MASTER THREAD: Powering house or other things with Model 3

[n2mb_racing]

70 degrees C at 90 amps continuous:

But yeah, if you want to pull the max current with minimal loss, you should use the relay precharge circuit shown earlier. For 400-600W, the XT90 or QS8 should be fine.

 

[PhysicsGuy]

Not sure what you mean. We run them on ebikes with soldered wires and the solder does not melt at those currents. But, if you want to push high currents, use the QS8.

I am not sure I know as much as you guys, but just off the top of my head I think e-bikes are typically 36 volts minimum (with 10 cells in series) and with 5 to 8 parallel channels can draw maybe 50 or 60 amps at close to peak throttle. I think that the more powerful bikes run around 54 volts. And, as Cali84 mentioned, those peak currents are somewhat transient for e-bikes and typical currents may be more in the 10 to 20 amp range. (20 amps implies 700 Watts at 36 volts, which is a lot of assistance/acceleration on an ebike.)

XT90s seem like fine connectors, but I am not sure I follow why a particular connector would influence, or stop, error messages in the vehicle?

 

[n2mb_racing]

I am not sure I know as much as you guys, but just off the top of my head I think e-bikes are typically 36 volts minimum (with 10 cells in series) and with 5 to 8 parallel channels can draw maybe 50 or 60 amps at close to peak throttle. I think that the more powerful bikes run around 54 volts. And, as Cali84 mentioned, those peak currents are somewhat transient for e-bikes and typical currents may be more in the 10 to 20 amp range. (20 amps implies 700 Watts at 36 volts, which is a lot of assistance/acceleration on an ebike.)

XT90s seem like fine connectors, but I am not sure I follow why a particular connector would influence, or stop, error messages in the vehicle?

Yup. 60-90 amps, 5 kW stuff. People run 10+ kW through the QS8 connectors.

Gladiator 72 Max - 51ah Sur-Ron Battery

In-Stock. Please allow 2-4 business days for shipment. Note that international orders may take additional time for processing. Meet the Gladiator 72 Max - a 72V battery like no other, with near limitless potential. With speed, power, and range, the 72 Max has it all. This battery is a higher...

chibatterysystems.com

Anyway, the point is that if you use an anti-spark connector, they have a pre-charge resistor built-in. There is an initial ring contact connected to the pre-charge resistor, so if you plug it in reasonably slowly, the pre-charge resistor will charge up the input capacitors of your inverter and prevent a big inrush current when the inverter is connected. So the car won't throw errors and shut down.

However, I don't know what it will do if you leave the inverter connected and the car goes to sleep and then wakes up again. It might still throw errors since it has to charge the input capacitors again. In that case, unplug and plug in again.

But, if you want the ideal solution, use the relay pre-charge circuit included earlier in this thread. It requires a few more parts, though. Using XT90AS or QS8 connectors is the lazy way to get it to work.

 

[PhysicsGuy]

Yup. 60-90 amps, 5 kW stuff. People run 10+ kW through the QS8 connectors.

Gladiator 72 Max - 51ah Sur-Ron Battery

In-Stock. Please allow 2-4 business days for shipment. Note that international orders may take additional time for processing. Meet the Gladiator 72 Max - a 72V battery like no other, with near limitless potential. With speed, power, and range, the 72 Max has it all. This battery is a higher...

chibatterysystems.com

Anyway, the point is that if you use an anti-spark connector, they have a pre-charge resistor built-in. There is an initial ring contact connected to the pre-charge resistor, so if you plug it in reasonably slowly, the pre-charge resistor will charge up the input capacitors of your inverter and prevent a big inrush current when the inverter is connected. So the car won't throw errors and shut down.

Thanks very much. That is pretty great. Do XT60 connectors also have that feature? Plugging them in slowly to reduce spark? (This is not for a car but for an e-bike battery application where I have been using Anderson connectors and have been concerned about sparking. XT60 might make an excellent replacement for a 30 or 45 amp Anderson connector. What do you think?

 

[n2mb_racing]

Thanks very much. That is pretty great. Do XT60 connectors also have that feature? Plugging them in slowly to reduce spark? (This is not for a car but for an e-bike battery application where I have been using Anderson connectors and have been concerned about sparking. XT60 might make an excellent replacement for a 30 or 45 amp Anderson connector. What do you think?

No, they do not. Only the xt90as version. There's also a regular XT90 without antispark, so make sure you get the right one. I have XT90 for discharge and xt60 for charging on my smaller packs. Works great.

