Weird issue possibly related to PF?

[dborn]

Hi all,
I have a basic understanding of electricity (volts, watts amps, etc) but I need your help in solving an issue I don't understand.

I bought a kit from evextend.com that includes a split-phase 24v inverter in the basement with 6 x 12v 100Ah AGM (2S3P) batteries. It also comes with a specially modified 24v battery charger, 30A detuned to 26A to draw up to 1000W 120vac from a 12vdc to 120vac 1500W inverter connected to my EV (Chevy Bolt) in the garage. This charger is used to top up the downstairs batteries while the big inverter runs the house. I have built a 25' 12ga extension cord that i plug into the car inverter, connected to a round 120v generator plug that is connected to a wall socket and 20' lumex 12ga solid wire that runs through the walls down to where i connect to the 26A charger. When I start up the car inverter, it runs for about 5 minutes before tripping its short-circuit protection. If I replace this cable with a 100' 14ga garden extension, it runs fine for hours.
I tested my heavy extension connected to the house wire going to the basement with a heavier load (hair dryer on MAX) for 10+ minutes, connected to a wall outlet in the garage and all is good, so there is no short.
I'm at a loss to explain what is going on and more importantly, how can I fix this without having to run a stupid extension cord from the garage to the basement.

Thanks for any insight and sorry for the long winded explanation, just trying to paint a complete picture.

 

[hwy17]

My only theory is that the voltage drop on the long extension cord is causing the charger to reduce its output and therefore reducing the load.

When you say defined to 26A, is it adjustable? I would turn it down more to see if that helps.

 

[dborn]

Well, the manufacturer detuned it for me (Schauer) so I don't know if it's a potentiometer inside or if it's some firmware reprogramming.
The car inverter (true sinewave Windy Nation) does have a digital readout for watts and there is no difference between the two (950-1050). I did have the 26A charger earthed with the split-phase inverter to the house but I disconnected that bond and there was no difference.
I do want to run more tests (like powering the hairdryer from the car inverter instead of a wall outlet).
I spoke to Eric from EVExtend and he mentioned something about the Power Factor that might be tricking the car inverter about being in a short circuit situation... all of his supplied hardware works great, it's just my homemade cable to bring power down to the basement from the adjoining garage that is giving me issues.
Edit: I was standing by the 26A charger when the car inverter tripped and a second before it happened, the fan on the charger slowed down.

 

[dborn]

I pulled out my trusty Kill-A-Watt meter and compared the stats between the hair dryer which pulls 1250W and has a PF of 1.0 which means it pulls 1250VA. I connected it then to the 24V/26A charger topping up the split-phase inverter batteries (supplying no load since I didn't want to switch the house to the inverter). Although the number of watts supplied was fairly low, the PF was 0.6
So the 1000W pulled by the 24V/26A charger at full load converts to 1600VA (above the supposed 1500W/1500VA capacity of the 12V inverter?)

My next test will be to run the entire system powering the house and comparing the Kill-A-Watt numbers between my special-built power cord to the basement v.s. the lighter 100' garden extension and try to see why one setup fails and not the other.

 

[Supervstech]

I pulled out my trusty Kill-A-Watt meter and compared the stats between the hair dryer which pulls 1250W and has a PF of 1.0 which means it pulls 1250VA. I connected it then to the 24V/26A charger topping up the split-phase inverter batteries (supplying no load since I didn't want to switch the house to the inverter). Although the number of watts supplied was fairly low, the PF was 0.6
So the 1000W pulled by the 24V/26A charger at full load converts to 1600VA (above the supposed 1500W/1500VA capacity of the 12V inverter?)

My next test will be to run the entire system powering the house and comparing the Kill-A-Watt numbers between my special-built power cord to the basement v.s. the lighter 100' garden extension and try to see why one setup fails and not the other.

Is it possible you have the wires incorrect on the cord? A LOT of people think the hot wire goes to the large blade, and it does not.

Also, #12 can carry 2400W, easily, while #14 will limit to 1800, and 100’ would be a lot of voltage drop, preventing as much wattage from being drawn.

Sounds like a mix of a few factors though. .6PF and a strong cord equal more than the inverter can handle for long.

 

[hwy17]

I wonder if there's an obscure effect here where the charger is generating a big surge near the top of the sine wave as it's rectifier refills capacitors and this surge is actually tempered by the higher resistance longer extension cord.

I'm not sure if that even makes theoretical sense, but some sort of weird edge case sounds likely.

 

[dborn]

Is it possible you have the wires incorrect on the cord? A LOT of people think the hot wire goes to the large blade, and it does not.

Also, #12 can carry 2400W, easily, while #14 will limit to 1800, and 100’ would be a lot of voltage drop, preventing as much wattage from being drawn.

Sounds like a mix of a few factors though. .6PF and a strong cord equal more than the inverter can handle for long.

