AC to DC 12 volt Power supply for RV without batteries

[Andonso]

I have a RV that's connected to shore power 24/7 and thinking of removing it's two house batteries and installing a regular PSU without charger to supply 12 volts for the RV.

I use to have a PD9280 installed that stopped working and also have a PowerMax PM4-75LK 75 Amp PSU that I'm thinking installing into another rv.

The RV has a 4000 watt generator.

One problem is the 4000 watt genny requires 12 volts in order to start. So if I remove all the batteries I would need to temporally connect some sort of battery in order to start the genny. I do keep some extra batteries on AC/DC chargers so it would be likely a 12 volt lead acid battery would be available to connect to the RV if ever needed to start the genny.

Questions arises what type of power supply to look for and how many amps are actually needed.

The RV has 9 12 volt lights of which some have LED bulbs. The absorption frig requires 12 volts to operate (I've been thinking of replacing the absorption frig with an electric sometime inf the future)

There are also some control switches in the stove hood that have some controls but aren't ever use except perhaps once in the while a remote generator starter switch.

I don't ever use the RV gas furnace as it's broken and installed in it's place an electric heater and also have an indoor gas catalytic heater with safety features.

So most of the RV relies on AC and very little on DC. I do sometimes use the RV 12 volt cig. receptacles to plug in 12 volt cig adapters and electronics.

After a little searching I'm finding psu's from around 10 to over 25 amps. some of which are switching power supplies.

e.g. I found this one MW Mean Well PDF-320-12 DC Output 12V 25A Power Supply

also many others however I'm not certain if I should be looking for a particular type or just any 12 vdc ac/dc psu that I can be connected to a Progressive Dynamics AC / DC distribution panel.

I thought I would post this question to determine if there's something I'm overlooking as most people install RV converters with battery charger in RVs to supply 12 volts and charge the house batteries.

I think ~10 to ~25 amps should be enough power for a 23 foot motorhome that's kept in one spot all the time?

[Andonso]

This is sort of an experiment as I don't know exactly how many amps the RV requires when without batteries.

I paid only $35.00 with shipping for the X-Power PSU.

I wouldn't use it as a charger and not certain if a few 12 volt lamps most of which most are LED and the absorption frig would cause an overload.

I rarely use the RV 12 volt lamps when there is 120 VAC. The most RV lamps use at any one time are usually 2. I'm uncertain how many 12 volt amps the absorption frig PCB requires?

When the power was down to 9.5 volts the Norcold frig was still working but started to produce a LO-DC error from it's display so it appears to work fine between 10 and 14 volts.

The RSP-500-15 voltage range is 13.5 to 18 volts (33.4 amps) whereas the RSP-500-12 range is 10 - 13.2 volts (41.7 amps)

The XP Power JPS250PS12 I'm unable to find an output voltage range, the datasheet shows it's output as 12 volts.

The amp rating is 21A when cooled with a cooling fan 18 CFM. This model I believe the fan runs all the time and may be variable.

It has a second amp rating of 17A when convection cooled .

Short Circuit Protection = Trip and restart (Hiccup mode), auto recover

What to look for if there is no voltage output range specs are other specifications.

datasheet

If it doesn't work out I have the Powermax PM4 75 watt or the Parallax 30 amp that needs a fan.

[landyacht318]

Dang bluetooth keyboard, twice, did something deleting a few paraghaphs.

The sp-320 series has hiccup mode on overload, shutting down until load is removed.

SPS's used as battery chargers should have constant current limiting on overload.

I'd get a SPS with the latter so that it can be used as a battery charger later on, and one with a voltage range upto 16 for equalizing flooded banks.

My rsp-500-15 voltage range is much wider than the spec sheet, 13.12 to 19.23v

[Andonso]

Ok I found a power supply from eBay using best offer. It's most often used for medial equipment.

The seller described as “Was never used but have some signs on metal " It's internals appear similar to the PD9280 except it doesn't have the battery charger portion of the psu and the huge heat sink. Cost from best offer is significantly less than a 30-35 watt RV converter charger.