 

[PhysicsGuy]

No, they do not. Only the xt90as version. There's also a regular XT90 without antispark, so make sure you get the right one. I have XT90 for discharge and xt60 for charging on my smaller packs. Works great.

Thanks very much. I ordered a few XT90as connectors. Thanks for guiding me to those. I had no idea that there were connectors that can basically do precharge.

On a slightly different subject, what is your opinion of the Renogy 700 Watt inverter as a choice for converting Tesla 14 volt power up to 110 AC? I am thinking of using that to charge a Jackery 1500 and a Jackery 1000 (at the same time), which would draw about 450 Watts. Are Renogy inverters pretty good? Comparable to Victron Phoenix?

 

[n2mb_racing]

Thanks very much. I ordered a few XT90as connectors. Thanks for guiding me to those. I had no idea that there were connectors that can basically do precharge.

On a slightly different subject, what is your opinion of the Renogy 700 Watt inverter as a choice for converting Tesla 14 volt power up to 110 AC? I am thinking of using that to charge a Jackery 1500 and a Jackery 1000 (at the same time), which would draw about 450 Watts. Are Renogy inverters pretty good? Comparable to Victron Phoenix?

I think they get good reviews, but I haven't used one. I bought a 48v 1500w inverter from Aims power when it went on sale for $280. AIMS power seems to get good reviews and the inverter looks very well made. It works very well and is silent. I'm running it with my 52v ebike battery. I figured that would allow me to run anything, since it isn't clear how much power you can pull from the 12v system on the refresh S without it complaining. I plan to slow charge the ebike battery from the 12v so the car doesn't have to power the peak loads.

But, I do remember pulling at least 700w just fine from my 3.

 

[PhysicsGuy]

I have heard rumors that the voltage from under the seat in a model Y may higher than 12 or 14 volts. Does anyone know what the voltage is in a new Model Y? The reason I would really like to find out soon, is that I just bought a 700 Watt Renogy inverter with an input voltage range of 10 to 16 volts. If the model Y voltage is outside that range (i.e., higher than 16 volts) I would like to return that before the return window closes. Thanks very much.

PS. I have a switch box with a 2 Ohm bypass resistor (precharge) and a nice ANL fuse. Works fine in a 2018 model 3 where the voltage under the seat is about 14 volts. Again, I would love to know if the voltage in a new model Y is 14 volts to if it is higher.

 

[stopcrazypp]

I have heard rumors that the voltage from under the seat in a model Y may higher than 12 or 14 volts. Does anyone know what the voltage is in a new Model Y? The reason I would really like to find out soon, is that I just bought a 700 Watt Renogy inverter with an input voltage range of 10 to 16 volts. If the model Y voltage is outside that range (i.e., higher than 16 volts) I would like to return that before the return window closes. Thanks very much.

PS. I have a switch box with a 2 Ohm bypass resistor (precharge) and a nice ANL fuse. Works fine in a 2018 model 3 where the voltage under the seat is about 14 volts. Again, I would love to know if the voltage in a new model Y is 14 volts to if it is higher.

Do you have a Model Y with a 15.5V low voltage battery? If so, any inverter you use with the car must support 16V as per the note in the manual:
"For vehicles manufactured after approximately November 2021, power inverters plugged into the low voltage power socket must support 16V DC input to function."
Model Y Owner's Manual | Tesla

If your car has Ryzen then you have the 15.5V system.
AMD Ryzen And 12V Li-Ion Battery Spotted In New Model 3/Y In US

Should be easier however to just measure it with a multimeter though.
Other threads say the voltage range on the front and rear sockets measure 14.2-15.7V depending on battery voltage.
Power Inverters for newer 16V Outlet Cars

 

[PhysicsGuy]

Do you have a Model Y with a 15.5V low voltage battery? If so, any inverter you use with the car must support 16V as per the note in the manual:
"For vehicles manufactured after approximately November 2021, power inverters plugged into the low voltage power socket must support 16V DC input to function."
Model Y Owner's Manual | Tesla

If your car has Ryzen then you have the 15.5V system.
AMD Ryzen And 12V Li-Ion Battery Spotted In New Model 3/Y In US

Should be easier however to just measure it with a multimeter though.
Other threads say the voltage range on the front and rear sockets measure 14.2-15.7V depending on battery voltage.
Power Inverters for newer 16V Outlet Cars

Thanks very much. I think that is what I have. I did not take the back seat out but I measured 15.5 volts at the cigarette port. I wonder if that can sometimes be higher? Anyway, I am going to get a Victron Phoenix inverter. Pricey, but it accepts up to 17 volts.

