)
DIY 280Ah 8s pack in a box (about 1100 in a plywood case)
Cart to attach it too ($75 bucks)
Comes in under the budget, pretty capable system - I built one.
Down sides: can not be paralleled to expand, only 800W PV limit (or add a SCC)

EDIT: I have the 2724 running on a 311Ah DIY pack, but never tried to start a small portable TS with it. Can't say for sure.

I’m not a welder, but I have a feeling such a small system would be impractical.

 

[MysanthropicBuilders]

MPP LVX 6048 =899 on Watts247 (refurbused unit) {$809 for new on Maximum solar + shipping}
48V DIY from cells 100Ah = (about) $1,000 in a plywood case.
Solar panels extra/optional
With tax and shipping it will be over the 2k budget but not by much.
down side - high idle

Smaller system, and more portable:
MPP 2724 $285 plus shipping (Maximum solar online)
DIY 280Ah 8s pack in a box (about 1100 in a plywood case)
Cart to attach it too ($75 bucks)
Comes in under the budget, pretty capable system - I built one.
Down sides: can not be paralleled to expand, only 800W PV limit (or add a SCC)

EDIT: I have the 2724 running on a 311Ah DIY pack, but never tried to start a small portable TS with it. Can't say for sure.

The smaller system should be able to handle it no? 2.7kw will power the table saw, which is the most power hungry tool I have right now... Not sure if I could get anything running with it to learn welding tho. You're talking about this one, right? https://maximumsolar.online/product/pip2724lv-mr/

This is where I get confused tho... I'm looking at the data sheet for that and it's only showing one connection for the battery. I can get the batteries for ~ 700 shipped (16x 3.2v 105ah), which I could change to 24v by running 8s2p correct? So I have two strings of 8 batteries... And the 2724 only has one battery port shown in its diagram. Do I literally combine the leads and it can balance the batteries somehow still? Or would I need to get a BMS to handle charging/discharging evenly, then plug the bms into the 2724?
Then when it comes to the solar panel... It says it handles up to 750w. There are some 315W panels on sale for $85 right now (https://clearenergypartners.store/p...Gtpo0k2Je6z2IanwztRZMVM74-t0JthgaAkMNEALw_wcB). Do I just wire both of those in series and run it to the 2724, and it handles everything from there?

And what about fuses?

 

[OffGridForGood]

The smaller system should be able to handle it no? 2.7kw will power the table saw, which is the most power hungry tool I have right now... Not sure if I could get anything running with it to learn welding tho. You're talking about this one, right? https://maximumsolar.online/product/pip2724lv-mr/

Yes that is the one I am using, I picked it due to the price, and the outlets built right into the left side of the inverter - complete with a couple USBs - was perfect for my mobile set up. This unit can only have 750W of PV solar panels attached - but if you need more charging, add a Solar Charge Controller separately.

This is where I get confused tho... I'm looking at the data sheet for that and it's only showing one connection for the battery.

I only have one connection on any Inverter I own. you build the batteries into a set connected to a Bus Bar or junction point, then that single point feeds via a disconnect to the Inverter. (ie the inverters only need one connection point for battery voltage)

I can get the batteries for ~ 700 shipped (16x 3.2v 105ah), which I could change to 24v by running 8s2p correct?

good price. don't build a 8s-2p single battery pack (at least not as your first build)
Instead build two separate packs of 8s, each with a BMS to protect the cells, and maintain balance between them.
Connect the two finished packs in parallel - pos to pos, neg to neg to a terminal point, that will then feed to a disconnect, and the disconnect will feed the inverter.

So I have two strings of 8 batteries... And the 2724 only has one battery port shown in its diagram. Do I literally combine the leads and it can balance the batteries somehow still? Or would I need to get a BMS to handle charging/discharging evenly, then plug the bms into the 2724?

The BMS's job is two-fold; 1) it will protect the pack and individual cells from over or under voltage and over current events, 2) it will keep the cells in balance with one-another as they charge above 3.4v per cell. Think of the BMS as a safety device, not a charging device.

Then when it comes to the solar panel... It says it handles up to 750w. There are some 315W panels on sale for $85 right now (https://clearenergypartners.store/p...Gtpo0k2Je6z2IanwztRZMVM74-t0JthgaAkMNEALw_wcB). Do I just wire both of those in series and run it to the 2724, and it handles everything from there?

It can handle two of those panels in series, PARALLEL, and the MPP 2724 has MC-4 connections right on the unit - same connections as the PV panels have, so it is very easy to connect for a beginner. Some users would need more than two panels to keep the batteries charged, it depends on use. I have just one 440W panel that charges my mobile unit. This works for me, because the mobile is not used constantly so it has plenty of time to recharge between my uses.
If you need more PV to keep up in the future, you can charge the batteries separately from the 2724 with a separate SCC that can handle higher PV input,

And what about fuses?

I like to build the DIY pack with a fuse internal to the pack. This was suggested to me on this forum by another member and it makes good sense - it is out of the way, never in the way, and there if you ever need it.
It would be smart to also fuse between the battery and the inverter with a 150 or 200A Class T fuse like the one by Blue Sea (fuse and holder).
Example of the DIY pack in a plywood box - with fuse between cells #4 and #5 - I used an ASL fuse here, because it fit well, A MEGA fuse could work too.
My wiring job is a mess in this photo!

 

[OffGridForGood]

I’m not a welder, but I have a feeling such a small system would be impractical.

The MPP 2724 will run a small wire feed - best to avoid the highest setting "D" for prolonged periods.
I repaired a steel gate post hinge a while back with the wire feed and the mobile 2724. It would have been a huge PITA to drag the diesel welder out for such a small welding job.
That said, this little inverter is not going to run a 200A stick welder.
The OP is just starting out, and learning as they go. For their budget, they can get their feet wet and build a portable unit as they say they want to do, and that unit can do some real world work, within reason. There are other inverter options they could go with, but I have real world experience with this one and can vouch for it's abilities.
The MPP 2724 is a simple little inverter that anyone can set up into a mobile portable power station, with at least 150A of battery behind it, it is basically a mobile 20A 120v outlet you can move around. It will run anything a 20A outlet can run.

 

[MysanthropicBuilders]

Thank you so much! I think I figured out what was confusing me (AIO v.s. inverter + charger, couldn't figure out why some people didn't have the separate solar charger). Now it's just a matter of waiting for things to come in stock at a decent price Just to make sure I got my supply list correct:
MPP 2724 x1 (MPPT Solar Charger / Inverter)
16x 3.2v 105ah LiFePo4 batteries (8s2p --> 24v)
2x 100a 24v lifepo4 BMS (1 per pack)
2x 100A fuse (1 per pack)
~10' 3/0 cable
6x 3/0 ring terminals / lug nuts / whatever you want to call them, the copper loops you put on the end of battery wires to hook to posts
2x single post bus bar (to combine battery packs before attaching to inverter)
Plywood + cart for mobility (and another sheet of plywood to attach the inverter to)
And a handful of screws to put the box together + screw everything down

 

[OffGridForGood]

2x 100A fuse (1 per pack)

I suggest 125A per pack
It is also handy to put a breaker right on the battery pack - to give you a simple way to shut down power to do work on the system.
I would also add one 150A Class T fuse to go between the invert and the bus (where the two packs parallel up) just as a safety thing.