How to - Export 12v DC to 120vAC power from LVB connection points

[bshaw]

You could get a spare female plug end, and not add any wiring, to use it as a 'prong cover' when you are not backfeeding.

Good call, I like this idea. I just noticed that the 30A/120V cord I purchased to make this connection shipped with a plastic protector on the male end. I will keep this piece and store it with my modified cable.

The 'terminal' output on these inverters is rated for 30a, the outlets are 15a.... so for backfeeding the house you should use the terminal connection from the Inverter for backfeed to house.

Yes, I was planning to wire up to the terminal connection for 30A.

You COULD get an oven or dryer 240v 'pigtail' and hard wire it.... and avoid the work of taking apart the 240v male if you combine the L1 L2 at the terminal end. You will not be able to run any 240 loads, because the L1/L2 will be in-phase.... but it would energize both legs for 120 loads and you wouldn't have to take apart the 240v M plug end to add a jumper.

I have a 240 plug that I will jump across the two hots when modifying the cable. Since my cable is 120V, it only has hot/neutral/ground, so combining on the terminal is not an option.

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[dtbaker61]

Yes, I was planning to wire up to the terminal connection for 30A.

I have a 240 plug that I will jump across the two hots when modifying the cable. Since my cable is 120V, it only has hot/neutral/ground, so combining on the terminal is not an option.

Yes, if you are using a nice fat heavy duty cord rated for 30a at 120v (hopefully 10awg fine stranded wire) then you will have to jumper at the 240 plug end.

I had mention the other possibility in case you were going to just buy a pre-made 240v pigtail such as one made for an oven or clothes dryer. They usually are 6' long or less, so that would only be an option if you are setting your inverter up less than 6' from your car charger (NEMA 14-50) outlet.

 

[ericNdfw]

Ok, got time to test out the inverter this afternoon. (2500w 12v connected straight to the jumper posts on the Mach-E) I have 2 refrigerato/freezers and one full size freezer.

The main fridge in our kitchen worked great and was surprisingly efficient given that it’s the largest. (27 cu ft french door Samsung with bottom freezer) according to my meter, it had relatively little startup spike and ran at about 130w continuous (5w when not running)

The full size freezer acted similarly.

The smaller(and much older)fridge, however, spikes to over 560w and then runs between about 140w and 250w. When it initially starts, the inverter beeps and AC voltage momentarily drops into double digits but recovers to 122 within a second or two. Is that “normal”? I’m guessing the car's DCDC unit is having to react to the sudden demand and that takes a moment.

attached video of that last behavior

 

[dtbaker61]

The smaller(and much older)fridge, however, spikes to over 560w and then runs between about 140w and 250w. When it initially starts, the inverter beeps and AC voltage momentarily drops into double digits but recovers to 122 within a second or two. Is that “normal”? I’m guessing the car's DCDC unit is having to react to the sudden demand and that takes a moment.

old refrig are pigs.... it will save you money to get rid of it and buy a new EnergyStar one if your really need the space.

If you had your MME 'on', you would likely not have seen the voltage drop as the DCDC would have been keeping the connection at 14+ volts. When it is 'off' it can take a 'low' voltage about 12.0 volts to wake up the dcdc.

 

[ericNdfw]

If you had your MME 'on', you would likely not have seen the voltage drop as the DCDC would have been keeping the connection at 14+ volts. When it is 'off' it can take a 'low' voltage about 12.0 volts to wake up the dcdc.

It was on.

 

[dtbaker61]

It was on.

aha, then you were seeing the voltage sag from the inrush current of the crappy old refrigerator motor. New ones have 'soft start'. This is also a good reason to have a 2500-3000 watt inverter even though the continuous output we expect to run the house are less than 500 watts.

 

[ericNdfw]

So I put together a pair of Anderson connectors to the ends of the wires that came with the inverter and was planning to attach to the battery posts yesterday but it looks like the only way to get to the positive post is to remove the entire frunk tub

Before I go through all of that trouble, has anyone else here found a better spot to connect a positive cable to? Like maybe rigging up something that attaches permanently the positive jumper cable post?

