Help with AC to DC converters

musigenesis · 01-25-2021, 11:37 PM

I need to wire up my bus with DC to power my diesel air heater and some fans and lights and eventually my tankless water heater. I currently have only a 15 amp inlet and no solar. It's not my intention to go off-grid, I just need basically an AC-to-DC converter setup (the battery is just to stabilize the converter output, as I understand it).

I think this is the main gear I'll need:

https://www.amazon.com/dp/B00A0V5HPC/
https://www.amazon.com/dp/B0030G7ZHM/
https://www.amazon.com/dp/B00B689UGA/
https://www.amazon.com/BNTECHGO-Sili...dp/B01CJJU6NU/
https://www.napaonline.com/en/p/NBP6565

Plus connectors and stuff. Is there anything major that I'm missing here?

Is there some simpler/cheaper way of doing the AC to DC conversion that I need? I was hoping to find a one-piece unit of some sort that plugs into an AC outlet and provides DC hookups for multiple appliances, but nothing like that seems to exist.

Thanks!

Rwnielsen · 01-26-2021, 12:55 AM

Typical RV DC converters have fused outputs as well as a battery charger.

https://www.amazon.com/Progressive-D..._t3_B01EXKUA3E

That little meter you linked to is nice to have, I have a few.

DeMac · 01-26-2021, 12:55 AM

If you are only running fans and lights off shore pwr, you could use a plug-in transformer until you need a more complex setup.
Might be a cheap, used landscape xfmr on your local craigslist, let-go, yard sale, etc.
Come to my house & I'll give you a freeby.

BeNimble · 01-26-2021, 01:54 AM

A cheap AC->DC is a UPS uninterrupted power supply. It plugs into AC and keeps the backup battery charged. They don't seem to have very big charge capacity, so might not keep up with all your loads. Bigger ones use 24 or 48v batteries, what batteries you have? 12v?

rossvtaylor · 01-26-2021, 05:15 AM

Hey Musigenesis, what's the total current draw of your 12V circuit? You can get 30 amp DC power supplies pretty cheaply. https://www.amazon.com/MENZO-Univers...1659503&sr=8-3

joeblack5 · 01-26-2021, 06:40 AM

A battery charger can do all of that and more.
Nowadays there are inverter battery charger that can charge at 40 amps at 12 volt, do a desulfate, start help.. alternator check.. have a digital voltage gauge.
The electronic ones are based on a switch mode power supply and are lightweight and the size of a shoe box.

Seems a good tool to have.

Johan

rffffffff · 01-26-2021, 07:16 AM

There’s no need to add the battery If you’re not going to use it, at least from my experience. I don’t have any batteries in my bus at the moment and my iota is cranking along.

You can ditch the Iq4 module too if you’re not going to use a battery, but at that point you’ll have just a glorified power supply for a lot of money, and you might as well look at the power supply linked for $18 or if you have an old or free computer laying around you can yank the power supply from that and have a strong 12v supply usually above 30a from that if I recall correctly.

If you’re going to use the iota in the future and it’s part of a bigger plan I definitely support that idea, but I would also consider stepping up to more than 30a if the price isn’t too much higher. 30a is only 360w equivalent of solar so if you’re going to have more panels than that consider more charger than that too, assuming it’s going to be a charger in the future.

A couple more things: 12awg wire is overkill for LED lights but probably a little small for the diesel heater, which draws a lot of energy in a surge on startup and can pull the voltage down (experience again) but my heater is like 25 feet from my distribution panel. If it’s closer you’re probably okay but I will run 10awg to the heater in the future.

Which brings up this:

Deyooxi 12 Way 12V Blade Fuse Block,12 Circuit ATC/ATO Waterproof Fuse Box Holder with LED Indicator Waterpoof Cover for 12V/24V Automotive Truck Boat Marine RV Van Vehicle (with 16 pcs Fuse) https://www.amazon.com/dp/B08H4Q9SYR...ing=UTF8&psc=1

Or something like it should be installed so all of the 12v power is fused.

I ran big, like 4awg, wires to the fuse panel from the charger, consider at least 8awg depending on distance if you’re staying with 30a, but nothing smaller than 10awg for sure to power the fuse block, then run the smaller wires from the block.