I would speculate that that battery has four cells in series (and an unknown number in parallel). They are possibly the type where 100% charge corresponds to 4.2 volts per cell. So I wonder why (or if) the voltage sometimes gets higher that 15.5 volts? ...

Possibly the dc-dc converter just charges it to only 15.5 V? That would correspond to a bit below 80% for four cells in series, which I guess is not a bad place to be. Does anyone know how Tesla is doing this and if 15.5 V is actually the maximum voltage?

 

[stopcrazypp]

Thanks very much. I think that is what I have. I did not take the back seat out but I measured 15.5 volts at the cigarette port. I wonder if that can sometimes be higher? Anyway, I am going to get a Victron Phoenix inverter. Pricey, but it accepts up to 17 volts.

I would speculate that that battery has four cells in series (and an unknown number in parallel). They are possibly the type where 100% charge corresponds to 4.2 volts per cell. So I wonder why (or if) the voltage sometimes gets higher that 15.5 volts? ...

Possibly the dc-dc converter just charges it to only 15.5 V? That would correspond to a bit below 80% for four cells in series, which I guess is not a bad place to be. Does anyone know how Tesla is doing this and if 15.5 V is actually the maximum voltage?

You can also just remove the access panel and trivially see if it is the 15.5V battery:

Model Y Owner's Manual | Tesla

Yes the 16V lithium is a 4S (4 in series) battery as per label) Tesla decided to use Lithium-ion cells instead of LFP, which is why the nominal/peak voltage is so high. At 4.2V that is 16.8V, but it seems Tesla isn't charging it to that voltage. Tesla's warning in the manual only warns about 16V, so presumably the sockets peak at around 16V (4.0V per cell). Others have measured a peak of 15.7V as linked previously. However, it's possible the measurement under the seat might be a bit higher than the sockets.

 

[n2mb_racing]

I'd guess it doesn't go above 16v.

 

[PhysicsGuy]

Thanks guys. I appreciate the advice and info.

I think the Victron Phoenix will handle 16 volts no problem. I wonder what other inverters, possibly a bit less expensive and heavy, might also be able to handle those higher input voltages?

Regarding the battery: 99 Wh is pretty small (but at least you can take it on a plane). (I think 100 Wh is the cutoff.) Just 4 cells, hmmm: are those 2170, 4680 or something in between? (Maybe they are systematically undercharged 4680s?)

 

[n2mb_racing]

Thanks guys. I appreciate the advice and info.

I think the Victron Phoenix will handle 16 volts no problem. I wonder what other inverters, possibly a bit less expensive and heavy, might also be able to handle those higher input voltages?

Regarding the battery: 99 Wh is pretty small (but at least you can take it on a plane). (I think 100 Wh is the cutoff.) Just 4 cells, hmmm: are those 2170, 4680 or something in between? (Maybe they are systematically undercharged 4680s?)

There's a teardown on YouTube. They are totally different cells. They are designed for low temp charge and discharge and very high current. Makes sense, they have to deliver enough power to bring the car to a safe stop if the main pack fails while driving on autopilot.

 

[stopcrazypp]

Thanks guys. I appreciate the advice and info.

I think the Victron Phoenix will handle 16 volts no problem. I wonder what other inverters, possibly a bit less expensive and heavy, might also be able to handle those higher input voltages?

Regarding the battery: 99 Wh is pretty small (but at least you can take it on a plane). (I think 100 Wh is the cutoff.) Just 4 cells, hmmm: are those 2170, 4680 or something in between? (Maybe they are systematically undercharged 4680s?)

Didn't you say the Renology you looked at can handle 16V?

The specs say:
High Voltage Alarm: 16V
Over Voltage Shutdown: 16.5V ± 0.5V DC
700W 12V Pure Sine Wave Inverter

So if there is overvoltage, presumably the inverter will shut itself down. If you buy it from Amazon you can easily return it if it turns out to not work. That is probably the best option.

I also linked a previous thread where people have posted inverters that worked for them.
Power Inverters for newer 16V Outlet Cars

If you need to build a precharge circuit, I used this plan, using the 12V SYSTEM (No PTC) plans with an 8 ohm 25W resistor. I only have a 12V car however.
Inverter Disconnect Switch with Precharge

Given you have a 16V car, you probably want to use a higher value resistor like maybe 12 ohm or higher. Otherwise you may overheat the resistor if you buy a 25W one. For example with 16V, an 8 ohm 25W resistor will put out 32W, more than the resistor is rated for. With a 12 ohm resistor that goes down to 21W. It may take longer to charge your precharge capacitor, but that's usually not an issue.
Watts/Volts/Amps/Ohms Calculator

 

[PhysicsGuy]

Didn't you say the Renology you looked at can handle 16V?