I'll see how well it works out to supply 12 vdc without batteries. If it doesn't, I'll install a battery with a converter/charger. I may add some fuses to both the DC out and AC in.

DigiKey XP Power JPS250PS12

Newark XP Power JPS250PS12

https://i.ebayimg.com/images/g/68EAAOSwECZUmsr2/s-l1600.jpg
https://i.ebayimg.com/images/g/cgEAAOSwyZ5Umsr~/s-l1600.jpg
https://i.ebayimg.com/images/g/qesAAOSwMpZUmssJ/s-l1600.jpg
https://i.ebayimg.com/images/g/o1cAAOSw7ThUmsr6/s-l1600.jpg

[Andonso]

I do have an old Parallax 30 amp that original came with Parallax 6300 whose fan stopped working.

Perhaps I can fix the fan to see if it can be used.

For now I found three used Mean Well on eBay and going to try one of them out.

MW Mean Well PDF-320-12 DC Output 12V 25A Power Supply

MW Mean Well SP-320-13.5 DC Output 13.5V 22A HAM Radio CB Audio Power Supply

Genuine MEAN WELL SP-480-12 12V 40A 480 Watt LED Power Supply

I'm leaning towards getting the Mean Well 13.5 22 amp psu which I thin is better quality than less expensive non name psus made in China?

E.g. I found several 12 volt 30 amp psu's, uncertain of their quality that are often used for LED lighting, CCTV, etc.

12V DC 360W 30A 110V-220V Switching Power Supply for LED Strip Light Driver CCTV

One of the above psus would be used without any batteries as I plan on removing the RV batteries. If it doesn't work out then I'll re-install one of of the RV batteries, (with charger) or perhaps find and install a couple of six volt golf cart deep cycle batteries.

Quality Deep Cycle batteries potentially can last from 15 to 20 years if maintained, where RV batteries typically have a shorter lifespan around ~10 years and sometimes less if often depleted under 50 percent charge and then recharged again, I think in at least in part what shortens the lifespan of batteries.

True deep cycle batteries uses heavier plates lasting longer, some I remember reading don't have or as much of a problem being nearly depleted and then recharged again and again. Which tends to build up sulfation. Some converters chargers such as some of the Progressive Dymanics have a desulfation stage where it produces a desulfation charger every so many hours for ~15 mins or so.

There are also desulfators with a wide range price range, that operate under various amps. from milliamps to several and more amps.

Such as Lead Acid Batteries 12v 24v 36v 48v Battery Regenerator 2A Auto Pulse Desulfator

and many others.

How much do they help to preserve a battery. I think it may depend how a battery is used and regularly charged.

Note: I rarely use RV 12 volt lighting. Normally either 120 Vac or a lithium flashlights that run off of 18650 batteries. I have at least a couple doze lithium batteries that I keep maintained. They're fairly long lasting and plentiful as they can be salvaged from laptop batteries.

some of my 12 volt rv lights have been swapped out for leds, that use less power.

So my current 12 volt needs are minimal , rarely used 12 volt lighting and an absorption frid.

I was also looking at Parallax 30 to 50 amp power supplies, however most I've seen come with a dist. panel that doesn't have enough AC breaker spaces for my needs.

30 amp.parallax power supply for a rec. vehicle

I picked up a Progressive Dynamics dist. panel with a 30 Amp AC main and up to 9 AC branch circuits.. I require addtional AC breaker spaces. Most of the dist. panels are limited to 5 ac breakers.

PROGRESSIVE DYNAMICS 30 AMP 120 VAC AC/DC POWER DISTRIBUTION PANEL

[time2roll]

BFL13 wrote:

time2roll wrote:
Just get a converter to replace the 9280. You don't need 80 amps. 30 to 45 is fine with just a converter. 5 to 10 amps is probably fine if you have a battery.

Likewise I would keep one battery in place to start the generator. Converter can keep it charged.

He has a couple of TrueCharge 10s that could do 20 in parallel ISTR, on the batteries lying around. Why not hook all those batteries lying around and the two TrueCharges to the MH and "have it all"?