Lastly, look into getting the 12v crimp terminals online too, hopefully a better brand than the mushy cheapest crap on Amazon, but they’re waaay overpriced when I find them locally so a whole kit saved me a ton of money.

I hope that helps!

rossvtaylor · 01-26-2021, 07:42 AM

rffffffff makes a good point about the crimped terminals. If you only need a couple, I like to use the "high temp" ones which you can generally find in the appliance parts drawers at any decent hardware store. They'll be in those little pull-out parts trays. But, as he points out, they're pricey there.

And yes, you don't need the battery...unless you need the battery.

musigenesis · 01-26-2021, 10:26 AM

Thanks for the advice, everybody. I think I'm going to cheap out here since right now I really just want the bare minimum that will let me install and run my heater off 120V. This is what I'm going to order:

40A Switching Power Supply
12V Blade Fuse Block
4 Gauge wire for connecting power supply to fuse block
12 Gauge wire for connecting fuse block to appliances
Butt Splice Crimp Connectors (to connect appliance wires with 12 ga)

This all seems like it will work?

Now I have to decide where to mount these. Most of my DC appliances are on the starboard side but the 15a inlet is on the port side. If I mount the power supply and fuse block on the starboard side, they would have to go underneath the sink.

rffffffff · 01-26-2021, 12:13 PM

That mostly seems good but you want to use ring terminals instead of butt splices:

https://www.amazon.com/dp/B01D8EJX3E..._zOfeGb3XV7CJV

Get some ring terminals for the #4 wire too and make sure you have a way to crimp it. Alternatively I’ve used screw on clamping ring terminals like these if you have little to do. Probably not as good but they haven’t let me down:

Conext Link RT4N-2 Set Screw Ring Terminal 2 Pack (4 Gauge, Nickel) https://www.amazon.com/dp/B01K40M364..._wTfeGbZ4HDT95

Rwnielsen · 01-26-2021, 12:21 PM

Home Depot and Lowe's both carry wire lugs, usually in bags of 2. #4 lugs are under $2 and are the way to go if you don't have a set of large crimpers, at least for your main lines.
If you later decide to add a battery , or 2, you'll need to replace that power supply with one that has a charging circuit. Otherwise you should be good to go

rffffffff · 01-26-2021, 12:25 PM

Only problem I’m seeing is that the power supply has small terminals for those ring terminals I just linked. You may have to go to 8awg in order to get them to fit with that supply. 8 is the minimum for 40amps, but voltage may sag if you pull too much current. When you’re plugged in it’s not that big of a deal I don’t think especially if the wires are relatively short.

rffffffff · 01-26-2021, 12:27 PM

Quote:

Originally Posted by Rwnielsen

Home Depot and Lowe's both carry wire lugs, usually in bags of 2. #4 lugs are under $2 and are the way to go if you don't have a set of large crimpers, at least for your main lines.
If you later decide to add a battery , or 2, you'll need to replace that power supply with one that has a charging circuit. Otherwise you should be good to go

I keep finding $5 pairs and $7 pairs and they’re always out of stock around here. That’s been a frustrating experience for me but it may be regional problems.

musigenesis · 01-26-2021, 01:00 PM

Would these work for the lugs?

https://www.amazon.com/gp/product/B08CV7MMHX/
https://www.amazon.com/gp/product/B017S9EINA/

Then I would also order some 8awg wire in case the #4 lugs don't fit on the power supply. The power supply and the fusebox will be next to each other so the leads should be very short.

My plan to mount these on the wall of my closet is maybe not a good one, since that would mean clothes would be hanging right next to them.

rossvtaylor · 01-26-2021, 01:06 PM

I have that same manual crimp tool...and a hydraulic...and the manual one works just fine. Those terminals look to be decent, too, as long as they fit....and that's hard to tell from afar. I'm glad to see you heading down this path. It will be cheaper and should work just fine for what you plan.

rffffffff · 01-26-2021, 01:59 PM

Those crimps and crimper look good. The power supply will heat up under load so it’s a good idea to give it some airflow. Just a hunch I would probably start with 6awg wire and you can file down the sides of the crimp if it’s too big and make it work.

musigenesis · 01-26-2021, 03:46 PM

What do you guys/gals think of RV power centers like this one? https://wfcoelectronics.com/product/wf-8935-35-amp/ I found a local person on Craigslist selling this exact model for $250. Seems like this would be plug and play and I could still add batteries and solar later if I ever wanted to? And it would only be 5X as expensive!

