[dtbaker]

I'd like to be able to access battery voltage directly from a standard mfg charge port to power external DC loads.... I have no experience with the standard type-2 J1772 connectors or the Tesla equiv since my EV is built to charge from 110vAC with on-board charger and 'regular' plug.

I am wondering if it is possible to access battery energy in the OEM mfg EVs, or are there components on the car side preventing energy export?

If I wire up a custom type-2 plug, what will it take to get energy OUT of a OEM ev?

 

[brian_]

No, the battery voltage does not appear on the J1772 connector, or the equivalent AC charging connectors around the world. It is only on DC charging connectors, whether they are separate from the AC charging connector (such as CHAdeMO or the Chinese system) or they are combined with the AC connector such as in CCS and the Tesla designs.

Even in systems with a DC charging connection, those contacts are not live until the onboard equipment and the charging station equipment (electric vehicle service equipment or EVSE) communicate and negotiate. The AC contacts are not live, either, and when everything is turned on they are normally only the input to the onboard charger, which will not run in reverse to convert high voltage DC from the battery into AC power.

There are power export standards supported by some connections and some equipment, but they usually export only AC power since it is rare for any EV to be connected to a DC charging station in a situation where export of power from the vehicle would be desired. So yes, you can do this in a Type 1 (120 V AC) or Type 2 (240 V AC) connection, but in an OEM EV if the manufacturer didn't design this in (and essentially no one has included it until very recently), it would be a major project.

What you're looking for ideally is Vehicle to Grid (V2G), or the Vehicle to home (V2H) version of that.

If modifying an existing vehicle, it would likely be easier to make an entirely separate connection of the HV DC from the pack to an inverter, although ~360V DC to 120 V or 240 V AC is not a common combination so off-the-shelf inverter availability would be poor. One variant of the Ford F-150 hybrid is now or will soon be available with this feature, so perhaps the hardware could be salvaged.

 

[dtbaker]

What you're looking for ideally is Vehicle to Grid (V2G), or the Vehicle to home (V2H) version of that.

If modifying an existing vehicle, it would likely be easier to make an entirely separate connection of the HV DC from the pack to an inverter, although ~360V DC to 120 V or 240 V AC is not a common combination so off-the-shelf inverter availability would be poor.

Yup, this tracks with where this project has been stalled for a while.... safe export of high-voltage DC is 'possible' with the right connectors. BUT Inverters suitable for grid-tie have no way to modulate the current, and Inverters designed for off-grid are all set up for 48vDC.

Right now, the cleanest path for V2H I can figure out is to put HV battery thru a dc-dc converter at 48vDC, and feed that to a 'standard' off-grid Inverter to be used ONLY when isolated from the Grid.

Problem is getting access to the mfg Battery without voiding warranties....

 

[brian_]

... BUT Inverters suitable for grid-tie have no way to modulate the current, and Inverters designed for off-grid are all set up for 48vDC.

Right now, the cleanest path for V2H I can figure out is to put HV battery thru a dc-dc converter at 48vDC, and feed that to a 'standard' off-grid Inverter to be used ONLY when isolated from the Grid.

One source is uninterruptible power supplies (battery backup systems) for computers - some of them use a lot of lead-acid batteries so the battery system voltage is much higher than 48V, and they are used instead of grid power rather than synched to it.

This has been done - with salvaged UPS inverters - by some Prius owners (who have been hacking high voltage batteries for two decades). Most people getting power from Prius use the 12 V battery and the car's DC-to-DC, but some go directly to the HV battery with one of these higher-voltage inverters.

I noticed that it has even been done with a commercial product, and I see that the company mentioned in that report still exists (or rather, exists again) as PlugOutPower. While the normal Prius (or other Toyota hybrid) battery voltage is lower than a typical battery-electric EV, these inverters work with the Prius Prime, which runs a 95S lithium-ion battery so it is at typical EV voltage (352 V nominal).

Search the web for "ups inverter prius" and you can find discussions of the approach using a salvaged UPS inverter.

 

[dtbaker]

I noticed that it has even been done with a commercial product, and I see that the company mentioned in that report still exists (or rather, exists again) as PlugOutPower. While the normal Prius (or other Toyota hybrid) battery voltage is lower than a typical battery-electric EV, these inverters work with the Prius Prime, which runs a 95S lithium-ion battery so it is at typical EV voltage (352 V nominal).

yes, PlugOutPower now has 3kw and 5kw ($2790) versions that will accept 350vDC nominal. Problem is access and safe connection/switching. OEM mfg tend to bury the battery deep, and use connections/wiring designed to keep consumers safely AWAY from the high voltage. For this particular group, we can probably DIY a solution, but it sure would be nice to use the DC charge port!

Search the web for "ups inverter prius" and you can find discussions of the approach using a salvaged UPS inverter.

most of the solutions I've ever come across are very low power.... maybe a couple hundred watts. I'd like more of a critical sub-panel backup in the 5kW range.

 

[john61ct]

This is just for emergencies?

I would just put in a separate house bank

and jerry rig a way to tap the EV as a charge source, one of several.

 

[dtbaker]

This is just for emergencies?

I would just put in a separate house bank

and jerry rig a way to tap the EV as a charge source, one of several.

I have grid-tied Solar..... in NM we have a tiered rate system, not TOU, so it doesn't make much sense to put in a Tesla PW or any AC-coupled BBU if I can avoid it because of the high cost of the 10-15kwhr of battery that the AC-coupled systems have internally. I'd much rather have an 'offgrid' 5kw inverter with a very small built in battery for short outages, and use my EV essentially as a big battery/generator for extended outages.

The Tesla solution for instance would cost me at least $12k to have installed by an authorized TW installer. I can probably cobble together an AIMs 6kw inv/chrg ($1500), a little 48vDC battery for short outages (4kWhr AGM for $1k), and a meanwell RSP-3000-48 ($500) as a 'generator' pulling from the EV for extended outages.... assuming I can locate a handy place to tap into the EV battery.... $3k instead of $12k to power a 50amp critical loads panel and using the 60kWhr capacity of the EV would give me a solid week of backup without any solar recharge.

The hell of it is there is no great way to use my existing PV panels to recharge the batteries or the EV when running off grid since the PV is running thru a grid-tied inverter.

 

[john61ct]

I lived for decades completely off grid, and personally would not do any alternative energy system that cut me off from whatever choices I felt made sense for my family.