The specs say:
High Voltage Alarm: 16V
Over Voltage Shutdown: 16.5V ± 0.5V DC
700W 12V Pure Sine Wave Inverter

So if there is overvoltage, presumably the inverter will shut itself down. If you buy it from Amazon you can easily return it if it turns out to not work. That is probably the best option.

I also linked a previous thread where people have posted inverters that worked for them.
Power Inverters for newer 16V Outlet Cars

If you need to build a precharge circuit, I used this plan, using the 12V SYSTEM (No PTC) plans with an 8 ohm 25W resistor. I only have a 12V car however.
Inverter Disconnect Switch with Precharge

Given you have a 16V car, you probably want to use a higher value resistor like maybe 12 ohm or higher. Otherwise you may overheat the resistor if you buy a 25W one. For example with 16V, an 8 ohm 25W resistor will put out 32W, more than the resistor is rated for. With a 12 ohm resistor that goes down to 21W. It may take longer to charge your precharge capacitor, but that's usually not an issue.
Watts/Volts/Amps/Ohms Calculator

Thanks very much. I kind of lean toward 100 Watt power resistors. I wonder if 2 ohm would be too low a resistance? I mean at 14 volts its fine, but a 16 volts at peak dissipation of 128 Watts could happen when the capacitors are showing short circuit nature. Though I guess that is pretty transient and brief. Maybe it's okay? What do you think? How transient and brief would that tend to be for a "typical" 800 Watt nominal inverter I wonder? Anyone?

 

[stopcrazypp]

Thanks very much. I kind of lean toward 100 Watt power resistors. I wonder if 2 ohm would be too low a resistance? I mean at 14 volts its fine, but a 16 volts at peak dissipation of 128 Watts could happen when the capacitors are showing short circuit nature. Though I guess that is pretty transient and brief. Maybe it's okay? What do you think? How transient and brief would that tend to be for a "typical" 800 Watt nominal inverter I wonder? Anyone?

I think you will only get an answer by testing yourself, especially given inverter designs vary and inverters generally don't specify how large a capacitor they use (none of the ones I saw when I researched my own purchase do). For the Bestek 1000W inverter I used (would not be compatible with 16V, it only goes up to 15V), it takes less than 5 seconds to charge (forget the exact time, it was only a few seconds) using an 8 ohm resistor.

A larger resistor only increases the time needed to charge the capacitor. Is there a particular reason why you have to use 2 ohms? Why not just pick one that you know won't overload it?

 

[n2mb_racing]

Thanks very much. I kind of lean toward 100 Watt power resistors. I wonder if 2 ohm would be too low a resistance? I mean at 14 volts its fine, but a 16 volts at peak dissipation of 128 Watts could happen when the capacitors are showing short circuit nature. Though I guess that is pretty transient and brief. Maybe it's okay? What do you think? How transient and brief would that tend to be for a "typical" 800 Watt nominal inverter I wonder? Anyone?

Go higher Resistance and lower wattage. The precharge resistors in XT90 are 5 ohms, but very low wattage. It's only going to be active for less than a second.

 

[PhysicsGuy]

Go higher Resistance and lower wattage. The precharge resistors in XT90 are 5 ohms, but very low wattage. It's only going to be active for less than a second.

Thanks. That makes sense. I was trying to remember why I chose such a low resistance. I think I was paranoid about the transition from precharge to direct connection. I was really afraid I might trip the car at that stage.

I guess I was not as worried about switching the precharge resistor switch to the on position because the 2 Ohms limits the current to 7 amps (at 14 V) and I did not thing that would be a problem.

Also, I understand that precharge is supposed to be exponential; but do you happen to have a sense of a typical time scale for that in practice? Would that tend to be sub-microsecond or maybe somehow millisecond or longer?

 

[stopcrazypp]

Thanks. That makes sense. I was trying to remember why I chose such a low resistance. I think I was paranoid about the transition from precharge to direct connection. I was really afraid I might trip the car at that stage.

I guess I was not as worried about switching the precharge resistor switch to the on position because the 2 Ohms limits the current to 7 amps (at 14 V) and I did not thing that would be a problem.

Also, I understand that precharge is supposed to be exponential; but do you happen to have a sense of a typical time scale for that in practice? Would that tend to be sub-microsecond or maybe somehow millisecond or longer?

Here's a general capacitor charging and current curve so you have an idea:

https://www.electronics-tutorials.ws/rc/rc_1.html