DC -> AC inverter, UPS questions/discussion

I doubt it.

Bob Wilson

 

Techntrek:

Love your your posts over at Solar. Very nice work there. The only thing I would have done differently is instead of using crimp connectors on the primary white & black cables connected to the Hybrid battery relay I would have soldered those.

Here's how: Strip the wire back alot. With a map gas torch heat up small concentrated area of wire end to tin.
Tin that area away from rubber coating. Your going to heat shrink it when done so don't need that coating to reach connector pretty.
.
With regular pcb solder tin the wire. You have to create double or triple thick strands of solder as regular pcb solder is too thin. Twist strands together. Find the ring connector that will fit snugly on your now tinned end. Don't have to mate it up to the rubber wire coating as you will use heatshrink to the ring when done. With ring on heat up the ring. Add more solder.
Wipe off excess with wet towel while solder is hot. Shrink it up. With a little trial & error you can make a perfect end
that will pull max current without failing.

Crimps work poorly under high current in a car as there's movement of the wire due to its weight and a tiny bit of loose creates heat and will start to arc or smoke. That intermittent arc can damage your really expensive Inverter. Crimps aren't to bad for a car stereo at the car battery as you can monitor the crimp for issues but buried in the Hybrid can would worry me. I can't watch it.

Other than this tiny detail your awesome.

 

You need to account for startup surge. That will be several thousand watts for your typical fridge, so its unlikely even a 1000 watt continuous inverter will start one.

 

Thanks. I had a good time doing it - and using it when necessary. Even my wife is proud to tell people that I can run the house from her Prius.

My worry with solder in this case is fragility over time due to vibration, and possibly loss of a good solder joint due to heat. It isn't too high of an amperage, considering a 3000 watt load at 200 volts is only 15 amps.

 

Nice stuff Tech.

There's so much solder on the wire and lug it melts really nice. Makes a perfect lug if done right. Try it next time.
It will pull max current.

 

Picked up a nice portable AC: SoleusAir, model SG-PAC-08E4 for $300 at Sears:

• 8,000 BTU / 760 W (5.9 A) = EER ~10.5
• 38.4 pints/day

My wife and I both noticed the unit is more effective and quieter than the older units we had been using. The only draw back is the small condensate tank. But this is not a problem for us as I've added a drain hose routed outside.

We had been using two older, portable AC units that in the past two months 'gave up the ghost.' They drew too much power for our Prius inverters and had with significantly higher noise:

• 12000 BTU / 1300 W (11.3A) = 9.23 EER
• 12000 BTU / 1240 W (10.5A) = 9.7 EER

I have not opened the unit up to check but I am hoping the condensate first passes over the condenser coils (the part that gets hot) before the catch basin. Regardless, it is an especially well performing unit and I'll probably pickup a second one for the bedroom.

We live in North Alabama where it gets hot in the summer. When night temperatures are in the 80s, air conditioning is critical to getting a good night's sleep. It is nice to have units that can operate off our our Prius inverters.

Now to dispose of two, old, possibly not repairable, portable AC units. There is a used appliance shop I'll check with on Monday. Otherwise, off to the Huntsville waste disposal facility. They have one Saturday each month for 'hazardous waste' and these are close enough. I'm not going to vent the old refrigerant.

Bob Wilson

 

Thanks Bob was looking for one for my bedroom also when that dreaded day comes.

That's a pretty good BTU. How big is your inverter to be able to start that unit up?

 

We have two:

• 1kw/1.2kw - modified sine-wave
• 1.5kw/3kw - sine-wave

I'll test both when the cooler weather arrives . . . we bought the extended warranty.

Bob Wilson

 

Yes please post.

 

Good deal, so you can run it when the utility service is down and still get a good night's sleep. So many times you hear of people hating life because a hurricane just rolled through and now its hot and sticky with no way to cool a single room. I bought a 8000 BTU window unit and will keep it even if I don't need it just for that reason.

 

Yes that's my reason. It would be impossible to sleep at night without ac. Its really hot this year like 80 at night.
I would like to buy the Liebert too. That's the smart way.

 

New info - additional brands/models of UPS, and an inverter, that are compatible with the Prius traction battery. I added the info to the end of the thread linked in my signature.

 

Massive ice storm this morning, tons of trees and limbs down, lost power at 2:21 am and switched over from my big generator to my Prius around 6. I would bet it will be days before we get power back this time. Have everything running - lights, TVs, DVRs, furnace and wood stove fan. Go Prius Power!

 

Awesome stuff Tech. Fill in where you live.

 

Will update it shortly. I'm in MD.

 

The Best 12V Power Inverters for DIY Campervans and RVs

 

Exeltech of Fort Worth TX makes excellent PSW inverters. Great gear, excellent support, and all made in the USA. Not cheap but I've found them to be worth it.

You might consider installing a transfer switch such as this one. You get to pick up to 8 breakers on your main panel and adapt them so that they can be fed power from a standby source. The switches have 3 stops- mains, off, standby. These kits are primarily intended for use with generators but they aren't picky about where the electricity comes from. It would provide a safe and easy method for switching back and forth if you predict a lot of blackouts.

Note that the one I linked is set up for split-phase 240VAC. If you were to use a common inverter, you would only be able to power one leg of this device, meaning only half of the 8 transfer switches would be active. There are several manufacturers and different styles, you could probably find one better suited for basic 120V. I just happened to link the first one I saw.

I've been using inverters to power an off-grid vacation cottage for decades now. Back in the day, the modified sinewave ones were looked down upon because electronics had a very hard time with the modified sine characteristics. Today it's different. Modern computers, TVs and household electronics are much more resilient to bad power. On the other hand electric motors (fans, fridges) are typically made a bit lighter and cheaper than they once were, and they always struggled with MSW power. Symptoms vary- some don't hit full RPM, some give an annoying hum noise.

 

It is rare for me to dump on consumer goods of Asian manufacture, but here I will. Personal direct experience with a few inverters from Taiwan and 'the mainland' has been problematic. Requiring cleaning up soldered connections, shielding adjacent points that should be no where near each other, and removing stray solder blobs, nuts and washers.

Particularly for in-vehicle use (high vibration environment), defects like that can be serious. Unless one opens newly purchased gadget and can recognize and correct defects, an apparent bargain may turn out otherwise. Not speaking as an electrical expert, but building a kit inverter decades ago gave me a sense of what to watch out for.

Exceltech deserves its good reputation and I have no doubt other manufacturers are their equal. This simply does not seem like a good category for bargain buys.

Perhaps for stationary applications, lower standards would apply. Against that is possibility that equipment may be operated in a location where no one is present for long periods.

 

US Consulates & embassies abroad buy power from the local utilities. They use it to run some large battery chargers. The battery chargers put the power in large battery banks. The batteries feed racks of inverters supplying familiar red white & blue 120v 60hz power within the building/compound.

Exeltech makes those inverters.