I'll double check but I'm fairly certain the cord has the right polarity all the way through.
The .6PF and strong/not too long cord is what I'm thinking too. I read somewhere (here?) that an inverter may be rated at 1500w but it really is able to supply 1500va. If that's the case, I'm asking 1667va from it (1000w / 0.6pf). The inverter has a watt display which hovers around 950-1050 with the charger plugged in.
I spoke with the inverter manufacturer's tech support and they think it should be able to supply the power and they asked many technical questions. I answered back and also tried to give a complete picture of the situation (all under 1000 words)
I'm trying to see from the charger manufacturer if I can dial it back a bit more (to keep it all at <= 1500va). I'm borderline able to use it with my special cord. I'm not too keen on running an extension cord through opened doors, going down stairs, etc.
My another option is possibly upgrading the 1500w inverter to a 2000w or even a 3000w unit. I'd rather not spend that extra $500 if I can avoid it though.

 

[dborn]

I wonder if there's an obscure effect here where the charger is generating a big surge near the top of the sine wave as it's rectifier refills capacitors and this surge is actually tempered by the higher resistance longer extension cord.

I'm not sure if that even makes theoretical sense, but some sort of weird edge case sounds likely.

If that's the case, I'm wondering if even increasing the inverter capacity might not cut it..?
Certainly looks like some sort of edge case. Just change a small parameter and it works or not.
I swapped my 0.6PF 1000w charger with a 1.0PF 1300w hair drier and all is fine too.

 

[hwy17]

If that's the case, I'm wondering if even increasing the inverter capacity might not cut it..?

12vdc to 120vac 1500W inverter connected to my EV (Chevy Bolt) in the garage

That one right? I think that should solve it. As long as the 12v supply doesn't then blow a fuse or something in turn.

 

[wpns]

Yeah, the impedance of the extension cord is moderating the PF, and reducing the current draw.

 

[time2roll]

Get a smaller pf corrected charger. Meanwell makes some good ones.

Yes I believe the power factor is an issue. Here is a quick read from Xantrex to help understand the increased apparent power required.
https://xantrex.com/library/inverte...inverter/power-factor-correction-white-paper/

 

[robbob2112]

Run a piece of 10/3 romex from your inverter to where the car charger is. Voltage drop and resistance are most likely causing the charger to switch to a lower charge rate.

For 26amps you need larger wire to avoid voltage drops.

I say 10/3 in case you ever want to run 240v down to there. Simpler than pulling it again and minimal cost delta. If you are absolutly 120% certain you aren't ever going to want 240v pull it anyway because you will change your mind. And if you don't do it remember me saying "I told you so" when you change your mind.

Otherwise pull 10/2 and be done with it. Extension cords of any type have no place in a permanent install.

 

[dborn]

That one right? I think that should solve it. As long as the 12v supply doesn't then blow a fuse or something in turn.

Exactly! The car's 12V system is capable of supplying up to 1600W until it starts discharging the battery, that's why I had the charger derated to 26A so it wouldn't draw much more than 1000W.

 

[dborn]

Thanks all for your responses!

Run a piece of 10/3 romex from your inverter to where the car charger is. Voltage drop and resistance are most likely causing the charger to switch to a lower charge rate.

For 26amps you need larger wire to avoid voltage drops.

I say 10/3 in case you ever want to run 240v down to there. Simpler than pulling it again and minimal cost delta. If you are absolutly 120% certain you aren't ever going to want 240v pull it anyway because you will change your mind. And if you don't do it remember me saying "I told you so" when you change your mind.

Otherwise pull 10/2 and be done with it. Extension cords of any type have no place in a permanent install.

I'm already using 12/2 romex (not lumex, sorry) wouldn't that make the problem even more apparent?
The 26amps is at 24volts so this only amounts to 8.5amps at 120volts.
The only extension cord I use is from the car to the wall closest to the house (about 25') after that, it's all proper cabling and outlets.
I'm pretty sure *I* would never need more that 120volts and since I plan on moving out in the next 5-10 years (when I retire), the next owner wouldn't know you told me so! ;-)
Seriously though, thanks for your insight, I appreciate it.

 

[dborn]

Yeah, the impedance of the extension cord is moderating the PF, and reducing the current draw.

Get a smaller pf corrected charger. Meanwell makes some good ones.

Yes I believe the power factor is an issue. Here is a quick read from Xantrex to help understand the increased apparent power required.
https://xantrex.com/library/inverte...inverter/power-factor-correction-white-paper/

Thanks for the link, I will read it.
I've already been in touch with the supplier of the complete kit (evextend) and he's confirmed that this can be an issue that some get. We're looking into replacing and/or upgrading the inverter to avoid this issue. I don't really want to get a smaller charger if I can avoid it, as this would limit my use of the whole-house inverter since it would also limit how much power I can get out of the car's traction battery to put back into the house batteries.