Multiple onboard chargers

I think I want to add two liquid cooled Brusa 16 amp chargers on the Rav4. It will cut charge time from 5 hours to 3 hours.

I would have to put them both on one dedicated J1772, and keep the remaining J1772 for the current 40 amp onboard charger. Then, at Roadster stations, I can pull the full 70 amps split to two J1772's.

At RV parks, I'll pull 40 amps from one 50 amp NEMA 14-50, and 32 amps from another.

If that works, I might do another two chargers for 5 total; 104 amps means 2 hour charge at 240-250 volts, but more likely 3 hours from three 208 volts public charge stations limited to 30 amps each.

Ya, that might work for 140 miles range.

Mine will have dedicated liquid cooling, and NOT tap into the existing cooling.

I have heard they are great chargers. Are those the ones that are discontinued? Are you getting a good deal on them? There are some 12.5 Amp 3.3kW ones out on the street from the Azure Dynamics liquidation. Jack Rickard has them on the EVTV store for $2,295 each.

I am probably not interested in faster charging but I did look into range extending ideas. One approach I had tried was to use approximately 10kWhr of batteries I had from my VW conversion, coupled to an inverter. I couldn't get the inverter and the 120v EVSE to stay on very long. I assumed it was because the inverter was a cheap one and probably putting out a modified sine wave. I looked into pure sine wave inverters and they were in the neighborhood of $500 so I gave up on that idea. It would have doubled as a back up power source for my house but I rarely have any outages so there was no payback there. Besides at 1.5Kw it was only going to be as fast as the 120v EVSE that comes with the car. Not fast.

In conclusion, I figured I could always find a 120v plug somewhere if I needed it.

Sounds good!! I am wondering what kind of mod is needed in the BMS in order to get this to work. Also, the title of this thread "104 amps", but the SAE J1772 L2 spec calls for maximum of 80amp.

waidy said:

Sounds good!! I am wondering what kind of mod is needed in the BMS in order to get this to work. Also, the title of this thread "104 amps", but the SAE J1772 L2 spec calls for maximum of 80amp.

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That is a good point about the BMS. I suspect the existing BMS (TMS) communicates and probably modulates the existing charger depending on State of Charge and temperature.

I think he was planning on using two J1772 plugs in parallel so each one would carry less than 80amps.

Ampster said:

waidy said:

Sounds good!! I am wondering what kind of mod is needed in the BMS in order to get this to work. Also, the title of this thread "104 amps", but the SAE J1772 L2 spec calls for maximum of 80amp.

Click to expand...

That is a good point about the BMS. I suspect the existing BMS (TMS) communicates and probably modulates the existing charger depending on State of Charge and temperature.

I think he was planning on using two J1772 plugs in parallel so each one would carry less than 80amps.

Click to expand...

My understanding is that there would be a separate J1772 inlet for the additional chargers. It's not quite parallel inputs in the sense that the AC inputs are paralleled. The paralleling would happen on the output (battery) side.

I think there is merit to the idea of having multiple inlets for multiple parallel chargers.

arnold

Brusa changed their mind, and won't discontinue these chargers. 16 amps each, so four additional chargers (five total) is:

16 + 16 + 16 + 16 + 40 = 104 amps

Three total J1772's, two additional J1772 each handling 32 amps

Two Brusa 16 amp chargers per J1772

**********

With three public J1772 EVSE's available, this setup can pull 90 amps

90 amps at 208 volts = 18.7kW charge rate * 88% = 16.45kW * 3.4 miles per kWh at 65mph on level roads = 56 miles per hour charge rate

***********

At campgrounds, with three NEMA 14-50, it can pull 104 amps

104 amps at 240 volts = 25kW charge rate * 88% = 22kW * 3.4 miles per kWh at 65mph on level roads = 74.8 miles per hour charge rate

***********

We don't need CAN bus to operate these, but it would be beneficial. They can operate as slaves in "AUTO" mode.

Cost about $12,000 for 4 Brusas.