The batteries will still be floated ok, plus be ready for any gen starting, and the Truchargers will provide 12v to the RV. No need to buy anything. 🙂

A single 10 amp TrueCharge and a single battery would work just fine as I said above.

Although I understand TrueCharge runs the fan 100% of the time... some may like the white noise and some could be a bit annoyed. OP can make that call.

[MEXICOWANDERER]

Calculating your total -projected- load amperage should be your number one goal. Nothing appreciates be loaded to near 100% capacity. And there are few things nuttier than the thought of applying algorithm voltage changes to a static pure resistive load. Load goes up and down? Lights brighten then dim? Fan speed too?

An RV converter with an adjustable fixed voltage setting would work fine. Set it to 12.00 volts and be done with it. No Delta T compensation involved. Unless of course you have gone Wile E Coyote on the rig's accessories and overload the primary DC distribution circuits.

LEGIT QUESTION....criticize at your peril 🙂

What is the max D.C. hotel burden of the newer, largest luxury rigs? An inverter cannot be counted as hotel burden, thank you.

[Andonso]

I recently purchased a Powermax PM4 75 watt converter charger and currntly have a Xantrex 10 amp true charge providing 12 volts and charging two RV batteries.

I'm thinking of installing the Powermax PM4 into a Class-B I'm working on or just keeping it as a backup in case the C ever needs to travel I can plug it in and install 1 - 3+ house batteries. I also have a 115 watt solar panel and a Mormingstar Tri-Star solar controller that can be used either with the C or B.
_________

When I remove the two RV batteries I don't see any reason to have a battery charger and only require a AC/DC converter.

I guess it's sort of an experiment and to save money on new batteries which I never really used in the last 10 years the RV been sitting connected to shore power. (other than a few times pud power went out for a few hours one or twice a year after a wind and rain storm.)

If needed I can run the Genny if the PUD power goes out.

I lived in a 44 foot RV without any sort of 12 volts and there isn't really any difference between full time living in a RV with 12 volts, other than your flipping on and off 12 volt lights instead of 120 VAC. The RV als had a 120 VAC compressor frig which are more efficient. Absorption frigs require 12 volts to operate are great for traveling but really not good for full timing. Their smaller and less efficient than electric compressor frigs.

For traveling in a RV yes it's neccsary to have 12 volts, converter / battery charger, house batteries and an absorption frig, plus all your other RV gas appliances.

Connected to PUD 24/7 not really necessary and think it's a waste of money as the batteries are never really used other than to filter and clean up 12 volts.

Power supplies, converters and inverters have seen alot improvements over the years and put out much cleaner 12 volts where batteries aren't really neccsary to produce cleaner power for more sensitive electronics.

So the questions remains how many amps and how many volts?

I'm thinking 13.5 vdc psu will be better than a 12 volts as there is a voltage drop with the long runs of DC wiring.

The two psus I'm currently looking at is a 25 amp 12 volt and a 22.4 amp 13.5 volt psu, which I'm thinking of getting instead of the 12 volts.

I'm uncertain how many amps will be a good amount to supply 12 volts to the RV which will be basically used for lighting and the frig.

10, 15, 20, 25 amps? I've come across a few new 8.5 to 12.5 amp 12 volt converters.

I have approx. 8 12 volts light @ ~2 amps each which if ever on at same time would draw approx. 16 amps, plus amps required for the frig.

So a 13.5 volt 22.5 amp psu should work ok.

I've lived in a RV for more than 25 years and it's really no different than full time than living in a mobile home. You tend to forget about the batteries and charger as if they don't exist as their rarely if ever used when connected to PUD 24/7.

Now a solar system (renewable energy) is much different as batteries are required to maintain the power system. A good solar system connected to PUD would want a good converter / charger to maintain the batteries when there is little or no sunlight.

If you have a wind generator the same thing. I've looked into water generators as that's another method to create energy to maintain batteries.

[BFL13]

time2roll wrote:
Just get a converter to replace the 9280. You don't need 80 amps. 30 to 45 is fine with just a converter. 5 to 10 amps is probably fine if you have a battery.