 

[dtbaker61]

So I put together a pair of Anderson connectors to the ends of the wires that came with the inverter and was planning to attach to the battery posts yesterday but it looks like the only way to get to the positive post is to remove the entire frunk tub

Before I go through all of that trouble, has anyone else here found a better spot to connect a positive cable to? Like maybe rigging up something that attaches permanently the positive jumper cable post?

you should connect to the 12v 'connection points', not the actual battery terminals. They can be accessed by removing the rear and driver's side 'beauty covers'. I don't think you'll have to remove the entire tub..... but you will have to cut a hole in the side cover big enough to access/store the Anderson that you bolt to the connection points.

 

[ericNdfw]

you should connect to the 12v 'connection points', not the actual battery terminals. They can be accessed by removing the rear and driver's side 'beauty covers'. I don't think you'll have to remove the entire tub..... but you will have to cut a hole in the side cover big enough to access/store the Anderson that you bolt to the connection points.

That would be optimal and is what I'm wanting to do. What I don't see is a clear place to attach the round terminals my cables already have. Especially for the positive post: there doesn't appear to be any kind of place to permanently secure it to. I'm wondering if anyone has fabricated one or found a better place to attach it. (I was asking about the battery posts because I don't see a way to attach like this elsewhere)

 

[dtbaker61]

That would be optimal and is what I'm wanting to do. What I don't see is a clear place to attach the round terminals my cables already have. Especially for the positive post: there doesn't appear to be any kind of place to permanently secure it to. I'm wondering if anyone has fabricated one or found a better place to attach it. (I was asking about the battery posts because I don't see a way to attach like this elsewhere)

I will be doing something similar soon, but haven't dug into it yet....

The negative 'connection post' looks super easy.... threaded and the D-ring should slip right on with a second nut to hold it in place.

The positive 'connection point' has the red plastic cover on it, and is a copper 'tab' that I was planning on drilling a hole thru if there wasn't one already there to bolt the + d-ring on for a better connection than jumper alligator clip for higher current export.

It might require removing the Frunk Tub to get a good view and access the positive connection tab, or you might be able to get it done just by removing the side beauty cover.

I will probably remove the tub because I want to add another access to the HV disconnect, and the fuse box itself in case I ever need to get into it.

 

[phidauex]

I'm going to be doing this shortly, so buying a few parts. Here is the direction I'm going in case anyone is curious.

I have a AIMS Power 12V, 1250W sine wave inverter/charger from a previous project. It is a nice unit, true sine wave, and the 1250W rating is true continuous, it can surge to 3750W for 20 seconds, though I do not expect to subject it to anything like that. The inputs are just two ~5/16 studs, with a built-in GFCI outlet on the side. It is small enough to fit down in the frunk tub.

To connect, I'm getting a set of Anderson SB120 cables, one for the inverter, and one for the car. I'll permanently mount one set in the car, to the LVB points along the drivers side. I'm getting a surface-mount bulkhead connector which I'll mount in the wall of the frunk, as high as I can. That way I can just drop the inverter into the frunk, connect the cable to the bulkhead, and be off and running.

I'm also adding a 200A Class T fuse to the + connection, to provide some fast blow capability in case of a short. Class T fuses are nice for battery projects because they have blades with holes in them so you can bolt them right to the cable and make them part of the cable assembly. My tentative plan is to drill a hole in the positive spade, bolt the Class T fuse to it, and then bolt the cable to the fuse. Wrap the assembly in some silicon self-sealing tape for accidental short protection.

Here are my parts, about $100 + the inverter.