For battery health, I think it would be wise to monitor the Tesla OBD port and shut down the additional chargers at 80% SOC and let the Tesla charger finish it off.

This sounds like a lot of work to do properly. For example, adding another cooling system for the Brusa chargers is non-trivial. It would be interesting to see a piping diagram for the air conditioning. My understanding is that the car uses a refrigerant to water heat exchanger so that the cabin and the TMS can get chilled water. A normal car just passes the cabin air over the refrigerant evaporator, a refrigerant to air heat exchanger, if you will. Anyway, getting access to the chilled water would definitely be useful instead of just adding a radiator to exchange heat out to the environment. Then again, the chilled water may just be a figment of my imagination....

Edit: As an engineer, this intrigues me. As a car owner, I'm not interested in doing this to my own car.

arnolddeleon said:

..........

My understanding is that there would be a separate J1772 inlet for the additional chargers. It's not quite parallel inputs in the sense that the AC inputs are paralleled. The paralleling would happen on the output (battery) side.

I think there is merit to the idea of having multiple inlets for multiple parallel chargers.

arnold

Click to expand...

Yes, given the amperage limitations of the J1772 that is the only way to get that many Amps into the car. I actually meant parallel in the context of the entire system. Both the input and output are parallel in the big picture and the chargers have to be isolated internally to safely operate in that mode. Brusa's are isolated so no problem there and I assume the Tesla charger in the RAV is isolated.
I view the AC inputs also as parallel because somewhere in that RV Park or charging station infrastructure is a common transformer. From the perspective of that transformer the chargers are in parallel and share a common ground. That is what I meant by parallel. I don't know if that is common terminology but that is how I understand it conceptually.

Back to Tony's design, it will be challenging to finding the closest point to the battery pack in order to carry 104 Amps into the pack. Certainly the existing charger conductors were maybe sized for 40 or 80 Amps. The motor draws a lot more than that so I would expect that Tony has already found that spot and has already taken a picture of it. LOL

EDIT. As I think about it more I realize that spot would be where one would connect a direct DC charger. I wonder what it would cost to reverse engineer the Super chargers and put that port on the side of the RAV. The RAV and the Tesla probably operate on the same voltage.

miimura said:

For battery health, I think it would be wise to monitor the Tesla OBD port and shut down the additional chargers at 80% SOC and let the Tesla charger finish it off.

This sounds like a lot of work to do properly. For example, adding another cooling system for the Brusa chargers is non-trivial. It would be interesting to see a piping diagram for the air conditioning. My understanding is that the car uses a refrigerant to water heat exchanger so that the cabin and the TMS can get chilled water. A normal car just passes the cabin air over the refrigerant evaporator, a refrigerant to air heat exchanger, if you will. Anyway, getting access to the chilled water would definitely be useful instead of just adding a radiator to exchange heat out to the environment. Then again, the chilled water may just be a figment of my imagination....

Edit: As an engineer, this intrigues me. As a car owner, I'm not interested in doing this to my own car.

Click to expand...

Yes, that sounds like a good charging algorithm. I have read somewhere that it takes as much time to go from 80%SOC to 100% as it does to go from 20%SOC to 80%, because of the way that current tapers off during the charging cycle.

There is a whole group of characters on http://www.diyelectriccar.com/ who have water cooled the various systems in their cars and that is something I have tried to avoid in my little VW conversion. No question, it will be expensive and take a lot of space.

The heat exchanges won't be chilled by the AC... just simple liquid cooled through a motorcycle size radiator and a 120 volt pump from a washing machine.

Any time the J1772 is powered, the pump(s) will siphon AC power from one leg of 240 volts. Simple, and works. Also, it adds no load to the current cooling system.

Superchargers at DC and won't power chargers. Using them is theft if you aren't plugging into a Tesla Model S.

Yes, I've found places to send DC power to the battery, and yes, I have taken pics!