He's also selling this electric RV oven for $350 (started to build a tiny house but gave up, so both these items are new in the box). I have an old Magic Chef propane stove/oven salvaged from a camper, but the actual oven part is just so small that I can't really use it for anything that I normally cook. It says this RV oven draws 1400W so it's basically a space heater in a little box.

rffffffff · 01-26-2021, 04:24 PM

I’ve never seen the power center but it looks like it would do the job, but I personally wouldn’t want to pay extra for it. Something goes wrong on that thing and it’s all junk most likely, where a power supply or fuse block is easy to replace components of. It’s clean though so I can see the attraction.

As far as the oven, 1400w is a lot if you’re on batteries and close to the limit of my little inverter generator so if you plan on being plugged in a bit I can see it working out but if you’re off grid that kinda electric use is rough. I haven’t seen a smallish propane oven but if you do I’m looking!

musigenesis · 01-26-2021, 10:00 PM

Quote:

Originally Posted by rffffffff

I’ve never seen the power center but it looks like it would do the job, but I personally wouldn’t want to pay extra for it. Something goes wrong on that thing and it’s all junk most likely, where a power supply or fuse block is easy to replace components of. It’s clean though so I can see the attraction.

Well, you convinced me to go ahead with the separate stuff, just ordered it all. I'm going to go 6awg (3' long) between the power supply and the fuse box, 10 awg (25' long but probably more like 10'-15') between the fuse box and the heater, and 12 awg for my Maxxair fan and other stuff.

Quote:

Originally Posted by rffffffff

As far as the oven, 1400w is a lot if you’re on batteries and close to the limit of my little inverter generator so if you plan on being plugged in a bit I can see it working out but if you’re off grid that kinda electric use is rough. I haven’t seen a smallish propane oven but if you do I’m looking!

Yeah, I'd only use an electric oven with shore power, which I'm planning to have most of the time. I bake bread at 475F which is the max temperature this electric oven is rated for (it's also big enough to hold the dutch oven I cook it in). I'm not sure if the little propane ovens can get that hot, or safely maintain it for 2+ hours, plus there's always the fear of running out of propane in the middle of a bake.

milkmania · 01-26-2021, 10:16 PM

Quote:

Originally Posted by musigenesis

I need to wire up my bus with DC to power my diesel air heater and some fans and lights and eventually my tankless water heater. I currently have only a 15 amp inlet and no solar. It's not my intention to go off-grid, I just need basically an AC-to-DC converter setup (the battery is just to stabilize the converter output, as I understand it).

I think this is the main gear I'll need:

https://www.amazon.com/dp/B00A0V5HPC/
https://www.amazon.com/dp/B0030G7ZHM/
https://www.amazon.com/dp/B00B689UGA/
https://www.amazon.com/BNTECHGO-Sili...dp/B01CJJU6NU/
https://www.napaonline.com/en/p/NBP6565

Plus connectors and stuff. Is there anything major that I'm missing here?

Is there some simpler/cheaper way of doing the AC to DC conversion that I need? I was hoping to find a one-piece unit of some sort that plugs into an AC outlet and provides DC hookups for multiple appliances, but nothing like that seems to exist.

Thanks!

bought this to do exactly what you're trying to do... I realize this link is sold out, but there's plenty others out there.
https://www.ebay.com/itm/AC-110V-220...72.m2749.l2649

This unit works perfectly for my temporary needs and it was under $20
https://photos.app.goo.gl/8AhnZYf7RmygMrcj8
https://photos.app.goo.gl/vB7ebAcQM4ugApQq9

and later, I'll be using this Intelli-Power 9100 I salvaged from a Class A
https://photos.app.goo.gl/MRakdKtcgLUuXCsR8

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