• AIMS Power 1250W inverter/charger: https://www.aimscorp.net/1250-watt-low-frequency-pure-sine-inverter-charger-12-vdc-to-120-vac.html
  • Honestly I wouldn't recommend this exact model if you are buying from scratch. The charger function, while I'll probably use it for FDRS programming and things, doesn't actually get you much in this case since this isn't a normal off-grid situation, and similarly the automatic transfer switch isn't very useful for a camping/intermittent backup situation. If you were shopping from scratch for a small camping/backup inverter, then I'd recommend something more like these:
  • 1000W, 12V sine wave: https://www.aimscorp.net/1000_Watt_Pure_Sine_Power_Inverter_12_Volt.html
  • 1500W, 12V sine wave: https://www.aimscorp.net/1500-Watt-Pure-Sine-Inverter.html
  • Important: If you are shopping for inverters, you get what you pay for, the cheaper the unit is, the more likely they are to be lying about the power quality, and lying about the power rating. Both of the above units have a 20 second surge to 2000W or 3000W respectively - if they were sold at Harbor Freight they would be marketing them as 2000W and 3000W inverters. So when shopping, make sure you are comparing apples to apples. You don't need to get AIMS, there are lots of good small inverters, but if the price seems to good - it is. Building a good inverter costs a little bit more money.
• Anderson SB120, 4 AWG cable kit - this eBay seller is selling kits with cable lengths I think will work well. They look like surplus from a floor polisher or something, but the price is much better than what you'd pay for a custom set, and they have nicely crimped lugs: https://www.ebay.com/itm/294687448798
  • This other ebay seller is selling SB175 kits made up with 2 AWG cable for a good price as an alternative: https://www.ebay.com/itm/254304445378
• Anderson SB120 bulkhead connection, from this Australian (ebay user jamdongear) who 3D prints them. Shnixky, and a reasonable price even including shipping from AU: https://www.ebay.com/itm/333846472563
  • If you went with an SB50 or SB175 cable kit, he sells a variety of bulkhead panels for those as well.
• Fuse, Mersen A3T200, rated for 160VDC, and 200A, fast blow type to protect semiconductors: https://www.ebay.com/itm/154307732927

I'll post some pics when I get things together, and if I change the plan along the way (which is a virtual certainty).

 

[dtbaker61]

I'm going to be doing this shortly, so buying a few parts. Here is the direction I'm going in case anyone is curious.

I have a AIMS Power 12V, 1250W sine wave inverter/charger from a previous project. It is a nice unit, true sine wave, and the 1250W rating is true continuous, it can surge to 3750W for 20 seconds, though I do not expect to subject it to anything like that. The inputs are just two ~5/16 studs, with a built-in GFCI outlet on the side. It is small enough to fit down in the frunk tub.

To connect, I'm getting a set of Anderson SB120 cables, one for the inverter, and one for the car. I'll permanently mount one set in the car, to the LVB points along the drivers side. I'm getting a surface-mount bulkhead connector which I'll mount in the wall of the frunk, as high as I can. That way I can just drop the inverter into the frunk, connect the cable to the bulkhead, and be off and running.

I'm also adding a 200A Class T fuse to the + connection, to provide some fast blow capability in case of a short. Class T fuses are nice for battery projects because they have blades with holes in them so you can bolt them right to the cable and make them part of the cable assembly. My tentative plan is to drill a hole in the positive spade, bolt the Class T fuse to it, and then bolt the cable to the fuse. Wrap the assembly in some silicon self-sealing tape for accidental short protection.

Here are my parts, about $100 + the inverter.