TonyWilliams said:

The heat exchanges won't be chilled by the AC... just simple liquid cooled through a motorcycle size radiator and a 120 volt pump from a washing machine.

Any time the J1772 is powered, the pump(s) will siphon AC power from one leg of 240 volts. Simple, and works. Also, it adds no load to the current cooling system.

Click to expand...

There is no neutral on the J1772. Won't you cause a ground fault if you use the ground and one leg of the 240V?

miimura said:

TonyWilliams said:

The heat exchanges won't be chilled by the AC... just simple liquid cooled through a motorcycle size radiator and a 120 volt pump from a washing machine.

Any time the J1772 is powered, the pump(s) will siphon AC power from one leg of 240 volts. Simple, and works. Also, it adds no load to the current cooling system.

Click to expand...

There is no neutral on the J1772. Won't you cause a ground fault if you use the ground and one leg of the 240V?

Click to expand...

Great point!! So, I have to use a 240 volt pump!

TonyWilliams said:

...........
Yes, I've found places to send DC power to the battery, and yes, I have taken pics!

Click to expand...

Is there room for a current clamp? I would love get a current clamp in there somewhere and have an Amps and Amphours readout.

If Tony has found a place to connect to the battery safely, perhaps one could then use the EP Tender. Putting out 22kW would keep the RAV4EV cruising for miles and miles.

http://green.autoblog.com/2013/07/26/ep-tender-ev-charging-on-the-go/

Hook it up for long trips, take it off the rest of the time.

For hooking up DC charging WHILE driving may trigger a few faults!!!

Yes, there's plenty of room to measure current.

TonyWilliams said:

miimura said:

TonyWilliams said:

The heat exchanges won't be chilled by the AC... just simple liquid cooled through a motorcycle size radiator and a 120 volt pump from a washing machine.

Any time the J1772 is powered, the pump(s) will siphon AC power from one leg of 240 volts. Simple, and works. Also, it adds no load to the current cooling system.

Click to expand...

There is no neutral on the J1772. Won't you cause a ground fault if you use the ground and one leg of the 240V?

Click to expand...

Great point!! So, I have to use a 240 volt pump!

Click to expand...

So.... a European washing machine?

Something like this:


• Non-submersible, high pressure, carpet cleaning, dispenser display, and pressure washers

Features
• 1/11 HP fan cooled motor • Thermoplastic housing
• Nylon volute
• Carbon/ceramic shaft seal • Double-insulated motor
(non-replaceable brushes
last 500-1000 hours)
• Includes bypass adapter
Series Specifications
Capacity: 625 LPH @ 3 m
Shut Off: 21.9 m
Discharge: 3/8" Barbed (9.5 mm)
Electrical: 230V, 50/60Hz, 0.6A, 132W
• 2.46 Bar • IP 22

TonyWilliams said:

I think I want to add two liquid cooled Brusa 16 amp chargers on the Rav4. It will cut charge time from 5 hours to 3 hours.

Click to expand...

Tony, the last time we spoke at a San Diego gathering you were keen to add another 10kw charger indentical to the stock (like tesla's twin chargers on the model s). This seems more elegant an approach; did you run into a road block with this?

ehelmholtz said:

Tony, the last time we spoke at a San Diego gathering you were keen to add another 10kw charger indentical to the stock (like tesla's twin chargers on the model s). This seems more elegant an approach; did you run into a road block with this?

Click to expand...

Let me ask a slightly different question which I have thought about since you raised this issue.

If you could add 100 miles of range for $15,000, would you rather do that or spend $12,000 for fast charging?

Ampster said:

ehelmholtz said:

Tony, the last time we spoke at a San Diego gathering you were keen to add another 10kw charger indentical to the stock (like tesla's twin chargers on the model s). This seems more elegant an approach; did you run into a road block with this?

Click to expand...

Let me ask a slightly different question which I have thought about since you raised this issue.

If you could add 100 miles of range for $15,000, would you rather do that or spend $12,000 for fast charging?

Click to expand...

Tough call....proly the range for me