30 amp variac instead of an autoformer?

Hi greenrv,

My inverter is capable of 23.3 amps (3000 watts continuous) @ 120 volts. I've seen it draw 242 amps @ 12 volts.

As far as wattage goes, I've seen the air conditioner drawing 1900. Add the fridge @ 325 and at 105 volts that's about 22 amps.

When I saw IOTA I thought of a converter--not a power supply.

I just looked at bestconverters and the IOTA goes up to 90 amps. Even two would only give me 190 of those 242 amps. Cost is 337 each plus the cost of a parallel kit @ $23.10. This is more than an autoformer.

Input voltage is listed as a disappointing 108 to 132 volts.

I only want to support the voltage when on shore power--particularly at campgrounds.

When I had the Cobra MSW inverter I often used double conversion, especially when there was only a 15 amp shore supply. However, I did not run the roof air on that inverter.

greenrvgreen wrote:


The reason I specified the Iota DLS is that it will provide continuous current at its rating virtually indefinitely. It is a POWER SUPPLY with (mediocre) multi-stage charging capabilities. Therefore it is perfect for this task.

With a $25 pendant you can link two similar DLS units and double your amperage. If you are on a 30A shore connection that is showing 90 volts (normally unusable), with line losses in the 30% range you will have perfect power from your inverter, perfectly protected. No autoformer or variac can do this.

If your inverter is capable of providing 30 amps, then at maximum draw your battery depletion rate would be ~8A (AC). Say you have a 300ah draw limit from you bank, that would be three hours.

But how often do we pull 22 amps? And how many people have an inverter capable of providing that? The realistic scenario is that your draw from inverter will never exceed your charge from the Iota, and you can continue for the entirety of your stay at the campground. I've done it and it works amazingly well!

Even better, you can add another, external charger powered by a gennie. During periods of heavy inverting, ANY charge voltage will contribute 100% of its amps to the battery.

Yeah you brought up The Perfect Point. Make your own UPS. And as a bonus the product is *clean*

Tuna--

The reason I specified the Iota DLS is that it will provide continuous current at its rating virtually indefinitely. It is a POWER SUPPLY with (mediocre) multi-stage charging capabilities. Therefore it is perfect for this task.

With a $25 pendant you can link two similar DLS units and double your amperage. If you are on a 30A shore connection that is showing 90 volts (normally unusable), with line losses in the 30% range you will have perfect power from your inverter, perfectly protected. No autoformer or variac can do this.

If your inverter is capable of providing 30 amps, then at maximum draw your battery depletion rate would be ~8A (AC). Say you have a 300ah draw limit from you bank, that would be three hours.

But how often do we pull 22 amps? And how many people have an inverter capable of providing that? The realistic scenario is that your draw from inverter will never exceed your charge from the Iota, and you can continue for the entirety of your stay at the campground. I've done it and it works amazingly well!

Even better, you can add another, external charger powered by a gennie. During periods of heavy inverting, ANY charge voltage will contribute 100% of its amps to the battery.

MEXICOWANDERER wrote:
...
My hawg will outperform the Furman. The 267 is a different range the 240 range not the 120 range! But the efficiency trumps my Sola so bad it isn't funny.

It will auto choose the range- so it is fully automatic. In reality it's a pretty specialized piece for the pro audio industry, with special emphasis put on clean power. The 240 vac range makes it easier for international tours to use local mains power without going through all of the equipment to switch the power supplies.

Hi Mex,

How is your Spanish?

http://www.reguladoresyups.com/

MEXICOWANDERER wrote:
Wish I could find the name of that +20% auto booster from Mexico I listed on this forum 5-years ago for Don. We talked about it.

It will take 50 volts and boost it to 60. More rationally, 100 volts and boost it automatically to 120. A good unit and inexpensive.

You want expensive? My SOLA is a -40% to +40% voltage correction device. 30 amperes 120vac. You do not want to know the price. It eats one hundred four watts, just sitting there, grinning.

Heck, you want expensive, look at the Furman AR Pro- will take anything between 80 and 267 volts and put out 120 vac +-4%. 97% efficiency...

Oh yeah? Well my dad can beat up your dad

Actually, :)

Thank you for that link. I'm going to download it and save it. Man, those are impressive numbers! My Sola goes off track at 62 volts (118 output). But the sucker is a real red-headed stepchild when it comes to efficiency. Oh well, I paid seventy-five dollars each for 2 of them in Santee, CA. in 1986. When I sell my six kilos of plutonium I'll be sure to consider it.

EDIT EDIT EDIT

My hawg will outperform the Furman. The 267 is a different range the 240 range not the 120 range! But the efficiency trumps my Sola so bad it isn't funny.

Hi green,

I used to do double conversion all the time using a Cobra 2500 watt stand alone inverter. However when I tried that with the Magnum 3000 watt the reverse polarity fuses on my 40 amp PD converter went to burnt fuse heaven IMMEDIATELY.

It is true that I was doing so with 10 year old marine batteries that were on their last legs--but I don't think IOTA would fair any better under a load of 120 amps.

The other issue is even if the IOTA was pumping out 80 amps there would be 40 being supplied from the battery bank. I have 556 (/2 = 278) which means after 6 or 7 hours I'd have to stop using double conversion.

greenrvgreen wrote:
Tuna, forgive me as I briefly give my broken record another spin:

Anyone with a decent inverter and batteries has 90% of what they need to cure any power issue short of a complete loss. Buy an Iota DLS charger and use an aux hookup instead of your shore power. Then charge with the Iota while inverting for your AC.

The Iota will chug along happily anywhere from 80 volts to 130 volts. I said EIGHTY volts. All that an Autoformer can do is take moderately good voltage (104v+) and turn it into perfect voltage. Below 104v it's just going to shut your power off. Your AC isn't going to have any issue with 104v, it's 90 v that it needs help with!

$4,000? I would sooner have a universal voltage battery charger and large inverter. Some battery in the middle as a buffer.

Heck, you want expensive, look at the Furman AR Pro- will take anything between 80 and 267 volts and put out 120 vac +-4%. 97% efficiency...

The AR-PRO uses a design based on a 25-tap toroidal autoformer. The toroidal design assures minimal leakage of stray magnetic fields and a highly efficient, compact package. The AR-PRO's circuitry monitors the incoming line voltage with each cycle. If a voltage change requires that a different tap be selected, the new tap is electronically switched in precisely at the zero-crossing, to avoid distorting the AC waveform. If necessary, the AR-PRO can switch taps as often as once each cycle.

$4,000. 50 lbs, rack mount. I've used the 2400 watt model a bunch for pro audio, never used the 3600 watt model though.

Wish I could find the name of that +20% auto booster from Mexico I listed on this forum 5-years ago for Don. We talked about it.

It will take 50 volts and boost it to 60. More rationally, 100 volts and boost it automatically to 120. A good unit and inexpensive.

You want expensive? My SOLA is a -40% to +40% voltage correction device. 30 amperes 120vac. You do not want to know the price. It eats one hundred four watts, just sitting there, grinning.