Inverters (12V to 120V - 240V) and Step-Up Transformers (120V to 240V)

[Philip]

I have had a 12-110V inverter in my van for a couple of years. It is a Traveller 3,000W Digital Power Inverter, sold at Tractor Supply for under $300.



Initially I bought it to use an electric pressure washer at the track (still need to think up a water tank for it!). It is not a pure but a modified sine wave inverter. It won't run my Nespresso machine.

It can charge a Redshift, but it takes a long time, possibly even longer than a 110V household power. I have been charging my MX with it between motos, but was only able to extend my practice day by maybe ~10 minutes. I also used it a few times while driving the van to/from the track.

The LED display shows only 550W when it runs, but the Kill-A-Watt Meter shows a more expected 1250W. I do not know who to believe. The van's engine has to be running, else the battery voltage drops too low in just 2-3 minutes.

Then, after buying a Redshift, I found a bunch of 12-220V inverters on a Chinese website with a reputable sounding name Banggood.com. This is a UKC® 12V To 220V 4000W Modified Sine Wave Inverter. For just $89 delivered from China to my door it was worth a try.



It draws too much current and shuts itself off in under a minute. I can get just a few seconds of "rapid" 220V charging out of it, LOL!

It might work if I get a (much) bigger van's alternator. Stock alternators for my van are rated at only 180 - 220 Amps. Or I could add several 12V batteries and keep them charged. Build my own Tesla Powerwall.

Does anyone have any practical experience with such inverter setups?

 

[WoodsWeapon]

Theres an Alta rep in Texas by the username Zoom at VitalMX that said he had a 220V inverter installed in his van. i inquired about details, but he never replied back.

 

[rayivers]

Right now the only inverter I own is a Sola 4kW online UPS (four 12V lead-acid batteries) for my computers, but I've owned several over the years & in my job I've worked on much larger ones (100kW) so the concept is familiar. A high-voltage, high-power inverter setup is one of the most demanding installations one can make in a car/truck, and if it's not correct from source to load it'll never work right, and may well burn stuff up (including your Alta charger).

As you know, even your smaller 3kW inverter will attempt to pull well over 200 amps continuously from your alternator and/or battery. This kind of current draw requires very careful attention to cable sizing & length, and all connections (under these kinds of current conditions I've seen thick steel spade connectors melt, and thin-strand copper wire burst into flame). You might want to throw a voltmeter across the DC input terminals with the inverter under load - I think you'll be quite surprised, and will get a much better idea of the arc-welder type loading these things can represent. I wouldn't be at all surprised to see < 6VDC right before the 4kW unit tripped out.

If you had a 250-300A alternator with 4/0 copper running direct to the inverter (all connections near-zero resistance) while the engine ran at sufficient rpm for full output, it should work fine as long as those conditions were maintained. If you then pull over and turn off the engine, the inverter will continue to try to pull 200A+ from the battery through the OEM charging cables, probably sized for 40A max.

Hopefully this is helpful... I don't mean to criticize your installation (which I know nothing about), just trying to bring 35 years of working on high-power AC/DC/RF/microwave equipment into the discussion. If you go way huge with cable, take the time to make every connection as perfect as possible & to the proper circuit point, supply more continuous power than your device can possibly use, and assume every active device may get stinking hot at some point, you should be good to go.

One other thing... a good step-up transformer can be an excellent way to turn 120VAC into 240VAC. I'd personally rather double the 120V output of a good-quality name brand inverter using a transformer, than use a questionable HV inverter.

Ray

 

[Fod]

I have had a 12-110V inverter in my van for a couple of years. It is a Traveller 3,000W Digital Power Inverter, sold at Tractor Supply for under $300.

View attachment 336

Initially I bought it to use an electric pressure washer at the track (still need to think up a water tank for it!). It is not a pure but a modified sine wave inverter. It won't run my Nespresso machine.

It can charge a Redshift, but it takes a long time, possibly even longer than a 110V household power. I have been charging my MX with it between motos, but was only able to extend my practice day by maybe ~10 minutes. I also used it a few times while driving the van to/from the track.

The LED display shows only 550W when it runs, but the Kill-A-Watt Meter shows a more expected 1250W. I do not know who to believe. The van's engine has to be running, else the battery voltage drops too low in just 2-3 minutes.

Then, after buying a Redshift, I found a bunch of 12-220V inverters on a Chinese website with a reputable sounding name Banggood.com. This is a UKC® 12V To 220V 4000W Modified Sine Wave Inverter. For just $89 delivered from China to my door it was worth a try.