• AIMS Power 1250W inverter/charger: https://www.aimscorp.net/1250-watt-low-frequency-pure-sine-inverter-charger-12-vdc-to-120-vac.html
  • Honestly I wouldn't recommend this exact model if you are buying from scratch. The charger function, while I'll probably use it for FDRS programming and things, doesn't actually get you much in this case since this isn't a normal off-grid situation, and similarly the automatic transfer switch isn't very useful for a camping/intermittent backup situation. If you were shopping from scratch for a small camping/backup inverter, then I'd recommend something more like these:
  • 1000W, 12V sine wave: https://www.aimscorp.net/1000_Watt_Pure_Sine_Power_Inverter_12_Volt.html
  • 1500W, 12V sine wave: https://www.aimscorp.net/1500-Watt-Pure-Sine-Inverter.html
  • Important: If you are shopping for inverters, you get what you pay for, the cheaper the unit is, the more likely they are to be lying about the power quality, and lying about the power rating. Both of the above units have a 20 second surge to 2000W or 3000W respectively - if they were sold at Harbor Freight they would be marketing them as 2000W and 3000W inverters. So when shopping, make sure you are comparing apples to apples. You don't need to get AIMS, there are lots of good small inverters, but if the price seems to good - it is. Building a good inverter costs a little bit more money.
• Anderson SB120, 4 AWG cable kit - this eBay seller is selling kits with cable lengths I think will work well. They look like surplus from a floor polisher or something, but the price is much better than what you'd pay for a custom set, and they have nicely crimped lugs: https://www.ebay.com/itm/294687448798
  • This other ebay seller is selling SB175 kits made up with 2 AWG cable for a good price as an alternative: https://www.ebay.com/itm/254304445378
• Anderson SB120 bulkhead connection, from this Australian (ebay user jamdongear) who 3D prints them. Shnixky, and a reasonable price even including shipping from AU: https://www.ebay.com/itm/333846472563
  • If you went with an SB50 or SB175 cable kit, he sells a variety of bulkhead panels for those as well.
• Fuse, Mersen A3T200, rated for 160VDC, and 200A, fast blow type to protect semiconductors: https://www.ebay.com/itm/154307732927

I'll post some pics when I get things together, and if I change the plan along the way (which is a virtual certainty).

all good stuff. AIMs are solid, and do have nice sine-wave output.... as noted the passthru AC and charge funtionality of that particular unit really isn't needed in this application. A unit with similar output without the built in charger and transfer switch will be several hundred dollars less expensive, and a bit smaller.

 

[phidauex]

all good stuff. AIMs are solid, and do have nice sine-wave output.... as noted the passthru AC and charge funtionality of that particular unit really isn't needed in this application. A unit with similar output without the built in charger and transfer switch will be several hundred dollars less expensive, and a bit smaller.

Indeed! I'm just using this one because I already had it from another project, but added links to a few "lighter" AIMS units that lack the charger and pass-through functions.

 

[GrumblesTheDog]

Any chance anyone has experience with this unit? (I know, I know, Harbor Freight/Hazard Fraught etc).
https://www.harborfreight.com/autom...peak-pure-sine-wave-power-inverter-57272.html

There's a pretty good YouTube video looking at power quality too, which is swaying me towards it:



We are being told to expect a loss of power in OH/KY thanks to the impending ice storm, and I only now thought about this. I won't use this for huge loads, and won't really need it regularly, this is more an emergency backup arrangement; we have a reasonably modern fridge, NG heat and water. Hopefully it won't burn my house down/toast my car?

 

[dtbaker61]

Any chance anyone has experience with this unit? (I know, I know, Harbor Freight/Hazard Fraught etc).
https://www.harborfreight.com/autom...peak-pure-sine-wave-power-inverter-57272.html

There's a pretty good YouTube video looking at power quality too, which is swaying me towards it:



We are being told to expect a loss of power in OH/KY thanks to the impending ice storm, and I only now thought about this. I won't use this for huge loads, and won't really need it regularly, this is more an emergency backup arrangement; we have a reasonably modern fridge, NG heat and water. Hopefully it won't burn my house down/toast my car?

It looks 'decent'.... but just has the two 15amp outlets for extension cords... kind of a bitch to run a cord from garage to frig. you can solve by making two male-male adaptors and backfeeding via two cords to *nearest* outlet on each 'leg' of your service; after turning off MAIN and all 220 circuits of course.

I prefer to use pure-sine inverters that have both outlets and a 30amp 'terminal block' so I can make a single adaptor cord to backfeed thru a NEMA 14-50 outlet in garage. The adaptor cord can be fabricated with both L1 and L2 energized by the terminal block 120v. Everything will be energized, but in-phase, so all 220v load circuits won't work... but should be turned OFF regardless.

something like this also for $300 or so via amazon
https://www.amazon.com/Inverter-2500W-Invert-Converter-System/dp/B07PLRCH61?th=1

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