Is there such a thing as a 12v UPS?

[hbn7hj]

Originally Posted by MobileCabin

Back to the original question. In addition to the Newmar product mentioned by booster, they have another with an internal battery for those momentary no power events. It might be closer to what is needed for this application:

https://powerwerx.com/newmar-mdp-25-...s-backup-power

I would like to hear from anyone who has used it.

Impressive.

A cheaper voltage stabilizer will handle anything but generator start and sudden power failure from a battery doesn’t happen like it does with 120 volt AC.

The hybrid battery system solves all your problems including the capacity one caused by running the fridge too cold. $1500 would fix you up-lithium battery, DC to DC charger and a switch. Don’t forget a voltage stabilizer for the electronics and a battery monitor or two.

You would have to install it yourself. If you can’t do that then get a voltage stabilizer for the electronics and turn ‘em off when you start the generator.

Or you could spend the money on the product mentioned.

I think we covered all your options.

[BigFatGuy]

Originally Posted by MobileCabin

Back to the original question. In addition to the Newmar product mentioned by booster, they have another with an internal battery for those momentary no power events. It might be closer to what is needed for this application:

https://powerwerx.com/newmar-mdp-25-...s-backup-power

I would like to hear from anyone who has used it.

DUDE!

Do you have any idea how long, across how many RV forums, and how many google searches i've tried to find THIS EXACT THING?

Many thanks!

[BigFatGuy]

Originally Posted by hbn7hj

I think we covered all your options.

I'm in awe.

[markopolo]

It's an interesting product for sure. The OP might need more than one though as he has indicated more than one problem. It doesn't have enough capacity to be a whole coach solution. And it's another battery that needs to be cared for. His existing batteries can be fully depleted by morning so this small 8 or 9Ah battery isn't going to help with that.

Is the proximate cause of the electrical problems actually dirty power or is it low voltage? Are the existing coach batteries near end of life?

What is the cause of the failed fridge controller boards? What is the operating voltage range for those particular boards? Is the wiring to the fridge undersized?

[booster]

Originally Posted by markopolo

It's an interesting product for sure. The OP might need more than one though as he has indicated more than one problem. It doesn't have enough capacity to be a whole coach solution. And it's another battery that needs to be cared for. His existing batteries can be fully depleted by morning so this small 8 or 9Ah battery isn't going to help with that.

Is the proximate cause of the electrical problems actually dirty power or is it low voltage? Are the existing coach batteries near end of life?

What is the cause of the failed fridge controller boards? What is the operating voltage range for those particular boards? Is the wiring to the fridge undersized?

Marko beat me too it, as I was thinking the same thing. There normally are not many things on a class b that would need server style backup capacity. Things like frig boards have come up over time and sometimes even have other than electrical causes like being loose, harness flop or pull, etc. Dirty power can be an alternator with a bad diode, even, or poor quality solar or shore charger.


Of course there can be exceptions like using a 12v native tv without the wall 110v brick, as that removes the tv's built in protection in most cases.



One thing that would be needed to be considered with the 25 amp unit linked would be that it's benefit will be reduced by some amount if it is used to stabilize all the coach power (25 amps may also not be quite enough) as UPS systems, by design and need, are point of use devices. They need to be right at the power use point to be the most effective. If you have more than one device downstream and wiring to run them, they will all still be talking to each other with any noise or fluctuations they generate, so you will not get rid of that side of the problem. For instance, if the heater in a 12v coffee maker clicks on and off in operation, it will send a spike on the line. A lot of 12v fans are variable speed now and do it with more efficient frequency drives. AC wiring can induce current in adjacent DC wiring.



I do think that when you look at dirty power in RVs you are much more likely to see the 110v AC with issues than the the DC side.

[BigFatGuy]

Yeah, I'm not planning to use this for the whole RV, just the fridge, and a small electronics cabinet... Cell booster, WiFi amplifier, that kind of thing.

Someone above pointed out this would not be a lot of help if I ran my battery down, my beer would still be warm in the morning. This is true... although an extra hour or two may well be enough to get me through til the sun comes up at dawn. Obviously, the best solution here is learning how to work the RV (which I'm much better at than I was 2 years ago), and a lithium upgrade (I'll have to see how good my profit-sharing bonus is at my new job.)

(Edited to add: if you want to see how dirty 12V power can be, set a couple of strings of your LED lights to 50% brightness, and put an oscope on your 12V rails.

[Bruceper]

You could use a battery with a power conditioner, although conditioners really aren't commonly found these days outside commercial use. There are 12 volt power conditioners.

[WJones]

Wouldn't simply adding an extra battery with a DC to Dc battery charger do the trick? ca.renogy.com/renogy-12v-dc-to-dc-on-board-battery-charger/?gclid=EAIaIQobChMIvqWU0_iQ5wIVGoeGCh041QBDEAAYASA AEgJPmPD_BwE

[hbn7hj]

Yep, but no one has picked up on that.

[booster]

Originally Posted by hbn7hj

Yep, but no one has picked up on that.

Very true, but be sure to look carefully at the full specs or call them if their allowable ripple isn't listed, which it often is not. If you are worried about dirty power it can easily come from chargers. I seem to remember some with upwards of 10% allowed from a while ago when someone listed them.

[BigFatGuy]

It would not be the same thing at all.

A UPS has three parts: a battery, a charger, and an output power supply... And that's the hard part to design well.

[hbn7hj]

Everyone solves problems in a little bit different manner. Don’t let us intimidate you.

I would put the hybrid system in and chargers would be off when the computers were on. Probably a different solution than anyone else. I’m sure your solution will work for you.

Computers on one system, charger on the other, if necessary.

Loads on the lithium system when starting the generator on the FLA system.

Your question added to everyone’s knowledge.

[BigFatGuy]

Originally Posted by hbn7hj

Everyone solves problems in a little bit different manner. Don’t let us intimidate you.
.

Rest assured, i come from a much older Internet, where being mean to each other wasn't frowned on.

[Nic7320]

Sounds like you have either insufficient battery for your needs, or bad wiring (a ground or 12 volt feed wire that is too small) or possibly a just bad connection. Frying electronic boards is a sign something is way out of whack.

But first I would do some math and see if all of your loads are simply too much for your battery capacity. If the math is too burdensome, it may be easier to measure the watt-hours consumed -- if you have the equipment. For example, Victron solar controllers have a switched DC output that measures the watt hours of load consumption, (they also measure of the watt hours of solar production). Some unbranded DC monitors do this as well, at less cost. Check Amazon or Ebay for these.

It's quite easy to overload a single lead acid type battery. So first see if that's the problem, and check your voltage drops to see if there's a wiring issue. But chances are you just need more battery capacity if you're dropping below 12 volts.

[falfal3]

Sounds to me as though you need a "Solar Generator" such as a Jackery 500 or a Bluetty 1500 depending on the wattage you require for your, particular, needs. These divices allow you to plug device into shore power and maintain a charge until shore power is lost, all the while supplying AC power. Same as a upc. Hope this helps.

[BigFatGuy]

Originally Posted by Nic7320

Sounds like you have either insufficient battery for your needs

This is true. Give me a few years and $10,000, and I'll have this whole rig set up NICE... but, for now, I'm doing it piecemeal.