View attachment 337

It draws too much current and shuts itself off in under a minute. I can get just a few seconds of "rapid" 220V charging out of it, LOL!

It might work if I get a (much) bigger van's alternator. Stock alternators for my van are rated at only 180 - 220 Amps. Or I could add several 12V batteries and keep them charged. Build my own Tesla Powerwall.

Does anyone have any practical experience with such inverter setups?

So your saying the reputable Banggood inverter is too manly for your van!

 

[Philip]

So your saying the reputable Banggood inverter is too manly for your van!

 

[snydes]

One other thing... a good step-up transformer can be an excellent way to turn 120VAC into 240VAC. I'd personally rather double the 120V output of a good-quality name brand inverter using a transformer, than use a questionable HV inverter.

Ray

Ray,
Can I use a step up transformer to get 240v from my Onan 4000 watt 120v generator that’s in my RV? I’ll be taking the Alta with me on some upcoming trips and I’d love to be able to charge on 240 without having to drag another generator with me.

 

[Fod]

View attachment 338

Yes, I'm saying what I said your saying when I said it. ....I think

 

[rayivers]

Can I use a step up transformer to get 240v from my Onan 4000 watt 120v generator that’s in my RV?

Yes - but Onans are pretty high-end generators, are you sure there's no 240V tap on the output connection terminal strip? You might get lucky and only have to change a jumper or two, and maybe the charger plug.

Ray

 

[snydes]

Yes - but Onans are pretty high-end generators, are you sure there's no 240V tap on the output connection terminal strip? You might get lucky and only have to change a jumper or two, and maybe the charger plug.

Ray

I haven't myself looked, but I was following some discussion on the same unit where someone else confirmed there was no 240v tap. I should look myself to be sure. I had some electrical engineers I know do the math as to what step-up transformer it would take but in the end it works out to be too scary close to my generators 33amp rating, and I don't want to risk smoking something when I'm away from home and need it for the important stuff. It's unfortunately looking like either dragging a second generator with just for charging or settling for charging on 120v.

 

[rayivers]

I understand completely. I've looked for 120V/240V brand-name enclosed 5kVA step-up transformers, but all I find online are either cheap eBay 'voltage converter' black boxes that I'd never recommend unless I'd bought, thoroughly checked out, & used one hard for a while, or $$ commercial-grade hardwired beasts.

It would be cool to find an Onan service manual / wiring diagram online for your generator model. Some of these heavy-duty units use multiple output windings for use in various USA/EU/etc. markets & power levels.

Ray

 

[snydes]

I’ll have to look into that more, it certainly would be ideal if it could be made to put out 240v.

 

[Kurlon]

Step up transformers are REALLY simple hardware, the eBay ones don't scare me based on cost.

 

[rayivers]

Step up transformers are REALLY simple hardware

Agreed - just metal & insulation ! Designing & building a safe, reliable, cool-running, reasonably-priced 5kW unit is not simple though, which is why quality ones cost so much.

the eBay ones don't scare me based on cost.

Me neither - they scare me because of all the Chinese-made power supplies I've opened up to find glop-coated undersize POS transformers, mostly either buzzing or burned up. Maybe there are some decent ones on eBay, but no way I'd just throw one across a high-power generator output without a careful going over first (just my $.02).

Ray

 

[Philip]

Not all inverters are created equal. Even though all of them are made in China.

Left to right...

Traveller, Tractor Supply
US market
3000W
12V - 110V
Modified sine wave
6 lbs
$299

UKC, Banggood.com
Chinese market
4000W
12V - 220V
Modified sine wave
3 lbs
$89

AIMS Power, Amazon.com
US market
4000W
12V - 110V - 240V
Pure sine wave
65 lbs
$899

Fox Instinct boot
Size 10 (11 nominal)
$599
(shown here for size reference)

 

[rayivers]

That AIMS unit looks pretty impressive - maybe it could serve as a seat to put your boots on too. Seriously... does it have a CE or UL rating? If so, I'd consider it 100% trustworthy to output a solid 4kW, fwiw.

 

[Philip]

Not sure about CE and UL certifications. There is an ISO9001 stickler and another small one with a royal crown.

I have added the weights, check them out. I am not convinced that making this thing so huge and heavy was necessary.

 

[Philip]

I stuffed the new inverter under the driver's seat. The previous one was held there securely by rubber bands. The new one will need to have two 1/8" thick steel straps to hold it in place safely. I do not want my feet crushed by it in case of an accident.