Likewise I would keep one battery in place to start the generator. Converter can keep it charged.

He has a couple of TrueCharge 10s that could do 20 in parallel ISTR, on the batteries lying around. Why not hook all those batteries lying around and the two TrueCharges to the MH and "have it all"?

The batteries will still be floated ok, plus be ready for any gen starting, and the Truchargers will provide 12v to the RV. No need to buy anything. 🙂

[time2roll]

Just get a converter to replace the 9280. You don't need 80 amps. 30 to 45 is fine with just a converter. 5 to 10 amps is probably fine if you have a battery.

Likewise I would keep one battery in place to start the generator. Converter can keep it charged.

[wa8yxm]

Well if all you want is a power supply.. I kind of favor the Progressive Dynamics 9100 line.. you can "upgrade" it to a 3 stage charger very easily (Add the optional charge wizard converting it into a 9200).

In your case I'd build my own supply.. but then I do that from time to time.

Since you need to start the genny. I'd go with a Group 24 battery and a 9100.

Option 2 is a 9100 and a "jump Start" Luggable battery pack. I have one of those too Very handy. Many tasks.

[Tom_M1]

A power supply is not meant to be a charger. Do like BFL13 says and get a converter. It does double duty as a charger and a power supply. Also get a 12 volt deep cycle battery.

[DrewE]

The generator starter needs quite a bit of current--mine takes somewhere around 90A according to my panel ammeter, on average, with considerable variation depending on how cold the temperature is, how close to up to speed the generator starter is turning, the phase of the moon, etc. You would have a hard time finding a switching power supply that would consistently provide sufficient current to start the generator without going into overcurrent shutdown mode or blowing an output fuse from the initial surge, and if you did find one it would be very much overkill for all the other uses.

You may be able to start the generator without a house battery by starting the main engine (which should engage the circuit to charge the house battery from the vehicle electrical system) and then starting the generator from the chassis battery. It may or may not work, depending on the exact design and robustness of the isolator and interconnection. If you have an emergency start switch for the main engine it stands a reasonable chance of working.

For other uses, I would think that ca. 25A or more would be easily sufficient.

If you do any camping on the road at all with this vehicle, a house battery is pretty much a necessity. I myself would not get rid of it unless I was also letting the registration and insurance lapse and hence deciding it's not going to be mobile anymore, but that's just me.

[BFL13]

I think this might be more robust than the Meanwell for continuous operation?

https://www.boatandrvaccessories.com/products/powermax-pm4-35-converter

I don't think any of these things "come with a charger". They just will charge as long as their voltage is above the battery's voltage.

[Andonso]

Ralph Cramden wrote:
Do you have slides? You might want to check the amp draw when running the slide motors. Some manufacturers, BAL for one, state not to operate theirs without a connected battery. I know the Lippert POS above floor slide on our Rockwood does not like it when a battery is not connected, the small motors on our Schwintek ward slide seem to be ok without one. Running without battery may be a good way to fry a motor.

No slides, it's an older 23' C-Class Fleetwood, E-350 with a 460 fuel injected engine, hd rear axle with dualies. Four speed transmission with OD and cruise. Plenty of power, when I was on the road I usually had a Jeep Toad behind it, would sometimes take it camping in the mountains, didn't do too bad on mountain roads in mud, snow and ice.

Has AC (air cond.) which I never use.

Anyway the DC consists mainly of lighting, absorption frig. and a 12 vdc water pump that's rarely ever used. I think the gas / electric water heater may require 12 volts to ignite? it's normally connected to AC.

I normally keep spare batteries on a trickle charger and have a B-Class camper van I'm working on.

it's mainly in 10 years I'ver rarely ever actually ever used the three batteries which are near the end of their life one 01/06 and two 01/07's. The 01/06 has lost electrolyte a couple of times and I removed it .

I really don't require batteries for power as the PUD rarely goes out, perhaps from 1/2 to a full day once or twice a year and I have a Onan 4000 what genny and a spare batteries to start it if it's ever actually needed.